Novel stereocontrolled approach to conformationally constrained analogues of l-glutamic acid and l-proline via stereoselective cyclopropanation of 3,4-didehydro-l-pyroglutamic ABO ester
作者:Makoto Oba、Naohiro Nishiyama、Kozaburo Nishiyama
DOI:10.1016/j.tet.2005.06.051
日期:2005.8
followed by appropriate functional group interconversion gave l-CCG-III and trans-3,4-methano-l-proline with complete stereocontrol. Synthesis of other diastereomers of l-CCG and cis-3,4-methano-l-proline was accomplished by alteration of the 3,4-methanoglutamic acid framework via carboxycyclopropanation of the olefin with sulfur ylide and subsequent Barton decarboxylation reaction of the original γ-carboxyl
分别使用3,4-化合物开发了一种新的立体控制方法,用于分别合成1-谷氨酸和l-脯氨酸的构象受约束的1-(羧基环丙基)甘氨酸(1-CCGs)和3,4-甲基-1-脯氨酸。双脱氢-1-焦谷氨酸衍生物作为常见的手性模板。用于这项工作的不饱和1-焦谷氨酸衍生物是一种新型的手性合成子,其中羧基官能团被保护为2,7,8-三氧杂双环[3.2.1]辛基(ABO酯)。使用重氮甲烷对烯烃进行立体定向环丙烷化,然后进行适当的官能团互变,得到具有完全立体控制的1-CCG-III和反式-3,4-甲基-1-脯氨酸。l-CCG和顺式的其他非对映异构体的合成-3,4-甲基-1-脯氨酸是通过使烯烃与硫内酯进行羧基环丙烷化,以及随后焦焦谷氨酸骨架中所含原始γ-羧基的巴顿脱羧反应,来改变3,4-甲基谷氨酸骨架的方法。