A concise practical synthesis (13 steps, ca. 10-12% overall yield) of the unnatural enantiomer of castanospermine ((-)-1) and its 1-epimer 2 from 2,3,4-tri-O-benzyl-D-xylose (3) is described. Key steps in the synthesis are two organometal aldehyde additions, vinylation of 3 to 4 and allylation of 6a to 11, both of which proceed with a considerably high degree of stereocontrol. The fused ring system is generated from the acyclic amino polyol derivative 16a by two successive S(N)2-type cyclizations. Notably, the annulation of the six-membered ring makes use of tetravalent phosphonium reagents (Appel or Mitsunobu type) which cyclize the amino alcohol 22a/b directly to 23a/b without need for N-deprotection and O-activation manipulations.
N-Methyl-L-glucosaminic Acid<sup>1</sup>
作者:M. L. Wolfrom、Alva Thompson、I. J. Hooper
DOI:10.1021/ja01215a061
日期:1946.11
KO, SOO Y.;LEE, ALBERT W. M.;MASAMUNE, SATORU;REED, LAWRENCE A. (III);SHA+, TETRAHEDRON, 46,(1990) N, C. 245-264
作者:KO, SOO Y.、LEE, ALBERT W. M.、MASAMUNE, SATORU、REED, LAWRENCE A. (III)、SHA+
DOI:——
日期:——
Higgins M. K., Bly R. S., Morgan S. L., Fox A., Anal. Chem., 66 (1994) N 17, S 2656-2668