2-Nitro-thioglycosides: α- and β-Selective Generation and Their Potential as β-Selective Glycosyl Donors
摘要:
Michael-type addition of thiolates to 2-nitro-D-glucal or to 2-nitro-D-galactal derivatives readily provides 2-deoxy-2-nitro-1-thioglycosides. Kinetic and thermodynamic reaction control permitted formation of either the alpha- or preferentially the beta-anomers, respectively. Addition of achiral and chiral thiourea derivatives to the reaction mixture increased the reaction rate; the outcome is substrate-controlled. The 2-deoxy-2-nitro-1-thioglycosides are excellent glycosyl donors under arylsulfenyl chloride/silver triflate (ArSCl/AgOTf) activation, and they provide, anchimerically assisted by the nitro group, mostly beta-glycosides.
2-Nitro Thioglycoside Donors: Versatile Precursors of β-<scp>d</scp>-Glycosides of Aminosugars
作者:Nadine Barroca、Richard R. Schmidt
DOI:10.1021/ol049729t
日期:2004.5.1
2-Nitro thioglycosides can be prepared by the Michael addition of thiophenol to 2-nitroglycal derivatives. NIS/TMSOTf activation of these 2-nitro thioglycosides, in the presence of alcohols, rapidly and cleanly led to the desired glycosides in good yield and beta-selectivity. Reduction of the nitro group allowed generation of the corresponding 2-acetamido glycosides.