CONFORMATIONAL-ANALYSIS OF DIOXA[2.2]ORTHOCYCLOPHANES

Conformations of dioxa[2.2]orthocyclophanes (5,8-dihydro-l,4-dibenzo[b ,f]di-oxocine) were examined by theoretical calculations and X-ray cry stallographic analysis. In the crystalline state a twist boat form was observed, which is identical to the structure predicted both by molec ular mechanics and molecular orbital calculations. By contrast, an uni que screw conformation was observed in a cyclophane having two dioxa[2 .2]orthocyclophane units within the molecule in the crystalline state. (C) 1998 Elsevier Science Ltd. All rights reserved.