Probing Structure-Property Relationships in a Family of Aryloxyphenoxy Propionate Herbicides Using Single Crystal X-Ray Diffraction Techniques

Extract

Aryloxyphenoxy propionates are a widely manufactured class of highly active grass-selective herbicides for use in various crops. Examples include VERDICT (1a), FUSILADE (1b), WHIP (1c), and ASSURE (1d). Figure 1 shows the general structure of aryloxyphenoxy propionates. All of these compounds contain a chiral center and each enantiomer of the optical pair exhibits significantly different herbicidal activity. The optically active isomers can be prepared by reacting the corresponding substituted phenoxyphenol with the S-(-)methyl lactate sulfonate ester (2). However, the optical yield from this type of reaction is usually less than 85%. Optical purification can be achieved by control of the crystallization.