摘要:

Resonances in the13C nmr spectra of nonylprodiginine, cyclononylprodiginine, methylcyclodecylprodiginine, and butylcycloheptylprodiginine were assigned using information from the literature, from high resolution spectra and double irradiation experiments, and from13C–15N couplings observed in samples of nonylprodiginine enriched with15N. Supplementation of cultures with sodium [1-13C]- and [1,2-13C]acetate gave13C-enriched prodiginines and the labeling patterns were established from13C nmr spectra. These indicated that rings A and B were formed in a similar manner to rings A and B in prodigiosin and other prodiginine pigments. Ring C and the C2-alkyl substituent were derived in part from acetate units that were condensed in a linear 12- or 14-carbon chain. The same pattern of acetate assembly has been found in ail actinomycete prodiginines examined.

ISSN:0008-4042    

DOI:10.1139/v78-194

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

The bromination of substituted 3-arylpropynes in acetic acid has been examined. The only products obtained are 1,2-dibromo-3-arylpropenes; the stereochemistry of the dibromides is predominantlytransexcept for the 4-methoxy isomer which gives 83%cisand 17%trans. In the presence of 0.1 Mlithium bromide all substrates give predominantlytransproducts. Combined with rate studies, these results indicate that these acetylenes react by an unsaturated cyclic bromonium ion except for the 4-methoxy case where phenonium ion stabilization of a vinyl cation is implicated. In the presence of lithium bromide a bromide ion catalyzed addition of molecular bromine (AdE3) occurs.

ISSN:0008-4042    

DOI:10.1139/v78-195

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

Proton magnetic resonance data for 6-methyl-2′-deoxyuridine and its 3′- and 5′-monophosphate derivatives are obtained in aqueous solution and compared with data for corresponding thymine derivatives. The data show that the derivatives of the 6-methyluracil base occupy thesynconformation. The presence of thesynbase leads to a flattening of the sugar ring and destabilization of theg+conformer about the C(4′)—C(5′) bond. This destabilization is particularly large at the 5′-nucleotide level and is discussed in terms of a repulsive interaction involving the 2-keto oxygen of the base and the negatively charged 5′-group.

ISSN:0008-4042    

DOI:10.1139/v78-196

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

Action of sodium borohydride upon sugar derivatives that contain an α-nitrooxirane grouping leads to reductive denitration producing high yiel ds of α-hydroxy-β-deoxy derivatives. Thus, 5,6-anhydro-1,2-O-isopropylidene-6-nitro-α-D-glucofuranose (2) gave 5-deoxy-1,2-O-isopropylidene-α-D-xylo-hexofuranose (3). The methyl 2,3-anhydro-4,6-O-benzylidene-3-nitrohexopyranosides having the β-D-talo(4), β-D-allo(5), and β-D-manno(6) configurations readily afforded methyl 4,6-O-benzylidene-2-deoxy- β-D-lyxo-hexopyranoside (10; from4) and its β-D-arabinoisomer (11; from5and6). The corresponding nitroepoxy glycoside ofα-D-taloconfiguration (7) reacted more slowly and gave a mixture of 3-epimeric 2-deoxyglycosides, the analogous α-D-lyxo(13) and α-D-xylo(14) compounds. The α-D-manno(8) and β-D-gulo(9) nitroepoxides proved unreactive under the same conditions. Stereochemical factors considered to be important in these denitrations are discussed.

ISSN:0008-4042    

DOI:10.1139/v78-197

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

Sulfene, generated from methanesulfonyl chloride and triethylamine in acetonitrile reacts with itself to form a tetramer which may be isolated as an acyclic crystalline pyridinium sulfonate salt,1. When sulfene is generated in tetrahydrofuran in the presence of pyridine, the 1,1,3,3-tetraoxide of 4,4a-dihydropyrido[1,2-d][1,5,2]dithiazine,11, is formed. Structural evidence (including nmr and mass spectra) for these compounds, for homologs of11, and for a series of acyclic polysulfonyl compounds derived from1is presented. An X-ray crystal structure determination was carried out on9, the 5,7-dimethyl homolog of11.

ISSN:0008-4042    

DOI:10.1139/v78-198

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

The polarized Raman spectra of single crystals of RbCdCI3and RbCdBr3(isostructural with NH4CdCl3) have been measured and analysed by comparison of the frequency shifts. The crystal structure of RbCdCl3refined by X-ray diffraction is also reported.

ISSN:0008-4042    

DOI:10.1139/v78-199

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

The principles according to which the acidic properties of fulvic acid solutions should be compared are demonstrated. An equilibrium function defined and measured for any mixture, including fulvic acid functional groups, will be a weighted average. A concentration change will generally affect this average by changing the relative values of the statistical weights. Concentration corrections are therefore required for the comparison of two fulvic acid solutions. A Chernozem Ah fulvic acid and the previously described Armadale fulvic acid Batch FA1 were examined in this way. They were found to have the same general chemical characteristics, but with somewhat different numerical values. The implications of these results for the definition of fulvic acid are considered.

ISSN:0008-4042    

DOI:10.1139/v78-200

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

Data from simulated titrations (pH, titer, and pM) were generated from literature values of equilibrium constants, and then submitted to various published methods of calculation to regenerate the indicated equilibrium constants. These calculations were done with error-free input data, and the same with imposed random errors. In other experiments data from real titrations were subjected to the same analysis, and additional checks were made on the output of the calculations with an ion-selective electrode as a probe for pM. One method of data analysis was prone to cause errors in the finally recovered constants, and causes for this are suggested.

ISSN:0008-4042    

DOI:10.1139/v78-201

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

Details of the synthesis and physical properties of octahedral transition metal complexes of the tridentate tris chelating ligand [Me2Ga(OCH2CH2NH2)(N2C3H3)]−are given. Crystals ofsym-fac-bis[dimethyl(ethanolamino)(1-pyrazolyl)gallato(N(2),O,N]nickel(II) are monoclinic,a = 11.7908(6),b = 7.3158(6),c = 12.5797(8), β = 97.035(7)°,Z = 2, space groupP21/nand crystals of themerisomer are monoclinic,a = 18.6617(7),b = 8.7941(4), c = 13.5670(8), β = 91,766(4)°,Z = 4, space groupP21/c. The structures were solved by Patterson and Fourier syntheses and were refined by full-matrix least-squares procedures to finalRvalues of 0.048 and 0.052 for 1881 and 2573 reflections withI ≥ 3σ(I) for thefacandmerisomers respectively. The nickel atoms in both structures were found to have distorted octahedral coordination geometry. Bond lengths (corrected for libration) are: Ni—O, 2.090(3); Ni—N, 2.085(3) and 2.112(3); Ga—O, 1.908(3); Ga—N, 2.010(3); and Ga—C, 1.979(5) and 1.981(6) Å for thefacisomer, and Ni—O, 2.045(4) and 2.049(4); Ni—N, 2.091 (4)-2.156(5); Ga—O, 1.898(4) and 1.899(4); Ga—N, two at 1.991 (5); and Ga—C, 1.948(8)-1.971 (7) Å for themerisomer.

ISSN:0008-4042    

DOI:10.1139/v78-202

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

Ultraviolet absorption and circular dichroism spectra of the strychnine alkaloids strychnine, β-colubrine, brucine, dihydrostrychnine, dihydro-β-colubrine, and dihydrobrucine have been investigated under various experimental conditions. It appears that at least five electronic transitions are required to account for the spectroscopic properties of these molecules in the ultraviolet region above 190 nm. Transitions, which are tentatively assigned as the1Lb,1La,1Bb, and1Bain the notation due to Platt, and an n → π* transition apparently make significant contributions to the spectra of ail of the molecules studied.

ISSN:0008-4042    

DOI:10.1139/v78-203

出版商:NRC Research Press    

年代:1978

数据来源: NRC