Conformational analysis of 2,3-substituted propenoates

Three X-ray structure analyses and theoretical conformational analyses comb ining molecular mechanics (SYBYL), semiempirical (AMI) and ab initio (HF/6- 31G*) calculations of nine 2,3-substituted propenoates are presented. The r esults of the quantochemical and crystallographic calculations and a survey of structural related molecules using the Cambridge Structural Database Sy stem are in concordance and show that steric hindering among substituents a nd possible inter and intramolecular hydrogen bonding are major factors tha t influence the geometrical configuration of substituents. The physical and chemical sense of these factors and the reasonable agreement between the s emiempirical and ab initio results as well as between theoretical and exper imental results have confirmed that the method which was applied for the th eoretical conformational analysis is good and useful for related organic mo lecules. (C) 2000 Elsevier Science B.V. All rights reserved.