摘要:

1H nuclear magnetic resonance studies onD-galactopyranoses with chirally deuterated hydroxymethyl groups revealed that the preferred rotamer about the C5—C6bond of theD-galactopyranoses was nottgbutgt. Studies on the stereochemistry of dehydrogenation ofD-galactose oxidase fromDactyliumdendroideswith chirally pure deuterated methyl β-D-galactopyranosides showed that there were two mechanisms for the enzymatic reaction: an efficientpro-Shydrogen atom specific oxidation and a far less efficient non-specific orpro-Rspecific oxidation.

ISSN:0008-4042    

DOI:10.1139/v87-191

出版商:NRC Research Press    

年代:1987

数据来源: NRC

摘要:

The X-ray crystal structure of 5,5-dimethyl-2-phenylimino-Δ3-1,3,4-thiadiazoline, C10H11N3S, has been determined. The compound is monoclinic,P21/c(No. 14), witha = 13.200(5),b = 6.340(4), andc = 13.823(4) Å, β = 113.50(4)°, andZ = 4. The structure was determined by direct methods and refined toR = 0.061,Rw = 0.067 for 1277 unique reflections. The molecule has theZconfiguration. The thiadiazoline ring is planar. C—N and N=N bond lengths are within the normal range. The C—S bond lengths are similar to those we have observed previously in thiazolidines. Angles differ markedly from an expected average 108°. The small C—S—C angle (90.6(2)°) is accompanied by larger C—N=N angles (114.9(3), 117.8(3)°). The phenyl ring is not coplanar with the thiadiazoline ring (dihedral angle 38.6(4)°) because of repulsive interaction of the phenylo-hydrogen atom with the sulphur atom.

ISSN:0008-4042    

DOI:10.1139/v87-192

出版商:NRC Research Press    

年代:1987

数据来源: NRC

摘要:

Theortho-directed lithiation of 3-tert-butyl- or 3-tert-butoxycarbonylaminopyridines (3) with alkyllithiums and reaction withN,N-diethylbenzamide followed by acid hydrolysis gave 3-amino-4-benzoylpyridine (6) in good yield. Reaction of BTBO with the glycine derivatives7a,band then reaction with6afforded 3-alkoxycarbonylaminomethylcarbonylamino-4-benzoylpyridines8a,b. Acid-catalyzed hydrolysis and cyclization of8a,byielded9, which on methylation gave 1,3-dihydro-1-methyl-5-phenyl-2H-pyrido[3,4-e]-1,4-diazepin-2-one (10) in 36% overall yield from3a.

ISSN:0008-4042    

DOI:10.1139/v87-193

出版商:NRC Research Press    

年代:1987

数据来源: NRC

摘要:

Sonolysis of cytosine has been studied at 630 kHz in the presence of air and nitrogen. The degradation products were identified by gas chromatographic – mass spectral analysis. Under aerated conditions the following products were found: urea, formyl urea, parabanic acid, isobarbituric acid, oxaluric acid, alloxan monohydrate, alloxantin, dialuric acid, and uracil glycols. Under nitrogen the degradation products were isobarbituric acid, alloxan monohydrate, and uracil glycols. The observed products have been used to develop a possible mechanism for the sonolytic degradation. There appears to be some similarity with the products reported from radiolysis studies of this compound. Sonolysis of thymine in the presence of air was reinvestigated and the gc–ms analysis shows that a previously reported, unidentified, product may be 5-hydroxy-5-methylbarbituric acid.

ISSN:0008-4042    

DOI:10.1139/v87-194

出版商:NRC Research Press    

年代:1987

数据来源: NRC

摘要:

The mechanism of the Claisen–Schmidt condensation, catalyzed by a series of activated barium hydroxide catalysts, is discussed. Two kinds of ketones are studied: R—CO—CH3(R = Me, Et, Pri, But) and acetophenone (R = Ph). The influence of the chemical and textural properties of the catalysts, as well as the nature of the solvent, are studied. The process is an interfacial solid–liquid reaction between the adsorbed carbanion and the benzaldehyde. The different structures of the adsorbed carbanion produced from Ph—CO—CH3and R—CO—CH3are analyzed by infrared spectroscopy, and could explain the different reactivities observed in the process. The kinetic runs are discussed.

ISSN:0008-4042    

DOI:10.1139/v87-195

出版商:NRC Research Press    

年代:1987

数据来源: NRC

摘要:

The rates and products of addition of 4-chlorobenzenesulfenyl chloride toE- andZ-3-methyl-2-pentene,E- andZ-3,4-dimethyl-2-pentene,E- andZ-3,4,4-trimethyl-2-pentene, and 2,4,4-trimethyl-2-pentene were studied to determine if the mechanism involved a tertiary β arylthio carbocation. It was found that the rates of addition are not as fast as one would predict based on the polar effects of the substituents on the rate of addition to mono- and disubstituted alkenes. The products are formed byanti-stereospecific addition as in the case of addition to 1,2-disubstituted alkenes. As a result it is concluded that the reaction occurs by means of the usual mechanism involving a bridged thiiranium ion.

ISSN:0008-4042    

DOI:10.1139/v87-196

出版商:NRC Research Press    

年代:1987

数据来源: NRC

摘要:

Thermolysis of a 5,5-dialkyl-Δ3-1,3,4-oxadiazolin-2-one in nitrobenzene containing an aryl isocyanate at 150° C affords a 1,3-diaryl-5,5-dialkylimidazolidine-2,4-dione, anN-arylcarbamoyl-3,3-dialkyloxindole, and a 3-aryl-2-arylimino-5,5-dialkyl-1,3-oxazolidin-4-one. Those products arise from attack of a diazoalkane, generatedinsitufrom the oxadiazolinone by thermal cycloreversion, on the isocyanate function. Two imidazolidine diones, three oxazolidinones, and 14 oxindoles were prepared.

ISSN:0008-4042    

DOI:10.1139/v87-197

出版商:NRC Research Press    

年代:1987

数据来源: NRC

摘要:

The stretched polymer film technique combined with -γ-irradiation has been employed to measure the polarized absorption (linear dichroism) spectra of radical anions of quinoline, isoquinoline, quinoxaline, phthalazine, phenylpyridine, 4,4′-bipyridyl, and 2,2′-bipyridyl. Profiles of polarized absorption spectra of all the radical anions are similar to those of the parent naphthalene or biphenyl radical anions. Those of radical cations of isoquinoline and 2,2′-bipyridyl are also similar to those of radical cations of their parent molecules. Quinoxaline radical cations, however, show quite a different spectrum from that of naphthalene radical cations; a long vibrational structure with ca. 550 cm−1intervals was observed and peaks of these vibrational bands were polarized parallel to the molecular short-axis or normal to the molecular plane.

ISSN:0008-4042    

DOI:10.1139/v87-198

出版商:NRC Research Press    

年代:1987

数据来源: NRC

摘要:

The polysulfano complexes (η5-C5H5)W(CO)3Q, where Q = SSR, SSSR, SS(O)R, and R = CH2C6H5andp-C6H4CH3have been prepared via treatment of (η5-C5H5)W(CO)3SH with RSphth, RSSphth, and RS(O)phth, respectively, at −20 °C, where phth =N-phthalimido. The complexes where Q = SSR and SSSR lost sulfur spontaneously in solution to give the thiolato complexes (η5-C5H5)W(CO)3SR and the disulfano complexes, respectively. The presence of PPh3accelerated this reaction for Q = SSR. Treatment of (η5-C5H5)W(CO)3SSR withm-chloroperbenzoic acid gave a mixture of complexes for which Q = SR, SO2R, SS(O)R, and higher oxidized sulfur ligands. As(C6H5)4[W(CO)5SH] reacted withp-CH3C6H4Sphth to give an unstable first product, tentatively identified as As(C6H5)4[W(CO)5SS-p-C6H4CH3], the isolated product being As(C6H5)4[W(CO)5S-p-C6H4CH3].

ISSN:0008-4042    

DOI:10.1139/v87-199

出版商:NRC Research Press    

年代:1987

数据来源: NRC

摘要:

Arsenic(III), antimony (III), and bismuth(III) oxides, sodium arsenite and bismuthate react with methanesulfonic anhydride, (CH3)2S2O5, to yield M(SO3CH3)3(M = As(III), Sb(III), and Bi(III)), Na[AsO(SO3CH3)2], and Na[Bi(SO3CH3)4], respectively, in quantitative yield. Reaction of arsenic(III) oxide with pure methanesulfonic acid yields oxo(methanesulfonato)arsenic(III), AsO(SO3CH3), which behaves as a non-electrolyte in 100% methanesulfonic acid. The compounds have been characterized by elemental analysis, conductance, infrared,1H nmr and thermal measurements. Their properties have been studied by ligand substitution and complex formation reactions. The M(SO3CH3)3(M = As(III), Sb(III), and Bi(III)) compounds are capable of functioning both as Lewis acids and bases. These compounds exhibit basic behaviour in 100% methanesulfonic acid. The synthesis of complex mathanesulfonates Cs[M(SO3CH3)4] (M = As(III), Sb(III), and Bi(III)) is also described.

ISSN:0008-4042    

DOI:10.1139/v87-200

出版商:NRC Research Press    

年代:1987

数据来源: NRC