La. Kutulya et al., NMR and molecular mechanics studies on configurational isomerism and conformational equilibrium of chiral cyclohexenones, J STRUCT CH, 42(1), 2001, pp. 84-91
Chiral diastereomers of 2-isopropyl-5-methyl-6-(4-phenyl)benzylcyclohex-2-e
none and their isomer 2-(4-phenylbenzyl)-3-methyl-6-isopropylcyclohexanone,
which are products of an acid-catalyzed intramolecular rearrangement of 3R
,6R-2-(4-phenylbenzylidene)-3-methyl-6-isopropylcyclohexamoe, were investig
ated to show that conformational analysis by molecular mechanics and H-1 NM
R spectroscopy permits an integrated solution of three structural problems:
double bond location in an aliphatic ring for isomeric products; determina
tion of the stereochemical configuration for the two diastereomers; evaluat
ion of the conformational equilibrium between the diastereomers. Based on t
he results of calculations, this is achieved by estimating the configuratio
n- and conformation-sensitive proton spin-spin coupling constants of the cy
clohexenone ring for alternative structures and correlating them with H-1 N
MR data.