(8) There rn qualltethn, data avelleble whkh suggest that carimkmgmeratlry reectkns, eg HD ex- of the CY protom in picolines, are mmt successful for positions 2 and 4 and leest efflcaciws at position 3. Valws for u-# metants derlved from the measuements of the pK& of amlm and dimethybl~ yrldines and of the SBCond pK& of the mespondlng hxidee are ca. 2.1 and 4.0 for the 6 and y posltlons, respectively.
