To what extent does the substituent conformation influence the kinetics of addition reactions on 5X-bicyclo[4.4.0]decan-2-ones?

Stereochemistry and relative rates kax and keq of addition reactions on the title compounds have been measured under four different reaction conditions (CH3MgI in Et2O and C6H6, and CH3Li in Et2O at 20°C and −78°C). In strict accordance with previous findings we show that the axial substituents are far less electronegative than their equatorial counterparts in equatorial attack reactions. Axial attack, however, is independent of the substituent conformation.