Chiroptical properties of tetrahydropyran-3,4-diols and 2-hydroxymethyltetrahydropyran-3-ols derived from l-arabinose, d-galactose, d-glucose, and d-xylose, and enantioselectivity in reduction with their complexes
lithium aluminium hydride has been studied. Low enantiomeric excess (⩽15%) was obtained, which was enhanced when an achiral modifier (ethanol, 2-propanol) was added to the complexes 10 and 11 prepared in situ . Enantioselective catalytic hydrogenation of Z -α-acetamidocinnamic acid was performed with the Rh(I)-norbornadiene complexes 2f and 4f , derived from the cis compounds 2a and 4a ; substantially
A simple and easy method for chemoselectivesynthesis of hexopyranosyl acetates and 2,3-disubstituted tetrahydropyrans from hex-2-enopyranosyl acetates was demonstrated. The former was achieved by hydrogenation catalyzed by Rh/Al2O3 in EtOAc/toluene solvent at 0 °C, while the latter was carried out using Pd/C in EtOH/AcOH at 25 °C.
展示了一种简单易行的方法,用于从乙酸-2-烯并吡喃糖基乙酸酯化学选择性合成乙酸己吡喃酯基乙酸酯和2,3-二取代的四氢吡喃。前者是通过Rh / Al 2 O 3在EtOAc /甲苯溶剂中于0°C催化氢化而实现的,而后者是通过Pd / C在25°C的EtOH / AcOH中进行的。