E-2-benzylidenebenzocycloalkanones. Stereostructure and NMR spectroscopic investigation

Series of E-2-benzylideneindanones (a), -tetralones (b) and -benzosuberones (c) with OCH3 (2-4), NO2 (5-7) and F (8-10) substitutions (ortho, meta and par-a) on their benzylidene moiety were synthesized by aldol condensation of the appropriate aldehydes and benzocyclanones. The stereostructure (conf iguration and conformation) and the electronic properties (conjugation of t he enone moiety with the aromatic rings) of the compounds were studied by I R, H-1 and C-13 NMR spectroscopy including also 2D-HSC, DNOE and DEPT measu rements. Ab initio calculations were carried out to corroborate the experim ental findings. (C) 1999 Elsevier Science B.V. All rights reserved.