Synthesis of Substituted Monohalobenzenes via Ortho-Selective Cross-Coupling of Dihalobenzenes with Electron-Donating Ortho-Directing Groups

Abstract

Dihalobenzenes that possess directing groups such as OH, CH₂OH, NH₂, NHAc, or NHBoc were subjected to ortho-selective cross-coupling with Grignard reagents in the presence of palladium-based catalysts to give the corresponding substituted monohalobenzenes. For the dibromo- and dichlorophenols and anilines, hydroxylated terphenylphosphines 1 and 2 were found to be effective ligands for palladium, whereas tricyclohexylphosphine was preferable for the dichlorobenzyl alcohols, dichloroanilides, and difluorobenzenes.

Key words

cross-coupling - palladium - site-selective - Grignard reagents - dihalobenzenes

References

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8

Phosphine 1 was purified and stored as the HBF₄ salt.