Safe, Metal‐Free, and Direct Synthesis of Dialkyl Acylmethylidenehydrazine‐1,1‐dicarboxylates from Dimethylsulfoxonium Acylmethylides and Dialkyl Azodicarboxylates

Abstract

N-Acylhydrazones are versatile electrophiles for the synthesis of nitrogen-containing compounds. Dialkyl acylmethylidenehydrazine-1,1-dicarboxylates are a class of N-acylhydrazones and were prepared efficiently from dimethylsulfoxonium acylmethylides and dialkyl azodicarboxylates. The reaction is temperature-controlled, generating tetraalkyl 3,6-diacyl-1,2,4,5-tetrazinane-1,2,4,5-tetracarboxylates as major products accompanied by dialkyl acylmethylidenehydrazine-1,1-dicarboxylates as byproducts at low temperature, or dialkyl acylmethylidenehydrazine-1,1-dicarboxylates only at high temperature. The current direct synthetic method is a safe and transition-metal-free route for the synthesis of dialkyl acylmethylidenehydrazine-1,1dicarboxylates.

Synthesis of 4‐(Trifluoromethyl)‐2,3‐Dihydrothiazoles from α‐Enolic Dithioesters and Imidoyl Sulfoxonium Ylides

“…Owing to their bench‐stable and readily available characteristics, they were also performed as the surrogates of diazo compounds to generate carbenes under metal‐catalyzed conditions. It is more fascinating that some transformations of sulfoxonium ylides could be conducted under catalyst‐free and additive‐free conditions [3a–d] . Recently, Cheng's group disclosed a kind of fluorinated imidoyl sulfoxonium ylide and successfully applied it in the synthesis of fluorinated pyrroles [4a] and pyridones, [4b] which demonstrated its potential to synthesize azo‐heterocycles decorated with CF 3 group.…”