2-Haloethyl 1-thioglycosides are excellent leaving groups when the 2-haloethyl function is activated with silver salts or Lewis acids. These thioglycosides can be synthesized on the original Černý route or for better compatibility with the needs of a more complex glycoside synthesis, in stepwise procedures via 2-(2-tetrahydropyran-2-yloxy)ethyl glycosides or trityl 1-thioglycosides. The initial step in glycosidation reaction presumably proceeds via a thiiranium ion, which is responsible for their increased reactivity compared with normal thioethers as leaving groups in glycoside syntheses. Basic features of this new system with respect to reactivity and selectivity in disaccharide syntheses are described.
2-卤乙基1-硫代糖苷在2-卤乙基功能被银盐或Lewis酸激活时是优秀的离去基团。这些硫代糖苷可以在原始Černý路线上合成,或者为了更复杂的糖苷合成需求与之更兼容,在通过2-(2-四氢吡喃-2-氧基)乙基糖苷或三苯基1-硫代糖苷的逐步程序中合成。糖苷化反应的初始步骤可能通过硫代环氧离子进行,这对于它们在糖苷合成中作为离去基团的反应性增加具有责任。描述了这种新系统在二糖合成中的反应性和选择性的基本特征。