Stereoselective Pd-Catalyzed Synthesis of Quaternary α-<scp>d</scp>-<i>C</i>-Mannosyl-(<i>S</i>)-amino Acids
作者:Marcello Di Giacomo、Massimo Serra、Marco Brusasca、Lino Colombo
DOI:10.1021/jo2002962
日期:2011.7.1
α-d-C-mannosyl-(S)-amino acids were obtained in a few steps comprising highly diastereoselective dihydroxylation of the glucal derivative double bond followed by the one-pot hydrolysis of the benzamido and acetate protecting groups. Main features of this method are the conciseness of the synthetic sequence, the high diastereoselection of the allylic alkylation step, the use of racemic α-amino acids as starting
在本文中,我们报告了α- d - C-甘露糖基- (S)-氨基酸的立体选择性合成方法,该方法利用关键步骤,通过氧化法制备了糖基衍生的π-烯丙基Pd(II)中间体的烯丙基烷基化反应。 Pd(0)物种添加到2,3-不饱和吡喃糖苷(伪糖)。4,6-二-O-乙酰基α-伪葡聚糖碳酸酯10a与外消旋的丙氨酸,缬氨酸和苯丙氨酸衍生的内酯反应得到相应的(4 S)-4-α- d - C-甘露糖基-2-苯恶唑-5(4 H)-ones是主要的非对映异构体,高收率。最终的α- d - C-甘露糖基-(在几个步骤中获得S)-氨基酸,包括对葡糖衍生物双键的高度非对映选择性二羟基化,然后对苯甲酰胺基和乙酸酯保护基进行一锅法水解。该方法的主要特征是合成顺序的简洁性,烯丙基烷基化步骤的高非对映选择性,使用外消旋α-氨基酸作为起始原料以及良好的总收率。