Efficient synthesis of selected phthalazine derivatives

Abstract

Four phthalazine derivatives have been prepared from substituted 2-bromobenzaldehyde acetals by a sequence involving: (1) lithiation and formylation; (2) deprotection; and (3) condensative cyclization with hydrazine. Two additional phthalazines were prepared by a similar sequence following direct lithiation of benzaldehyde acetals substituted by anion-stabilizing groups at C3. These syntheses can be conveniently carried out to give phthalazines in overall yields of 40 - 70%. © 2011-2012 by Walter de Gruyter GmbH.