Stereoselective formation of carbon-carbon bonds via SN2- displacement: Synthesis of substituted cycloalkyl[b]indoles

Article abstract of DOI:10.1021/jo051146p

A general asymmetric synthesis of substituted cycloalkyl[b]indoles has been accomplished. The key features of this approach are (1) the utilization of a Japp-Klingemann condensation/Fischer cyclization to prepare cycloalkyl[b] indolones, (2) the asymmetric borane reduction of these heterocyclic ketones with (S)-OAB to obtain enantiomerically pure alcohols, and (3) the stereoselective S_N2-displacement of these indole alcohol substrates with a carbon nucleophile under Mitsunobu conditions to set the C₁ or C₃ tertiary carbon stereocenter. The use of trimethylphosphine (PMe₃) and bis(2,2,2-trichloroethyl) azodicarboxylate (TCEAD) was found to have an effect on the Mitsunobu dehydrative alkylation.