No abstract

The synthesis of forty‐one phenazines, mono‐substituted with alkyl, alkoxy, alkylthio and alkylsulphonyl groups is described. Phytotoxicity was highest in the alkyl series and both 1‐ and 2‐methylphenazines are highly effective. herbicides. Although several n‐alkyl, branched alkyl and n‐alkoxyphenazines were highly fungicidal and acaricidal, only 2‐t‐octylphenazine combined high dual activity with negligible phytotoxicity.

A rapid, convenient conversion of 1,2‐dimethylpyrazolium salts (1) to 1‐methylpyrazoles (2) is accomplished in piperidine or 3‐methylpiperidine at temperatures ≥ 106°. This demethylation represents a particularly useful procedure for the synthesis of 3‐ and 5‐substituted aminopyrazoles, which are not readily obtainable by other methods. The 50:50 mixture of piperidinopyrazole isomers 2b can be obtained directly by treating 3‐chloro‐1,2‐dimethyl‐5‐phenylpyrazolium iodide (3b) with piperidine in ethanol at 106°.

Zur Untersuchung auf Antitumor‐Wirkung wird eine Reihe von 2‐Aroyl1,3‐diaminopropan‐Derivaten (IV) bzw. (VI) durch Mannich‐Reaktion aus den entsprechenden Acetophenonen (I) bzw. (V) hergestellt.

The synthesis and biological activity of twenty-six halophenazines is described. The Wohl-Aue reaction and the new method for cyclisation of 2-nitrodiphenylamines by oleum were found to be the most convenient methods of synthesis.Phytotoxicity of a characteristic type was higher in foliar spray than in pre-emergence tests. Chlorine substitution appeared to confer higher activity than other halogen substituents, and in the chlorophenazines activity decreased with increasing substitution. Both 1-and 2-chlorophenazine were highly effective herbicides.Acaricidal and fungicidal activity showed similar responses to structural changes, and optimum activity, together with a low level of phytotoxicity, was reached with 1,4-dichlorophenazine.