The methyl-transfer reactions from several substituted methyl arenesulfonates to potassium benzenesulfonate in sulfolane have been studied with respect to both rates and equilibria. Because the reactions were followed by proton NMR of the methoxy group, only cases of methyl arenesulfonates with quite distinct methoxy chemical shifts from the unsubstituted ester could be studied, and this, in fact, required the use of ortho substituents. Hammett plots for these data were thus impossible, but a plot of log k+ vs. log K, although somewhat scattered, did allow an estimation of the rate of the identity reaction for the unsubstituted compound. These methyl arenesulfonates, as well as methyl iodide, were placed roughly on the scale of equilibrium methylating agents studied earlier in the same solvent. Methyl 2,4,6-trinitrobenzenesulfonate is a very reactive substance not compatible with sulfolane. It is soluble and stable only in thionyl chloride among a large number of solvents attempted and methylates a few weak nucleophiles more extensively than methyl trifluoromethanesulfonate. apparently simple model for the SN2 reaction.The majority of the theoretical work, as well as a little(2) Arnett, E.

The process of sorting leads identified via screening can be made more efficient by the application of experimental design strategies. Such strategies were applied during the course of optimization of a series of 4-aryl-l,2,4triazole-5(1H)-thiones which were initially identified as being herbicidal in greenhouse screens. Through application of a Free-Wilson strategy and subsequent sequential simplex optimization, potency improvements of 25 000-fold over the unsubstituted phenyl compound have been realized in a hydroponic cucumber assay. Synthesis of these analogues will be discussed as well as the development of the QSAR model which relates structural modifications to potency.

The development of an estimator for vapor pressure based upon organic functional groups is described. This vapor pressure calculator permits prediction of vapor pressure for a wide range of structural classes. The statistical quality of the derived coefficients is presented as well as the quality of the prediction of the training set of compounds. The calculator is then used to predict the vapor pressure of recently introduced agrochemicals to illustrate its performance. The significance of this calculator is that the agrochemical scientist can readily estimate the effects on vapor pressure of altering specific structural features of a molecule.

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This report describes the development of an efficient solid-phase synthesis protocol and adaptation of reported solution phase procedures for the synthesis of the cyclic depsihexapeptide destruxin A and related analogs. The solid-phase method described is based on standard Fmoc peptide chemistry, including a new synthetic method for the assembly of the depsi bond-containing unit. In order to select analogs of destruxin A for synthesis and evaluation of insecticidal activity, the work of Hellberg et al., describing a set of Z-descriptors for amino acid side-chains comparing their physicochemical properties, was utilized. Destruxin A and 27 different analogs with structural variations in four residues were synthesized and insecticidal activity was evaluated via injections into tobacco budworm (Heliothis virescens) larvae. Several destruxin A analogs were found to be at least as potent as the native compound.