Etude en rmn 13C de bicyclo[4,n,0]alcanones-3 trans α-substitués. Influence de la nature et de l'orientation du substituant sur le déplacement chimique du 13C du carbonyle

Abstract

The 13C nmr spectra of α, αα, and αα′ substituted trans-fused bicyclo [4,n,0]alkan-3 ones, are described. Substituent effects are discussed in terms of their electron withdrawing character, axial or equatorial configuration, and cyclohexane deformation. 13C=O chemical shifts are shown to be based on the polarization of π bond and on C=O/X non-bonded interactions. As in ir and uv spectroscopy, 13C nmr is a convenient method for detecting an a substituent configuration in fixed ring ketones.