Synthesis and Structural Analysis of 5-Deoxy-5-[(<i>R</i>)- and (<i>S</i>)-methylphosphinyl]-α,β-<scp>d</scp>-manno- and -<scp>l</scp>-gulopyranoses

Abstract

Abstract Methyl 5,6-dideoxy-2,3-O-isopropylidene-6-nitro-α-d-lyxo-hex-5-enofuranoside (10) was prepared from d-mannose in 7 steps. Addition of methyl methylphosphinate to 10, followed by the catalytic hydrogenation and diazotization, afforded methyl 5-deoxy-2,3-O-isopropylidene-5-[(methoxy)methylphosphinyl]-α-d-lyxo-hexofuranoside, which was then converted into 6-O-triphenylmethyl and 6-O-tetrahydropyranyl derivatives (14, 15). By reduction with sodium dihydrobis(2-methoxyethoxy)aluminate, followed by acid hydrolysis, both 14 and 15 provided the d-mannopyranoses (together with a minor proportion of l-gulopyranoses) having a methylphosphinylidene group in place of the ring oxygen. These were converted into 1,2,3,4,6-penta-O-acetyl derivatives, whose structures and conformations were established by spectroscopy.