Intramolecular Cyclizations of <i>o</i>-Acylbenzyllithiums. Formation of Benzocyclobuten-1-ol Derivatives and Their Thermal Isomerization
作者:Kazuhiro Kobayashi、Masataka Kawakita、Masaharu Uchida、Koichi Nishimura、Tohru Mannami、Susumu Irisawa、Osamu Morikawa、Hisatoshi Konishi
DOI:10.1021/jo982366o
日期:1999.5.1
The formation of benzocyclobutenol derivatives by intramolecular cyclizations of o-acylbenzyllithiums is described. Treatment of o-(trialkylsilylmethyl)phenyl ketones with lithium diisopropylamide (LDA) followed by quenching of the resulting benzylic carbanions with chlorotrialkylsilane resulted in stereoselective formation of the corresponding 1-trialkylsiloxy-2-(trialkylsilyl)benzocyclobutenes in
描述了通过邻酰基苄基锂的分子内环化形成苯并环丁烯醇衍生物。用二异丙基氨基锂(LDA)处理邻-(三烷基甲硅烷基甲基)苯基酮,然后用氯代三烷基硅烷淬灭所得的苄基碳负离子,从而以良好的产率立体选择性地形成了相应的1-三烷基甲硅烷氧基-2-(三烷基甲硅烷基)苯并环丁烯。随后,发现邻酰基-间甲氧基苄基锂在环化成苯并环丁-1-醇衍生物中很好地起作用。通过将6-甲基-2,3,4-三甲氧基二苯甲酮与LDA脱质子化而生成的2-苯甲酰基-3,4,5-三甲氧基苄基锂与氯代三甲基硅烷反应,得到相应的1-(三甲基甲硅烷氧基)苯并环丁烯。2-新戊酰基-3-甲氧基苄基锂的环化,在LDA脱质子作用下,由2-甲基-6-甲氧基苯基叔丁基酮原位生成的苯甲酸在-78℃下自发进行,得到相应的苯并环丁烯-1-醇。我们还描述了这些1-三甲基甲硅烷氧基-2-(三烷基甲硅烷基)苯并环丁烯的热异构化结果。