Furoin

General description and preparation:

Furoin or 1,2-di(furan-2-yl)-2-hydroxyethanone [552-86-3] is a white crystalline solid with the melting point of 136-137 °C.^[1] It can be produced from furfural via benzoin condensation in presence of cyanide ion^[2] or N-heterocyclic carbene catalyst as various thiazolium and imidazolium ions.^[3] They can be further supported as a recyclable precatalysts, which upon treatment with a base, catalyze furfural self-condensation coupling reaction into furoin.^[4] Furoin synthesis from furfural is also catalyzed by vitamin B1 (thiamine). In 1957, Ronald Breslow proposed the mechanism of reaction that involves a relatively stable carbene form of thiamine, which was the first evidence for the existence of persistent carbenes.^[5]

Application of Furoin:

Furoin can be used in synthesis of pyrazine and quanoxiline derivatives by condensation with diamines.^[6] Different tetrasubstituted pyroles can be prepared from furoin as α-hydroxy ketone via a base-promoted three-component reaction with malononitrile and alcohols^[7] or 1,3-dicarbonyls and ammonium acetate.^[8]

Product categorization (Chemical groups):

Main category:

• Alcohols / Phenols / Hydroxy compounds
• Ketones / Ketals / Aminals

Second level:

• Aromatic compounds

Third level:

• Furan derivatives

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