Lewis and protic acid mediated Nicholas reactions of 3-acetoxycyclohept-1-en-4-ynedicobalt hexacarbonyl: site selectivity of nucleophile incorporation
摘要:
Nicholas reactions on the cation derived from the cyclic allylic acetate alkynedicobalt complex 1 favour the gamma-site kinetically for most nucleophiles, with increasing amounts of of-products in cases with greater nucleophilicity. Some regiocontrol in introduction of a specific nucleophilic fragment is possible by using different nucleophiles. Under conditions where reversibility is possible, the thermodynamically favoured site is exclusively gamma-. (c) 2005 Elsevier Ltd. All rights reserved.