Organic Stereochemistry and Conformational Analysis from Enantioselective Chromatography and Dynamic Nuclear Magnetic Resonance Measurements

1995 ◽  
Vol 28 (4) ◽  
pp. 163-170 ◽  
Author(s):  
Francesco Gasparrini ◽  
Lodovico Lunazzi ◽  
Domenico Misiti ◽  
Claudio Villani
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Conformational Analysis ◽  
Enantioselective Chromatography ◽  
Dynamic Nuclear Magnetic Resonance ◽  
Nuclear Magnetic

Conformational analysis of 3-substituted-2,3,4,5-tetrahydro-1-benzoxepin by 1H and 13C nuclear magnetic resonance

1987 ◽  
Vol 65 (11) ◽  
pp. 2575-2594 ◽  
Author(s):  
A. Lachapelle ◽  
M. St-Jacques
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Conformational Analysis ◽  
Methyl Derivative ◽  
13C Nuclear Magnetic Resonance ◽  
Conformational Equilibria ◽  
Solvent Systems ◽  
Dynamic Nuclear Magnetic Resonance ◽  
Twist Boat ◽  
Nuclear Magnetic

2,3,4,5-Tetrahedro-1-benzoxepin (8) and its 3-substituted derivatives (9–13) have been studied by 1H and 13C dynamic nuclear magnetic resonance in a few solvent systems. The results show that, while 8 and its methyl derivative 9 exist solely in chair forms (C for 8 and Ce:Ca (96:4) for 9), the twist-boat (TB) conformation contributes significantly to the conformational equilibria of the derivatives 3-methoxy 10 (Ca:Ce:TB, 70:20:10), 3,3-dimethyl 11 (C:TB, 90:10), 3,3-methylmethoxy 12(Ca:Ce:TB, 89:4:7), and 3,3-dimethoxy 13 (C:TB, 92:8). The analysis of several factors (steric, electrostatic, and electronic) on the conformational behaviour of these molecules shows why the TB form is a viable conformational alternative to destabilized chair forms in this benzoxepin system.

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