Enantiomers of 8-(3-tert-butylamino-2-hydroxypropoxy)-3,4-dihydro-3-oxo-2H- (1,4)benzothiazine: racemic resolution, chiral synthesis and biological activity.

We report the resolution of racemic (+/-)-1 with (R)-(+)-methylbenzyl isocianate and the synthesis of (R)-1 and (S)-1 via Sharpless chiral epoxidation. The enantio- and tissue-selectivity of such enantiomers, as beta- and alpha-adrenoceptor antagonists, were studied. Compound 1, while confirming the potent beta-blocking activity, displayed a modest enantio-selectivity towards beta 1- and beta 2-adrenoceptors. All the compounds displayed no activity as alpha-adrenoceptor blockers.