Stereoselective total syntheses of atrochrysone, torosachrysone and related 3,4-dihydroanthracen-1(2H)-ones

Abstract

The total synthesis of the pre-anthraquinones atrochrysone 1 and torosachrysone 2 in both enantiomeric forms is described. The synthesis relies on the regioselective Tebbe methylenation of a chiral diester followed by an intramolecular enol ether acylation with N-triflyl-4-(dimethylamino)pyridinium triflate. The resulting 3-methoxycyclohex-2-enone 9 is condensed with suitable orsellinic acid derivatives to yield after deprotection the optically active 3,4-dihydroanthracen-1(2H)-ones 1 and 2. This flexible approach can be used for the synthesis of ¹³C-labelled compounds and should provide access to a series of analogues.