Enantioselective Ruthenium-Catalyzed 1,3-Dipolar Cycloadditions between <i>C</i>-Carboalkoxy Ketonitrones and Methacrolein: Solvent Effect on Reaction Selectivity and Its Rational
作者:Khalid B. Selim、Arnaud Martel、Mathieu Y. Laurent、Jérôme Lhoste、Sandrine Py、Gilles Dujardin
DOI:10.1021/jo5001737
日期:2014.4.18
A catalytic 1,3-dipolarcycloaddition between carboalkoxy ketonitrones and methacrolein under the effect of chiral ruthenium Lewis acid (R,R-1) was developed with high regio-, diastereo-, and enantiocontrol. The diastereochemical outcome of the cycloaddition reaction is marked by a significant solvent effect, and a divergent endo or exo control can be tuned by an appropriate choice of both the solvent
Isoxazolidine nucleosides bearing an hydroxyl group at C3, have been prepared in only three steps, with overall high yields. The synthetic approach is based on the 1,3-dipolar cycloaddition of 3-carboxyalkyl- or acylnitrones to vinyl acetate, followed by condensation with silylated thymine or 5-fluorouracil and NaBH4 reduction.