Efficient synthesis of 2,6,7,8-tetrahydroxyindolizidines (castanospermine analogues) via the dipolar cycloadditions of N-benzyl-C-(tetrofuranos-4-yl)nitrones to methyl acrylate
作者:Ma Isabel Torres-Sánchez、Pastora Borrachero、Francisca Cabrera-Escribano、Manuel Gómez-Guillén、Manuel Angulo-Álvarez、Eleuterio Álvarez、Sylvain Favre、Pierre Vogel
DOI:10.1016/j.tetasy.2007.08.001
日期:2007.8
The dipolar cycloaddition of (Z) -N-benzyl-(3-O-benzy]-1,2-O-isopropylidene-alpha-D-ribofuranos-5-ylidene)amin e N-oxide to methyl acrylate gives a 53:16:26:5 diastereomeric mixture of isoxazolidine derivatives. The dipolar cycloaddition of the xylo analogue to methyl acrylate is more diastereoselective, producing a 44:13:43 mixture of only three diastereomers. The ribo-configured adducts have been converted (4 steps only) into the new (2R,6S,7S,8R,8aR)-, (2S,6S,7S,8R,8aR)-, (2S,6S,7S,8R,8aS)- and (2R,6S,7S,8R,8aS)-2,6,7,8-tetrahydroxyindolizidines. Similarly, the two xylo-configured major isoxazolidine derivatives were converted into the known derivatives (2R,6S,7R,8R,8aS)- and (2S,6S,7R,8R,8aR)-2,6,7,8-tetrahydroxyindolizidines. The six isomeric indolizidine derivatives obtained have been evaluated for their inhibiting activities towards 15 glycosidases. Only the (2R,6S,7S,8R,8aR)-configured isomer is a selective inhibitor of amyloglucosidases from Aspergillus niger (IC50 = 350 mu M) and,from Rhizopus mold (IC50 = 90 mu M, K-i = 195 mu M, non-competitive), the other indolizidines show very little inhibitory activity at 1 mM concentration. (C) 2007 Elsevier Ltd. All rights reserved.