A. M. Pinchuk

Structural sensitivity in phosphorylation of enamines—derivatives of β-aminocrotonic acid with diphenylchlorophosphine

Abstract The reaction of ‘push–pull’ enamines—derivatives of β-aminocrotonic acid with diphenylchlorophosphine has been investigated. Structural sensitivity of the reaction was found and is discussed.

Addition of some aminoheterocycles to N-benzyl-3-cyanopyridinium chloride

5-Aminopyrazoles react with N-benzyl-3-cyanopyridinium chloride giving 1-benzyl-3-cyano-4-(5-aminopyrazol-4-yl)-1,4-dihydropyridines with high regioselectivity. 5-Aminoisoxazole, 2-aminothiazole and 6-aminouracil react analogously.

Dealkylation of 4-phosphorylated 5-alkoxypyrazoles: Easy synthetic access to P-chloro ylides†

The chlorination of 5-alkoxypyrazoles containing bis-(dialkylamino)- or diphenylphosphino groups at the4-position afforded highly unstable chlorophosphoni-um chlorides that dealkylated giving chlorobis(di-alkylamino)- and chlorodiphenylphosphonium(3-methyl-5-oxo-1-phenyl-5H-pyrazol-4-yl)ides. The P-chloro ylides do not react with aromatic aldehydes, but chlorine atoms are easily substituted with OH, NH2 ArNH, and Et2N residues. They also exhibit basic properties and add hydrogen chloride with protonation at N-2.

C-phosphorylation of formaldehyde and crotonaldehydeN,N-dimethylhydrazones

The first representatives of hydrazones having trivalent phosphorus at the azomethine carbon atom or the carbon atom vinylogous to it were synthesized by reactions of formaldehyde and crotonaldehydeN,N-dimethylhydrazones with PBr3 and diphenylchlorophosphine in the presence of organic bases. Some properties of the compounds synthesized were studied.

Phosphorylation of 2-Alkoxycarbonyl-5-(1',3'-diaza-1'-butenyl-3'-methyl)thiophenes and 2-alkoxycarbonyl-5-(1',3'-diaza-1'-butenyl-3'-methyl)furans by Trivalent Phosphorus Halides

In previous work [1], we have demonstrated the feasibility of using the 3-methyl-1,3-diaza-1-butenyl (N,N-dimethylformamidine) substituent as a protective and activating group in the phosphorylation of 2-aminothiazoles, which permits to prepare phosphorus derivatives of thiazole with a free amino function. The use of this approach for the synthesis of phosphorylated derivatives of other types of amino heterocycles holds considerable preparative interest. We have found that the electron-donating properties of the N,N-dimethylformamidine substituent permits the regioselective phosphorylation of 5-amino-2-alkoxycarbonylthiophenes and 5-amino-2alkoxycarbonylfurans by trivalent phosphorus halides under mild conditions at the position C(3) of heterocycle to give 3-dihalophosphines 3a, 4a, and 4b, which are valuable reagents for the synthesis of various 3-phosphorylated thiophene and furan derivatives, in particular, 5-8.