Synthesis of biliverdins with stable extended conformations. Part I
作者:José Iturraspe、Sara E. Bari、Benjamín Frydman
DOI:10.1016/0040-4020(94)01102-6
日期:1995.2
Biliverdins with extended conformations stabilized by intramolecular ethyl bridges were obtained by base treatment of helical biliverdins with 2-chloroethyl side chains. Thus, neobiliverdin IXβ (6) was obtained by reaction of 13,18-di-(2-chloroethyl)-biliverdin 5 with DBU. During the reaction the 2-chloroethyl-C(13) residue underwent an intramolecular substitution reaction with N-24 while the 2-chloroethyl-C(18)
通过对带有2-氯乙基侧链的螺旋式胆素进行碱处理,获得了具有通过分子内乙基桥稳定的扩展构象的胆素。因此,通过使13,18-二-(2-氯乙基)-胆小素5与DBU反应获得新胆小素IXβ(6)。在反应过程中,2-氯乙基-C(13)残基与N-24进行分子内取代反应,而2-氯乙基-C(18)残基进行消除反应以形成乙烯基残基。通过合成[ 15 N-24]-二氢-新胆色素IXβ(19)和[ 15 N-23]-二氢佛兰素(31)。然后将该方法应用于合成新胆小素IXδ,这是从海蛇Turbo cornutus卵巢中分离得到的天然产物。结论是,当2-氯乙基侧链位于biliverdin的C(3)(或当量C(17))和C(2)(或当量C(18))位置时,消除反应导致乙烯基基本培养基中的残留物;在任何其他β-吡咯位置上,用碱处理都会通过分子内取代反应形成七元环。