Abstract
The variable temperature (298-178 K)
1
H NMR spectra of tetrahydro-1,4-benzothiazepines
1-10
are described and discussed. Compounds
2-10
exist as two puckered mirror-image (enantiomorphic) conformers, with benzothiazepine ring chair-to-chair interconversion barriers of
ca
. 10 kcal mol
−1
in CD
2
Cl
2
solution. A similar interconversion was detected for compound
1
, of lower symmetry. The ground state conformations of
1-10
were assigned on the basis of the magnitudes of
1
H-
1
H vicinal coupling constants. The
1
H and
13
C NMR spectral assignments were determined by
1
H-
1
H COSY, HETCOR, and NOESY experiments. The stereochemistry and conformation of compound
1
was further confirmed by a single crystal X-ray structure determination.