Conformational Study of N-Methyl-5,6-dihydro-7H,12H-dibenz[c,f]-azocine by Nuclear Magnetic Resonance Spectroscopy

Abstract

A study of the n.ni.r. spectra of N-methyl-5,6-dihydro-7H,12H-dibenz[c,f]azocine, its deuterated derivative, and its conjugate acid in deuteriochloroform and in trifluoracetic acid at 27 and at -62' has shown that the n~olecule prefers the rigid "crown" conformation. From the equilibrium constant for the equilibrium flexible * crown at 27 and at -62", AH and AS values of -3.2 f 0.5 kcal/mol and -7 f 3 e.u. respectively were determined, indicating the preference for the crown conformer. A barrier to interconversion of the flexible to crown form at -62O was determined to be 15.3 f 0.3 kcal/mol.These parameters provide the first experiniental data pertinent to the conforniational properties of the 1,4-cyclooctadiene system.Une ttude des spectres de rtsonance magnttique nuclCaire du N-mCthyl dihydro-5,6-7H,12H dibenz- [Traduit par le journal]

Structural studies of dibenz[c,f]azocines. I. N-Methyl-5,6-dihydro-7H,12H-dibenz[c,f]azocine

“…The n.m.r, studies of N-methyldibenzazocine by Renaud et al (1973) established that the molecules in solution exhibit two conformations of the azocine ring, with 96.5 % in the boat-chair and 3.5 % in the twistboat conformations. The present X-ray analysis has shown that in the solid state the azocine ring is in the boat-chair conformation.…”

“…The conformational properties in solution of the N-methyl derivative have been determined by Renaud, Layton & Fraser (1973) from a study of its n.m.r, spectrum. The latter also plan to carry out further n.m.r, studies on different N-alkyl derivatives in order to provide information on the steric effects in these eight-membered ring systems.…”

The Dibenzosuberenone Scaffold as a Privileged Substructure: From Synthesis to Application

“…The Renaud group reported an improved synthesis of azocine 286 in six steps and a study on its conformational analysis using NMR spectroscopy (Scheme 46). 177 The brief synthesis of azocine 286 began with oxidative cleavage of 5-dibenzosuberenone (1) by potassium permanganate to give dicarboxylic acid 287; the final step is the treatment of dibromo compound 288 with methylamine to afford azocine 286 in 57% yield. The 1 H NMR studies show that the molecule 286 prefers the rigid-crown conformation such as 285B.…”

Catalytic asymmetric synthesis of 1,1′-spirobi[indan-3,3′-dione] via a double intramolecular C–H insertion process

“…Notes and references † Bis(a-diazo-b-keto ester) 2 was prepared from diphenylmethane-2,2Adicarboxylic acid 11 Reactions were carried out as follows: 2 mol % of catalyst was added to a stirred solution of diazo compound 2 (0.20 mmol) in the indicated solvent (2 ml) at the indicated temperature under argon. After the reaction proceeded to completion, the solvent was evaporated in vacuo and the residue was treated with 90% aqueous DMSO (1.5 ml) at 120 °C for 1 h. Standard workup followed by chromatography provided (R)-1. b Overall isolated yield.…”