NEW PARAMETERS FOR PREDICTING H-1-NMR CHEMICAL-SHIFTS OF PROTONS ATTACHED TO CARBON-ATOMS

A parameter set has been compiled for predicting the H-1 NMR chemical shifts of protons attached to carbon atoms. It is based on simple addi tivity rules and currently comprises 728 base values and about 2000 in crements. For methyl groups, increments for alpha- and beta-substituen ts have been developed and parameter sets previously reported for meth ylene and methine groups have been amended. New rules have been added for allenes and acetylenes. The parameter set is part of a recently pu blished computer program for estimating proton chemical shifts [1] tha t automatically searches for appropriate substructures and applies var ious strategies to find suitable parameters for lacking substituents.