ChemInform Abstract: Novel S-Alkylation Products from 'Isolated Thiamin Ylide' via Thiaminium Neothiaminthiolate Ion Pair

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 undergo a facile interconversion in EtOH