Synthesis of methyl 2-O-alpha-D-mannopyranosyl-alpha-D-talopyranoside and methyl 2-O-alpha-D-talopyranosyl-alpha-D-talopyranoside

Treatment of methyl 3-O-benzyl-2-O-(2,3,4,6-tetra-O-acetyl-alpha-D-mannopyranosyl)-alpha-D- mannopyranoside (1) with tert-butyldiphenylsilyl chloride in N,N-dimethylformamide afforded methyl 3-O-benzyl-6-O-tert-butyldiphenylsilyl-2-O-(2,3,4,6-tetra-O-acetyl -alpha-D- mannopyranosyl)-alpha-D-mannopyranoside (2). Oxidation of 2 with pyridinium chlorochromate, followed by reduction of the carbonyl group, and subsequent O-deacetylation afforded methyl 3-O-benzyl-6-O-tert-butyldiphenylsilyl-2-O-alpha-D-mannopyranosyl- alpha-D- talopyranoside (5). Cleavage of the tert-butyldiphenylsilyl group of 5 with tetrabutylammonium fluoride in oxolane, followed by hydrogenolysis, gave methyl 2-O-alpha-D-mannopyranosyl-alpha-D-talopyranoside (7). O-Deacetylation of 1 gave methyl 3-O-benzyl-2-O-alpha-D-mannopyranosyl-alpha-D-mannopyranoside (8). Treatment of 8 with tert-butyldiphenylsilyl chloride afforded a 6,6'-disilyl derivative, which was converted into a 2',3'-O-isopropylidene derivative, and then further oxidized with pyridinium chlorochromate. The resulting diketone was reduced and removal of the protecting groups gave methyl 2-O-alpha-D-talopyranosyl-alpha-D-talopyranoside (15). The structures of both 7 and 15 were established by 13C-n.m.r. spectroscopy.     

Bacterial mutagenicity of some methyl 2-cyanoacrylates and methyl 2-cyano-3-phenylacrylates

The mutagenic potential of three alkyl 2-cyanoacrylate adhesives, three commercial alkyl 2-cyanoacrylate adhesives and three methyl 2-cyano-3-phenylacrylates, was assessed using the Salmonella/microsome mutagenicity assay. Compounds were tested with and without Aroclor 1254-induced rat-liver homogenate (S9 mix). The methyl 2-cyanoacrylate adhesives were mutagenic in the standard plate test with S. typhimurium strain TA100 with and without S9 activation. Methyl 2-cyano-3-(2-bromophenyl)acrylate revealed a direct mutagenic action to S. typhimurium strain TA1535. The compounds most toxic towards the bacterium S. typhimurium, were the methyl 2-cyanoacrylate adhesives (greater than 500 micrograms/plate). All alkyl 2-cyanoacrylate adhesives were tested in a modified spot test for volatile compounds with tester strain TA100. Mutagenic and toxic effects were observed with the three methyl 2-cyanoacrylate adhesives. It can be concluded from the results that the bacterial toxicity and mutagenicity of methyl 2-cyanoacrylate adhesives may be due to the methyl 2-cyanoacrylate monomer.     

Preparation of methyl 2,3-di-O-mesyl-4,6-thioanhydro-alpha-D-galactopyranoside and methyl 2-O-mesyl-4,6-thioanhydro-alpha-D-gulopyranoside

Two 2-oxa-7-thiabicyclo[4.2.0]octane derivatives, 4 and 10, with the D-galacto and D-gulo configuration, respectively, were obtained from methyl alpha-D-glucopyranoside. The thietane cyclization involved a thio-Mitsunobu reaction resulting in a 6-thioacetate, which underwent selective base-catalyzed intramolecular nucleophilic substitution at a C-4 mesylate. The structures of 4 and 10 were elucidated by X-ray diffraction analysis.     

Synthesis of methyl 2- and 4-pyridyl disulfide from 2- and 4-thiopyridone and methyl methanethiosulfonate

In 1982, methyl 2-pyridyl disulfide was reported as a new reagent for the titration of thiol groups in peptides and proteins and for their temporary blocking with the thiomethyl group [T. Kimura et al. (1982) Anal. Biochem. 122, 274-282]. We have synthesized this compound (and its 4-pyridyl isomer) by a rapid and convenient procedure which is preferable to that in the original report. Our method involves the thiomethylation of the appropriate thiopyridone by methyl methanethiosulfonate.     

Mutagenic action of methyl 2-cyanoacrylate vapor

Alkyl 2-cyanoacrylate adhesives were tested for mutagenicity in Salmonella typhimurium strains TA98, TA100, TA1535 and TA1538. Both a normal spot test and a spot test specially designed to test volatile compounds were used. The adhesives were also tested in the plate incorporation assay. These investigations showed that methyl 2-cyanoacrylate adhesives are mutagenic in strain TA100. The spot test for volatile compounds showed that it is the vapors from the methyl 2-cyanoacrylate monomer that are responsible for the mutagenic effect. One can conclude that working with methyl 2-cyanoacrylate adhesives entails exposure to vapors with a mutagenic effect and may therefore pose a carcinogenic hazard. Because the adhesives are used in industry, their mutagenic effect has a special importance in work environment.     

CO2 laser photoacoustic spectrum of methyl anthranylate

The spectrum of pure methyl anthranylate C₂H₂NO₂ (methyl 2-aminobenzoate),an important fragrant in the perfume industry, has been determinedin the 9 – 11 µm region of the i.r. portion in theelectromagnetic spectrum using a CO₂, laser photoacoustic spectrometercombined with phase sensitive detection. Large signals wereobserved with the simple experimental set-up used in this studyindicating the utility of this technique for quick on-line quantitativeand qualitative analysis. From the obtained data an ultimatesensitivity limit of several p.p.b.v. for methyl anthranylatein the air can be derived for the present system. However, furtherimprovements of the sensitivity, leading to the sub p.p.b.v.region, are readily anticipated by use of a more sophisticateddesign (multipass cell and improved quality of optical components).     

Synthesis of methyl 4,6-O-benzylidene-2,3-dideoxy-2-C-formyl-alpha-D-erythro-hex-2-enopyranoside

The synthesis of the title compound was achieved in seven steps and 61% overall yield from methyl alpha-D-glucopyranoside.     

Synthesis of the anomers of methyl 2-acetamido-2-deoxy-d-galacto-furanoside and -pyranoside

On treatment with methanol in the presence of Amberlite IR-120 (H⁺) resin, 2-acetamido-2-deoxy-d-galactose yielded a mixture of four isomers, the methyl 2-acetamido-2-deoxy-α- and -β-d-galactofuranosides and their corresponding pyranosides. The isomers were separated preparatively on Dowex-1 ion-exchange resin, and analytically by high-pressure liquid chromatography, and identified by their m.p. and specific rotation and by assays of periodate uptake and formaldehyde liberated.     

Lipase-catalyzed enantioselective hydrolysis of methyl 2-fluoro-2-arylpropionates in water-saturated isooctane

Lipases from Candida rugosa, Candida antartica B and Carica papaya are employed as the biocatalyst for the hydrolytic resolution of methyl 2-fluoro-2-arylpropionates in water-saturated isooctane, in which excellent to good enantioselectivity without the formation of byproducts is obtained for the papaya lipase when using (R,S)-2-fluoronaproxen methyl ester (1) and methyl (R,S)-2-fluoro-2-(4-methoxyphenyl)propionate (2), but not methyl (R,S)-2-fluoro-2-(naphth-1-yl)propionate (3) as the substrates. The thermodynamic analysis indicates that the enantiomer discrimination for the papaya lipase is driven by the difference in activation enthalpy for compound 1, 2 or (R,S)-naproxen methyl ester (4). The kinetic analysis also demonstrates that in comparison with (S)-4, the insertion of the 2-fluorine moiety in (R)-1 has increased k₂, but not K_m, and consequently the lipase activity.     

Synthesis and anti-inflammatory activity of 2-aryloxy methyl oxazolines

A series of potential biologically active 2-aryloxy methyl oxazolines 3a-n have been synthesized from substituted hydroxybenzenes 1a-n with good chemical yield. The compounds 3a-n were screened for their anti-inflammatory, ulcerogenic, cyclooxygenase activities and also for their acute toxicity. The potency of the compounds was compared with that of the standard drugs, aspirin and phenyl butazone. The outcome indicates that compounds 3b (48.2%), 3h (48.5%) and 3l (46.5%) offered significant anti-inflammatory activity with low ulcerogenic activity than the standard drugs.     

Synthesis of 3-deoxy-d-arabino-2-heptulosonic acid 7-phosphate by phosphorylation of methyl (methyl 3-deoxy-d-arabino-heptulopyranosid)onate

3-Deoxy-d-arabino-2-heptulosonic acid 7-phosphate (5), the first committed intermediate in aromatic amino acid biosynthesis, has been synthesized in good yield by treatment of methyl (methyl 3-deoxy-d-arabino-2-heptulopyranosid)onate with diphenylphosphoric chloride under mild conditions to give the 7-diphenyl phosphate. Catalytic removal of the phenyl residues, followed by base-catalyzed hydrolysis resulted in formation of (methyl 3-deoxy-d-arabino-2-heptulopyranosid)onic acid dihydrogen 7-phosphate (4), which yielded a crystalline tris-(cyclohexylammonium) salt. Acid-catalyzed hydrolysis of 4 afforded 5, which was used to purify 3-dehydroquinate synthase.     

Homologation of methyl 2-azido- and 2-acetamido-3,4-di-O-benzyl-2-deoxy-D-hexopyranosides with allyloxymethylmagnesium chloride.

Methyl 2-azido-2-deoxy-hexodialdo-1,5-pyranosides of the alpha-, beta-D-gluco and alpha-D-manno configuration as well as methyl 2-acetamido-2-deoxy-hexodialdo-1,5-pyranosides of the alpha- and beta-D-gluco configuration, protected at positions 3 and 4 with O-benzyl groups were reacted with an excess of allyloxymethylmagnesium or (phenyldimethylsilyl)methylmagnesium chlorides to afford mixtures of C-6 stereoisomeric heptopyranosides. Configuration of the products separated by column chromatography was assigned by 1H NMR data.