38824-30-5Relevant articles and documents
Conformational analysis of 3-substituted-2,3,4,5-tetrahydro-1-benzoxepin by 1H and 13C nuclear magnetic resonance
Lachapelle, A.,St-Jacques, M.
, p. 2575 - 2594 (2007/10/02)
2,3,4,5-Tetrahydro-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 equilibra 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.