Aryl Radical Cyclizations of 1-(2‘-Bromobenzyl)isoquinolines with AIBN−Bu<sub>3</sub>SnH: Formation of Aporphines and Indolo[2,1-<i>a</i>]isoquinolines
作者:Kazuhiko Orito、Shiho Uchiito、Yoshitaka Satoh、Takashi Tatsuzawa、Rika Harada、Masao Tokuda
DOI:10.1021/ol990360v
日期:2000.2.1
text] Radical cyclization of alkoxy-substituted 1-(2'-bromobenzyl)-3,4-dihydroisoquinolines 1 with AIBN-Bu3SnH gave 6a,7-dehydroaporphines 2 preferentially. A steric repulsion between the respective alkoxy groups at the 7- and 3'-positions gave 5,6-dihydroindolo[2,1-a]isoquinolines 3 in a "disfavored" 5-endo cyclization mode. Radical cyclizations of the related substrates, such as 1-(2'-bromobenzoyl)isoquinolines
[反应:见正文]用AIBN-Bu3SnH对烷氧基取代的1-(2'-溴苄基)-3,4-二氢异喹啉1进行自由基环化,优先得到6a,7-脱氢紫杉醇2。在7-和3'-位的各个烷氧基之间的空间排斥以“不利的” 5-内-环化模式得到5,6-二氢吲哚并[2,1-a]异喹啉3。还发现相关底物如1-(2'-溴苯甲酰基)异喹啉或1-(2'-溴-α-羟基苄基)异喹啉的自由基环化产生相应的氧杂卟啉或羟磷灰石。