EFFICIENT TOTAL SYNTHESIS OF (-)-ILIMAQUINONE

The total synthesis of (-)-ilimaquinone, a metabolite isolated from se a sponges, is described. The key step of the synthesis is the attachme nt of the quinone moiety to the drimane skeleton. Alkylation of enone 11 obtained in four steps from the readily available diketone 8, with tetramethoxybenzyl bromide 15 as the alkylating agent, led to addition product 16 in excellent yield. The presence of the tetramethoxybenzyl group induced stereoselective hydrogenation of the exo olefin 18, lea ding to the required isomer in a 9:1 ratio. Treatment of compound 21 w ith eerie ammonium nitrate (CAN) afforded formation of the quinone and deprotection of only one methyl ether in one step to furnish the desi red ilimaquinone 1.