LEWIS-ACID MEDIATED REACTIONS OF N-ARYLSULFONIMIDOYL CHLORIDES WITH ALKENES - SOME STERIC EFFECTS OF ALKENE SUBSTITUTION

The Lewis acid-mediated reaction of N-phenyl-S-(4-methylphenyl)sulfoni midoyl chloride with alkenes was explored in order to determine the ef fect of alkene substitution on the stereochemical outcome of the react ion. With monosubstituted alkenes, benzothiazines are produced with re latively low diastereoselection, with one unique exception, trimethyls ilylethene. 1,1-Disubstituted alkenes give products with even lower st ereoselectivity. With trisubstituted alkenes, steric effects begin to change the course the reaction from one which can be rationalized as a cycloaddition to one which seems to definitely produce a carbocationi c intermediate. Interestingly, the stereoselection observed in the rea ction of (E)- and (Z)-2-butenes shows large deviations from the norm w ith (E)-2-butene giving rise to two diastereomeric benzothiazines in a ratio of 45:1.