adduct, 17, of cyclopentadiene and 2-methoxy-5-methyl-1,4-benzoquinone was reduced with sodium borohydride to the ketol 18, whose acetate 19 was further reduced with zinc amalgam to the monoketone 20. Reaction of 20 with vinyllithium gave the allylic alcohol 21, which underwent very ready dehydration with rearrangement to give the tricyclic enol ether 27, which was hydrolyzed to ketone 28a. Hydrogenation
环戊二烯和
2-甲氧基-5-甲基-1,4-苯醌的 Diels-Alder 加合物 17 用
硼氢化钠还原为酮醇 18,其
乙酸酯 19 用
锌汞齐进一步还原为单酮 20。 20与
乙烯基锂得到
烯丙醇21,其经过非常容易的脱
水和重排得到
三环烯醇醚27,其
水解为酮28a。19 加氢得到二氢产物 30,用
锌汞齐将其还原为酮 31。后者用
乙烯基锂处理得到
烯丙醇 32。这比其类似物 21 更稳定,但经过
水解和脱
水生成二烯酮 33在Triton B存在下用2-甲基-1,3-
环戊二酮(5)处理32得到
三环中间体35,其
水解产物36,