Synthesis of the 2-Deoxyisomaltose Analogue of Acarbose by an Improved Route to Chiral Valieneamines
作者:Tina M. Tagmose、Mikael Bols
DOI:10.1002/chem.19970030318
日期:——
A 2-deoxyisomaltose analogue of acarbose was stereoselectively synthesised in 11 steps with a total yield of 7% starting from 2,6-dibromo-2, 6-dideoxy-D-mannono-1,4-lactone (6). The latter was reduced to the lactol, converted to the methyl glycoside (7) and hydrogenated to the methyl 6-bromo-2,6-dideoxyglycoside (8). Benzylation of the hydroxy groups, elimination of bromine to a 5-ene and Ferrier carbocyclisation
从 2,6-dibromo-2, 6-dideoxy-D-mannono-1,4-lactone (6) 开始,通过 11 个步骤立体选择性合成了阿卡波糖的 2-脱氧异麦芽糖类似物,总收率为 7%。后者被还原为乳醇,转化为甲基糖苷 (7) 并氢化为甲基 6-溴-2,6-二脱氧糖苷 (8)。羟基的苄基化,溴消除成 5-烯和 Ferrier 碳环化得到 (2S, 3R)-2,3-bisbenzyloxycyclohex-5-enone (12)。在 –110°C 下 1, 2-加成苄氧基甲基锂得到叔醇 13 的 6:1 混合物;(1S) 异构体是主要的异构体。与异氰酸三氯乙酰酯反应得到氨基甲酸酯 19,当它脱水成氰酸酯时,自发地进行 [1,3] σ 重排成异氰酸酯,在加入甲醇后得到氨基甲酸甲酯 20。