Phosphorus and arsenic carbohydrate derivatives
A series of O-diphenylphosphinyl monosaccharide derivatives, e.g. 1,2:5,6-di-O-cyclohexylidene-3-O-diphenyl phosphinyl--D-glucofuranose , has been synthesised by reaction of a free hydroxy group in a sugar with Ph_2PCl. C-Diphenylphosphinyl and diphenylarsino derivatives, e.g. methyl 4,6-O-benzylidene-3-deoxy-3-C-diphenylarsino--D-altropyranoside , were synthesised via reaction of Ph2PLi or Ph2AsLi with p-tosyl, mesyl, epoxy or carbonyl substituted sugar reagents. Steric factors play a large part in determining the reactivity of the precursor sugars towards the phosphorous or arsenic nucleophilic reagents. Conformations of the arsenic and phosphorus derivatives were assigned from the 13C, 1H and 31P NMR spectra. Analogous phosphinyl and arsino derivatives have the same conformations in solution. Generally, the pyranosides prefer the 4C1 conformation in solution while the furanoses and furanosides prefer a symmetrical twist. Ribofuranosides ,  and , prefer the 2T3 conformation as to the mannofuranosides , , ,  and , whereas xylofuranose derivatives  and  prefer the 3T2. The solid state NMR of  and  were also obtained and compared with the solution NMR. No major conformational differences were evident. The following alicyclic carbohydrate derivatives were also synthesised - 1,4:3,6-dianhydro-2,5-dideoxy-2,5-bis-C-diphenylarsino-L-iditol , 1,4:3,6-dianhydro-5-deoxy-5-C-diphenylarsino-2-O-p-tosyl-L-gulitol , 1,4:3,6-dianhydro-2-deoxy-2-C-diphenylarsino-L-iditol  and the 2-O- p -tosyl derivative  and 1,4:3,6-dianhydro-5-C-diphenyl-phosphinyl-2-O- p -tosyl-L-iditol . Reactions of the carbohydrate derivatives with transition metal hexacarbonyls were also carried out. Methyl 4,6-O-benzylidene-2-deoxy-2-C-diphenylarsino--D-altropyranoside  gave a tetracarbonyl complex  on reaction with Cr(CO)_6 and two products from W(CO)_6, viz W_2(CO)_8(AsPh_2)_2  and the dimer [W_2(CO)_9(H)L]. - . The bridged dimer W_2(CO)_10(AsPh_2)_2  was obtained from the reactions of the bis-diphenylarsino derivatives of L-iditol  and diisopropylidene-D-galactose . The complex [Rh(1,5-cyclooctadiene)L]. &'43 BF_4. -  was synthesised on reaction of the chlororhodium dimer [Rh(COD)Cl]_2 with the bis-diphenylarsino-L-iditol derivative [L&'61 99].