摘要:

When cultured in stirred fermentors the yeastCandidabogoriensisproduces extracellular glycolipids in yields of 0.5 to 1 g/l. The principal component of these is a crystalline sophorosyl hydroxy fatty acid, the structure of which has been established as 13-[(2′-O-β-D-glucopyranosyl-β-D-glucopyranosyl)-oxy]docosanoic acid 6′,6″-diacetate. The hydroxy acid portion of the molecule probably has theL-configuration. A monoacetyl glycolipid is also present as a minor component.

ISSN:0008-4042    

DOI:10.1139/v68-057

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

The preparation of several new estrane, androstane, and 19-norpregnane derivatives with unnatural configuration is discussed. A synthesis of both enantiomers (16b) and (18) from estrone is described. The structure and configuration of the compounds reported are established on the basis of their physical properties.

ISSN:0008-4042    

DOI:10.1139/v68-058

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

The mass spectra of three desaurins and four related 3,5-bismethylene-1,2,4-trithiolanes have been interpreted with the aid of metastable peak assignments and accurate mass measurements. Strong molecular ion peaks are observed in the case of the aryl desaurins but not in that of their trithiolane counterparts. A variety of fragmentation pathways are postulated for the molecular ions, including cleavage on either side of a carbonyl group and elimination of a molecule of acylthioketene. In the case of the desaurins the latter process results in the formation of acylthioketene molecular ions, which could be distinguished from the doubly charged desaurin molecular ions. In the case of two of the trithiolanes, it is proposed that the ions resulting from loss of acylthioketene from the molecular ions undergo a novel type of McLafferty rearrangement and loss of carbon suboxysulfide to give aryl mercaptan molecular ions.

ISSN:0008-4042    

DOI:10.1139/v68-059

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

An efficient, 8-step synthesis of (+)-α-cyperone (1) from (−)-α-santonin (5) is described. The key steps of the sequence involve the conversion of the keto ester8into the substituted octalone9, by hydrogenation of the former in the presence of the homogeneous catalyst tris(triphenylphosphine)-chlororhodium, and the pyrolysis of the keto carbonate 16, which produces (+)-α-cyperone in good yield.

ISSN:0008-4042    

DOI:10.1139/v68-060

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

Dimethylaminomethyl acetate, a postulated intermediate in the Polonovski reaction, has been isolated for the first time in 80% yield from the reaction between trimethylamineN-oxide and one equivalent of acetic anhydride. With more acetic anhydride the dimethylaminomethyl ester gaveN,N-dimethyl acetamide and two other products which have been identified as 2-(dimethylaminornethyl)acrylic acid and 2,2-bis(acetoxymethyl)-3-(dimethylamino)propionic acid. The manner of formation of these two products has been clarified by using deuterium and13C labelled reagents.Hydrolysis of deuterated dimethylaminomethyl acetate prepared from trimethyl-d9amineN-oxide and acetic anhydride gave satisfactory yields of dimethyl-d6amine and formaldehyde-d2.

ISSN:0008-4042    

DOI:10.1139/v68-061

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

The hydrogen isotopic exchange with basic and acidic agents has been widely investigated with the aim of preparing fully deuterated biphenylene. It has been noted that the very strong base KOD completely decomposes the hydrocarbon, while the strong base NaOD leads to random exchange, and the medium strength base Ca(OD)2gives preferential exchange in α-position. Since the stability of biphenylene is less in acid mixtures than in basic ones, only acids of medium strength, which give preferential exchange in β-position, can be used.Good results in preparing fully deuterated biphenylene are obtained from two methods. The first of these consists of two exchanges which occur successively; one with an acid mixture and the other with a base. Both agents are of medium strength. The second method entails repeated exchanges with the strong base NaOD supported on Ca(OD)2. The latter method gives the highest isotopic purity and the best yield, as well as being much easier to carry out.

ISSN:0008-4042    

DOI:10.1139/v68-062

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

Hydrogenation of alkyl 2-oximino-α-D-arabino-hexopyranosides in the presence of palladium on charcoal and hydrochloric acid gave mixtures of the alkyl 2-amino-2-deoxy-α-D-hexopyranoside hydrochlorides with theglucoandmannoconfigurations in about 90% yields. The fraction ofglucocompound varied substantially with the nature of the alkyl group; viz., methyl, 71%; ethyl orn-propyl, 62%; isopropyl, 80%. More of themannocompound is formed, viz., isopropyl, 50%, when the 3,4,6-triacetate of the oximinoglycoside is hydrogenated. Hydrogenation of methyl 6-O-(2-oximino-α-D-arabino-hexopyranosyl)-β-D-glucopyranoside gave an about equimolar mixture of the two configurations.

ISSN:0008-4042    

DOI:10.1139/v68-063

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

Methods for the preparation of the hydrochlorides of 2-amino-2-deoxy-D-glucose (D-glucosamine) and 2-amino-2-deoxy-D-mannose (D-mannosamine) from tri-O-acetyl-D-glucal and of 2-amino-2-deoxy-D-galactose (D-galactosamine) and 2-amino-2-deoxy-D-talose (D-talosamine) from tri-O-acetyl-D-galactal are described. The reactions involve addition of nitrosyl chloride to the acetylated glycal followed by conversion of the adduct to acetylated derivative of the 2-oximinohexose and reduction of the oxime to amine.

ISSN:0008-4042    

DOI:10.1139/v68-064

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

The reaction of the dimeric nitrosyl chloride adducts of tri-O-acetyl-D-glucal and tri-O-acetyl-D-galactal with alcohols and phenols in dimethylformamide at room temperature provides the corresponding tri-O-acetyl-2-oximino-α-D-hexopyranosides in good to excellent yields. The condensation can also be carried out in tetrahydrofuran in the presence of pyridine or simply in refluxing methylene chloride for the simple alkyl alcohols. The stereospecificity of the reaction is extreme; only products of one configuration for both glycosidic linkage and the oximino group were detected. This result is rationalized on the basis of acis-configuration for a tri-O-acetyl-2-nitroso-D-glycal intermediate in the H1 half-chair conformation. The introduction of methyl groups on the carbon of the methoxy group of methyl α-D-glucopyranosides causes a progressive deshielding of the anomeric proton. The data indicate that isopropyl α-D-glycopyranosides avoid the orientation for the aglycon which has the anomeric hydrogen projecting between the two methyl groups of the aglycon. Methyl tri-O-acetyl-6-O-(tri-O-acetyl-2-oximino-α-D-arabino-hexopyranosyl)-β-D-glucopyranoside was prepared in 70% yield to illustrate the use of the method for the preparation of an α-linked disaccharide.

ISSN:0008-4042    

DOI:10.1139/v68-065

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

Reaction of nitrosyl chloride with acetylated glycals affords, with a high degree of stereospecificity, dimeric acetylated 1,2-cis-2-deoxy-2-nitroso-α-D-aldopyranosyl chlorides. Reaction of acetylated glycals with dinitrogen tetroxide, depending on the reaction conditions, can give either acetylated 2-deoxy-2-nitroso-α-D-aldopyranosyl nitrates as dimers or acetylated 2-nitroglycals. The mechanisms of these reactions are discussed.

ISSN:0008-4042    

DOI:10.1139/v68-066

出版商:NRC Research Press    

年代:1968

数据来源: NRC