2-Diphenylarsino-, 2-diphenylphosphinyl-, and 2-triphenylstannyl-derivatives of methyl 4,6-O-benzylidene-2-deoxy-α-D-altropyranoside. Crystal structure of the phosphinyl derivative

Article abstract of DOI:10.1016/0022-328X(95)05529-X

Reaction of methyl 2,3-anhydro-4,6-O-benzylidene-α-D-allopyranoside (3) with PhnMLi gives methyl 4,6-O-benzylidene-2-deoxy-2-M-α-D-altropyranoside (4; M=Ph2As, Ph2P or Ph3Sn).Compound (4, M=Ph2P) is readily oxidised in air to the phosphinyl derivative (4, M=Ph2P(O)).Characterisation of (4, M=Ph2As, Ph2P(O), or Ph3Sn) was achieved by NMR spectroscopy, including solid state NMR spectroscopy, for (4, M=Ph2As) and (4, M=Ph3Sn), and by X-ray crystallography for <4, M=Ph2P(O)>.In the solid state both the benzylidene and pyranose rings in <4, Ph2P(O)>, adopt chair conformations.The pentavalent phosphorus atom has a distorted tetrahedral geometry with C-P-C valency angles in the narrow range from 105.7(3) to 106.0(3) deg and the C-P-O valency angles ranging from 111.3(3) to 115.6(2) deg; the P-C_aryl bond lengths are 1.808(5) and 1.815(6) Anagstroem, while the P-C_alkyl bond length is slightly larger, being 1.829(6) Angstroem.Intermolecular H-bonding, involving HO and O(P) centres, links the molecules in the crystal.Keywords: Tin; Phosphorus; Arsinic; Pyranosides; Crystal structure