Nickel-Catalyzed Reductive Coupling of Alkynes and Epoxides
摘要:
Nickel-catalyzed, intramolecular and intermolecular reductive coupling of alkynes and epoxides affords synthetically useful homoallylic alcohols of defined alkene geometry. Very high regioselectivity is generally observed, and cyclizations proceed with complete selectivity for endo epoxide opening. This catalytic reaction represents the first use of a non-pi-based electrophile in a growing class of nickel-catalyzed, multicomponent coupling reactions, and is the first catalytic method of reductive coupling of alkynes and epoxides that is effective for both intermolecular and intramolecular cases, and mechanistically distinct from these, possibly involving a nickella(II)oxetane.
Catalytic reductive carboncarbon bond-forming reactions of alkynes
摘要:
Enantioselective nickel/phosphine-catalyzed reductive Coupling of alkynes and aldehydes provides rapid access to synthetically useful allylic alcohols with high enantiomeric excess. A related reaction involving epoxides is enantiospecific, transforming alkynes and chiral terminal epoxides into enantiomerically pure homoallylic alcohols containing a trisubstituted olefin of defined geometry. A gram-scale example of each of these processes is described. (C) 2003 Elsevier Ltd. All rights reserved.