Abstract: A pharmaceutically acceptable base addition salt of an organoboronic acid of formula (XXX): wherein: P is hydrogen or an amino-group protecting moiety; R is hydrogen or alkyl; A is 0, 1 or 2; R1, R2 and R3 are independently hydrogen, alkyl, cycloalkyl, aryl or —CH2—R5; R5, in each instance, is one of aryl, aralkyl, alkaryl, cycloalkyl, heterocyclyl, heteroaryl, or —W—R6, where W is a chalcogen and R6 is alkyl; and where the ring portion of any of said aryl, aralkyl, alkaryl, cycloalkyl, heterocyclyl, or heteroaryl in R1, R2, R3 or R5 can be optionally substituted.