New synthetic applications of aryllead triacetates. N-arylation of azoles.

Abstract

Treatment of a variety of azoles or their anions with p-tolyllead triacetate in the presence of copper-(II) acetate afforded the corresponding IV-aryl derivatives, normally in excellent yields. Room temperature arylation of an aminobenzimidazole derivative was chemoselectively directed to the amino group.

Modern Synthetic Methods for Copper‐Mediated C(aryl)O, C(aryl)N, and C(aryl)S Bond Formation

“…[104] However, Avendano and co-workers showed that imidazoles, pyrazoles, indazoles, and benzimidazoles were all suitable substrates for N-arylation with p-tolyllead triacetate (1.1-1.5 equiv) as the aryl donor with the copper catalyst [Cu(OAc) 2 ] in stoichiometric amounts (Scheme 96). [101][102] 1,2,4-Triazole was a poor substrate, but it was shown that the sodium salt reacted much better under the same conditions to afford only one regioisomer in high yield. In a chemoselectivity study, it was shown that the aminobenzimidazole 207 reacted solely at the N atom of the aniline group, although the product was only isolated in 50 % yield.…”

Five‐Membered Heterocycles: 1,2‐Azoles. Part 1. Pyrazoles

“…An efficient synthesis of b-hydroxyethyl-pyrazoles 364 and 365 from propylene and styrene oxide using Cs 2 CO 3 has been reported [316]. Through the use of Bi, B and Pb derivatives and copper-catalyzed cross-coupling reactions it is possible to make NÀC bonds between pyrazoles and unsubstituted phenyl rings [317][318][319][320], or between indazoles and aryl rings [321]. 8.5.1.1.5 N-Acylation (see also Section 8.6.4.2) N-Acetylated pyrazoles are obtained from N-unsubstituted pyrazoles by treatment with acetyl chloride (alone or in the presence of pyridine) or acetic anhydride.…”

Copper‐catalyzed N‐Arylation of Imidazoles with Aryl or Heteroaryl Halides Facilitated by Dimethylglyoxime in Water

“…[1][2][3][4] Although their synthesis has been accomplished successfully using aryllead triacetate, [5][6][7] triarylbismuth, 8 arylstannane, 9 arylsiloxanes 10 and arylboronic acid [11][12][13] reagents etc., these methods often employ expensive reagents or substrates requiring multistep syntheses, and some are highly toxic, which limits their utilization in synthetic chemistry.…”