An ab initio study of conformational properties of lenthionine

Ab initio calculations at HF/6-31 + G* level of theory for geometry optimization and MP2/6-31 + G*//HF/6-31 + G* level for a single point total energy calculation are reported for lenthionine (1,2,3,5,6-pentathiepane) (1). The unsymmetrical twist-chair (TC) conformation was calculated to be the most stable conformation of 1. The unsymmetrical twist-boat (TB) form was found to be 33.0 kJ mol(-1) less stable. Conformational racemization of TC can take place via plane symmetrical chair geometry as transition state and requires 50.7 kJ mol(-1). (C) 2003 Elsevier B.V. All rights reserved.