ISSN:
0018-019X
Keywords:
Chemistry
;
Organic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
A preparation of glycosylphosphonates (27, 28, 36, 38, and 39) from 2-azido-2-deoxy-glycoses (26,35, and 37) and the synthesis of the non-isosteric phosphonate analogue 3a of lipid X(2) are described. The 2-azido group was introduced by azidonitration. Treatment of the 1-O-acetyl-2-azido-2-deoxy-β-D-galactopyranose 22 with 1.5-3 equiv. of P(OMe)3 and 1.2-2.5 equiv. of TfOSiMe3 gave mainly recovered starting material. In P(OMe)3 as the solvent, the dimethyl phosphoramidate 24 was obtained by way of a Staudinger reaction, even in the presence of TfOSiMe3. Treatment of the benzylated α-D-galacto-trichloroacetimidate 26, however, with P(OMe)3 and TfOSiMe3 gave a 1:1 mixture of the α- and β-D-galacto-phosphonates 27 and 28, while the acetylated α-D-gluco- imidate 35 led to the α-D-gluco-configurated phosphonate 36. The stereoselectivity of the phosphonate formation is related to the relative ease of formation of oxonium-ion intermediates from 26 and 35. Starting from the phosphonate 36, deacetylation, benzylidenation, reduction of the azido group, acylation with (R)-3-(benzyloxy)tetradecanoic acid and deprotection yielded the desired compound 3a which was crystallized in the presence of 2 equiv. of (aminomethylidyne)trimethanol (Tris.). The structure of the phosphonates was deduced from their 1H-, 13C-, and 31P-NMR spectra.
Additional Material:
2 Tab.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/hlca.19870700516
