Total synthesis of (.+-.)-solavetivone and aglycone A3. Regio- and stereo-selective Birch reduction of 6,10-dimethyl-2-hydroxy-spiro[4.5]deca-6,9-dien-8-one.
(±)-Solavetivone (1) was synthesized by a new spiro-annelation reaction and a unique regio- and stereo-selective reduction of the spiro-dienone (4) to give (5), the structure of which has been determined by X-ray crystal-lography.
Total synthesis of (.+-.)-solavetivone and aglycone A3. Regio- and stereo-selective Birch reduction of 6,10-dimethyl-2-hydroxy-spiro[4.5]deca-6,9-dien-8-one.
Total synthesis of (±) -solavetivone (1), a spirovetivane phytoalexin, was achieved. The metal catalyzed decomposition of the phenolic diazoketone (8) gave the spiro-dienone (6), selective reduction of which afforded the hydroxy-enone (5). The regio-and stereo-selective Birch reduction of 5 provided a high yield of the hydroxy-spiro-enone (9), whose structure was determined by X-ray crystal analysis. Compound 9 was transformed to (±) -1 and the aglycone A3 in several steps.