Functionalized organolithium compounds: Generation via reductive lithiation and nucleophilic addition to N-phenethylimides. Access to functionalized dihydropyrrolo[2,1-a]isoquinolinones

摘要

A procedure for producing 1,4-dianion equivalents consists of reductive lithiation, induced by 4,4.-di-tert-butylbiphenylide, of functionalized phenyl sulfides. Nucleophilic addition of 4-lithio-2-(trimethylsilylmethyl) but-1-ene 1 and 2-(3-lithiopropyl)-2-trimethylsilyl-1,3-dithiane 2 thus prepared to N-phenethyl-cis-norbor-5-en-2,3-dicarboximide 9 afforded the corresponding alpha-hydroxy lactams in good yields. Besides, access to C-10b substituted alpha,beta-unsaturated pyrroloisoquinolinones 3 was efficiently achieved via a tandem organolithium nucleophilic addition - N-acyliminium ion cyclization sequence and subsequent retro Diels-Alder reaction. The methodology can be extended to functionalized oganolithiums, but the N-acyliminium cyclization fails if the allylsilane moiety is present. (C) 1998 Elsevier Science Ltd. All rights reserved. [References: 36]