A cycloaddition is a pericyclic chemical reaction , in which two or more unsaturated molecules or parts ... of the bond multiplicity. ref GoldBookRef title Cycloaddition file C01496 ref The resulting reaction ... 2 cycloaddition, the 1,3 dipolar cycloaddition a 3 2 cycloaddition and cyclopropanation of a carbene with an alkene a 2 1 cycloaddition. This type of reaction is non polar addition reaction . Reaction ... 4n electrons for example the 2 2 cycloaddition these proceed in a suprafacial antarafacial sense ... ref Image CinnamicAcidCycloAddition.png 400px center Cinnamic Acid CycloAddition Image Bpe resorcinol cycloaddition.png right thumb Cycloaddition of trans 1,2 bis 4 pyridyl ethylene Supramolecular chemistry Supramolecular effects can influence these cycloadditions. The cycloaddition of trans 1,2 ... Qcane.png 500px center In the i j ... cycloaddition notation i and j refer to the number of atoms involved in the cycloaddition. In this notation a Diels Alder reaction is a 4 2 cycloaddition and a 1,3 dipolar addition such as the first step in ozonolysis is a 3 2 cycloaddition. The IUPAC preferred ... reaction and the dipolar reaction both become a 4 2 cycloaddition. The reaction between norbornadiene and an activated alkyne is a 2 2 2 cycloaddition. Types of cycloaddition Diels Alder reactions The Diels Alder reaction is a 4 2 cycloaddition reaction. File Diels alder 1,3 butadiene Ethylene .png Diels Alder reaction Huisgen cycloadditions The Huisgen cycloaddition reaction is a 2 3 cycloaddition. File Huisgen.png 500px 1,3 cycloaddition Nitrone olefin cycloaddition The nitrone olefin 3 2 cycloaddition Nitrone olefin cycloaddition is a 3 2 cycloaddition. File NitrGen.png Nitrone olefin cycloaddition ... radical analogs, however these are not strictly speaking pericyclic reactions. When in a cycloaddition charged or radical intermediates are involved or when the cycloaddition result is obtained ... with true pericyclic cycloadditions. One example of a formal 3 3 cycloaddition between a cyclic enone ... more details
The Bradsher Cycloaddition Chemical Reaction Reaction , also known as the Bradsher Cyclization Reaction is a form of the Diels Alder Reaction which involves the 4 2 addition reaction addition of a common Diels Alder Reaction dienophile with a cation ic Aromaticity aromatic azadienes such as acridizinium or Isoquinoline isoquinolinium . File Bradsher Cyclization.jpg Bradsher Cycloaddition example The Bradsher Cycloaddition was first reported by C. K. Bradsher and T. W. G. Solomons in the Journal of the American Chemical Society Journal of the American Chemical Society in 1958. ref C. K. Bradsher, T. W. G. Solomons, J. Am. Chem. Soc., 80, 933, 1958 ref ref Merck Index, 14th Ed. ref ref C. K. Bradsher, J. A. Stone, Journal of Organic Chemistry J. Org. Chem. , 33, 519 1968 ref References Reflist Category Chemical reactions ca Reacci de cicloaddici de Bradsher ... more details
The 1,3 dipolar cycloaddition , also known as the Huisgen cycloaddition or Huisgen reaction , ref cite journal title Kinetics and Mechanism of 1,3 Dipolar Cycloadditions first Rolf last Huisgen journal Angewandte Chemie International Edition volume 2 issue 11 date November 1963 pages 633 645 url http www3.interscience.wiley.com cgi bin abstract 106572717 ABSTRACT doi 10.1002 anie.196306331 format abstract ref ref cite journal title 1,3 Dipolar Cycloadditions. Past and Future first Rolf last Huisgen journal Angewandte Chemie International Edition volume 2 issue 10 date October 1963 pages 565 598 ... of concerted, pericyclic cycloaddition s. It is the reaction between a 1,3 dipole and a dipolarophile ... Huisgen.png center frame The Azide alkyne Huisgen cycloaddition . Proof of mechanism Although this was once ... to verify the concerted mechanism. Reactivity Concerted processes such as the 1,3 cycloaddition .... Using competition reaction experiments, relative rates of addition for different cycloaddition ... of products, the actual selectivity in these cycloaddition reactions is varied. For example ... V. Fokin, K. Barry Sharpless title A Stepwise Huisgen Cycloaddition Process Copper I Catalyzed Regioselective ... ref Image 1,3 cycloaddition between Benzonitrile N oxide and a mono substituted ethylene.png 500px See ... LUMO Interactions during 1,3 Cycloaddition Reactions.png 750px See The Concerted Nature of 1,3 Dipolar ... Azide s and alkyne s react in the Azide alkyne Huisgen cycloaddition . Diazo compounds are 1,3 dipoles in the Diazoalkane 1,3 dipolar cycloaddition . Nitrone s react with alkenes to form isoxazolidine ... cycloaddition of ozone . This is followed by a retro 1,3 dipolar cycloaddition and then a 1,3 dipolar cycloaddition of the fragments. Fullerene s and carbon nanotube nanotubes can undergo a 1,3 dipolar cycloaddition with an azomethine ylide in the Prato reaction . References references External ... 5 ar 3,1 de 1,3 Dipolare Cycloaddition nl 1,3 dipolaire cycloadditie ... more details
antarafacial geometry required for concerted, thermal 2 2 cycloaddition can be achieved in reactions ... in the cycloaddition product. Electron withdrawing substituents on the ketene and donating substituents ... has allowed access to cycloaddition products in high enantiomeric excess. ref Wynberg, H. Staring ... with ketenes. Examples of all three modes of cycloaddition are discussed in this section. Ketenes ... File KetScope1.png center Ketenes react with alkenes to provide cyclobutanones. If the product of a cycloaddition ... Ketenes undergo 2 2 cycloaddition with ketones and aldehydes to give lactones. Lewis acid catalysis ... accelerate the cycloaddition, they are not of general utility since they also accelerate dimerization .... The success of the reaction is often determined by the relative rates of cycloaddition and dimerization ... more details
Trimethylenemethane cycloaddition is the formal 3 2 annulation of trimethylenemethane TMM derivatives to two atom pi system s. Although TMM itself is too reactive and unstable to be stored, reagent s which can generate TMM or TMM synthon s in situ can be used to effect cycloaddition reactions with appropriate electron acceptor s. Generally, electron deficient pi bond s undergo Cyclic compound cyclization with TMMs more easily than electron rich pi bonds. ref Yamago, S. Nakamura, E. Org. React. 2003 , 61 , 1. doi 10.1002 0471264180.or061.01 ref Introduction Trimethylenemethane is a neutral, four carbon molecule composed of four pi bonds thus, it must be expressed either as a non Kekul molecule or a zwitterion . The orbital energy levels of TMM reveal that it possesses Singlet state singlet and triplet state s generally, these states exhibit different Reactivity chemistry reactivity and Functional selectivity selectivity profiles. ref Baseman, R. J. Pratt, D. W. Chow, M. Dowd, P. J. Am. Chem. Soc. 1976 , 98 , 5726. ref A singlet 3 2 cycloaddition, when it is concerted, is believed to proceed under HOMO LUMO frontier orbital control. When electron rich TMMs are involved, the A orbital ... is a general problem that affects the rate and yield of 3 2 cycloaddition reactions involving this class ..., 3 2 cycloaddition affords isomeric mixtures of methylenecyclopentanes. Three classes of compounds ... these problems, either very high concentrations of alkene must be used or the cycloaddition must be intramolecular ..., the reactive 2 component of the cycloaddition below switches from the C C to the C O double bond ... in many TMM cycloaddition reactions is a significant advantage for instance, the trans ring junction in TMM cycloaddition adduct 2 was carried through in a synthesis of brefeldin A . ref Trost ... with Other Methods Comparison with other methods Although 1,3 dipolar cycloaddition is a useful method ... TMM cycloaddition, rely on the generation of a suitable three atom component for combination with a stable ... more details
The Diazoalkane 1,3 dipolar cycloaddition is a 1,3 dipolar cycloaddition an organic reaction between a 1,3 dipole diazo compounds diazo compound notably diazomethane and a dipolarophile . When the dipolarphile is an alkene , the reaction product is a pyrazoline . ref Advanced organic chemistry reaction mechanisms , Reinhard Br ckner ref The reaction product of a cycloaddition between diazomethane and glutaconic acid trans diethyl glutaconate is a 1 pyrazoline. ref cite doi 10.1016 j.tetlet.2004.04.097 ref This reaction is 100 Regioselectivity regioselective because the diazo terminal nitrogen atom bonds exclusively to the alpha carbon of the ester . The reaction is also a syn addition , and the configuration in the dipolarophile is preserved. The 1 pyrazoline is unstable and isomerization isomerizes to the 2 pyrazoline due to favorable conjugated system conjugation with the ester group. With phenyldiazomethane as the reactant the regioselectivity is reversed and the reaction is extended even further by simple air organic oxidation of the 2 pyrazoline to the pyrazole . File Diazoalkane 1,3 dipolar cycloaddition.svg center Diazoalkane 1,3 dipolar cycloaddition. Another example of a diazo cycloaddition is a diazo thioketone coupling . References Reflist DEFAULTSORT Diazoalkane 1,3 Dipolar Cycloaddition Category Cycloadditions Category Heterocycle forming reactions ar 3,1 zh 1,3 ... more details
The Azide Alkyne Huisgen Cycloaddition is a 1,3 dipolar cycloaddition between an azide and a terminal ... reaction . American chemist K. Barry Sharpless has referred to this cycloaddition as the cream of the crop ... 11 2004 AID ANIE2004 3.0.CO 2 5 pmid 11433435 ref Image Huisgen.png center Huisgen 1,3 dipolar cycloaddition ... 3 as a mixture of 1,4 adduct and 1,5 adduct at 98 C in 18 hours. The standard 1,3 cycloaddition ... TBAF Catalyzed 3 2 Cycloaddition of 2 Aryl 1 nitroethenes with TMSN3 under Solvent Free Conditions ... conditions. Copper catalysis A notable variant of the Huisgen 1,3 dipolar cycloaddition is the copper I catalyzed variant, no longer a true concerted cycloaddition, in which organic azides and terminal ... Huisgen Cycloaddition Process Copper I Catalyzed Regioselective Ligation of Azides and Terminal ... dipolar cycloaddition and thus should not be termed a Huisgen cycloaddition. This reaction is better termed the Copper I catalyzed Azide Alkyne Cycloaddition CuAAC . While the reaction can be performed ... center click polymer The copper mediated azide alkyne cycloaddition is receiving widespread ... Cycloaddition and its Application to Polymer Science and Surface Modification author R.A. Evans issue ... solvents, copper I and inert atmospheres to do the cycloaddition with many polymers makes the click label inappropriate for such reactions. An aqueous protocol for performing the cycloaddition with free ... Huisgen 3 2 dipolar cycloaddition reaction author A. J. Dirks, S. S. van Berkel, N. S. Hatzakis ... in the 1970s, which he ran at elevated temperatures. ref 1,3 Dipolar Cycloaddition Chemistry, published ... Wenzel Torn e title Cu Catalyzed Azide Alkyne Cycloaddition year 2008 journal Chemical Reviews ... Accelerated Cu Catalyzed Azide Alkyne Cycloaddition A Mechanistic Report year 2007 journal J. Am ... catalysis The ruthenium catalysed 1,3 dipolar azide alkyne cycloaddition RuAAC gives the 1,5 triazole ... Ruthenium Catalyzed Cycloaddition of Alkynes and Organic Azides year 2005 journal J. Am. Chem. Soc ... more details
Orphan date February 2011 correct title reason bracket 6 4 cycloaddition 6 4 Cycloaddition is a chemical reaction between a six atom pi system and a four atom pi system, leading to a ten membered ring. Because this is a higher order cycloaddition, issues of periselectivity arise in addition to the usual concerns about regio and stereoselectivity. Six atom pi systems that have been employed in the reaction include tropone and tropone derivatives, fulvene s, and cycloheptatriene cobalt complexes. ref Rigby, J. H. Org. React. 1997 , 49 , 331. doi http dx.doi.org 10.1002 0471264180.or049.02 10.1002 0471264180.or049.02 ref Introduction 6 4 Cycloaddition is a thermally allowed, higher order cycloaddition process leading to ten membered rings. Although most linear, acyclic trienes do not give 6 4 products selectively, cyclic trienes give high yields of 6 4 products in many cases. Both cycloheptatrienes and fulvenes can be employed in this reaction, and electron deficient tropone s in particular work well. The pericyclic and transition metal mediated versions of the reaction are stereocomplementary the former gives exo products, and the latter endo products, with essentially complete selectivity in nearly all cases. The possibility of building complex carbocyclic frameworks efficiently has ... and Stereochemistry Metal free reaction The metal free version of the 6 4 cycloaddition takes place ... also has the proper symmetry and orbital coefficients to participate in 6 4 cycloaddition the NHOMO ... reaction The metal promoted 6 4 cycloaddition using a tropone metal complex is a stepwise, photolytic process that lacks the periselectivity issues of the purely thermal 6 4 cycloaddition. The mechanism ..., M. E. Day, C. S. Organometallics 2006 , 25 , 974. ref Scope and Limitations 6 4 Cycloaddition ... 6 4 cycloaddition bicyclo 4.4.1 undecanes and bicyclo 5.3.0 decanes require multiple steps, harsh ... than quartz filtered light. See also 4 3 cycloaddition 4 3 cycloaddition References reflist 2 Category ... more details
correct title reason bracket 4 3 cycloaddition Context date October 2010 4 3 Cycloaddition is the annulation of an allyl or oxyallyl cation with a four atom pi system to form a seven membered ring. It represents one of the relatively few synthetic methods available to form seven membered rings stereoselectively in high yield. ref Rigby, J. H. Pigge, F. C. Org. React. 1997 , 51 , 351. doi http dx.doi.org 10.1002 0471264180.or051.03 10.1002 0471264180.or051.03 ref Introduction Symmetry allowed 4 3 cycloaddition is an attractive method for the formation of historically difficult to access seven membered rings. Neutral dienes and cationic allyl systems most commonly oxyallyl cations may react in a concerted or stepwise fashion to give seven membered rings. A number of dienes have been employed in the reaction, although cyclic, electron rich dienes such as those found in the pyrrole and furan ring systems are the best 4 systems for this process. Intramolecular variants are also efficient. ref Harmata, M. Elahmad, S. Barnes, C. L. Tetrahedron Lett. 1995 , 36 , 1397. ref span style float right padding right 50px padding top 15px 1 span center File 43Gen.png center Recent developments have focused on expanding the scope of enantioselective 4 3 cycloadditions and the range of conditions available for generating the key oxyallyl cation intermediate. Mechanism and Stereochemistry Prevailing ... substitution rather than cycloaddition. ref Henning, R. Hoffmann, H. M. R. Tetrahedron Lett. 1982 , 23 , 2305. ref The cycloaddition itself may be either concerted or stepwise, depending on the nature ... . Stereochemistry Stereochemical control in the 4 3 cycloaddition is not as strict as in the Diels ... of oxyallyl cations for cycloaddition. Reducing agents used include copper bronze ... of a new covalent bond before the cycloaddition itself takes place. These reactions thus .... See also 6 4 cycloaddition 6 4 cycloaddition References reflist 2 DEFAULTSORT 4 3 Cycloaddition ... more details
Orphan date January 2011 In organic chemistry, an intramolecular Diels Alder cycloaddition is a Diels Alder reaction in which the diene and a dienophile are both part of the same molecule. The reaction leads to the formation of the same cyclohexene like structure as usual for a Diels Alder reaction, but as part of a more complex fused or bridged cyclic ring system. Reaction products Because the two reacting groups are already attached, two basic modes of addition are possible in this reaction. Depending on whether the tether that links to the dienophile is attached to the end or the middle of the diene, fused or bridged polycyclic ring systems can be formed. ref M. Nantz, G. Zweifel. Modern Organic Synthesis an Introduction. W.H. 2 Freeman and Company, 2007, pg 429 430 ref The tether than attaches the two reacting groups also affects the geometry of the reaction. As a result of its Conformational isomerism conformational and other structural restrictions, the exo vs endo results ref P.Y Bruice. Organic Chemistry. Pearson Education, Inc. 2007 ref are usually not based on the simple intermolecular Diels Alder reaction effects. Applications Intramolecular Diels Alder reaction Diels Alder cycloaddition is extremely useful for the formation of naturally occurring polycyclic rings. The reaction provides ready access to polycyclic compounds with a great deal of stereoselectivity . The following are several useful drugs whose complete synthesis have been accomplished using the intramolecular Diels Alder reaction. Solanapyrone A Solanapyrone A is an inhibitor of mammalian DNA polymerase and , repair type DNA polymerase. The compound was isolated from the phytopathogenic fungi Alternaria solani , the cause of early blight in tomato and potato plants. The drug is being look as an anti cancer medication. ref B. Lygo, M. Bhatia, J.W.B Cooke, D.J Hirst. Synthesis of solanapyrones A and B. Tetrahedron Letters, 2003 ref Salvinorin A Isolated from the hallucinogenic sage, Salvia Divinorum ... more details
correct title reason bracket Nitrone olefin 3 2 cycloaddition The nitrone olefin 3 2 cycloaddition reaction is the combination of a nitrone with an alkene or alkyne to generate an isoxazoline or isoxazolidine via a 3 2 cycloaddition process. ref Confalone, P. N. Huie, E. M. Org. React. 1988 , 36 , 1. doi 10.1002 0471264180.or036.01 ref Introduction When nitrones are combined with either alkenes or alkynes, 3 2 cycloaddition leads to the formation of a new C C bond and a new C O bond. The cycloadditions is stereospecific with respect to the configuration of the alkene however, diastereoselectivity in reactions of C substituted nitrones is often low. ref Tufariello, J. J. Ali, S. A. Klingele. H. O. J. Org. Chem. 1979 , 44 , 4213. ref Regioselectivity is controlled by the dominant frontier orbitals interacting during the reaction, and substrates with electronically distinct substituents tend to react with high regioselectivity. Intramolecular versions of the reaction have been used to synthesize complex polyclic carbon frameworks. Reduction of the N O linkage leads to 1,3 aminoalcohols. span style float right padding right 50px padding top 30px 1 span center File NitrGen.png center Mechanism and Stereochemistry Synthesis of Nitrones Nitrones are generated most often either by the oxidation of hydroxylamines or condensation of monosubstituted hydroxylamines with carbonyl compounds ketones or aldehydes . The most general reagent used for the oxidation of hydroxylamines is mercury II ... padding right 50px padding top 20px 4 span center File NitrMech3.png center 3 2 Cycloaddition The 3 2 cycloaddition itself is a concerted, pericyclic process whose regiochemistry is controlled by the frontier ... of cycloaddition. Consistent with FMO control of the reaction, the more electron withdrawing substituent .... The rules for predicting alkene cycloaddition products based on the relevant FMOs apply to substituted ... cycloaddition. ref Dagne, E. Castagnoli, Jr., N. J. Med. Chem. 1972 , 15 , 356. ref span style ... more details
Image Nitrone general structure 2D.png 150px right thumb General structure of a nitrone A nitrone is the Amine oxide N oxide of an imine and a functional group in organic chemistry . The general structure is R sub 1 sub R sub 2 sub C NR sub 3 sub sup sup O sup sup where R sub 3 sub is different from H. A nitrone is 1,3 dipole in 1,3 dipolar cycloaddition s. It reacts with alkene s to form an isoxazolidine Image Nitrone cycloaddition.png 500px Nitrone cycloadditions One example of this reaction type is the reaction of various Baylis Hillman reaction Baylis Hillman adducts with C Phenyl N methylnitrone forming an isoxazolidine in which R sub 1 sub is phenyl , R sub 2 sub is hydrogen and R sub 3 sub is a methyl group ref Diastereoselectivity of Nitrone 1,3 Dipolar Cycloaddition to Baylis Hillman Adducts Branislav Dugovi , Lubor Fi era, Christian Hametner and Nada Pr nayov c. Arkivoc 2004 BS 834A http www.arkat usa.org home.aspx?VIEW MANUSCRIPT&MSID 877 Article ref . Nitrones react with terminal alkyne s and a copper salt to beta lactam . This reaction is also called The Kinugasa reaction ref The reactions of copper I phenylacetylide with nitrones Manabu Kinugasa and Shizunobu Hashimoto J. Chem. Soc., Chem. Commun., 1972 , 466 467, DOI 10.1039 C39720000466 ref for example in this reaction ref A novel synthesis of lactam fused cyclic enediynes by intramolecular Kinugasa reaction Runa Pal and Amit Basak Chem. Commun. , 2006 , 2992 2994, DOI 10.1039 b605743h ref Image Kinugasa reaction.png 500px center Kinugasa reaction application The first step in this reaction is a dipolar cycloaddition of the nitrone with the in situ generated copper I acetylide to a 5 membered ring structure which rearranges in the second step. References reflist Category Functional groups de Nitrone es Nitrona fr Nitrone nl Nitron ja pl Nitrony pt Nitrona ru fi Nitronit zh ... more details
The Staudinger synthesis ref cite journal journal Angew. Chem. Int. Ed. doi 10.1002 anie.200702965 pmid 18022986 title Hugo Ugo Schiff, Schiff Bases, and a Century of Lactam Synthesis year 2008 last1 Tidwell first1 Thomas T. volume 47 issue 6 pages 1016 1020 ref , named after the German chemist Hermann Staudinger , is a method to prepare beta lactam lactam s. An imine reacts with a ketene in a formal 2 2 cycloaddition to give the cyclic amide. History The reaction was discovered in 1907 ref cite journal author H. Staudinger journal Justus Liebigs Ann. Chem. year 1907 volume 356 pages 51 123 doi 10.1002 jlac.19073560106 title Zur Kenntniss der Ketene. Diphenylketen ref but did not attract much interest until the 1940s, when the structure of penicillin was elucidated. The lactam moiety of the first synthetic penicillin was constructed using this cycloaddition, ref cite journal author J.C. Sheehan, E.L. Buhle, E.J. Corey , G.D. Laubach, J.J. Ryan journal J. Am. Chem. Soc. year 1950 volume 72 pages 3828 9 doi 10.1021 ja01164a534 issue 8 ref and it remains a valuable tool in synthetic organic chemistry. References references Category Name reactions Category Cycloadditions reaction stub nl Staudinger synthese zh ... more details
3 2 cycloaddition of nitrones and allenolates David Gonz lez Cruz, David Tejedor, Pedro de Armas, Ezequiel ... ref Image OnWaterReactionApplication.png 400px 3 2 cycloaddition of nitrones and allenolates In this reaction ... 3 2 1,3 dipolar cycloaddition dipolar cycloaddition product then rearranges to a isoxazole ... more details
distinguish Annulment Annulation derived from annulus mathematics annular , occasionally annelation in organic chemistry is a chemical reaction in which a new ring is constructed on another molecule often another ring . ref GoldBookRef title annulation url http goldbook.iupac.org A00367.html GoldBookRef title annelation url http goldbook.iupac.org A00365.html ref Image AnnulationStrategies.png 400px Annulation A intramolecular ring closing B transannulation C cycloaddition Examples are the Robinson annulation , Danheiser annulation and certain cycloaddition s. Annular molecules are constructed from side on condensed cyclic segments, for example helicene s and acene s. In transannulation a bicyclic molecule is created by intramolecular carbon carbon bond formation in a large monocyclic ring. An example is the samarium II iodide induced ketone alkene cyclization of 5 methylenecyclooctanone which proceeds through a ketyl intermediate ref Construction of Bicyclic Ring Systems via a Transannular SmI2 Mediated Ketone Olefin Cyclization Strategy Gary A. Molander, Barbara Czak , and Michael Rheam J. Org. Chem. 2007 72 5 pp 1755 1764 Article DOI 10.1021 jo062292d ref Image KetoneOlefinCyclization.png 400px Ketone olefin cyclization Benzannulation The term benzannulated compounds refers to derivatives of cyclic compound s usually aromatic which are fused to a benzene ring. Examples are listed in the table below class wikitable style text align center Benzannulated derivative Source of cyclic compound Benzopyrene Pyrene Quinoline rowspan 2 Pyridine Isoquinoline Chromene rowspan 2 Pyran Isochromene Indole rowspan 2 Pyrrole Isoindole Benzofuran rowspan 2 Furan Isobenzofuran Benzimidazole Imidazole Transannular interaction A transannular interaction in chemistry is any chemical interaction favorable or nonfavorable between different chemical bond non bonding molecule molecular functional group groups in a large ring or macrocycle ref Experimental evidence in support of transannul ... more details
The Ojima lactam is an organic compound of some importance in the commercial production of Taxol total synthesis Taxol . This lactam was first synthesized by Iwao Ojima ref cite journal title New and efficient approaches to the semisynthesis of taxol and its C 13 side chain analogs by means of lactam synthon method author Iwao Ojima, Ivan Habus, Mangzhu Zhao, Martine Zucco, Young Hoon Park, Chung Ming Sun and Thierry Brigaud journal Tetrahedron journal Tetrahedron volume 48 issue 34 year 1992 pages 6985 7012 doi 10.1016 S0040 4020 01 91210 4 ref . The organic synthesis is an illustration of asymmetric synthesis via a chiral auxiliary . The reaction centers around an imine lithium enolate cycloaddition . In order to ensure the correct stereochemistry the phenyl group and the silyl ether must adopt a cis configuration in the lactam lactam a chiral auxiliary is used in the enolate synthesis. The enolate synthesis starts from glycolic acid . The hydroxyl group is protected by a benzyl group and the carboxylic acid is activated by reaction with thionyl chloride to the acid chloride . The acid chloride reacts with the chiral auxiliary trans 2 phenyl 1 cyclohexanol . The benzyl group is then removed and replaced by a TES silyl ether by reaction with triethylsilyl chloride . Reaction with organolithium reagent phenyllithium affords the enolate . Image OjimaTailPartI.svg center 600px Ojima lactam I The imine synthesis is a reaction of Silazane hexamethylene silazane with phenyllithium to a strong amide base followed by a condensation reaction with benzaldehyde . Image OjimaLactamPartII.svg center 500px Ojima lactam II Both imine and enole intermediate join in a cycloaddition reaction followed by an intramolecular nucleophilic acyl substitution of the amine with expulsion of the chiral auxiliary to the cis isomer cis lactam . The triethylsilyl group is removed by hydrogen fluoride and the benzoyl group is added in a Schotten Baumann reaction . Image OjimaLactamPartIII.svg c ... more details
Image Azoxy group 2D.png thumb right 150px The structure of the azoxy functional group, where R is a substituent . Image Azoxybenzene 2D skeletal.png thumb right 150px Azoxybenzene diphenyldiazene oxide , an example of an azoxy compound. Azoxy compounds are a group of chemical compound s sharing a common functional group with the general structure RN N sup sup O sup sup R. ref GoldBookRef file A00567 title azoxy compounds ref They are considered Amine oxide N oxides of azo compound s. Azoxy compounds are 1,3 dipole s. They give 1,3 dipolar cycloaddition with double bonds. Azoxy compounds are suspected to be genotoxic. References Reflist Guideline On The Limits Of Genotoxic Impurities http www.emea.eu.int pdfs human swp 519902en.pdf Category functional groups fr Azoxy nl Azoxyverbinding ja zh ... more details
2 2 may refer to 2 2 road , a high capacity four lane road with at grade intersections 2 2 car body style , a car configuration with two rear seats rather than three, for a total of four seats Pontiac 2 2 , an automobile model produced by Pontiac Motor Division of General Motors Two Plus Two Publishing 2 2 5 , a slogan used in George Orwell s Nineteen Eighty Four 2 2 5 song , a single by Radiohead 2 2 ? , an anti Vietnam War song by The Bob Seger System, released in January 1968 2 2 channel , a national Ukrainian language TV channel 2 2 Photocycloaddition , a cycloaddition type reaction See also 4 number 2 2 disambiguation disambig nl 2 2 sv 2 2 zh 2 2 ... more details
The DeMayo reaction is a photochemical reaction in which the enol of a 1,3 diketone reacts with an alkene or another species with a C C bond and the resulting cyclobutane ring undergoes a retro aldol reaction to yield a 1,5 diketone ref Li, Jie Jack. Named Reactions A Collection of Detailed Reaction Mechanisms. Springer 2003, p. 105. ref Image Demayo reaction.png The DeMayo reaction The net effect is to add the two carbon atoms in the C C double bond between the two carbonyl groups of the diketone. It is thus useful in syntheses both as a relatively selective way to join two parts of a molecule and as a way to apply the more developed chemistry of 1,3 diketone synthesis to 1,5 diketones. The first part is a 2 2 cycloaddition . The ensuing retro aldol cleavage is favored by the relative instability of the cyclobutane ring. External links 1. Some background and examples http rawalgroup.uchicago.edu litmeetings demayo.htm Link References Reflist Category Organic reactions ... more details
Thioketenes are organosulfur compound s analogous to ketene s with the general formula R sub 2 sub C C S, where R is alkyl or aryl . Thioketene ethenone is also the name of the compound CH sub 2 sub C S, which is the simplest thioketene. Thioketenes are reactive, tending to polymerize. Some thioketenes are produced as transient species upon pyrolysis of 1,2,3 thiadiazoles. ref Otto Albrecht Neuman Editor . Rompps Encyclopedia of Chemistry, Frank sche Publishing House, Stuttgart, 1983, 8. Edition, p. 4242, ISBN 3 440 04513 7. ref Bis trifluoromethyl ketene CF sub 3 sub sub 2 sub C C S is a rare example of a stable thioketene. ref Maynard S. Raasch A stable thioketene is Bis trifluoromethyl thioketene. I. Synthesis and cycloaddition reactions J. Org. Chem., 1970, volume 35, pp 3470 3483. DOI 10.1021 jo00835a064 ref Another stable thioketene is carbon subsulfide S C C C S . References references Category Sulfur compounds Category Ketenes de Thioketene ... more details
are replaced by smaller methyl groups. Another example is a photochemical 2 2 cycloaddition with two ... 400px Cycloaddition silicon tether Without the tether, the exo isomer forms. ref Diastereoselective intramolecular photochemical 2 2 cycloaddition reactions of tethered l valinol derived tetrahydrophthalimides ... more details
with one triazole unit bridging two metal centers, and is an effective catalyst for the click cycloaddition ... 2459 2461 doi 10.1039 b719724a title Click Cycloaddition Catalysts Copper I and Copper II tris ... more details
Infobox scientist name Rolf Huisgen image Rolf Huisgen and Franz Marc s Mandrill.JPG image size alt caption Rolf Huisgen 2004 in front of the painting Mandrill from Franz Marc birth date birth date and age 1920 06 13 df yes birth place Gerolstein , Rhineland Palatinate , Germany death date death place nationality Germany German field Chemist work institution University of Munich alma mater University of Munich doctoral advisor Heinrich Otto Wieland known for 1,3 Dipolar cycloaddition prizes 1961 Liebig Medal Rolf Huisgen born 13 June 1920 is a German chemist. He was born in Gerolstein and studied in Munich under the supervision of Heinrich Otto Wieland . After completing his Ph.D. in 1943 and his habilitation in 1947, he became professor at the University of T bingen in 1949. He came back to the University of Munich in 1952 where he stayed dedicated to the research long after his emeritation in 1988. ref cite journal title Rolf Huisgen A Gentleman Scholar with Energy and Passion author Jeffrey I. Seeman journal Helvetica Chimica Acta volume 88 issue 6 pages 1145 1153 year 2005 doi 10.1002 hlca.200590097 ref Besides his 1,3 Dipolar cycloaddition , which are also known as the Huisgen cycloaddition or Huisgen reaction , ref cite journal title Kinetics and Mechanism of 1,3 Dipolar Cycloadditions first Rolf last Huisgen journal Angewandte Chemie International Edition volume 2 issue 11 date November 1963 pages 633 645 url http www3.interscience.wiley.com cgi bin abstract 106572717 ABSTRACT doi 10.1002 anie.196306331 ref ref cite journal title 1,3 Dipolar Cycloadditions. Past and Future first Rolf last Huisgen journal Angewandte Chemie International Edition volume 2 issue 10 date October 1963 pages 565 598 url http www3.interscience.wiley.com cgi bin abstract 106572678 ABSTRACT doi 10.1002 anie.196305651 ref he had a big influence on chemistry departments in Germany and Austria, due to his large number of habilitants becoming professors. Ivar Karl Ugi , Johann Mulzer , Ber ... more details
a highly stereoselective and convergent strategy that involves two important cycloaddition reactions a thermally induced intramolecular 4 2 cycloaddition reaction involving an o quinone and a tetrasubstituted ... 2 2 2 cycloaddition reaction between two acetylenic units. ref name Nicolaou Nicolaou, K ... more details
pdf Cycloaddition mechanism and the solvent dependence of rate Pure & Appl. Chem. 1980, Vol.52, pp.2283 ... Dipolar cycloaddition s. Also 1,4 dipolars ref name Takahisa , 1,5 dipolars, etcetera exist. Examples ... See also Zwitterion Ylide 1,3 dipole 1,3 Dipolar cycloaddition Betaine References references Category ... more details
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