Chemo-, stereo- and regioselective hydrogenolysis of carbohydrate benzylidene acetals. Synthesis of benzyl ethers of benzyl α-d-, methyl β-D-mannopyranosides and benzyl α-D-rhamnopyranoside by ring cleavage of benzylidene derivatives with the LiAlH4-AlCl3 reagent
作者:András Lipták、János Imre、János Harangi、Pál Nánási、András Neszmélyi
DOI:10.1016/0040-4020(82)80083-5
日期:1982.1
Treatment of benzyl α-(1) and methyl β-d-mannopyranoside (2) with α,α-dimethoxytoluene gave the exo and endo isomers (3,5 and 4,6) of the dibenzylidene derivatives of 1 and 2. Hydrogenolysis of the exo isomers (3 and 5) with a molar equivalent of AlH2Cl gave the 3-0-benzyl-4,6-0-benzylidene derivatives (7 and 21), whereas the endo isomers (4 and 6) gave the 2-0-benzyl-4,6-0-benzylidene compounds (8
用α,α-二甲氧基甲苯处理苄基α-(1)和甲基β-d-甘露吡喃糖苷(2),得到1和2的二亚苄基衍生物的外向异构体和内向异构体(3,5和4,6)。用摩尔当量的AlH 2 Cl对外型异构体(3和5)进行氢解,得到3-0-苄基-4,6-0-亚苄基衍生物(7和21),而内消旋异构体(4和6)得到2-0-苄基-4,6-0-亚苄基化合物(8和22)。2-0烯丙基醚9的7,3-0烯丙基衍生物(10)的8和化合物21和22用的AlH的附加摩尔当量处理2在回流C1和产物的4-O-苄基-6-羟基衍生物(11、12、23和24),而在22的情况下,还分离出6-0-苄基-4-羟基异构体(25)。通过11和12的脱甲基,3,4-(13)和2,4-二-0-苄基(14)的醚。准备了1个。甲苯磺酸11和12的合成,以及随后产物的还原(15和16),使得部分受保护的苄基α-d-鼠李吡喃糖苷衍生物(17-20)的制备成为可能。合成的化合物的结构通过1