Synthesis of <i>C</i>-Septanosides from Pyranoses via Vinyl Addition and Electrophilic Cyclization
作者:Raghu Vannam、Mark W. Peczuh
DOI:10.1021/ol401769k
日期:2013.8.16
A two-step synthesis of C-septanosides from pyranoses is reported. Vinyl addition to tetra-O-benzyl d-glucose, d-galactose, and d-mannose gave the corresponding allylic alcohols. Electrophilic cyclization followed by treatment with iodine gave iodomethyl C-septanosides suitable for substitution reactions. The cyclizations were diastereoselective, giving cis-1,2 configured C-septanosides. Selectivity
据报道,由吡喃糖苷酶分两步合成C-庚糖苷。在四-O-苄基d-葡萄糖,d-半乳糖和d-甘露糖上加乙烯基得到相应的烯丙基醇。亲电环化,然后用碘处理,得到适合于取代反应的碘甲基C-庚糖苷。环化是非对映选择性的,得到顺式-1,2构型的C-庚糖苷。选择性通过亲电加成模型合理化,该模型可调用烯丙基系统的构象。这种新方法通常应适用于各种C-庚糖苷的合成。