Regioselectivity and stereoselectivity of electrophilic quaternization of substituted 2-allyl(2-cyclohexen-1-yl)thionicotinic acids to thiazolo[3,2-a]pyridinium salts
Electrophilic trans quaternization of substituted 2-[2-cyclohexen-1-ylthio(seleno)]pyridines to 4a,10-a-cis-4,4a-trans-l,2,3,4,4a,10a-hexahydrobenzothiazolo(selenazolo)[3,2-a]pyridinium salts