A robust selective allylation of 1-methyl-l-α-rhamnose was developed using di-n-butyltin oxide (n-Bu₂SnO) as the catalyst. Proton sponge was found to be the optimal base for high regioselective control. The optimized condition afforded the 3-O-allylated rhamnose in excellent regioselectivity (>20:1) and 82% isolated yield on a 50 g scale. A scalable isolation/purification process was developed which afforded the desired product in 72% yield with 1530 ppm of Sn. The residual Sn level can be further reduced to <20 ppm by treatment with scavengers. This catalytic system also showed outstanding potential in the selective benzylation of the same substrate.

中文翻译：

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1-甲基-1-α-鼠李糖吡喃糖苷的可扩展Sn催化区域选择性烯丙基化

1-甲基的鲁棒选择性烯丙基化升-α鼠李糖用二开发Ñ -butyltin氧化物（Ñ -Bu ₂的SnO）作为催化剂。发现质子海绵是高区域选择性控制的最佳基础。优化的条件提供了3- O-烯丙基鼠李糖，具有出色的区域选择性（> 20：1），并且在50 g规模下分离产率为82％。开发了可扩展的分离/纯化工艺，该工艺以72％的收率提供了1530 ppm的Sn所需的产品。通过用清除剂处理，残余的锡含量可以进一步降低到<20 ppm。该催化体系在相同底物的选择性苄基化反应中也显示出突出的潜力。