Synthesis and analysis of the sterically constrained l-glutamine analogues (3S,4R)-3,4-dimethyl-l-glutamine and (3S,4R)-3,4-dimethyl-l-pyroglutamic acid
作者:Cristina M Acevedo、Eugene F Kogut、Mark A Lipton
DOI:10.1016/s0040-4020(01)00501-4
日期:2001.7
in the cyclic depsipeptides callipeltin B, callipeltin A, and papuamide A—were synthesized from a common intermediate derived from l-pyroglutamic acid. The diastereoselective introduction of the methyl groups was accomplished by cuprate addition and enolate alkylation, followed by a kinetic epimerization of the C-4 methyl substituent. (3S,4R)-3,4-Dimethyl-l-glutamine shows a conformational restriction
非环状氨基酸(3 S,4 R)-3,4-二甲基-1-焦谷氨酸和(3 S,4 R)-3,4-二甲基-1-谷氨酰胺-存在于环状大肽肽callipeltin B,callipeltin中A和木瓜酰胺A-是由衍生自1-焦谷氨酸的常见中间体合成的。甲基的非对映选择性引入是通过铜酸酯加成和烯醇化烷基化,然后是C-4甲基取代基的动力学差向异构化来实现的。(3 S,4 R)-3,4-二甲基-1-谷氨酰胺显示侧链的构象限制,这可能与其在天然产物中的生物学功能有关。