Rapid Preparation of Variously Protected Glycals Using Titanium(III)
摘要:
Glycosyl chlorides and bromides can be rapidly converted to glycals in high yield by reaction with (Cp2Ti[III]Cl)(2). This reagent tolerates a wide range of common carbohydrate protecting groups, including silyl ethers, acetals, and esters; the methodology provides a general route for the preparation of glycals substituted with both acid- and base-labile functionality. A reaction mechanism is proposed that is based on heteroatom abstraction to give an intermediate glycosyl radical. This radical reacts with a second equivalent of Ti(III) to yield a glycosyltitanium(IV) species. P-Heteroatom elimination from the glycosyltitanium(IV) complex gives the glycal.
Chemoselective and Diastereoselective Synthesis of
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‐Aryl Nucleoside Analogues by Nickel‐Catalyzed Cross‐Coupling of Furanosyl Acetates with Aryl Iodides
作者:Yuxi Li、Zheng Wang、Luyang Li、Xiaoying Tian、Feng Shao、Chao Li
DOI:10.1002/anie.202110391
日期:2022.1.3
The facile synthesis of C-aryl nucleoside analogues from readily available furanose acetates and aryl iodides is disclosed. This nickel-catalyzed cross-electrophile coupling showed good functional-group compatibility and excellent β-selectivity. The high chemoselectivity with respect to aryl iodides enabled the efficient preparation of a variety of C-aryl halide furanosides suitable for various po