Solvent steric effects. V. Azobis-2-methyl-3-phenyl-2-butane. Absolute configuration of some derivatives of 2-methyl-3-phenylbutane

1972 ◽  
Vol 37 (7) ◽  
pp. 1073-1075 ◽  
Author(s):  
Michael J. Tremelling ◽  
J. Michael. McBride
Keyword(s):  
Absolute Configuration ◽  
Steric Effects ◽  
Derivatives Of

Absolute configuration at C(20) of the derivatives of 21-nor-5α-cholane-20,24-diol

1980 ◽  
Vol 45 (9) ◽  
pp. 2443-2451
Author(s):  
Vladimír Pouzar ◽  
Miroslav Havel
Keyword(s):  
Absolute Configuration ◽  
Side Chain ◽  
Chemical Correlation ◽  
The Absolute ◽  
Derivatives Of

Derivatives of 21-nor-5α-cholane-20,24-diol XI and XIX were prepared by stepwise construction of the side-chain in the position 17β. Their absolute configuration at C(20) was determined on the basis of chemical correlation with the derivatives of 21-nor-5α-cholan-20-ol, XVI and XXIV. The absolute configuration of alcohols XVI and XXIV was determined from the ratio of the yields in which they are formed during the reduction of ketone X and using the benzoate rule. To compounds XI-XVIII the configuration 20R and to compounds XIX-XXVI the configuration 20S has been assigned.

Conformational analysis and steric effects of substituents in derivatives of 3-oxo-, 3-imino-, and 3-methylenecyclohexene

1997 ◽  
Vol 46 (11) ◽  
pp. 1891-1896
Author(s):  
O. V. Shishkin ◽  
E. V. Solomovich ◽  
M. Yu. Antipin ◽  
A. S. Petrenko ◽  
L. A. Kutulya
Keyword(s):  
Conformational Analysis ◽  
Steric Effects ◽  
Derivatives Of

Nuclear magnetic resonance characterization of the ring conformations of monosubstituted derivatives of 1,3-dioxa-5,6-benzocycloheptene

1983 ◽  
Vol 61 (1) ◽  
pp. 109-115 ◽  
Author(s):  
R. St-Amour ◽  
M. St-Jacques
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Substituent Effects ◽  
Steric Effects ◽  
Slow Exchange ◽  
Conformational Properties ◽  
Derivatives Of ◽  
Ring Conformations ◽  
Twist Boat

The conformational properties of 2-alkyl (Me, Et, i-Pr, and t-Bu) and 2-phenyl derivatives of 1,3-dioxa-5,6-benzocycloheptene (1) were studied by 13C dnmr. Analysis of slow exchange spectra at 100.6 MHz indicates that all derivatives except tert-butyl exist in an equilibrium of chair (major) and twist-boat (minor) conformations. Substituent effects on the position of the equilibrium are rationalized in terms of steric effects.

scholarly journals Circular Dichroic Properties of Flavan-3-ols

1999 ◽  
Vol 23 (7) ◽  
pp. 450-451
Author(s):  
Hendrik van Rensburg ◽  
Petrus J. Steynberg ◽  
Johann F. W. Burger ◽  
Pieter S. van Heerden ◽  
Daneel Ferreira
Keyword(s):  
Absolute Configuration ◽  
Heterocyclic Ring ◽  
The Absolute ◽  
Derivatives Of ◽  
Circular Dichroic

CD data of all four diastereoisomers of the permethylaryl ether 3- O-acetyl derivatives of a series of flavan-3-ols permit assignment of the absolute configuration at the stereocentres of the heterocyclic ring.

X-ray crystal structure analysis of a bisepoxide derived from secologanin: the structure and absolute configuration

1983 ◽  
Vol 61 (2) ◽  
pp. 282-283 ◽  
Author(s):  
Stanley C. Nyburg ◽  
Pik Y. Siew ◽  
Gavin N. Saunders ◽  
John R. Purdy ◽  
Stewart McLean
Keyword(s):  
Crystal Structure ◽  
Structure Analysis ◽  
Absolute Configuration ◽  
Dimethyl Acetal ◽  
Crystal Structure Analysis ◽  
Side Chain ◽  
Bench Mark ◽  
Chemical Transformations ◽  
X Ray ◽  
Derivatives Of

The structure and absolute configuration of a bisepoxide (2) produced by oxidation of tetraacetylsecologanin dimethyl acetal (1) with m-chloroperbenzoic acid have been established by X-ray crystal structure analysis. Epoxidation of the vinyl side chain is unexceptional; epoxidation of the β-alkoxyacrylate moiety is novel. This determination represents a valuable bench mark for configurational assignments, since the bisepoxide has been correlated by chemical transformations with a number of synthetic and naturally-occurring derivatives of secologanin.

Substituted carbonyl derivatives of the Group VI transition metals. II. Complexes with tritolylphosphines

1971 ◽  
Vol 24 (12) ◽  
pp. 2471 ◽  
Author(s):  
JA Bowden ◽  
R Colton
Keyword(s):  
Steric Effects ◽  
Molar Ratio ◽  
Mass Spectral Data ◽  
Group Vi ◽  
Mass Spectral ◽  
Carbonyl Derivatives ◽  
Nuclear Magnetic Resonance Spectra ◽  
Metal Hexacarbonyls ◽  
Cis And Trans ◽  
Derivatives Of

The reactions of the three tritolylphosphines (ortho, meta, and para) with the metal hexacarbonyls, M(CO)6 (M = Cr, Mo, W), have been investigated under a variety of conditions of temperature, ultraviolet irradiation, and molar ratio. The products were of the general formulae M(CO)5L and cis and trans M(CO)4L2 [L = tri-tolylphosphine] although not all the tetracarbonyl complexes could be prepared. Infrared and nuclear magnetic resonance spectra of these compounds showed interesting trends as the ligand was varied. ��� In addition, a novel series of derivatives with tri(o- tolyl)phosphine (pot) has been isolated, which on the basis of infrared, N.M.R., and mass spectral data are formulated as π- (pot)M(CO)3. ��� The nature of the above reactions and the properties of the products are explained in terms of an argument based on steric effects.

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