Thallium benzotriazolate, reaction with

BetMIC is characterized by two key properties first, the good leaving ability of the benzotriazole (Bet) moiety and, second, the high acidity of the methylene protons. BetMIC is reactive with ketones to afford 4-ethoxy-2-oxazolines (94), which can be hydrolyzed to synthetically useful a-hydroxyaldehydes (95). It must be noted that unlike TosMIC, BetMIC forms 94/96 without the presence of highly toxic thallium alkoxides. The reaction works well in the absence of ethanol and provides better yields when using aliphatic ketones. With aromatic ketones, for example, ben-zophenone, partial conversion to oxazoline occurs probably due to steric effects. Reaction of BetMIC with aldehydes typically generates oxazoles 97 (Scheme 7.24) [43,44]. 

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