Catalytic generation and trapping of acylmetals containing Ni and Cu with enolates
摘要:
Carbonylative cyclization of iodoarenes and iodoalkenes containing a proximal enolate precursor can selectively provide either cyclic ketones or lactones in the presence of Ni or Cu catalysts via trapping of putative acylmetal derivatives with C-or O-enolates, respectively; the ring size and regioselectivity of the reaction may be predicted based on two generalizations derived from the recently developed corresponding Pd-catalyzed reaction. (C) 1998 Elsevier Science Ltd. All rights reserved.
Treatment of alkenyl and aryl iodides and bromides containing an appropriateα, β-unsaturatedcarbonyl group with a catalytic amount (3–5 mol %) of either a Pd(O) or a Pd(II) complex, e.g., Pd(PPh3)4, and a base, e.g., NEt3, can induce highly regioselective cyclization via intramolecular carbopalladation; formation of exocyclic alkenes can also be highly stereoselective.