作者:Nicolas Houllier、Sonia Gouault、Marie-Claire Lasne、Jacques Rouden
DOI:10.1016/j.tet.2006.09.057
日期:2006.12
(-)-N-Benzyl cytisine has been stereoselectively substituted in moderate to high yields on its carbon 6 (Csp(3) a to the pyridone nitrogen). The reaction involved the in situ trapping of the carbantion formed by reaction of lithium diisopropyl amide (LDA) and its reaction with electrophiles (alkyl, allyl, benzyl halides, non-enolizable aldehydes, and Weinreb amide). In the absence of an electrophile or with its addition after the formation of the carbanion, a dimeric structure was isolated (yield: 42%) resulting from the 1,4-addition of the carbanion on the pyridone ring of another cytisine molecule. Deprotection of the benzyl group (Olofson's reagent) allowed the formation of 6-substituted derivatives of the natural product, cytisine, a potent agonist of nicotinic receptors of subtype alpha(4)beta(2). (c) 2006 Elsevier Ltd. All rights reserved.
(-)-N-苯甲基 cytisine 在其碳6位(Csp³,连接至吡啶酮氮)上已进行了立体选择性取代反应,获得了中等至高的产率(Csp³ 碳连接到吡啶酮氮)。该反应涉及通过锂二异丙基胺(LDA)与 cytisine 反应生成的卡拜离子的原位捕获及其与亲电试剂(烷基、烯丙基、苯甲基卤化物、不可烯醇化的醛以及Weinreb酰胺)的反应。在没有亲电试剂存在的情况下,或者在卡拜离子形成后再加入亲电试剂,则会得到一个二聚体结构(收率:42%),这是由于卡拜离子在另一分子 cyti sine 的吡啶酮环上发生了1,4-加成。通过脱保护苯甲基基团(Olofson试剂),成功合成了天然产物cytisine的6-取代衍生物,其是α4β2烟碱型受体的强效激动剂。
(C)2006 Elsevier Ltd. 保留所有权利。