摘要:

The results of incorporation studies of doubly-labelled sodium acetate-13C2into the stress metabolites produced by fungal invasion of potato tubers are presented. The13C-labelling patterns for 10 sesquiterpenes have been determined by13C nmr. Two of these products have not been described previously and their structural elucidation is discussed. The biosynthetic interrelationships of these compounds are considered in detail.

ISSN:0008-4042    

DOI:10.1139/v78-106

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

2-Pyrrolecarbonitrile has been acylated to its 4-formyl, trichloroacetyl, ester, and thiolester derivatives. Further reactions gave other 2,4-difunctionalized compounds. These included conversion of the 2-nitriles to the corresponding 2-aldehydes. Subsequent removal of the aldehyde group afforded several 3-substituted pyrroles in good yield.

ISSN:0008-4042    

DOI:10.1139/v78-107

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

The HNO2deamination ofn-butylamine-1-14C (1-NH2-1-14C) in aqueous HClO4gave an-butyl-14C alcohol (1-OH-14C) with about 0.7% scrambling of the label from C-1 to C-2, and asec-butyl-14C alcohol (2-OH-14C) which showed extensive scrambling between C-1 and C-4, as well as small amounts of rearrangement of the label into C-2 and C-3. Analysis of the data suggested that about 2.5% of the2-OH-14C product could be derived from equilibrating protonated methylcyclopropane intermediates. The HClO4catalyzed decomposition of 3-(n-butyl-1-14C)-1-phenyltriazene (1-NNNHPh-1-14C) gave the unrearranged1-OH-1-14C and a2-OH-14C which showed only about 17–18% scrambling from C-1 toC-4. It is suggested that the different results observed in the deamination and the triazene decomposition may be due to a more ready initial formation of an ion pair in the triazene decomposition.

ISSN:0008-4042    

DOI:10.1139/v78-108

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

Infrared and Raman spectra of solid β-alanine, taurine and ciliatine (β form) are analysed. A normal mode calculation is made. The given valence force fields of the three crystalline molecules are very similar. It shows the N—CαH2—CβH2— radical is electronically equivalent in the three molecules.

ISSN:0008-4042    

DOI:10.1139/v78-109

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

A number of gas phase ion molecule reactions of protonated species with acyl halides have been examined by ion cyclotron resonance spectroscopy. A number of these reactions are found to involve an addition–elimination reaction having the character of an acidic solvolysis process. Observation of the occurrence or non-occurrence of such reactions and a consideration of appropriate thermochemical data allow a set of criteria to be formulated governing the feasibility of observing the acidic solvolysis reaction. In addition a number of mechanistic inferences are made concerning intermediates involved in the various reactions.

ISSN:0008-4042    

DOI:10.1139/v78-110

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

The introduction of hex-5-enopyranoside residues into methylated acidic polysaccharides is effected by reduction of uronic acid residues, followed by reaction with triphenyl phosphite methiodide, and dehydroiodination. The selective hydrolysis of hex-5-enopyranosidic linkages with characterization of the 6-deoxyglycos-5-uloses thus formed and location of the aglyconic hydroxyl groups thus exposed has been demonstrated for methylated derivatives of birch xylan and gum arabic. The reaction sequence provides a new method for linkage analysis of acidic polysaccharides.

ISSN:0008-4042    

DOI:10.1139/v78-111

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

Hofmann degradation of glycosiduronamide linkages in methylated polysaccharides furnishes pentodialdose derivatives to which any sugar residues external to uronic acid residues remain attached together with degraded methylated polysaccharides carrying aglyconic hydroxyl groups. The selective degradation has been carried out on methylated derivatives of birch xylan, gum arabic, and the capsular polysaccharide fromKlebsiellatype 47. Procedures for the degradation of methylated polysaccharides in the vicinity of uronic acid residues are assessed.

ISSN:0008-4042    

DOI:10.1139/v78-112

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

The reluctance of 2-acetamido-2-deoxy-D-glucose to undergo base catalyzed addition with nitromethane was overcome by using the acetamidoglycose in the form of a substituted acyclic aldehydo derivative. 2-Acetamido-2-deoxy-D-glucose diethyl dithioacetal was isopropylidenated to yield 2-acetamido-2-deoxy-3,4:5,6-di-O-isopropylidene-D-glucose diethyl dithioacetal which on demercaptalation afforded 2-acetamido-2-deoxy-3,4:5,6-di-O-isopropylidene-aldehydo-D-glucose. The aldehydo derivative readily underwent base catalyzed addition of nitromethane to give the expected epimers 3-acetamido 1,3-dideoxy-4,5:6,7-diO-isopropylidene-1-nitro-D-glycero-D-gulo-heptitol and 3-acetamido-1,3-dideoxy-4,5:6,7-di-O-isopropylidene-1-nitro-D-glycero-D-ido-heptitol which, after deisopropylidenation by mild acid treatment, were converted under modified Nef reaction conditions to give 3-acetamido-3-deoxy-D-glycero-D-gulo-heptose and 3-acetamido-3-deoxy-D-glycero-D-ido-heptose, respectively.

ISSN:0008-4042    

DOI:10.1139/v78-113

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

The steroid analogue 4,4a,5,6,7,8-hexahydro-2(3H)-naphthalenone was hydroxylated at C-8α, C-8β, and C-4a byRhizopusarrhizus. Similar products were obtained by peracid oxidation of the corresponding enol ethers: hydroxylation of estr-4-ene-3,17-dione by the same fungus occurred at the analogous C-6 and C-10 positions. These results are consistent with a mechanism of microbial hydroxylation involving the enol form of the Δ4-3-ketone. Data from the incubations withR.arrhizusof androst-4-ene-3,17-dione specifically labelled with deuterium at C-4, C-6α, or C-6β and from those of other deuterium labelled substrates have been interpreted in terms of a mechanism of C-β hydroxylation involving a rate-determining step before enolization of the ketone, followed by rapid enolization and oxidation of the enol to give the 6β-hydroxy-Δ4-3-ketone. The kinetic isotope effect,kH/kD, for the hydroxylation of androst-4-ene-3,17-dione at C-6β has been found to be 1.2 ± 0.1.

ISSN:0008-4042    

DOI:10.1139/v78-114

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

The electrochemical behaviour of Sb(III) and Sb(V) in water–HF mixtures (2.5 to 50% HF) and in anhydrous HF is described. A Teflon capillary dropping mercury electrode is proposed for polarographie investigations in these fluorinated media. It is shown, by classical or puise polarography, that Sb(III) can be reduced to Sb(0), as in acidic non-fluorinated media. The electrochemical reaction becomes reversible by addition of Cl−, Br−or I−. Sb(V) is not electroactive in the various HF-media, except when it is introduced as the SbCl5. In this case, the two polarographie waves of Sb(V) disappear with time because of SbF6−formation. Analytical applications to the determination of Sb(III) in water–HF and in anhydrous HF are discussed.

ISSN:0008-4042    

DOI:10.1139/v78-115

出版商:NRC Research Press    

年代:1978

数据来源: NRC