:The 2-benzoylcyclohexane-1,3-diones, the triketones, are a novel class of bleaching herbicides whose mode of action is the inhibition of the enzyme p-hydroxyphenylpyruvate dioxygenase. The structureÈactivity relationships of this chemical class are elucidated. An ortho-substituent on the aryl ring is an absolute requirement for herbicidal activity. Beyond that, the herbicidal activity of these compounds is best correlated with the overall electron deÐciency of the benzoyl group induced by 2,4-disubstitution of the aryl ring, with the most electron-deÐcient analogs being the most active. Moreover, the degree of electron deÐciency of the benzoyl group is outwardly manifested in the acidity of the molecule. The activity of these compounds is further enhanced through additional aromatic substitution in the 3-position of the aryl ring. The greater activity of these 2,3,4-trisubstituted aryl analogs over the 2,4-disubstituted aryl analogs is due to increased intrinsic activity.1998 Society of Chemical Industry ( Pestic. Sci., 54, 377È384 (1998)

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Amino acids have been developed as educts for the preparation of optically pure -amino aliphatic ketones. The amino group of the L-amino acid was first blocked as a suitable acyl derivative, namely, acetyl, benzoyl, ethoxycarbonyl, or benzenesulfonyl. Then the lithium carboxylate was formed and treated with alkyl-and alkenyllithium or Grignard reagents. Thus butyl, allyl, and vinyl organometallics were added to the lithium carboxylates of L-a-N-substituted alanine, valine, O-benzyltyrosine, methionine, serine, and «-(ethoxycarbonyl)lysine to yield the corresponding optically pure ketones, protected as amides, sulfonamides, or carbamates.-Amino acids are generally inexpensive compounds, readily available in many structural types and in enantiomerically pure form. We have been exploring the possibility of using a variety of them as chiral educts for the preparation of optically and regiochemically pure aamino ketones. Previously, we have shown that aryl organometallic reagents may be added to L-TV-(ethoxycarbonyl) -or JV-(phenylsulfonyl)alanine to yield the op- (6) Floyd,

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