2-Nitro Thioglycoside Donors: Versatile Precursors of β-d-Glycosides of Aminosugars
摘要:
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.
An efficient N-heterocycliccarbenecatalyzed glycosylation of 2-nitrogalactals with alcohols and phenol has been developed for the first time. A wide variety of 1,2-cis-2-nitroglycosides can be obtained with good to excellent yields and high to excellent α-selectivities.
An Efficient Route toward 2-Amino-β-<scp>d</scp>-galacto- and -glucopyranosides via Stereoselective Michael-Type Addition of 2-Nitroglycals
作者:Weihua Xue、Jiansong Sun、Biao Yu
DOI:10.1021/jo900609s
日期:2009.7.17
Under the catalysis of DMAP or PPY in CH2Cl2, the Michael-typeaddition of nucleophiles to 2-nitrogalactal or 2-nitroglucal leads in excellent yields and stereoselectivity to the corresponding β-galacto- or -glucopyranosides, which are ready precursors to the biologically significant β-d-galactosamine and -glucosamine units.