摘要:

The rates and products of solvolysis of propylene oxide and propylene sulfide in acetic acid have been determined. The results show that terminal attack is preferred, although not exclusively, and that the sulfide is the less reactive by a factor of 50–60. This difference is accounted for mainly in the preexponential factor. Solvent isotope effects are also observed.

ISSN:0008-4042    

DOI:10.1139/v68-176

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

p-Nitrophenyl acetate and other esters except formates, will acylate the unprotected diamino acids homolysine, lysine, and ornithine, exclusively at the ω-amino group at pH 11. At lower alkaline pH's, the reaction is preferential but not selective. The reaction with diaminobutyric acid and diaminopropionic acid is not selective at any alkaline pH. ϵ-N-Acetyllysine can be prepared directly by the action of excess phenyl acetate on lysine at pH 11.

ISSN:0008-4042    

DOI:10.1139/v68-177

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

The synthesis ofL-phenyl-d5-alanine-2,3,3-d3is described. The synthetic route involved the enzymatic deacylation of acetylphenyl-d5-alanine-2,3,3-d3, which was obtained by catalytic reduction (deuteriumation) of the hydrolyzed 2-methyl oxazolone derivative of benzaldehyde-d6. The ultraviolet, infrared, and optical rotatory dispersion spectra ofL-phenylalanine-d8are reported along with some corresponding data on the deuterated intermediates.

ISSN:0008-4042    

DOI:10.1139/v68-178

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

The reaction between 1,2,3-thiadiazoles, unsubstituted in the 5-position, and a strong base such as an organolithium compound, sodamide, sodium methylsulfinyl carbanion, or potassiumt-butoxide results in cleavage of the thiadiazole ring system with evolution of nitrogen and formation of alkalimetal alkynethiolate. Subsequent addition of an alkyl or acyl halide to the reaction mixture produces 1-alkynyl thioethers. 4-(5-Phenyl-1,2,3-thiadiazolyl)lithium, obtained from 5-phenyl-1,2,3-thiadiazole and methyl-or phenyllithium, reacts with methyl iodide to give 4-methyl-5-phenyl-1,2,3-thiadiazole.

ISSN:0008-4042    

DOI:10.1139/v68-179

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

not available

ISSN:0008-4042    

DOI:10.1139/v68-180

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

not available

ISSN:0008-4042    

DOI:10.1139/v68-181

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

The reactions of several substituted 5-chloropyrazoles with hydrazine hydrate and guanidine, respectively, were investigated in ethanol and dimethyl formamide media. In certain cases, only SN2 reactions occurred, while in others the 5-hydrazino- and 5-guanidopyrazoles reacted still further to yield related compounds with two pyrazole rings. On the basis of the intermediates and the different condensation products isolated, reaction schemes are proposed for the reactions discussed.

ISSN:0008-4042    

DOI:10.1139/v68-182

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

The nuclear magnetic resonance spectrum, at −40°, of the crude mixture obtained by the reaction of ethanesulfenyl chloride with 3,4-dihydro-2H-pyran at −40° clearly supports the view that the product istrans-2-chloro-3-ethylthiotetrahydropyran. The possibility that there is initial formation of 3-chloro-2-ethylthiotetrahydropyran followed by its rapid rearrangement to 2-chloro-3-ethylthiotetrahydropyran is ruled out because of the stability of 3-chloro-2-ethylthiotetrahydropyran to distillation under vacuum. The latter compound is obtained as a mixture ofcisandtransisomers by the reaction of ethyl mercaptan with 5-chloro-3,4-dihydro-2H-pyran in the presence of sulfur dioxide.

ISSN:0008-4042    

DOI:10.1139/v68-183

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

L-Tyrosine was converted stereospecifically toN-benzoyl-2-(p-methoxybenzyl)-3-hydroxy-4-cyanopyrrolidine (10) which had a specific optical rotation. Anisomycin was converted also toN-benzoyl-2-(p-methoxybenzyl)-3-hydroxy-4-cyanopyrrolidine (16) which had a specific rotation. The infrared spectra of the synthetic compound and the derivative of anisomycin were superimposable with each other. This result showed that the absolute configuration of the three asymmetric centers in (10) of synthetic origin were 2S, 3S, 4S, and those in (16) were 2R, 3R, 4R. Thus, anisomycin should have the absolute stereochemistry 2R, 3S, 4S as depicted in the structure (2). Hydrolysis of the hydroxy nitriles (8) and (10) gave an identical amide (3) which should have the absolute stereochemistry 2S, 3S, 4R as shown in structure (3).

ISSN:0008-4042    

DOI:10.1139/v68-184

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

The alkaloid sedridine (1) is formed stereospecifically by catalytic hydrogenation of optically active α-picolyl methyl carbinol (2). The levorotatory1gave on action ofp-nitro benzaldehyde two μ-aryl oxazines, one crystalline and levorotatory, the other oily and dextrorotatory. This is the first example where both epimers of a μ-aryl oxazine could be detected. The configurations and the conformations of these isomers (10and11) and those of sedridine have been discussed in terms of their nuclear magnetic resonance spectra, with particular reference to spin-decoupling evidence.

ISSN:0008-4042    

DOI:10.1139/v68-185

出版商:NRC Research Press    

年代:1968

数据来源: NRC