摘要:

4-Acetamido-2,4,6-trideoxy-D,L-arabino-hexopyranose, a desmethyl analog of N-acetyl-L-hoTantosamine, the glycosidic residue of the cardenolide HoTarosine A and holantosines C and D, has been prepared via a novel intramolecular rearrangement of an amino alcohol and has been characterized by single-crystal X-ray diffraction.

ISSN:0732-8303    

DOI:10.1080/07328308508070191

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Recently, we described the high-yield synthesis of chiral [2.2.1J cryptands incorporating carbohydrates. Models show that variations of substituents in the carbohydrate fragment, e.g. in 4,6-O-acetals, may lead to asymmetric modifications in close proximity to the molecular cavity of the ligand, and therefore, to changes in enantiomeric differentiation. We wanted to obtain the cryptand2with an axial phenyl group, as shown in Fig.1, which is in contrast to a cryptand (1) obtained earlier with an equatorial phenyl group.

ISSN:0732-8303    

DOI:10.1080/07328308508070192

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

D-Glucose was transformed stereoselectively into (7R,8S)8-benzyloxy-7-hydroxy-2-methyl-9-octadecene from which both enantiomers of disparlure, (7R,8S)-(+)-and (7S,8R)-(-)-7,8-epoxy-2-methyloctadecane, sex pheromone of the gypsy moth, were obtained in four and three steps, respectively.

ISSN:0732-8303    

DOI:10.1080/07328308508070193

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Allyl ethers are widely used for the “temporary” protection of hydroxy groups in carbohydrates. The allyl group is conveniently removed by isomerization and subsequent cleavage of the labile prop-1-enyl group.2The rearrangement of allyl ethers to prop-1-enyl ethers is readily achieved by treatment with potassium t-butoxide in dimethyl sulfoxide, using tris(tripheny1phosphine)rhodium chloride, palladium on activated charcoal and by an ene reaction with diethylazodicarboxylate. acidic conditions, ozonolysis followed by alkaline hydrolysis, reaction with alkaline permanganate solution, or treatment with mercuric chloride in the presence of mercuric oxide. The isomerization of allyl ethers to prop-1-enyl ethers can also be carried out in the presence of palladium on carbon or complex bis(benzonitrile)palladium(11) chloride. Bruce and Roshan-Ali' showed that derivatives of allyl phenyl ether are smoothly cleaved by this complex. This has made it possible to remove the protecting group in a one-pot operation. We have now investigated the effect of palladium catalysts on the isomerization and cleavage of the allyl group in carbohydrate derivatives.

ISSN:0732-8303    

DOI:10.1080/07328308508070194

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Recently we have described1high pressure (4+2) cycloaddition of l-methoxybuta-1,3-diene (1)to 2,3-0-isopropylidene-D-glyceraldehyde (z), which gives rise to chiral cycloadducts3(Scheme). action was carried out under high-pressure conditions (22 kbar, 50°C. diethyl ether as solvent, 20 h, 80% yield)2 four diastereoisomeric adducts were formed in a ratio of 3a:3b:3c:3d=66:16:13:5. The reaction mixture was separated by column chromatography yielding two fractions which contained diastereoisomeric mixtures (3a+3b) and (3c+3d), respectively. Absolute configuration at the C-5 carbon atom in both mixtures was established by chemical correlation.' These results prompted us to use a mixture (3a+3b), being stereochemically pure at C-5 chiral center, in the synthesis of optically active methyl 4-deoxyheptosides (Scheme).

ISSN:0732-8303    

DOI:10.1080/07328308508070195

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

This is a scanned image of the original Editorial Board page(s) for this issue.

ISSN:0732-8303    

DOI:10.1080/07328308508070180

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor