Simple preparation of cobaloxime dienyl complexes and their exo selective Diels–Alder cycloadducts
摘要:
A new method for the synthesis of cobaloxime dienyl complexes (cobaloxime = pyridine(dimethylglyoxime)(2)Co) which involves a zinc-mediated hydrocobaltation of enynes is reported. Use of this dienyl complex synthesis method allows subsequent Diels-Alder reactions of these complexes to be accomplished without isolation of the dienyl complexes. A new silane-based cobaloxime-substituted cycloadduct demetallation protocol is then reported which provides Diels-Alder cycloadducts and cobalt complexes which have been recycled into the zinc-mediated dienyl complex synthesis. (C) 2003 Elsevier B.V. All rights reserved.