Push–pull alkenes, which bear electron-donating and -accepting group(s) at both termini of a C═C double bond, respectively, are of interest not only for their unique electronic properties but also for their importance as versatile building blocks in organic synthesis. In the world of ketene acetals having the push–pull alkene skeleton, ketene N,S-acetal is most likely the biggest family according to the number and types of these compounds. The first ketene N,S-acetal compound was reported in 1956. As a cyclic ketene N,S-acetal compound, nithiazine, the first lead structure of neonicotinoid insecticides, was reported in 1978. The characteristics of ketene N,S-acetals, which have the structural feature of ketene S,S-acetals and enaminones, make them versatile and easy to use, especially in cyclization and multicomponent reactions for the synthesis of various heterocyclic systems and related natural products. There has been an increasing wealth of information about the synthesis and synthetic applications of...

Chemistry of Ketene N,S-Acetals: An Overview.

https://www.rsc.org/suppdata/GC/C0/C0GC00373E/C0GC00373E.PDF

Three-component solvent-free synthesis of highly substituted bicyclic pyridines containing a ring-junction nitrogen

Catalyst-free one-pot four-component domino reactions in water–PEG-400: highly efficient and convergent approach to thiazoloquinoline scaffolds

An efficient one-pot multicomponent approach to 5-amino-7-aryl-8-nitrothiazolo[3,2-a]pyridines

Novel and convenient synthesis of polyfunctionalized quinolines, quinolones and their annulation reactions

Ketene S,S-acetals 2 react with 2-almino-1-ethanethiol to afford the substituted 2-methylenethiazolidines 3. The structure of these products as ketene N,S-acetals is confirmed by spectroscopic data. Compounds 3a-f react with esters of α,β-yunsaturated acids to give thiazolo[3,2-a]pyrid-5-one derivatives 4, 6, and 7 through an electrophilic addition and cyclocondensation sequences

Zhi-Tang Huang

Papers

Synthesis of Heterocyclic Ketene N,S-Acetals and Their Reactions with Esters of α,β-Unsaturated Acids

Synthesis of Heterocyclic Ketene N,S‐Acetals and Their Reactions with Esters of α,β‐Unsaturated Acids.