Chemical Aspects of the Restricted Rotation of Esters, Amides, and Related Compounds

2006 ◽  
pp. 143-166 ◽  
Author(s):  
Christophe Dugave
Keyword(s):  
Restricted Rotation ◽  
Related Compounds

Photochemistry of cyclic α-hydroxy ketones. I. The nature and genesis of the photoproducts from steroidal 5-hydroxy 6-keto steroids and related compounds

1988 ◽  
Vol 66 (2) ◽  
pp. 214-226 ◽  
Author(s):  
Shirley Stiver ◽  
Peter Yates
Keyword(s):  
Hydrogen Transfer ◽  
Deuterium Atom ◽  
Radical Center ◽  
Nonplanar Geometry ◽  
Restricted Rotation ◽  
Development Control ◽  
Preferred Direction ◽  
Hydroxyalkyl Radical ◽  
Major Factors ◽  
Related Compounds

Photolyses of 5-hydroxy-5α- and 5β-cholestan-6-one and their 3β-acetoxy- and 3β-benzyloxy derivatives in benzene or ethanol proceed stereospecifically with retention of configuration at C-5 to give the corresponding lactones, 6-oxa-B-homocholestan-7-ones. Photolyses of 3β-acetoxy-7α-deutero-5-hydroxy-5α- and 5β-cholestan-6-ones also proceed stereospecifically to give the corresponding 5-deutero lactones. 3β-Acetoxy-5-deuteroxy-5α- and 5β-cholestan-6-one give on irradiation 1:3 and 7:1 mixtures, respectively, of the corresponding 7aα- and 7aβ-deutero lactones. Irradiation of 3β-acetoxy-5-methoxy-5α-cholestan-6-one in ethanol leads to the stereoselective formation of ethyl 3β-acetoxy-5-methoxy-5,6-seco-5α-cholestan-6-oate, while that of 3β-acetoxy-5α-cholestan-6-one gives mainly photoreduction products. These observations are interpreted in terms of α-cleavage of the C-5—C-6 bond of the ketols to give alkyl acyl diradicals that undergo hydrogen transfer to give hydroxy ketenes, which then form the lactones. It is proposed that retention of configuration at C-5 results from two major factors—the nonplanar geometry of the hydroxyalkyl radical center, and fast hydrogen transfer in the diradical, the latter resulting from restricted rotation about the C-9—C-10 bond. The specific transfer of the 7α-deuterium atom in the 7α-deutero ketols is attributed to these factors and to the preferred direction of opening to the diradical on α-cleavage. The O-deuterium labelling results are interpreted in terms of product development control in the conversion of the hydroxy ketenes to the lactones and are in accord with restricted rotation about the C-9—C-10 bond. The photolysis of 3β-acetoxy-5-amino-5α-cholestan-6-one proceeds stereoselectively to give the 5β-lactam analogue of the 5β-lactone formed from the analogous 5α-ketol.

Synthesis of N-methyl-N-(2,2,2-trichloro-1-arylaminoethyl)formamides and related compounds as potential fungicides

1980 ◽  
Vol 33 (3) ◽  
pp. 613 ◽  
Author(s):  
HG Grant ◽  
LA Summers
Keyword(s):  
Room Temperature ◽  
Amide Bond ◽  
Restricted Rotation ◽  
Related Compounds

The synthesis of several analogues of the chloralformamide fungicides is reported. The compounds, which comprise N-methyl-N-(2,2,2-trichloro- 1-arylaminoethyl)formamides and related alkoxyethyl and aryloxyethyl derivatives, exist at room temperature as two isomers due to restricted rotation about the C-N amide bond. The results of their evaluation as fungicides are reported.

Zebrafish models for hallucinogenic-related compounds

2013 ◽  
Author(s):  
A. V. Kalueff ◽  
A. M. Stewart ◽  
V. Gjeloshi ◽  
D. Kondaveeti ◽  
N. Neelkantan ◽  
...  
Keyword(s):  
Related Compounds
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