Experiments Directed Towards the Synthesis of Anthracyclinones. XXXII. Synthesis of Anthraquinone Aldehydes

Abstract

Syntheses of C2 anthraquinone aldehydes from the commercially availableanthraru¯n (1) have been investigated. A synthesis of the keto aldehyde(2) in nine steps and 73% overall yield was achieved. Syntheses of (2)exploiting selective oxidations of either a C-boundallyl group by Wacker oxidation to introduce the methyl keto functionality orof a C-bound prop-1-enyl moiety by dihydroxylation andoxidative cleavage to generate the C2 formyl group were also developed. Thealdehyde (27) was synthesized in seven steps and in 81% overall yieldfrom (1), and syntheses of the phenolic aldehydes (33), (34), and (35), the C1benzyloxy aldehyde (36) and the anthracene aldehyde (37) were also developed.