STEREOSELECTIVE EPOXIDATIONS AND ELECTROPHILIC ADDITIONS TO PARTIAL ERGOT ALKALOIDS AND CONFORMATIONALLY-FIXED STYRENES - EXPERIMENTAL AND THEORETICAL MODELING EVIDENCE FOR THE IMPORTANCE OF TORSIONAL STEERINGAS A STEREOCONTROL ELEMENT

Partial ergot alkaloid substrates and related conformationally-fixed s tyrenes undergo epoxidation, osmium tetraoxide dihydroxylation, and hy drobromination with a level of stereoselectivity which cannot be expla ined by steric control but is consistent with electrophilic attack to minimize torsional strain. Force-field modeling is consistent with the importance of torsional steering as the dominant stereochemical contr ol element.