Cortezano-Arellano Omar, Meléndez-Becerra Camilo A, Cortés Fernando, Sartillo-Piscil Fernando, Cordero-Vargas Alejandro
Instituto de Química, Universidad Nacional Autónoma de México, Circuito exterior s/n, Ciudad Universitaria, 04510 México, D.F., Mexico.
Centro Conjunto de Investigación en Química Sustentable UAEMex-UNAM, carretera Toluca-Atlacomulco Km 14.5, Toluca 50200, Mexico.
Carbohydr Res. 2014 Jul 1;393:51-9. doi: 10.1016/j.carres.2014.04.005. Epub 2014 Apr 13.
Stereoselectivity in the C-glycosidation of lactones derived from D-fucose by following Kishi's method, which involves the addition of a nucleophile onto a carbohydrate-derived lactone and subsequent reduction of the lactol, was found to be reliant on the nature of the C2 and C3 protective groups. Lactones bearing TBDMS protecting groups selectively afford 1,3-trans products (α anomer), in which the stereoselective outcome is in apparent concordance with Woerpel's model. On the other hand, their benzylated congeners produce the 1,3-cis products (β anomer) as the major diastereoisomers. The latter results suggest an abnormal behavior during the stereoselective nucleophilic substitution at the anomeric position of the benzylated lactones.
通过遵循岸义人的方法对源自D-岩藻糖的内酯进行C-糖苷化反应时的立体选择性被发现依赖于C2和C3保护基的性质。该方法涉及向碳水化合物衍生的内酯上添加亲核试剂，随后还原内酯醇。带有叔丁基二甲基硅烷基（TBDMS）保护基的内酯选择性地生成1,3-反式产物（α异头物），其立体选择性结果与沃尔佩尔模型明显一致。另一方面，它们的苄基化类似物则以1,3-顺式产物（β异头物）作为主要非对映异构体。后一结果表明在苄基化内酯的异头位置进行立体选择性亲核取代过程中存在异常行为。
