Pd-Catalyzed Umpolung Chemistry of Glycal Acetates and Their [2,3]-Dehydrosugar Isomers
作者:Juyeol Lee、Young Ho Rhee
DOI:10.1021/acs.orglett.1c04004
日期:2022.1.21
Glycals and their [2,3]-dehydrosugar derivatives have commonly been used in synthetic chemistry as electrophiles. Here we report a Pd-catalyzed polar inversion (umpolung) of this reaction, where the glycals and isomers can be used as nucleophiles. The reaction showed high regio- and stereoselectivity in the presence of numerous aromatic and aliphatic aldehydes. The synthetic utility of this reaction
The application of an efficientglycosylation methodology using 2,3-unsaturated sugars to synthesize critical precursors required for the totalsynthesis of an antibiotic, vineomycin B2 (1), was demonstrated. The required disaccharide, the acurosyl rhodinose derivative of 1, was prepared by chemoselective glycosylation using a 2,3-saturated glycosyl acetate corresponding to the rhodinose moiety and
证明了使用有效的糖基化方法的应用,该方法使用2,3-不饱和糖来合成抗生素vinevinecin B 2(1)的总合成所需的关键前体。所需的二糖,即1的氨基磺基罗丹糖衍生物,是通过化学选择糖基化反应制得的,使用的化学成分为2,3-饱和的糖基乙酸酯,对应于若丹糖部分; 2,3-的不饱和乙酸基糖基乙酸酯,对应于核糖部分。此外,由β-氧代叔醇和若丹糖组成的1的右侧链是通过在离子液体中减压下使用2,3-不饱和乙酸糖基酯通过强力的糖基化方法构建的。
The first totalsynthesis of vineomycinB2 (1) has been accomplished. The aglycon segment, a vineomycinone B2 derivative, and the glycon segment, an α-L-acurosyl-L-rhodinose derivative, were prepared via C-glycosylation using an unprotected sugar and powerful chemoselective O-glycosylation using a 2,3-unsaturated sugar, respectively, as the key steps. Furthermore, effective and simultaneous introduction
Stereoselective Synthesis of β-<scp>d</scp>-Manno-heptopyranoside via Cs<sub>2</sub>CO<sub>3</sub>-Mediated Anomeric <i>O</i>-Alkylation: Synthesis of a Tetrasaccharide Repeat Unit of <i>Bacillus thermoaerophilus</i> Surface-Layer Glycoprotein
Stereoselectivesynthesis of d-glycero- and l-glycero-β-d-mannoheptosides has been achieved by cesium carbonate-mediated β-selective anomericO-alkylation of the corresponding d-mannoheptoses. In addition, this method has been utilized in the total synthesis of a tetrasaccharide repeat unit of Bacillus thermoaerophilus surface-layer glycoprotein.
Mitsunobu reactions of glycals with phenoxide nucleophiles are SN2′-selective
作者:Aditya Sobti、Gary A. Sulikowski
DOI:10.1016/s0040-4039(00)73065-6
日期:1994.5
The C-3-hydroxyl group of L-rhamnal (4) and D-glucal 7 underwent S(N)2'-selective Mitsunobu displacements with substituted phenoxide nucleophiles. These reactions provide access to the corresponding alpha-arylglycoside.