Developing a Modern Approach To Account for Steric Effects in Hammett-Type Correlations Academic Article uri icon

abstract

  • The effects of aryl ring ortho-, meta-, and para-substitution on site selectivity and enantioselectivity were investigated in the following reactions: 1) enantioselective Pd-catalyzed redox-relay Heck reaction of arylboronic acids, 2) Pd-catalyzed ?-aryl elimination of triarylmethanols, and 3) benzoylformate decarboxylase-catalyzed enantioselective benzoin condensation of benzaldehydes. Through these studies, it is demonstrated that the electronic and steric effects of various substituents on se-lectivities obtained in these reactions can be described by NBO charges, the IR carbonyl stretching frequency, and Sterimol values of various substituted benzoic acids. An extended compilation of NBO charges and IR carbonyl stretching frequen-cies of various substituted benzoic acids was used as an alternative to Hammett values. These parameters provide a correla-tive tool that allows for the analysis of a much greater range of substituent effects because they can also account for prox-imal and remote steric effects.

publication date

  • October 1, 2016