Regioselective and enantiospecific rhodium-catalyzed allylic alkylation reactions using copper(I) enolates: synthesis of (-)-sugiresinol dimethyl ether.
The transition metal-catalyzed allylic alkylation represents a fundamentally important cross-coupling reaction for the construction of ternary carbon stereogenic centers. We have developed a regioselective and enantiospecific rhodium-catalyzed allylic alkylation of acyclic unsymmetrical allylic alcohol derivatives using copper(I) enolates to prepare beta-substituted ketones. This protocol represents a convenient asymmetric Claisen rearrangement surrogate in which alpha-substituted enolates permit the introduction of an additional stereogenic center. The synthetic utility of this transformation was highlighted in the construction of a trans-1,2-disubstituted cyclohexene and the total synthesis of (-)-sugiresinol dimethyl ether. Finally, we anticipate that copper(I) enolates may prove useful nucleophiles in related metal-catalyzed reactions.
Evans
P Andrew
PA
Department of Chemistry, Indiana University, Bloomington, IN 47405, USA. paevans@indiana.edu
Leahy
David K
DK
D000478:Alkylation; D000498:Allyl Compounds / Q000737:chemistry*; D002384:Catalysis; D003300:Copper / Q000737:chemistry*; D032485:Cryptomeria / Q000737:chemistry; D004952:Esters / Q000737:chemistry*; D017705:Lignans / Q000138:chemical synthesis*; D009942:Organometallic Compounds / Q000737:chemistry; D020005:Propanols / Q000737:chemistry*; D012238:Rhodium / Q000737:chemistry; D013237:Stereoisomerism
D000498:Allyl Compounds; D004952:Esters; D017705:Lignans; D009942:Organometallic Compounds; D020005:Propanols; C006463:allyl alcohol; D003300:Copper; D012238:Rhodium