Stereoelectronic Control in Regioselective Carbohydrate Protection

详细信息    查看全文

• 作者：Hai Dong ; Yixuan Zhou ; Xiaoliang Pan ; Fengchao Cui ; Wei Liu ; Jingyao Liu ; Olof Ramstr枚m
• 刊名：The Journal of Organic Chemistry
• 出版年：2012
• 出版时间：February 3, 2012
• 年：2012
• 卷：77
• 期：3
• 页码：1457-1467
• 全文大小：613K
• 年卷期：v.77,no.3(February 3, 2012)
• ISSN：1520-6904

文摘

Organotin-mediated regioselective protection has been extensively used in organic synthesis for many years. However, the mechanistic origin of the resulting regioselectivity is still not clear. By the comparison of the steric and stereoelectronic effects controlling the geometry of five-membered rings formed from neighboring group participation, from intramolecular acyl group migration, or from orthoester transesterification on pyranoside rings, a theory on the pattern resulting from the reaction with dibutyltin oxide is presented. It is thus suggested that the regioselectivity of organotin-mediated protection is controlled by analogous steric and stereoelectronic effects as in neighboring group participation and acyl group migration, mainly dependent on the stereoelectronic effects of the pyranoside itself, and not related to complex stannylene structures. An organotin protection mechanism is also suggested, emanating from steric and stereoelectronic effects, nucleophilicity, and organotin acyl migration.