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

Authors
KENAR JA NICKON A
Citation
Ja. Kenar et A. Nickon, AXIAL AND EQUATORIAL HYDROGEN SHIFTS IN METHYL-SUBSTITUTED CYCLOHEXYLIDENES - STEREOCHEMICALLY-DEPENDENT ISOTOPE EFFECTS AND BYSTANDER ASSISTANCE, Tetrahedron letters, 35(52), 1994, pp. 9657-9660
Citations number
22
Categorie Soggetti
Chemistry Inorganic & Nuclear
Journal title
Tetrahedron letters → ACNP
ISSN journal
00404039
Volume
35
Issue
52
Year of publication
1994
Pages
9657 - 9660
Database
ISI
SICI code
0040-4039(1994)35:52<9657:AAEHSI>2.0.ZU;2-9
Abstract
Carbenes were generated from 4-t-butyl-cis-2-methylcyclohexanone (4a) and from 4-t-butyl-cis-2-trans-6-dimethylcyclohexanone (8a, and its co rresponding 2,6-d(2) analog 8b) by conventional Bamford-Stevens reacti ons. Product analysis revealed that an equatorial CH3 assists migratio n of a geminal H more efficiently than does an axial CH3 by a factor o f about 4.6. The primary deuterium isotope effect (k(H)/k(D)) for axia l shift (I-ax) is ca. 1.5 times greater than for equatorial shift (I-e q) in the anchored dimethyl substituted carbene 9.