A simple, efficient access to functionalized pyrrolobenzazepines related to the ABC core of cephalotaxine
作者:Eduardo R. de Oliveira、Françoise Dumas、Jean d'Angelo
DOI:10.1016/s0040-4039(97)00709-0
日期:1997.5
Tetracyclic nitrile 19a and ester 19b, exhibiting the ABC core of cephalotaxine 1a, were prepared through KH-induced cyclization of thioimides 14a and 14b, respectively. This new ring-closure methodology proved to be particularly efficient: thus nitrile 19a was obtained in only 7 steps with a 17 % overall yield from commercially available, inexpensive safrole 2.
四环腈19a和酯19b表现出头孢他辛1a的ABC核心,分别通过KH诱导的硫酰亚胺14a和14b环化制备。这种新的闭环方法被证明是特别有效的:因此,仅通过7个步骤就可以从市售的廉价黄樟脑2中获得腈19a,总收率为17%。