摘要:

During the past two decades, there has been a rapidly growing interest in the field of intra- and interspecific chemical communication. Insect pheromones in particular have been intensely studied with respect to their potential use as a component of integrated pest management.1Structural identification and chemical synthesis of these so-called “semiochemicals” have developed in harmony with the biological research evaluating structure-activity relationships. Most of the pheromones identified, studied, and synthesized come from the orderLepidoptera: very often these pheromones consist of long-chain olefinic compounds in which regio- andcis/trans-isomerism determine their biological activity. Several well documented reviews have appeared, emphasizing both coupling of alkyl halides or similar electrophilic substrates with metallo-organic reagents (“Wurtz-chemistry”) and carbonyl olefination, such as the Wittig reaction and its huge variety of modifications for regio- and stereoselectiveC-Cbond formation.2-8The importance of chirality in pheromone perception by insects has been recognized and the role of optical isomerism and diastereoisomerism in behavioral discrimination has been firmly established through the combination of synthesis and bioassay. Some reviews bring good insight into the diverse strategies employed in synthesizing chiral pheromones,8,9originating principally from the ordersColeopteraandHymenoptera. In spite of the increasing efficiency of asymmetric synthesis in the semiochemical field10, only few methods afford highly optically pure compounds with known absolute configuration. On the other hand, optical resolution is not always satisfactory and the absolute configuration of the resolved material has to be determined by some means.11Enantiospecific synthesis starting from naturally occuring chiral molecules such as amino or hydroxy acids, terpenes and sugars appears to be the safest path leading to highly optically pure pheromones. The prominent role of readily available carbohydrate starting materials within this “chiral synthon approach” has been clearly demonstrated.12The present review offers a 1976 to 1990 literature survey of the use of hexoses (mainly D-glucose and derivatives) and pentoses for the enantiospecific synthesis of chiral pheromones, issuing principally from the orderColeoptera.13

ISSN:0732-8303    

DOI:10.1080/07328309108543898

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Experimental1H NMR chemical shifts were related to results obtained from theoretical calculations, in this case the HSEA approach, in order to obtain information about conformational equilibria about the glycosidic bond of disaccharides. Assuming the existence of the exo-anomeric effect, it was shown that the sign of torsion angle Ψ can be obtained tentatively from the1H N M R chemical shifts.

ISSN:0732-8303    

DOI:10.1080/07328309108543899

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The title compound was prepared in eight steps starting from 2-acetamido-2-deoxy-D-mannose. This commercially available compound was first transformed into known 3-acetamido-1,3-dideoxy-1-nitro-D-glycero-D-galacto-heptitol (2) and then, into 3-acetamido-4,5,6,7-tetra-O-acetyl-2,3-dideoxy-D-manno-heptose (6b). Using a Wittig-Wadsworth-Emmons reaction, aldehyde 6b was then converted into ethyl 5-acetamido-6,7,8,9-tetra-O-acetyl-3,4,5-trideoxy-2-(t-butyldimethyl)silyloxy-D-manno-nonenoate (8). AfterO-deacetylation, saponification of the ester group and simultaneous deprotection of the silyloxy enol ether,N-acetyl-4-deoxy-D-neuraminic acid1was obtained in an overall yield of about 30% from 2.

ISSN:0732-8303    

DOI:10.1080/07328309108543900

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The (4S,5S)-2-phenyl-4,5-dimethyl-4-formyl-4,5-dihydro-oxazole (4),viathe α, β-unsaturated ester5andre-face addition of nitrogen and sulfur nucleophiles, gave eventually theribo-imidazolino hexose 15 and the methyl α and β-2,3,4-6-tetradeoxy-4-C-methyl-4-trifluoroacetamido-3-thia-L-ribo-hexopyranoside (16). Additionviathe adduct17afforded thearabino-3,4-diamino derivative20and theriboisomer20a, the 3-fluoro-L-riboproduct22, the 2,3-unsaturated L-hexose21and theerythro-2,3,4,6-tetradeoxy compound23. The conformational feature, in solution, of the reported L-hexoses is also discussed on the basis of their1H NMR data.

ISSN:0732-8303    

DOI:10.1080/07328309108543901

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Anomeric deoxygenation of D-glucopyranoside derivatives afforded suitable starting compounds for the synthesis of protected 2-azido-1,5-anhydro-2-deoxy-D-mannitols. The latter intermediates were converted after removal of the protecting groups, into the following analogues of 2-acetamido-2-deoxy-D-mannose:i.e.2-acetamido-1,5-anhydro-2,6-dideoxy-D-mannitol, 2-acetamido-1,5-anhydro-2-deoxy-D-mannitol, 2-acetamido-1,5-anhydro-2-deoxy-D-mannitol 6-(disodium phosphate) and 2-acetamido-1,5-anhydro-2-deoxy-D-mannitol 6-(hexadecyl sodium phosphate).

ISSN:0732-8303    

DOI:10.1080/07328309108543902

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

3-Deoxy-D-erythro-2-hexulosonic acid (KDG), an important metabolite of bacterial polysaccharides degradation was prepared from D-glucose in six stepsviathe synthesis of 2,4-O-isopropylidene-D-erythrose and subsequent Wittig-Horner condensation followed by smooth deprotections of protecting groups. Overall yield was 35% from D-glucose.

ISSN:0732-8303    

DOI:10.1080/07328309108543903

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Octa-O-acetylsucrose (1) was regioselectively hydrolyzed by the lipase AK from Pseudomonas sp. in aqueous buffer and two hepta-O-acetylsucroses and two hexa-O-acetylsucroses were obtained by column purification. After analysis by NMR methods, four products were shown to be 3,4,6,1′,3′,4′,6′-hepta-O-acetylsucrose (2), 2,3,4,6,1′,3′,6′-hepta-O-acetylsucrose (3), 3,4,6,1′,3′,6′-hexa-O-acetylsucrose (4) and 2,3,4,6,3′,6′-hexa-O-acetylsucrose (5).

ISSN:0732-8303    

DOI:10.1080/07328309108543904

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Alkyl and thioalkyl α-glycosides ofN-acetylneuraminic acid have been prepared in near quantitative yield and with complete stereoselectivity, under the Williamson reaction conditions using RONa or RSNa, respectively, in ROH or RSH as solvent.

ISSN:0732-8303    

DOI:10.1080/07328309108543905

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Synthesis of three tetrasaccharides, namely,0-α-L-fucopyranosyl-(1→3)-0-(2-acetamido-2-deoxy-β-D-glucopyranosyl)-(1→3)-0-(β-D-galactopyranosyl)-(1→4)-β-D-glucopyranose (7),0-α-L-fucopyranosyl-(1→4)-0-(2-acetamido-2-deoxy-β-D-glucopyranosyl)-(1→3)-0-(β-D-galactopyranosyl)-(1→4)-D-glucopyranose (9), and0-α-L-fucopyransoyl-(1→3)-0-(2-acetamido-2-deoxy-β-D-glucopyransoyl)-(1→6)-0-(β-D-galactopyranosyl)-(1→4)-D-glucopyranose (15) has been described. Their structures have been established by13C NMR spectroscopy.

ISSN:0732-8303    

DOI:10.1080/07328309108543906

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The major component of the oviposition attractant pheromone of the mosquitoCulex pipiens fatiganswas shown to be (-)-(5R, 6S)-6-acetoxy-5-hexadecanolide (1).1For the chemical synthesis of this optically active pheromone,2carbohydrates such as D-mannitol2iand 2-deoxy-D-ribose21have been utilized as chiral templates. In this laboratory the natural pheromone has been synthesized from (S)- and (R)-O,O-isopropylideneglyceraldehyde independently, using diastereoselective dihydroxylation as the key step.2mWe now describe an enantiospecific synthesis of the pheromone from D-glucose.

ISSN:0732-8303    

DOI:10.1080/07328309108543907

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor