Inter- and intramolecular isocarbon couplings of cobalt-complexed propargyl radicals: challenging the consensus

Intermolecular coupling reactions of Co-2(CO)(6)-complexed, gamma-ethyl propargyl radicals occurred with higher DL-diastereoselectivity than intramolecular cyclizations of isocarbon analogues (de(inter)-de(intra)<= 52%). The observed phenomenon was interpreted in terms of a tandem action of two main determinants-sterics and CH/pi coordination with the latter being enabled by the methoxy groups located on the periphery of the aromatic nuclei (4-, 3,4-, 3,4,5-). (C) 2010 Elsevier Ltd. All rights reserved.