Certain heretofore unknown tertiary α‐isocyanacetanilides 1 are reported for the first time, prepared by methods necessarily different from those employed to prepare the previously cited aliphatic α‐isocyano‐acetamides 2. Like 2, 1 has been shown to readily undergo dialkylation with alkyl halides. Moreover, 1 also gives rise to oxazole and oxazoline derivatives upon reaction with acyl halides and aldehydes, respectively, resembling the similarly activated α‐isocyano esters and sulfones. Further, in a demonstrable ring‐chain tautomeric equilibration, apparently restricted to tertiary amides, 1 readily cyclizes, providing the only known synthesis of 5‐amino‐2,4‐unsubstituted oxazoles 3. In other examples 4‐chloro and 4‐alkyl‐5‐amino‐oxazoles are produced. The materials and reactions are characterized, and compared with previous related studies.
The synthesis and SAR of herbicidal N-substituted 2,6-bis(polyfluoromethyl)-l,2-dihydropyridine-3,5-dicarboxylates are described. N-Substituted dihydropyridines were readily prepared by treatment of the corresponding dihydropyridyl anions with electrophiles. Herbicidal activity of the N-substituted dihydropyridines is correlated with the rate of hydrolytic cleavage of the N-substituent to afford 2 or 3. Dihydropyridine 2 is shown to undergo oxidation in the soil to afford herbicidal 1, thereby relating the activity of N-substituted dihydropyridines to the corresponding aromatic herbicides.
A convenient new method for the preparation of thionophosphine sulfides is described. These compounds undergo a modified FriedelLCrafts reaction with benzene and provide a route for the synthesis of unsymmetrical phosphinodithioic acids, unobtainable from reactions employing phosphorus pentasulfide (P&o).
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