Enantiospecific synthesis of (+)-(R)-6,7-dimethoxy-2-methyl-4-phenyl-1,2,3,4-tetrahydroisoquinoline from (+)-(S)-2-methylamino-1-phenylethanol (halostachine)
作者:Steven J. Coote、Stephen G. Davies、David Middlemiss、Alan Naylor
DOI:10.1039/p19890002223
日期:——
Acid-promoted cyclisation of (+)-(R)-N-(3,4-dimethoxybenzyl)halostachine tricarbonylchromium at –20 °C is highly stereoselective, proceeding with retention of configuration, to yield, after removal of the tricarbonylchromium unit, homochiral (+)-(R)-6,7-dimethoxy-2-methyl-4-phenyl-1,2,3,4tetrahydroisoquinoline. In contrast, cyclisation of (–)-(R)-N-(3,4-dimethoxybenzyl)halostachine under acidic conditions
(+)-(R)-N-(3,4-二甲氧基苄基)卤代鸟嘌呤三羰基铬在–20°C的酸促进环化反应具有高度立体选择性,保留构型,在除去三羰基铬单元后,得到纯手性(+)-(R)-6,7-二甲氧基-2-甲基-4-苯基-1,2,3,4四氢异喹啉。相反,(–)-(R)-N-(3,4-二甲氧基苄基)卤水藤碱在酸性条件下于–20°C的环化显示较差的立体选择性,主要产生四氢异喹啉产物,相应于构型反转,(+)-(R)-6,7-二甲氧基-2-甲基-4-苯基-1,2,3,4-四氢异喹啉,ee为54%。