An Improved Method for the Preparation of N-Unsubstituted 1,4,5,6-Tetrahydrocyclopenta[b]pyrroles: Synthesis of an Azaprostacyclin Analogue and Its 7-Cyano Derivative
作者:Brigitte Rousseau、Fredy Nydegger、Albert Gossauer、Bärbel Bennua-Skalmowski、Helmut Vorbrüggen
DOI:10.1055/s-1996-4388
日期:1996.11
Paal-Knorr cyclization of 2-acetonylcyclopentanone derivatives can be carried out most efficiently by reaction with hexamethyldisilazane (HMDS) when the reagents are previously adsorbed on alumina. By this procedure, the unstable pyrroloprostacyclin derivative rac-6a has been synthesized in 66% yield from racemic 6-oxoprostaglandin E1 (rac)-5b. In order to obtain less sensitive pyrroloprostacyclin derivatives, rac -6a has been transformed into the stable nitriles rac -7a and rac -7b by cyanation of the pyrrole ring with chlorosulfonyl isocyanate in the presence of triethylamine and subsequent cleavage of the protecting groups, respectively.
2-乙酰基环戊酮衍生物的Paal-Knorr环化反应可以通过与六甲基二硅氮烷(HMDS)反应进行最有效的实验,当试剂事先被吸附在铝土矿上时。通过这种方法,已从外消旋的6-氧类炎症小分子E1 (rac)-5b合成了不稳定的吡咯类前列腺素衍生物rac-6a,产率为66%。为了获得不易敏感的吡咯类前列腺素衍生物,rac-6a已被转化为稳定的氰化物rac-7a和rac-7b,这通过在三乙胺存在下用氯磺酰异氰酸酯对吡咯环进行氰化反应,并随后切割保护基团而实现。