Mhamed Lemhadri

Suzuki Coupling of Cyclopropylboronic Acid With Aryl Halides Catalyzed by a Palladium–Tetraphosphine Complex

Abstract The tetraphosphine all‐cis‐1,2,3,4‐tetrakis(diphenylphosphinomethyl)cyclopentane (Tedicyp) in combination with [Pd(C3H5)Cl]2 affords a very efficient catalyst for the coupling of cyclopropylboronic acid with aryl bromides and aryl chlorides. Higher reactions rates were observed with aryl bromides than with aryl chlorides; however, even in the presence of 1–0.4% of catalyst, a few aryl chlorides gave the coupling products in good yields. A wide variety of substituents such as alkyl, methoxy, trifluoromethyl, acetyl, benzoyl, formyl, carboxylate, nitro, and nitrile on the aryl halides are tolerated. The coupling reaction of sterically very congested aryl bromides such as bromomesitylene or 2,4,6‐triisopropylbromobenzene also proceeds in good yields.

Synthesis of (E)-1-Aryl Alk-1-en-3-ones by Tetraphosphine/Palladium-Catalysed Heck Reactions of Alk-1-en-3-ones with Aryl Bromides

The tetraphosphine cis,cis,cis-1,2,3,4-tetrakis(diphenylphosphinomethyl)cyclopentane in combination with [Pd(C 3 H 5 )Cl] 2 affords a very efficient catalyst for the Heck reaction of alk-1-en-3-ones with aryl bromides. If appropriate reaction conditions are used (NaOAc as base, hydroquinone as stabilising agent and DMF as solvent) high yields of (E)-1-aryl alk-1-en-3-one derivatives are obtained. In general, higher reaction rates were observed with electron-poor aryl bromides, but the electron-rich aryl bromides 4-N,N-dimethylaminobromobenzene and 4-bromoanisole also led to the arylated enones. Even with sterically very congested aryl bromides such as 9-bromoanthracene, 2,4,6-trimethylbromo-benzene or 2,4,6-triisopropylbromobenzene, the expected (E)-1-aryl alk-1-en-3-ones were obtained in moderate to good yields. Moreover, several reactions can be performed with as little as 0.1% catalyst.