Preparation and Transmetallation of a Triphenylstannyl ?-D-Glucopyranoside: A highly stereoselective route to ?-D-C-glycosidesvia glycosyl dianions
作者:Oliver Frey、Matthias Hoffmann、Valentin Wittmann、Horst Kessler、Peter Uhlmann、Andrea Vasella
DOI:10.1002/hlca.19940770730
日期:1994.11.2
The triphenylstannyl β-D-glucopyranoside 4 was synthesized in one step from the 1,2-anhydro-α-D-glucopyranose 3 with (triphenylstannyl)lithium (Scheme 1). Transmetallation of 4 with excess BuLi, followed by quenching the dianion 7 with CD3OD gave (1S)-1,5-anhydro-3,4,6-tri-O-benzyl-[1-2H]-D- glucitol (8) in 81% yield (Scheme 2). Trapping of 7 with benzaldehyde, isobutyraldehyde, or acroleine gave the
由1,2-脱水-α-D-吡喃葡萄糖3与(三苯基锡烷基)锂一步合成三苯基锡烷基β-D-吡喃葡萄糖苷4(方案1)。的金属转移4用过量的丁基锂,随后淬火二价阴离子7与CD 3 OD,得到(1个小号)-1,5-脱水-3,4,6-三ö苄基- [1- 2 H] -D-葡萄糖醇(8),产率为81%(方案2)。用苯甲醛,异丁醛或丙烯醛诱捕7得到预期的β-D构型的产物11、12和13丰产。由酰基氯例如乙酰基或苯甲酰氯制备C-酰基糖苷是不可行的,但是将苯甲腈添加到7中产生84%的苯甲酰化产物14。用MeI处理7导致15(30%)以及18的40%,C-烷基化伴随卤素-金属交换。预先加入锂2- thienylcyanocuprate的的产率增加15%至50%,并使用硫酸二甲酯代替将MeI导致77%15。除了使用烯丙基溴作为亲电试剂以外,没有检测到α-D-异头物,它以1:1的异构体混合物形式生成16和17。