5‐phosphorylated 1,2‐disubstituted imidazoles

4‐Phosphorylated 1,2‐disubstituted imidazoles

“…In the present study, we report on the synthesis of 4-phosphorylated 1,2-disubstituted imidazoles starting from available 5-phosphorylated derivatives [2]. A synthetic method was developed based on peculiarities of imidazolium salts' thermal decomposition.…”

“…We suggested that thermal decomposition of 1,3-dimethyl-2-R-5-phosphorylimidazolium salts would also mainly lead to 4-phosphorylated imidazoles because like the NO 2 -group, an electron-accepting phosphoryl group should have a greater effect on the lone electron pair of N (1). Toward this end, (imidazol-5-yl)diamidophosphonites 2a-d were synthesized [2] and then by standard oxidative procedures were transformed into the corresponding 5-phosphorylated derivatives 3a-d, 4a-d (Scheme 1).…”

“…In addition, treatment of 14a with dimethylamine followed by oxidation with selenium afforded the starting selenophosphonate 9a. It should be noted that in 31 P NMR spectrum signals of compounds 14a-c are downfield (δ 146-147 ppm) compared with signals of (imidazol-5-yl)dichlorophosphines observed at δ 121-127 ppm [2]. Dichlorophosphines 14b,c are viscous liquids distillable in vacuo with slight decomposition.…”

“…Whereas, it is typical of compound 4a-c that the C(5)-P atom exhibits a doublet at δ 120.0-124.2 ppm (with J C-P 143 Hz). Thus, the values of chemical shifts of C(4) and C(5) atoms could be considered for the determination of the position of phosphorous atom in the imidazole ring which has been already reported earlier [2].…”

“…For instance, 1-methyl-2-dimethylaminoimidazole reacts readily with acylating, formylating reagents, sulfenyl chlorides, adds isocyanates, enters into Mannich reaction affording exclusively 5-substituted imidazole derivatives [1]. The reactions with PCl 3 and AlkLi take the same course [2]. Namely, earlier we have reported that 1-methyl-2(R)-disubstituted imidazoles (R = NMe 2 , SMe, Ph) reacted with excess of PCl 3 in pyridine to give 5-dihalophosphine derivatives.…”