Novel S-Alkylation Products from "Isolated Thiamin Ylide" via Thiaminium Neothiaminthiolate Ion Pair

Article abstract of DOI:10.1021/jo00289a017

The ambident anion character of thiamin ylide was demonstrated by alkylation reactions of the "isolated thiamin ylide" under neutral or basic conditions.Alkylation with alkyl halides yielded S-alkyl derivatives of the yellow form of thiamin (pyrimidopyrimidine derivatives) instead of 2-alkylthiamin.These and previous results provide chemical evidence that thiamin ylide and thiaminium neothiaminthiolate (8) undergo a facile interconversion in EtOH.