Molecular Structure of Heterocycles: 6. Solvent Effects on the 17O Nmr Chemical Shifts of 5-Trichloromethylisoxazoles

a multilinear-regression analysis using the kamlet-abboud-taft (kat) solvatochromic parameters in order to elucidate and quantify the solvent effects on the 17o chemical shifts of three 5-trichloromethylisoxazoles [(1a) non-, (1b) 3-methyl- and (1c) 4-methyl-substituted] is reported. the chemical shifts of ring oxygen atom, o1, of compounds 1a-c show dependencies (in ppm) on the solvent polarity-polarizability of -4.8p*, -3.2p*, -8.9p*, on the solvent hydrogen-bond-donor (hbd) acidities 0.9a, -0.2a, -2.7a and the solvent hydrogen-bond-acceptor (hba) basicities -0.4b, 1.9b, 0.9b, respectively. the data of net charges of o1 and dipole moment, obtained from mo calculations (am1), are compared with the solvent effect parameters obtained for compounds 1a-c.