From simple diols to carbohydrate derivatives of phenylarsonic acid

A series of spiro-arsoranes bearing a phenyl moiety as the fifth substituent were synthesized applying open-chain, as well as cyclic vicinal diols, as chelating molecules by condensation reactions in aprotic solvents. The products synthesized are the spiro compounds of the general formula PhAs(DiolH(-2))(2) derived from the vicinal diols meso-2,3-butanediol, PhAs(meso-2,3-ButdH(-2))(2) (1), exo-cis-2,3-norbornanediol, PhAs{exo-cis-NobdH(-2)}(2) (2), cis-1,2-cyclopentanediol, PhAs(cis-1,2-CptdH(-2))(2) (3), anhydroerythritol, PhAs(AnErytH(-2))(2) (4), cis-1,2-cyclohexanediol, PhAs(cis-1,2-ChxdH(-2))(2) (5), and rac-trans-1,2-cyclohexanediol, rac-{PhAs(trans-1,2-ChxdH(-2))(2)} (6) which were identified as mononuclear compounds. A novel dimeric double-spiro environment for oxyarsoranes was found in the reaction products derived from the sterically demanding diols 1,1'-bicyclohexyl-1,1'-diol {PhAs(BhxdH(-2))O}(2) (7) and perfluorpinacol, {PhAs(FpinH(-2))O}(2) (8). The stability of the compounds in acidic and neutral aqueous media in the presence of organic co-solvents was investigated. A convenient synthetic procedure for spiro-oxyarsoranes, applying water as the solvent, was developed and proven to be advantageous. All of the compounds synthesized in this study were characterized by means of melting-point measurement, single-crystal X-ray analysis, NMR, IR, Raman, UV/vis, and mass spectrometry. The principles found for these reactions were valid for the methyl glycosides of beta-D-ribofuranose and alpha-D-mannopyranose. The spiro-arsorane derived from methyl alpha-D-mannopyranoside, PhAs(Me-alpha-D-Manp2,3H(-2))(2) (9), is the first example of a structurally characterized carbohydrate-arsenic(V) compound.