Highly Selective β-Mannosylations and β-Rhamnosylations Catalyzed by Bis-thiourea
                                
                                    
                                        作者:Qiuhan Li、Samuel M. Levi、Eric N. Jacobsen                                    
                                    
                                        DOI:10.1021/jacs.0c04255
                                    
                                    
                                        日期:2020.7.8
                                    
                                    We report highly beta-selective bis-thioureas-catalyzed 1,2-cis-O-pyranosylations employing easily accessible acetonide-protected donors. A wide variety of alcohol nucleophiles, including complex natural products, glycosides, and amino acids were beta-mannosylated and beta-rhamnosylated successfully using an operationally simple protocol under mild and neutral conditions. Less nucleophilic acceptors such as phenols were also glycosylated efficiently in excellent yields and with high beta-selectivities.