Sonogashira/N-acyliminium ion aromatic π-cyclisation processes: access to tetra- and pentacyclic lactams
摘要:
Application of the Sonogashira reaction of N-alkynylimides with 2-iodophenol or 2-iodo-N-tosylaniline affords 2-(N-alkylimino)-benzofurans and indoles in good yield. Selective partial reduction of the latter followed by treatment with TsOH generates N-acyliminium ions, which cyclise to afford tetra- and pentacyclic lactams in good yield. The latter are reduced to the analogous cyclic amines by BH3. (C) 2008 Elsevier Ltd. All rights reserved.
Condensation of methyl 2-acylbenzoates with 2-arylethanamines or 2-acylanilines in the presence of trifluoroacetic acid resulted in the formation of isoindolo[1,2-a]isoquinolines or isoindolo[2,1-a]quinolines, respectively, in moderate to excellent isolated yields.