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Transformation, par 1′anhydride acètique, d'aldèhydes à caractére èlectrophile prononcè; catalyse par des pyridines. 1. Acyloïnes et hydrates di‐o‐acètylès d'aldèhydes
Author(s) -
Baudet P.,
Otten Cl.
Publication year - 1970
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19700530610
Subject(s) - chemistry , pyridine , acetic anhydride , conjugate acid , medicinal chemistry , electrophile , catalysis , steric effects , yield (engineering) , enol , benzaldehyde , benzothiazole , organic chemistry , ion , materials science , metallurgy
2‐Benzothiazole‐carbaldehyde is transformed into di‐O‐acetyl‐enol‐(benzothiazolecarboxyl‐2)‐oin in the presence of acetic anhydride and of pyridine as catalyst. Without pyridine or with 2,6‐lutidine no reaction occurs. A mechanism of this reaction is proposed. No reaction was observed in the case of benzaldehyde. Choral reacts with acetic anhydride in the presence of pyridine as well as of 2,6‐lutidine as catalyst to give 1,1‐diacetoxy‐2,2,2‐trichloro‐ethane. A mechanism is proposed, in which in an intermediate state the acetate ion (and not pyridine, for steric reasons) attacks the carbon of the carbonyl function of the conjugate acid with the acetylium cation to yield 1,1‐diacetoxy‐2,2,2‐trichloro‐ethane. These two reactions occur only with aldehydes whose carbonyl is very electrophilic, and seem to be a possible way to point out the presence of an acylium cation in pyridine medium.