René Mornet

Synthesis, azido-tetrazole equilibrium studies and biological activity of 1-(2-azido-6-chloropyrid-4-yl)-3-phenylurea, a photoaffinity labeling reagent for cytokinin-binding proteins

1-(2-Azido-6-chloropyrid-4-yl)-3-phenylurea was synthesized using known methods. Azido-tetrazole equilibrium for this compound was studied in various solvents, and the azide tautomer was found to be largely predominant. However, in water solution, it is suspected to exist in the tetrazole form in a significant amount. Like other 2,6-disubstituted pyridylurea analogs, it exhibits high cytokinin activity, and it is easily photolysable. Thus it appears to be a good candidate as a photoaffinity labeling reagent for cytokinin-binding proteins, receptors in particular. In the absence of the 6-chloro substituent, the tetrazole form was the only existing tautomer. The corresponding compound does not exhibit cytokinin activity and is not photolysable.

Synthesis of the 3,5,3′,5′‐3H4‐2,2′‐diphenylene‐iodonium cation and of its 4‐nitro derivative

The 3,5,3′,5′-3H4-2,2′-diphenyleneiodonium cation [3H]-1 was synthesized in three steps from cold 2,2′-diaminodiphenyl. The nitration of [3H]-1 gave easily the 4-nitro derivative [3H]-2. These two compounds which contain four tritium labels were obtained with a high specific activity, and are proposed as tools to study the interaction of 2,2′-diphenyleneiodonium cations with redox enzymes, especially flavoproteins. Copyright

Synthesis and properties of a photoaffinity labeling reagent for protoporphyrinogen oxidases, the target enzymes of diphenyl ether herbicides.

A diazoketone 3 has been synthesized in two steps from acifluorfen 1, a diphenyl ether herbicide. Like the parent compound 1, the diazoketone 3 is toxic to plant cells and inhibits protoporphyrinogen oxidase, the molecular target of diphenyl ether herbicides. On photolysis of 3 in methanol, the generated carbene mainly undergoes the Wolff rearrangement to a ketene which further adds methanol, but many other products are observed. A tritiated derivative of 3 has been prepared which is suitable for photoaffinity labeling experiments.

Hg(II)-ACTIVATION IN THE CHEMOSELECTIVE SUBSTITUTION OF CHLORINE BY THE AZIDE ION IN CHLOROPHOSPHOROTHIONATE ESTERS

Abstract In chlorophosphorothionate or dichlorophosphorothionate esters, Hg(II)-coordination to the S-atom facilitates nucleophilic attack at P of the azide ion, to afford the corresponding azido derivatives in good yields. The chemoselectivity of this reaction vs C-substitution is also greatly improved.