Synthetic Studies on Glycopeptides Concerned with Defense Response of Plants. I. Syntheses of Supprescins A and B.
作者:Takuya KANEMITSU、Yukio OGIHARA、Tadahiro TAKEDA
DOI:10.1248/cpb.45.643
日期:——
Two glycopeptides, supprescins A and B, that suppress the production of pisatin, a phytoalexin of pea, were synthesized. In the synthesis of supprescin A, condensation of 3, 4, 6-tri-O-acetyl-2-azido-2-deoxy-α-D-galactopyranosyl trichloroacetimidate or its glycosidic β isomer with N-(carbobenzoxy)-L-seryl-O-benzyl-L-seryl-glycine methyl ester was carried out in the presence of trimethylsilyl trifluoromethanesulfonate (TMSOTf) to give the monoglycosyl tripeptide derivatives. For the synthesis of supprescin B, glycosylation of 2, 3, 4, 6-tetra-O-acetyl-α-D-galactopyranosyl bromide and 1, 2, 3, 6-tetra-O-benzoyl-α-D-galactopyranose was promoted by silver trifluoromethanesulfonate (AgOTf) to provide a disaccharide derivative. The coupling of diglycosyl imidate, 2, 3, 4, 6-tetra-O-acetyl-β-D-galactopyranosyl-(1→4)-3, 6-di-O-benzoyl-2-azido-2-deoxy-D-galactopyranosyl trichloroacetimidate, and N-(carbobenzoxy)-L-seryl-O-benzyl-L-seryl-glycyl-4-benzyl-L-aspartyl-5-benzyl-L-glutamyl-O-benzyl-L-threonine methyl ester in the presence of TMSOTf afforded the diglycosyl hexapeptide derivatives. Reduction, followed by N-acetylation, and then removal of the remaining protecting groups afforded the desired supprescin B.
两种糖肽,抑制蛋白A和B,能够抑制豌豆中一种植物抗毒素——豌豆素的合成,它们已被制备出来。在制备抑制蛋白A的过程中,三甲基硅基三氟甲磺酸酯(TMSOTf)的存在下,将3,4,6-三-O-乙酰基-2-叠氮-2-脱氧-α-D-半乳糖吡喃糖基三氯乙酰亚胺酯或其糖苷β异构体与N-(羧基苄氧羰基)-L-丝氨酸-O-苄基-L-丝氨酰甘氨酸甲酯进行缩合反应,得到单糖基三肽衍生物。在制备抑制蛋白B的过程中,2,3,4,6-四-O-乙酰基-α-D-半乳糖吡喃糖基溴和1,2,3,6-四-O-苯甲酰基-α-D-半乳糖吡喃糖在三氟甲磺酸银(AgOTf)的促进下进行糖基化反应,生成二糖衍生物。在TMSOTf的存在下,将二糖基亚胺酯,2,3,4,6-四-O-乙酰基-β-D-半乳糖吡喃糖基-(1→4)-3,6-二-O-苯甲酰基-2-叠氮-2-脱氧-D-半乳糖吡喃糖基三氯乙酰亚胺酯与N-(羧基苄氧羰基)-L-丝氨酸-O-苄基-L-丝氨酰甘氨酰-4-苄基-L-天冬氨酰-5-苄基-L-谷氨酰-O-苄基-L-苏氨酸甲酯进行偶联反应,得到二糖基六肽衍生物。随后进行还原、N-乙酰化和剩余保护基团的去除,最终得到了所需的抑制蛋白B。