4-Phenyl-1,2,4-triazole-3,5-dione (PTAD) is an azodicarbonyl compound. PTAD is one of the strongest dienophiles and reacts rapidly with dienes in Diels-Alder reactions.[1] The most prominent use of PTAD was the first successful synthesis of prismane in 1973.[2]
Synthesis
The compound was first synthesized in 1894 by Johannes Thiele and O. Stange. The oxidation of 4-Phenylurazol with lead tetroxide in sulfuric acid yielded small quantities of the substance.[3] It took til 1971 when a practical synthesis was published. The synthesis starts from hydrazine and diethyl carbonate. The product of this step is reacted with phenyl isocyanate and subsequently transformed to the 4-Phenylurazol. Cyclization and subsequent oxidation yields PTAD (6) gebildet wird.[4]
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