Conformational analysis of biphenyl derivatives. I. A novel steric constant from the internal rotation rate of 2,2 '-bis-(N-substituted carbamoylmethyl)biphenyl by means of dynamic NMR

A novel scale of steric substituent constant E-s(D) is defined from the cor relation of the logarithms of the internal rotation rate (k(r)) at 393 K wi th Hancock (E-s(c)) steric constant by means of dynamic NMR. In the inhibit ion of Pseudomona species lipase by 2,2'-bis-(N-substituted carbamoylmethyl )biphenyls (1-8), the logarithms of bi-molecular rate constants are multipl y correlated with both the Taft substituent constant sigma* and E-s(D).