Lewis acid stereocontrolled additions of a silyl ketene acetal to 2,3-di-O-isopropylidene-d-glyceraldehyde nitrones. Synthesis of l-isoxazolidinyl nucleosides
作者:Pedro Merino、Eva M del Alamo、Maite Bona、Santiago Franco、Francisco L Merchan、Tomas Tejero、Odile Vieceli
DOI:10.1016/s0040-4039(00)01674-9
日期:2000.11
The reaction of O-methyl-O-tert-butyldimethylsilyl keteneacetal with N-benzyl and N-methyl-2,3-O-isopropylidene-d-glyceraldehyde nitrones in the presence of boron trifluoride etherate afforded the corresponding isoxazolidin-5-ones in excellent yields and anti-selectivities. The obtained compounds were used as key intermediates for the synthesis of isoxazolidinyl nucleosides of the l-series.
Stereoselective synthesis of l -isoxazolidinyl thymidine from N -benzyl-1,2-di- O -isopropylidene- d -glyceraldehyde nitrone (BIGN)
作者:Pedro Merino、Eva M del Alamo、Santiago Franco、Francisco L Merchan、Ana Simon、Tomas Tejero
DOI:10.1016/s0957-4166(00)00094-x
日期:2000.4
A synthetic approach to L-isoxazolidinyl nucleosides is demonstrated by the stereoselective conversion of N-benzyl-1,2-di-O-isopropylidene-D-glyceraldehyde nitrone (BIGN) into cis and trans L-isoxazolidinyl thymidine. The methodology consists of the 1,3-dipolar cycloaddition of BIGN with either vinyl acetate or a vinyl base to give key intermediates that are easily transformed into the target compound. The experimental results of the cycloaddition reactions can be qualitatively explained by theoretical ab initio calculations. (C) 2000 Elsevier Science Ltd. All rights reserved.