Several 14-hydroxy-E-homoeburnane diastereoisomers have been synthesized and studied by 1H and 13C n.m r spectroscopy. The relative configurations and predominating conformations have been established. It has been shown that previous assignments of C-17 and C-20 signals of trans-D/E-ring-fused Vinca alkaloids must be reversed.
几个14羟基Ê -homoeburnane非对映体已被合成,并通过研究1 H和13 C ^纳米- [R光谱。已经建立了相对构型和主要构象。它已经显示,C-17和先前分配C-20的信号的反式- d / é -RING稠合长春花生物碱必须扭转。
An enantio-controlled route to (+)-vincamine (1), an eburnane alkaloid used as cerebral vasodilator, has been developed starting from the optically active enedione (2) which can be easily obtained by asymmetric aldol cyclization.