Mechanism of Organocuprate Conjugate Addition: Observation of Cuprate-Olefin Complexes and Li-Coordinated Intermediates in the Reaction of Lithium Dimethylcuprate(l) with 10-Methyl- DELTA sup (1,9) -2-octalone. sup (la)
06 April 1989
When 10-methyl-DELTA sup (1,9) -2-octalone is treated with halide-free lithium dimethylcuprate(l), (Me sub 2 CuLi) sub 2, cuprate-olefin (2) and Li-carbonyl (3) complexes are observed by sup (13) C NMR at 78C. Upon warming to -50C, a new species (4) appears which was both Co-olefin and Li-carbonyl complexation. With time this complex is converted into the enolate (5) of cis-9,10-dimethyl-2-octalone, the product of organocuprate conjugate addition. An electron-transfer mechanism has been proposed for this reaction, but our results support other mechanistic proposals.