While investigating the ferric chloride mediated coupling1 of catharan
thine (1) with vindoline (3) and their derivatives (2,4), the borane c
omplexes of 15',20'-anhydrovinblastine2 (AVLB), 20'-deethyl-AVLB and N
-demethyl-AVLB (9,10,11) have been synthesized. The corresponding base
s (6,7 and 8) have also been obtained in high yield.