STEREOCHEMISTRY OF OXYGENATED 10-MEMBERED RINGS - X-RAY CRYSTAL-STRUCTURE, THEORETICAL CALCULATIONS AND H-1 AND C-13 NMR-STUDIES OF BENZO-10-CROWN-3 ETHER IN SOLUTION AND IN THE SOLID-PHASE

The title molecule crystallizes in space group P21/c, with a = 7.2705( 20), b = 10.825(3), c = 12.790(5) Angstrom,beta = 93.51(3)degrees and Z = 4. The solid phase C-13 NMR spectrum is discussed in relation to t hat obtained in solution. A dideuterio derivative has been synthesized to aid in the spectral assignments. Conformational preferences of the 10-membered ring in the solid state are compared with results of mole cular mechanics calculations using MM2 and quantum mechanical methods employing the AM1 approach. (C) 1997 Elsevier Science B.V.