摘要:

The stability of the complexes AgBF4•2 vinyl chloride and AgBF4•2 vinyl fluoride has been determined and compared with that of AgBF4•2 propylene. The much lower stability of the halo-olefin complexes has been attributed partly to weaker interaction of these less basic olefins with the silver ion and partly to configurational restrictions imposed upon the complexed halo-olefin molecules as a result of their higher permanent dipole moment.

ISSN:0008-4042    

DOI:10.1139/v71-219

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

The long-range shielding effects of the C=O and C—H bonds were reexamined by the method described in part IV of this series, with the objective of resolving the discrepancies between some of the conclusions presented and earlier findings by Zürcher. The C—H bond magnetic anisotropy was treated as a variable and found to be small enough to be negligible. Upon omission of this term, both electrostatic and magnetic anisotropy effects had to be invoked to account for the shielding effects of the carbonyl group.The necessary geometric quantities were calculated from atomic coordinates for androsterone, as determined by X-ray crystallography, and freely rotating methyl groups were approximated by superpositions of 24 conformations of the group. The results were in essential agreement with those obtained with the use of geometric factors computed as described in part IV.

ISSN:0008-4042    

DOI:10.1139/v71-220

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

The calculation of chemical shift values by the method used in parts I–V (1–5) has been extended to a derivation of the shielding effects of the ethylene–ketal and −thioketal groups. For these studies ketal and thioketal derivatives of monoketoandrostanes were prepared. The chemical shifts of the C-18 and -19 methyl protons in these compounds are reported for the solvents CDCl3, CCl4and benzene.Representing both groups by point dipoles, values for the anisotropies and forK, a parameter descriptive of the electric field effect, were derived for various, coincidental, locations of the magnetic and electric dipoles along the symmetry axes of the two groups.

ISSN:0008-4042    

DOI:10.1139/v71-221

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

Methyl 4-O-methyl-α-DL-lyxopyranoside (6) and methyl 4-deoxy-β-DL-erythro-pentopyranoside (3) were obtained in excellent yield as the sole isolable products of the reaction of osmic acid in pyridine oncis-2,5-dimethoxy-5,6-dihydro-2H-pyran (2) and 2-methoxy-5,6-dihydro-2H-pyran (1), respectively. Hydrolysis of6and3gave respectively 4-O-methyl-DL-lyxose (9) and 4-deoxy-DL-ribose (8).The attack on the double bond of1and2occurs nearly completely if not exclusively from the unhindered side, remote from the substituent. These results indicate that1must be predominantly in the conformation in which the C-2 alkoxy group isquasiaxial.

ISSN:0008-4042    

DOI:10.1139/v71-222

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

2,3,6,7,8,9-Hexahydro-1H-cyclohepta[gh]phenalene (7) has been prepared via the tricyclic ketone 3-oxo-1,2,3,7,8,9,10,10a-octahydrocyclohepta[de]naphthalene (1) and the tetracyclic ketone 1-oxo-2,3,6,7,8,9-hexahydro-1H-cyclohepta[gh]phenalene (6). Conversion of the tricyclic ketone1into 1-oxo-1,2,3,3a,5,5a,6,7,8,9-decahydro-4H-cyclohepta[cd]phenalene (8) and reduction of this tetracyclic ketone to 1,2,3,3a,5,5a,6,7,8,9-decahydro-4H-cyclohepta[cd]phenalene (9), followed by aromatization, gave 5,5a,6,7,8,9-hexahydro-4H-cyclohepta[cd]phenalene (10) (73 %) together with the desired isomeric 2,3,6,7,8,9-hexahydro-1H-cyclohepta[gh]phenalene (7) (23%).

ISSN:0008-4042    

DOI:10.1139/v71-223

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

Non-equivalence of the benzylic hydrogens was found in severalN-phenyl-ortho-hydroxybenzyl-amines and, where possible, activation parameters were calculated for the processes causing non-equivalence. Hindered rotation about the aromatic carbon-nitrogen bond was the rate determining process with an ortho-t-butyl group on the aniline ring. Exchange of phenolic and amino hydrogens was studied over a range of temperature and concentration. Both intermolecular and intramolecular exchange were observed. The latter may be the first example of such a process to be studied by n.m.r.

ISSN:0008-4042    

DOI:10.1139/v71-224

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

The treatment of α- and β-D-xylopyranosyl chloride 2,3,4-tri(chlorosulfate) and the corresponding α-D-lyxoderivative with a catalytic quantity of sodium iodide in methanol solution resulted in the removal of the chlorosulfate groups and rapid methanolysis of the anomeric chlorine atoms. The methanolysis proceeded with predominant inversion in each case (80–90 %), independent of the orientation of the C-2 substituent. In the presence of sodium methyl mercaptide, however, thioglycosides having an inverted configuration were produced from 1,2-cischlorides, and thioglycosides having an unchanged anomeric configuration were formed from 1,2-transchlorides. It is proposed that all these glycosidations occur via a free pentopyranosyl chloride intermediate, and that under the basic conditions of thioglycosidation a 1,2-anhydro intermediate is formed from 1,2-transchlorides.

ISSN:0008-4042    

DOI:10.1139/v71-225

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

Some new unsaturated tricyclic hydrocarbons have been synthesized using a sequence of some general usefulness.

ISSN:0008-4042    

DOI:10.1139/v71-226

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

The mass spectra of seven cyclicN-nitrosamines were examined for characteristic fragmentation patterns. Accurate mass measurements on three of the compounds indicated that the M-17 and M-30 peaks resulted from molecular ion losses of •OH and •NO respectively. The loss of • OH was rationalized in terms of a McLafferty-type rearrangement.

ISSN:0008-4042    

DOI:10.1139/v71-227

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

Reaction between sodium salts of 3-amino-2-cyano-3-mercapto acrylhydrazides and two halocompounds resulted in the formation of some 4-iminothiophenes that were found to be quite stable. Their i.r., u.v., and n.m.r. spectra are described here together with one of their tautomeric forms obtained after acetylation.

ISSN:0008-4042    

DOI:10.1139/v71-228

出版商:NRC Research Press    

年代:1971

数据来源: NRC