After 50 minutes the excess diazomethane is neutralized with the addition of acetic acid (10 ml). The solvent is removed under vacuum leaving a clear yellow liquid. The crude product is then diluted with acetic acid (240 ml) and stirred while zinc powder (72 g, 1.10 moles) is slowly added. The reaction is heated in a 70° C. water bath for 1 hour, after which time ether (500 ml) is added and the solution filtered. The ether layer is washed with brine (100 ml) and then with a solution of saturated bicarbonate. The ether layer is separated and dried over sodium sulfate. The solvent is removed under vacuum leaving a clear yellow oil. The crude 2-(5-ethoxyhept-1-yl)bicyclo[3.3.0]octan-7-one {hexahydro-4-(5-methoxyheptyl)-2(1H)-pentalenone} is chromatographed on silica gel and subsequently kugelrohred under vacuum leaving compound VI as a clear, colorless oil (12 g, 0.045 moles).
