Synthesis and biological activity of enantiomeric pairs of phosphosulfonate herbicides

The phosphosulfonates are a new class of soil-active herbicides which contr ol a variety of annual grass and broadleaf weeds. Chirality at the phosphor us atom afforded the opportunity to explore stereospecific requirements for herbicidal activity. Chiral (hydroxymethyl)phosphinate intermediates were enzymatically resolved (Pseudomonas fluorescens lipase) from the racemic mi xtures and then used to prepare two pairs of enantiomeric phosphosulfonates . Biological testing of the enantiomeric phosphosulfonate herbicides demons trated that, in each case, the herbicidal activity was attributed to the () enantiomer and that the (+) enantiomer is more active than the racemate.