Keglević D, Kojić-Prodić B, Banić Z, Tomić S, Puntarec V
Rudjer Bosković Institute, Zagreb, Croatia.
Carbohydr Res. 1993 Mar 17;241:131-52. doi: 10.1016/0008-6215(93)80101-j.
1,6-Anhydro-4-O-benzyl-beta-muramic acid 1',2-lactam (2) was prepared by reduction of 1,6-anhydro-2-azido-4-O-benzyl-2-deoxy-3-O-[(R)-1- methoxycarbonylethyl]-beta-D-glucopyranose (1) followed by cyclisation. Debenzylation of 2 (-->3) and glycosylation of HO-4 with 3,4,6-tri-O-acetyl-2- deoxy-2-phthalimido-beta-D-glucopyranosyl chloride afforded 75% of a beta-(1-->4)-linked disaccharide derivative (7). Removal of the Phth group from 7, then acetylation, and O-deacetylation yielded 4-O-(2-acetamido-2-deoxy-beta-D-glucopyranosyl)-2-amino-1,6-anhydro-3-O- [(R)- 1-carboxyethyl]-2-deoxy-beta-D-glucopyranose 1',2-lactam (10) Acetolysis of the 1,6-anhydro ring in the 4-acetate (4) of 3 and the 3',4',6'-triacetate (9) of 10, with saponification of the products 5 and 11, afforded 2-amino-3-O- [(R)-1-carboxyethyl]-2-deoxy-D-glucopyranose 1',2-lactam (6) and 4-O-(2-acetamido-2-deoxy-beta-D-glucopyranosyl)-2-amino-3- O-[(R)-1-carboxyethyl]-2-deoxy-beta-D-glucopyranose 1',2-lactam (12), respectively. The structure of 12 corresponds to that of the disaccharide unit characteristic of the glycan chains of bacterial spore peptidoglycan. 1H NMR spectroscopy indicated that the beta-D-glucopyranose ring in the 1,6-anhydro 1',2-lactam derivatives adopts the BO,3 conformation. On cleavage of the 1,6-anhydro ring by acetolysis, the D-glucopyranose ring adopts the 4C1 conformation. X-ray analysis of 2, 4, and 5 confirmed the proposed structures. Molecular mechanics and molecular dynamics simulations were used to follow the transformation of the BO,3 conformation of the D-glucopyranose ring via transition states to the 4C1 form.
1,6-脱水-4-O-苄基-β-胞壁酸1',2-内酰胺（2）是通过还原1,6-脱水-2-叠氮基-4-O-苄基-2-脱氧-3-O-[(R)-1-甲氧基羰基乙基]-β-D-吡喃葡萄糖（1）然后环化制备的。2（→3）的脱苄基反应以及HO-4与3,4,6-三-O-乙酰基-2-脱氧-2-邻苯二甲酰亚氨基-β-D-吡喃葡萄糖基氯的糖基化反应得到了75%的β-(1→4)-连接的二糖衍生物（7）。从7中除去邻苯二甲酰基，然后进行乙酰化和O-脱乙酰化反应，得到4-O-(2-乙酰氨基-2-脱氧-β-D-吡喃葡萄糖基)-2-氨基-1,6-脱水-3-O-[(R)-1-羧基乙基]-2-脱氧-β-D-吡喃葡萄糖1',2-内酰胺（10）。3的4-乙酸酯（4）和10的3',4',6'-三乙酸酯（9）中1,6-脱水环的乙酰解反应，以及产物5和11的皂化反应，分别得到了-2-氨基-3-O-[(R)-1-羧基乙基]-2-脱氧-D-吡喃葡萄糖1',2-内酰胺（6）和4-O-(2-乙酰氨基-2-脱氧-β-D-吡喃葡萄糖基)-2-氨基-3-O-[(R)-1-羧基乙基]-2-脱氧-β-D-吡喃葡萄糖1',2-内酰胺（12）。12的结构与细菌芽孢肽聚糖聚糖链特征性二糖单元的结构相对应。1H NMR光谱表明，1,6-脱水1',2-内酰胺衍生物中的β-D-吡喃葡萄糖环采用BO,3构象。通过乙酰解裂解1,6-脱水环时，D-吡喃葡萄糖环采用4C1构象。对2、4和5的X射线分析证实了所提出的结构。使用分子力学和分子动力学模拟来跟踪D-吡喃葡萄糖环从BO,3构象通过过渡态转变为4C1形式的过程。
