8-Benzyloxy-5-methoxy-3,4-dihydronaphthalene-2-carboxylic
acid (34) has been prepared by a four-step sequence from
5-methoxy-8-hydroxy-3,4-dihydronaphthalen-1(2H)-one. Condensation of the
unsaturated acid (34) with ethyl (S)-prolinate in the presence of dicyclohexylcarbodiimide
afforded the amide (35) which was enantioselectively cyclized to the bromo
lactone (37). Debromination with tributyltin hydride and subsequent reaction of
the lactone with methyllithium afforded (-)-(2R)-2-acetyl-8-benzyloxy-5-methoxy-1,2,3,4-tetrahydronaphthalen-2-ol. Removal of the
benzyl ether by catalytic hydrogenation and oxidation of the resulting phenol
with thallium(III) nitrate afforded the title chiral dienone.
8-苄氧基-5-甲氧基-3,4-二氢萘-2-羧酸 (8-Benzyloxy-5-methoxy-3,4-dhydronaphthalene-2-carboxylic)
8-Benzyloxy-5-methoxy-3,4-dihydronaphthalene-2-carboxylic acid (34)是通过以下四个步骤制备的
5-甲氧基-8-羟基-3,4-二氢萘-1(2H)-酮。不饱和酸
不饱和酸 (34) 与(S)-脯氨酸乙酯在二环己基碳二亚胺存在下缩合,得到酰胺 (35)
在二环己基碳二亚胺存在下,不饱和酸 (34) 与(S)-脯氨酸乙酯缩合,得到酰胺 (35)。
内酯 (37)。用氢化三丁基锡进行脱溴反应,然后将内酯与甲硫醇反应生成溴内酯(37)。
内酯与甲基锂反应,得到 (-)-(2R)-2-乙酰基-8-苄氧基-5-甲氧基-1,2,3,4-四氢萘-2-醇。通过催化去除
催化加氢去除苄基醚,并用硝酸铊(III)氧化生成的苯酚。
硝酸铊(III)氧化除去苄基醚,得到标题手性二烯酮。