Stereoselective <i>N</i>-Glycosylation of 2-Deoxythioribosides for Fluorescent Nucleoside Synthesis
                                
                                    
                                        作者:Guillaume Mata、Nathan W. Luedtke                                    
                                    
                                        DOI:10.1021/jo3014929
                                    
                                    
                                        日期:2012.10.19
                                    
                                    An efficient method for the N-2-deoxyribosylation of modified nucleobases by 2-deoxythioriboside donors is reported. In the presence of an in situ silylated nudeobase, thioglycosides can be activated with NIS/HOTf to give nucleosides in high yields and with good beta-selectivity. By tuning the protecting groups on the C3 and CS hydroxyls, alpha/beta ratios ranging from 1.0:4.0 to 4.5:1.0 can be obtained. This strategy is applicable to the synthesis of various nucleosides, including ring-expanded pyrimidine derivatives containing sulfur that have previously been reported in low yields. The utility of this approach is further demonstrated by the synthesis of fluorescent nucleosides analogues such as quinazoline and oxophenothiazine that should find broad utility in DNA-folding and recognition studies.