Investigations in the fie ld of substituted furanurona ldehydes steric directivity of the nitromethane condensation
Summary1. The condensation of the anomeric methyl 2,3-di-O-benzyl-D-xylofuranosiduronaldehydes with nitromethane has been studied.2. It has been shown that the position of the substituent at the glycosidic center has an influence on the steric directivity of this reaction.3. The structure of the 6-nitro-6-deoxyhexofuranosides synthesized has been confirmed by their conversion into known derivatives of methyl D-glucofuranosides.
Nitromethane-Condensation Reaction with 5-Aldehydes of Pentodialdofuranosides
Treatment of methyl 2, 3-di-O-benzyl-α-L-arabino-pentodialdo-1, 4-furanoside (1) with nitromethane in the presence of sodium methoxide afforded an epimeric mixture of methyl 2, 3-di-O-benzyl-6-deoxy-6-nitro-α-L-altro-(2c) and -β-D-galactofuranoside (3c) in a ratio of 2.5 : 1. On the other hand, the analogous treatment of 3-O-benzyl-1, 2-O-isopropylidene-α-D-xylo-pentodialdo-1, 4-furanose (7b) with nitromethane gave 3-O-benzyl-6-deoxy-1, 2-O-isopropylidene-6-nitro-α-D-glucofuranose (8b) predominantly.
Identification of Dihydroxy Aromatic Compounds in a Low-Temperature Pyrolysis Coal Tar by Gas Chromatography−Mass Spectrometry (GC−MS) and Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR MS)
Dihydroxy aromatics in coal tar undergo rapid coupling reactions with each other and with some coal-derived species during coal pyrolysis and liquefaction. However, only limited information on the structure of dihydroxy aromatics is known. In this study, Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) and gas chromatography−mass spectrometry (GC−MS) were used to characterize the dihydroxy aromatics in a low-temperature pyrolyzed coal tar and its distillate and residue fractions. Negative-ion electrospray ionization (ESI) FT-ICR MS spectra of coal-tar-derived samples had low molecular masses and narrow mass ranges. Negative-ion ESI is extremely selective for the dihydroxy aromatics present in coal tar. The O2 class species had the highest ion intensity among the species in the negative-ion FT-ICR mass spectrum for each sample. Dihydroxy compounds with an aromatic core structure of benzene, indan, biphenyl (and/or acenaphthene), and naphthalene were identified in the distillate fract...