AXIAL AND EQUATORIAL HYDROGEN SHIFTS IN METHYL-SUBSTITUTED CYCLOHEXYLIDENES - STEREOCHEMICALLY-DEPENDENT ISOTOPE EFFECTS AND BYSTANDER ASSISTANCE

[摘要] Carbenes were generated from 4-t-butyl-cis-2-methylcyclohexanone (4a) and from 4-t-butyl-cis-2-trans-6-dimethylcyclohexanone (8a, and its corresponding 2,6-d(2) analog 8b) by conventional Bamford-Stevens reactions. Product analysis revealed that an equatorial CH3 assists migration of a geminal H more efficiently than does an axial CH3 by a factor of about 4.6. The primary deuterium isotope effect (k(H)/k(D)) for axial shift (I-ax) is ca. 1.5 times greater than for equatorial shift (I-eq) in the anchored dimethyl substituted carbene 9.

[发布日期] 1994-12-26