5-Deoxy-5-phosphinyl-£>-xylopyranoses

Reduction of 10 with lithium aluminum hydride (LAH) in ether furnished19 an intermediate, presumably the phosphine derivative 11, which was treated with acid to effect ring enlargement, giving the 5-phosphino-D-xylopyranose derivative 14. This compound was immediately converted by air oxidation19 into the stable crystalline compounds, 5-deoxy-3-0-methyl-5-C-(phosphinyl)-D-xylopyranose (15) and the 5-C-(hydroxyphosphinyl) derivative 16 in overall yields of 15 and 3.5%, respectively, from 10. Compound 16 was obtained in 90% yield from 15 by oxidation with bromine.19 No mutarotation was observed19 for compounds 15 and 16 in water during 48 h. 

Besides the four diastereoisomers 19-22, a small proportion of a byproduct was isolated (2.7% overall yield from 10), to which structure 23, namely, 5-C-[(R)-(l-acetoxyethenyl)phosphinyl]-l,2,4-tri-0-acetyl-5-deoxy-S-O-methyl- -D-xylopyranose-4, was assigned24 from the... 

These results,23 therefore, provided further proof for the formation of 5-deoxy-5-C-(phosphinyl)- and -(hydroxyphosphinyl)-D-xylopyranoses (15 and 16) from the 5-phosphinyl-D-xylofuranose precursor 10. 

Other than the 5-deoxy-5-phosphinyl-D-xylopyranoses described in the previous Subsection, there has been reported35 only one example of a different type of 5-deoxy-5-phosphinylpentopyranose. 

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