One-Pot Synthesis of 4-Substituted 3,4-Dihydro-3-methoxyisocoumarins via Carboxylation of α-Substituted 2-Lithio-β-methoxystyrenes with Carbon Dioxide
作者:Kazuhiro Kobayashi、Toshiyuki Nagaoka、Yuu Shirai、Wataru Miyatani、Yuki Yokoi、Hisatoshi Konishi
DOI:10.1002/hlca.201100297
日期:2012.2
zopyran‐1‐ones), 4‐substituted 3,4‐dihydro‐3‐methoxyisocoumarins 2, can be obtained by a one‐pot process from α‐substituted 2‐bromo‐β‐methoxystyrenes 1. Thus, lithium 2‐(1‐aryl(or methyl)‐2‐methoxyethenyl)benzoates are conveniently generated via the Br/Li exchange between 1 and BuLi, followed by the action of CO2 on the resulting α‐substituted 2‐lithio‐β‐methoxystyrenes. Upon treating with concentrated
可以通过一锅获得一种新型的异香豆素(= 1 H-异色n-1-酮= 1 H -2-苯并吡喃-1-酮),4-取代的3,4-二氢-3-甲氧基异香豆素2。由α-取代的2-溴-β-甲氧基苯乙烯制备1。因此,通过1和BuLi之间的Br / Li交换可方便地生成2-(1-芳基(或甲基)-2-甲氧基乙烯基)苯甲酸锂,然后通过CO 2对生成的α-取代的2-lithio-苯甲酸作用β-甲氧基苯乙烯。在室温下用浓盐酸处理后,这些苯甲酸锂会发生内酯化反应,从而以相对较高的收率提供所需的3,4-二氢异香豆素2。