1. Department of Chemical & Screening Sciences, Wyeth Research, 87 Cambridge Park Drive, Cambridge, Massachusetts 02140, AstraZeneca Pharmaceuticals, EST(Chem) 26F17, Mereside, Macclesfield, Cheshire SK10 4TG, U.K., and Openeye Scientific Software, 3600 Cerrillos Road, Suite 1107, Santa Fe, NM 87507