The oxidation of methyl α-D-glucopyranoside with methyl sulproxide and acetic anhydride

The relative proportions of carbonyl, O-acetyl, and O-(methylthio)methylsugars resulting from the partial oxidation of methyl α-D-glucopyranoside with methyl sulphoxide and acetic anhydride have been investigated@ the preparation of the 2- and 6-(methylthio)methyl ethers of methyl α-D-glucopyranoside is described.     

Na+-dependent methyl β-thiogalactoside transport in Salmonella typhimurium

We have studied the role of sodium ions in methyl β-thiogalactoside (TMG) transport via the melibiose permease (TMG II) in SalmonellaTMG uptake via TMG Il in anaerobic, starved and metabolically poisoned cells is dependent on an inward-directed Na⁺ gradient.Cells which have been partially depleted of endogenous substrates show H⁺ extrusion upon sodium-stimulated TMG influx.Measurements of the electrochemical H⁺ gradient in cells, starved in different ways for endogenous substrates, suggest that this proton extrusion is probably not linked to the actual translocation mechanism but is the result of metabolism induced by TMG plus Na⁺ uptake.     

Monomolar acetalations of methyl α-d-mannosides—synthesis of methyl α-d-talopyranoside

Methyl α-d-mannopyranoside (1 mole) reacts with 2,2-dimethoxypropane (1 mole), to give the 4,6-O-isopropylidene derivative (2) which rearranges to the 2,3-O-isopropylidene derivative (4). Compound4 can also be prepared by graded hydrolysis of methyl 2,3:4,6-di-O-isopropylidene-α-d-mannopyranoside. Successive benzoylation, oxidation, and reduction of4 provides a useful route to a number ofd-talopyranoside compounds. Methyl α-d-mannofuranoside (1 mole) reacts with 1–2 moles of 2,2-dimethoxypropane to give the 5,6-O-isopropylidene derivative (16) in 90% yield.     

On the mortality ofTribolium castaneum adults treated sublethally as larvae with pirimiphos methyl,Nosema whitei and pirimiphos methyl—N. whitei doses

NeonateTribolium castaneum larvae were treated with 0.5 ppm pirimiphos methyl, 1.6×10⁴ spores/gNosema whitei alone and 0.5 ppm+1.6×10⁴ spores/g combined and the resulting adult mortality recorded. All treatments increased the mortality of the beetles significantly (P<0.01), though the combined dose gave a lower mortality than either the microsporidian or the insecticide alone.      

Preparation of α and β anomers of various isomeric methyl O-d-galactopyranosyl-d-galactopyranosides. Standards for interpretation of 13C-n.m.r. spectra of d-galactopyranans

The four isomers of methyl O-β-d-galactopyranosyl-β-d-galactopyranoside were prepared by condensation of 2,3,4,6-tetra-O-acetyl-α-d-galactopyranosyl bromide with appropriate, partially O-substituted derivatives of methyl β-d-galactopyranoside. Reaction of 3,4,6-tri-O-acetyl-1,2-O-(1-ethoxyethylidene)-α-d-galactopyranose with the same acceptors, in the presence of mercuric bromide, led to the formation of α and β linkages. Thus, it was possible to assign ¹³C-n.m.r. resonances of α and β anomers of methyl O-d-galactopyranosyl-β-d-galactopyranosides. In terms of application of these shift values and those of related d-galactobioses to the structural analysis of d-galactopyranans by shift comparisons, some generalizations can be made. For β-d-galactopyranans, the resonances of glycosyloxylated carbon atoms of methyl O-β-d-galactopyranosyl-β-d-galactopyranosides are sensitive to structure and appear to have typical values, whereas limited variation was observed with shifts of C-1′ signals. On the other hand, for assigning structures to d-galactopyranans containing α linkages, the C-1′ shifts (at higher field) of methyl O-α-d-galactopyranosyl-β-d-galactopyranosides are sensitive to linkage position, whereas those of glycosyloxylated carbon atoms vary only a little.     

Sequential synthesis and 13C-N.m.r. spectra of methyl β-glycosides of (1→4)-β-d-xylo-oligosaccharides

The reaction of 2,3-di-O-acetyl-4-O-benzyl-α,β-d-xylopyranosyl bromide (2) with methyl 2,3-di-O-acetyl-β-d-xylopyranoside gave methyl O-(2,3-di-O-acetyl-4-O-benzyl-β-d-xylopyranosyl)-(1→4)-2,3-di-O-acetyl-β-d-xylopyranoside (22). Catalytic hydrogenolysis of 22 exposed HO-4′ which was then condensed with 2. This sequence of reactions was repeated three more times to afford, after complete removal of protecting groups, a homologous series of methyl β-glycosides of (1→4)-β-d-xylo-oligosaccharides. ¹³C-N.m.r. spectra of the synthetic methyl β-glycosides (di- to hexa-saccharide) are presented together with data for six other, variously substituted, homologous series of (1→4)-d-xylo-oligosaccharides.     

A synthesis of methyl 4,6-di-O-Methyl-α-d-mannopyranoside

A new route is described for preparing methyl 4,6-di-O-methyl-α-d-mannopyranoside (5) via methyl 2,3-di-O-p-tolylsulfonyl-α-d-mannopyranoside (3) as an intermediate. The retention of the mannopyranoside configuration and ring form was confirmed by proton n.m.r. spectroscopy and by m.s. of peracetylated aldononitrile derivatives. Mass-spectral fragmentation-pathways previously proposed were confirmed for 5-O-acetyl-2,3,4,6-tetra-O-methyl-, 2,5-di-O-acetyl-3,4,6-tri-O-methyl-, and 3,5-di-O-acetyl-2,4,6-tri-O-methyl-d-mannononitrile.     

НОВЫЙ ВИЗЕЙСКИЙ РОД СПИРИФЕРИД-Grandispirifer gen.nov.

1957年春,地质陈列馆胡承志、牛业华在云南路南老第三系地层中采集了一批哺乳类化石,其中的一部分标本已经研究发表(周,1958)。在这篇报告中,我们又描述了一个完整的雷兽类的头骨,代表一个新的渐新世种。此外,尚有一些未经描述的材料,也将陆续予以描述发表。路南老第三系地层,经过对最近采集的一些哺乳类化石的研究,表明这是到目前为止,代表华南地区最完整的一个老第三系剖面,包括从上始新统至上渐新统间的全套地层,和几个不同时代的脊推动物化石层。进一步的地层调查和化石的系统采集,将对华南老第三系地层的了解和区域对比提供重要的基本研究资料。     

Determination of the 13C chemical-shift tensors in a single crystal of methyl α-d-glucopyranoside.

The chemical shielding tensors and their direction cosines of the ¹³C nuclei in a single crystal of methyl α-d-glucopyranoside were determined by the high-resolution solid state n.m.r. technique. The results were used to assign the ¹³C cross-polarization, magic angle spinning (c.p.-m.a.s.) spectrum of a polycrystalline sample of that compound. The differences between the ¹³C chemical shifts observed in the c.p.-m.a.s. spectrum of the solid and of solutions of methyl α-d-glucopyranoside are discussed in terms of the different types of hydrogen bonds formed in the crystalline state and in solution.     

Synthesis of derivatives of methyl β-sophoroside

Selective tritylation of methyl β-sophoroside (1) and subsequent acetylation gave the 3,4,2′,3′,4′-penta-O-acetyl-6,6′-di-O-trityl derivative, which was O-detritylated, and the product p-toluenesulfonylated, to give methyl 3,4,2′,3′,4′-penta-O-acetyl-6,6′-di-O-p-tolylsulfonyl-β-sophoroside (4) in 63% net yield. Compound 4 was also obtained in 69% yield by p-toluenesulfonylation of 1, followed by acetylation. Several, 6,6′-disubstituted derivatives of 1 were synthesized by displacement reactions of 4 with various nucleophiles. Treatment of 4 with sodium methoxide afforded methyl 3,6:3′,6′-dianhydro-β-sophoroside. Several 6- and 6′-monosubstituted derivatives of 1 were prepared, starting from the 4,6-O-benzylidene derivative of 1.     

Proteases as catalysts of enantioselective α-amino ester hydrolysis: 2. Pronase-catalysed hydrolysis of tryptophan methyl ester

The influence of pH, temperature, EDTA and metal ions on the rate of hydrolysis of methyl esters of d- and l-tryptophan by pronase from Streptomyces griseus has been studied. pH, Ca²⁺ and Co²⁺ ions have different effects on the hydrolysis of d- and l-substrates, which permits the enantioselectivity of the reaction to be regulated. Maximum enantioselectivity was observed at pH 7 in the presence of 10^?3–10^?2m Co²⁺. The data obtained are compared with the literature data for the hydrolysis of other low molecular weight substrates by pronase. It is suggested that leucine aminopeptidase makes a considerable contribution to the observed esterase activity of pronase.     

Sagittopteris belemnopteroides gen.et sp.nov.在山西的发现

山西晚古生代植物自赫勒(Halle,1927)研究以来向为世人瞩目。解放后,李星学(1963)又对华北广大地区月门沟群的化石进行了详细研究,补充了前人的不足。近年来,山西省区域地质调查队在1/20万区域地质调查和一系列的专题研究中,采集了大量化石标本。笔者在鉴定中发现不少有意义的分子,本文报道的即系其中之一。化石为作者之一肖素珍于1976年在晋东南参加剖面测制时采集的。本种在山西其他地区亦有出现。如太原西山、沁水杏峪、柳林、沁     

Reaction of derivatives of methyl 2,3-O-benzylidene-6-deoxy-α-L-mannopyranoside with butyllithium: Synthesis of methyl 2, 6-dideoxy-4-O-methyl-α-L-erytho-hexopyranosid-3-ulose

Methyl 2,3-O-benzylidene-6-deoxy-α-L-mannopyranoside (2) reacted with butyllithium to give a mixture of 1,5-anhydro-3-C-butyl-1,2,6-trideoxy-L-ribo-hex-1-enitol (3) and its L-arabino analogue (4), together with methyl 2,3,6-trideoxy-α-L-erythro-hex-2-enopyranoside (5). In contrast, the 4-O-methyl analogue (8) of 2 was converted by butyllithium into methyl 2,6-dideoxy-4-O-methyl-α-L-erythro-hexo-pyranosid-3-ulose (9), which was further characterized as its oxime 10. The 4-O-benzyl analogue of 8, obtained as two separate diastereoisomers (6 and 7) differing in configuration at C-2 of the dioxolane ring, gave a complex mixture of products on treatment with butyllithium.     

Nucleophilic replacement reactions of sulphonates : Part VII. Selective tosylation of methyl 2-benzamido-2-deoxy-α-D-glucopyranoside and a synthesis of methyl 2-benzamido-2,3,6-trideoxy-α-D-ribo-hexopyranoside

Selective tosylation of methyl 2-benzamido-2-deoxy-α-D-glucopyranoside at room temperature gave a mixture of the 6-sulphonate and the 3,6- and 4,6-disulphonates in yields of 25, 20, and 12%, respectively. Treatment of the 4-acetate of the 3,6-disulphonate with iodide ion gave the 3,6-di-iodo-D-gluco derivative, with overall retention of configuration involving participation of the 2-benzamido substituent in the substitution of the 3-tosyl group and formation of an intermediary oxazolinium ion. Reduction of the 3,6-di-iodo derivative gave methyl 2-benzamido-2,3,6-trideoxy-α-D-ribo-hexopyranoside. The disulphonates, characterised as their monoacetates, were synthesised from methyl 2-benzamido-4,6-O-benzylidene-2-deoxy-α-D-glucopyranoside by unambiguous routes, each of which was superior to selective tosylation.