Conformational Analysis of Retinoic Acids: Effects of Steric Interactions on Nonplanar Conjugated Polyenes.

ABSTRACT: Retinoic acids and other vitamin A analogs contain a trimethylcyclohexenyl ring in conjugation with a polyene chain joined at carbon-6 (C6) and carbon-7 (C7). A MP2-SCS/cc-pVDZ// B3LYP/6-31G(d) 2-D potential energy surface was computed for all-trans retinoic acid, which had 6 minima (3 enantiomeric pairs). The global minima were distorted s-gauche enantiomers (_6-7 = 53°) with half-chair conformations of the ring. Distorted s-gauche enantiomers (_6-7 = 55°) with inverted half-chair ring conformations were 1.7 kJ/mol above the global minima. The s-trans enantiomers (_6-7 = 164°) were 11.3 kJ/mol above the global minima. Steric energies were computed by the method of Guo and Karplus to identify key structural elements in retinoic acid

SUBMITTER: Cox BD 

PROVIDER: S-EPMC4364447 | biostudies-literature | 2013 May

REPOSITORIES: biostudies-literature