An overview is given of the CoMFA (comparative molecular field analysis) and CoMSIA (comparative molecular similarity indices analysis) methodologies that are established ligand-based molecular design tools widely used by medicinal and pesticide chemists. In the absence of a three-dimensional structure of the target biopolymer, CoMFA and CoMSIA often provide a practical solution to an otherwise intractable problem of proper characterization of ligand-receptor interactions. These techniques are especially important in agrochemistry, where the number of known molecular structures of pesticide targets is limited. The use of CoMFA and CoMSIA in the agrochemical field for modelling the interactions of insecticides, fungicides, herbicides and herbicide safeners with their target binding sites is illustrated by using some selected published work. The CoMFA and CoMSIA models developed have been used successfully to map the properties of unknown receptors, construct hypotheses for ligand-receptor interactions, optimize lead structures, design novel active compounds, and predict biological activities. The application of CoMFA by the present authors for deriving a binding site hypothesis for dichloroacetamide-type herbicide safeners is described in somewhat more detail.

2-Methy lamín o-1-cyclopen tene-1-dithiocarboxy lie acid (II) can be obtained in low yield from cyclopentanone with, carbon disulfide and methylamine; no other 2-alkylamino analogs can be synthesized. The amino group of 2-amino-1-cyclopen tene-1-d.ithiocarboxylic acid (I) and that of its methyl ester (VII) can be substituted by the alkylamino group by an amine exchange reaction, yielding the corresponding 2-alkylamino-1-cyclopen tene-1dithiocarboxylic acid (II) or its methyl ester (III-V, VIII-XII), respectively. The structures, including tautomeric forms of the synthesized compounds, were proved by ir and nmr spectroscopy.In previous research it was found that 2-amino-lcyclopentene-l-dithiocarboxylic acid (I) synthesized by Takeshima and coworkers8 exerts a marked antifungal action against various fungi.4 The steric arrangement of the functional groups in this compound permits the formation of six-membered chelates with metals, which fact may be responsible for the biological activity, too. Chelation plays an important role in the

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