BENZOTRIAZOLE-MEDIATED CONVERSIONS OF AROMATIC AND HETEROAROMATIC ALDEHYDES TO FUNCTIONALIZED KETONES

Aromatic and heteroaromatic aldehydes reacted with benzotriazole and t riethyl orthoformate in THF to give the corresponding alpha-(benzotria zol-1-yl)aryl ethyl ethers 7 in good yield. The novel acyl anion precu rsors 7 underwent smooth lithiation at the methine group followed by t rapping with alkyl halides, aldehydes, ketones, and imines to yield th e expected substituted intermediates of type 9, which were hydrolyzed under mild conditions without isolation. Benzaldehyde, methyl-, chloro -, and methoxy-substituted benzaldehydes, 1-naphthalenecarboxaldehyde, 2- and 3-furaldehydes, 2- and 3-thiophenecarboxaldehydes, and 2-pyrid inecarboxaldehyde were all transformed in this manner into a variety o f aryl and heteroaryl ketones with alkyl (10), alpha-hydroxyalkyl (12 and 13), alpha-aminoalkyl (14) and acyl(15) substituents.