Highly efficient palladium precatalysts of homoscorpionate bispyrazolyl ligands for the more challenging Suzuki–Miyaura cross-coupling of aryl chlorides?

Dalton Transactions Pub Date: 2010-07-06 DOI: 10.1039/C003174G

Abstract

Highly efficient palladium precatalysts {[RN{-(CH2)n-pz3,5-Me2}2]PdCl2}m [m = n = 1; R = 2,6-Me2C6H3 (1), 2,4,6-Me3C6H2 (2), CH2Ph (3) and m = n = 2; R = CH2Ph (4)] of a series of homoscorpionate bispyrazolyl ligands for the Suzuki–Miyaura cross-coupling of the more challenging aryl chloride substrates are reported. In particular, the palladium 1–4 precatalysts carried out the Suzuki–Miyaura cross-coupling of a wide variety of aryl chloride substrates bearing electron withdrawing, electron donating and heteroaryl substituents. Remarkably enough, the molecular structure determination of the 1–4 precatalysts by X-ray diffraction studies revealed the presence of anagostic [C–H?Pd] type interactions in the mononuclear 1–3 complexes of methylene bridged bispyrazolyl ligands whereas the ethylene bridged analog 4 yielded an interesting dimeric 20-membered macrometallacyclic complex devoid of any such interaction.

Graphical abstract: Highly efficient palladium precatalysts of homoscorpionate bispyrazolyl ligands for the more challenging Suzuki–Miyaura cross-coupling of aryl chlorides
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