摘要:

Metastable peaks for the fragmentation C2H5N+• → C2H4N+ + H•have been studied in the first field-free region of a double focussing mass spectrometer. Isomeric structures of C2H5N+•ions derived from a variety of precursor molecules were characterised by their metastable peak shape and kinetic energy release. The identifications were aided by appropriate deuterium labelling experiments. Four isomeric ionsrwere shown to retain their structural identity within the ion energy and lifetime ranges observable in these experiments. Ion (a), generated from aziridine was found to be indistinguishable from its open chain isomerThe results closely parallel those previously found for the isoelectronic C2H5N+•ions, but the differences in characteristic kinetic energy release are smaller. A simple deuterium exchange labelling experiment may be necessary for the unequivocal identification of C2H5N+•ion structures.

ISSN:0008-4042    

DOI:10.1139/v76-145

出版商:NRC Research Press    

年代:1976

数据来源: NRC

摘要:

The oxidative dimerization of 3-alkyl-2-methylindoles to1has been found to occur with several primary 3-alkyl and one secondary 3-alkyl groups. A tertiary 3-alkyl group prevents dimerization of the intermediate 3-hydroxyindolenine. These new dimers undergo the same acid-catalyzed rearrangement as1a.

ISSN:0008-4042    

DOI:10.1139/v76-146

出版商:NRC Research Press    

年代:1976

数据来源: NRC

摘要:

2-Alkyl (or aryl) indoles react readily with phenylhydrazine in hydrochloric–acetic acid to giveo-aminophenylpyrazoles7, if the 2-substituent is of small or moderate size, or else 3-aminoindoles, if the 2-substituent is sufficiently bulky. The 3-aminoindoles readily undergo oxidative dimerization to indolylidene aminoindolesEvidence is provided for the mechanisms of formation of these two kinds of products.

ISSN:0008-4042    

DOI:10.1139/v76-147

出版商:NRC Research Press    

年代:1976

数据来源: NRC

摘要:

Regioselective and stereoselective routes to 2- and/or 4-substitutedvic-triazolo(4,5-b)pyrid-5-ones have been established, and series of 4- and 2-β-D-ribofuranosyl derivatives have been prepared as candidate substrates for, and potential inhibitors of, the enzymes of polynucleotide synthesis. Structural assignments were made by comparison of spectroscopic properties (pmr, uv) with those of appropriate model compounds, and on the bases of proton chemical shift and coupling constant patterns in the ribose moieties, it is proposed that 4-β-D-ribofuranosyl-vic-triazolo(4,5-b)pyrid-5-ones adopt conformations with 'highanti' sugar–base torsional angles. A facile ribofuranose → ribopyranose conversion is observed with a 2-β-D-ribofuranosyl-vic-triazolo(4,5-b)pyrid-5-one.

ISSN:0008-4042    

DOI:10.1139/v76-148

出版商:NRC Research Press    

年代:1976

数据来源: NRC

摘要:

The stereospecific total synthesis of the pentacyclic tetrasubstituted intermediate39is described. The conversion of this material to the delphinine type alkaloid chasmanineIVby the method worked out recently by the same group (1) is envisaged.

ISSN:0008-4042    

DOI:10.1139/v76-149

出版商:NRC Research Press    

年代:1976

数据来源: NRC

摘要:

A re-examination of the Li–In system, based on thermal and X-ray diffraction analysis of 42 alloys, shows it to be more complex than originally reported. This complexity is more consistent with the analogous Li–Tl and Li–Ga systems. The solid solubility of Li in In is about 1.5 at% Li, while that of In in Li appears to be very low. The homogeneous Li–In phase extends from about 46 at% to between 55 and 63 at% Li, depending on the temperature. Of the 11 new phases, 5 with the nominal compositions Li7In4, Li2In, Li8In3, Li3In, and Li4In(λ) are stable at room temperature, while Li5In2, Li73In27(η), Li11In4, Li4In(κ), Li6In and Li12In occur at higher temperatures.

ISSN:0008-4042    

DOI:10.1139/v76-150

出版商:NRC Research Press    

年代:1976

数据来源: NRC

摘要:

The photochemistry ofcis-[Rh(cyclam)X2]+(where X = Cl, Br, or I) andcis-[Rh(en)2Cl2]+have been studied. Whilst only halide aquation is observed for the cyclam complexes, amine aquation is the principal reaction mode for the ethylenediamine complex. In each case, the photosensitivity was greater for charge transfer excitation than ligand field excitation. Although this wavelength dependence was also exhibited for the correspondingtranscomplexes, the dependence on the leaving group which wasfor thetranscomplexes is completely reversed forcis-[Rh(cyclam)X2]+wherefor ligand field excitation.The behaviour ofcis-[Rh(en)2Cl2]+andcis-[Rh(cyclam)I2]+is seen to be consistent with the preferential amine activation predicted by the photochemical model proposed by Zink. The change in photospecificity observed withcis-[Rh(cyclam)Cl2]+andcis-[Rh(cyclam)Br2]+is interpreted as the result of distortion from effective tetragonal symmetry which causes the repulsive energy to become progressively more localized in the metal–halide bond.

ISSN:0008-4042    

DOI:10.1139/v76-151

出版商:NRC Research Press    

年代:1976

数据来源: NRC

摘要:

Ethyl azidoacetate was reacted with thiophene-2,3-dialdehyde, in which the two formyl groups are free or in which one of them is blocked as the diethyl acetal, to yield, after cyclization, thieno[2,3-c] and -[3,2-c] pyridines and pyridones, respectively. The structures of the intermediate products were established by nmr; a reaction scheme is proposed. [Journal translation]

ISSN:0008-4042    

DOI:10.1139/v76-152

出版商:NRC Research Press    

年代:1976

数据来源: NRC

摘要:

Ethyl azidoacetate reacts with 2,5-, 2,4-, and 3,4-thiophenedialdehydes to yield products of both mono- and dicondensation. Cyclization of the thiophene derivatives thus obtained leads to substituted thienopyrroles, to systems involving two pyrrole rings orthocondensed to one thiophene ring, or to thieno[3,4-c]pyridones and pyridines. The structures of the compounds obtained from various syntheses were established by nmr. [Journal translation]

ISSN:0008-4042    

DOI:10.1139/v76-153

出版商:NRC Research Press    

年代:1976

数据来源: NRC

摘要:

Raney nickel reduction of the diesters of thieno dipyrroles proceeds by a desulfuration. Treatment of the dipyrrole diesters thus obtained leads to three fundamental systems; 2,2′-, 2,3′-, and 3,3′-dipyrroles. [Journal translation]

ISSN:0008-4042    

DOI:10.1139/v76-154

出版商:NRC Research Press    

年代:1976

数据来源: NRC