Irradiation of 4,4-dimethyl-3-[(2-cyclopentenyl)methoxy]-2-cyclohexen-1-one, prepared from 4,4-dimethyl-3-phenylthio-2-cyclohexen-1-one and (2-cyclopentenyl) methanol, gave a tetracyclic intramolecular [2+2]photocycloadduct 7. Treatment of 7 with iodotrimethylsilane followed with tributyltin hydride afforded 3,3,11-trimethylbicyclo[6.3.0]undecane-2,6-dione(12). Methylenation of 12 afforded 6-methylene-3,3,11-trimethylbicyclo[6.3.0] undecan-2-one, the known intermediate to precapnelladiene.
用 4,4-二甲基-3-[(2-
环戊烯基)甲氧基]-
2-环己烯-1-酮和(2-
环戊烯基)
甲醇辐照制备 4,4-二甲基-3-[(2-
环戊烯基)甲氧基]-
2-环己烯-1-酮,得到四环分子内[2+2]光环加成物 7。用
碘三甲基
硅烷处理 7,然后用氢化三
丁基锡处理,可得到 3,3,11-三甲基双环[6.3.0]
十一烷-2,6-二酮(12)。将 12 进行甲基化可得到 6-亚甲基-3,3,11-三甲基双环[6.3.0]
十一烷-2-酮,即已知的前庚二烯中间体。