N-Heterocyclic Carbene-Assisted, Bis(phosphine)nickel-Catalyzed Cross-Couplings of Diarylborinic Acids with Aryl Chlorides, Tosylates, and Sulfamates

Abstract

Efficient bis(phosphine)nickel-catalyzed cross-couplings of diarylborinic acids with aryl chlorides, tosylates, and sulfamates have been effected with an assistance of N-heterocyclic carbene (NHC) generated in situ from N,N'-dialkylimidazoliums, e.g., N-butyl-N'-methylimidazolium bromide ([Bmim]Br), in toluene using K3PO4·3H2O as base. In contrast to bis(NHC)nickel-catalyzed conventional Suzuki coupling of arylboronic acids, mono(NHC)bis(phosphine)nickel species generated in situ from Ni(PPh3)2Cl2/[Bmim]Br displayed high catalytic activities in the cross-couplings of diarylborinic acids. The structural influences from diarylborinic acids were found to be rather small, while electronic factors from aryl chlorides, tosylates, and sulfamates affected the couplings remarkably. The couplings of electronically activated aryl chlorides, tosylates, and sulfamates could be efficiently effected with 1.5 mol % NiCl2(PPh3)2/[Bmim]Br as catalyst precursor to give the biaryl products in excellent yields, while 3-5 mol % loadings had to be used for the couplings of non- and deactivated ones. A small ortho-substitutent on the aromatic ring of aryl chlorides, tosylates, and sulfamates was tolerable. Applicability of the nickel-catalyzed cross-couplings in practical synthesis of fine chemicals has been demonstrated in process development for a third-generation topical retinoid, Adapalene.

Pincer‐Nickel‐Catalyzed Cross‐Coupling of Aryl Sulfamates with Arylzinc Chlorides

“…Methyl 4′‐Methylbiphenyl‐4‐carboxylate: 5g 1 H NMR (400 MHz, CDCl 3 ): δ = 2.29 (s, 3 H), 3.82 (s, 3 H), 7.15 (d, J = 7.9 Hz, 2 H), 7.41 (d, J = 8.1 Hz, 2 H), 7.52 (d, J = 8.4 Hz, 2 H), 7.98 (d, J = 8.4 Hz, 2 H) ppm. 13 C NMR (101 MHz, CDCl 3 ): δ = 21.23, 52.14, 126.85, 127.17, 128.67, 129.73, 130.16, 137.14, 138.17, 145.63, 167.10 ppm.…”

Recent Advances in the Schiff Bases and N‐Heterocyclic Carbenes as Ligands in the Cross‐Coupling Reactions: A Comprehensive Review

“…Ke and co-workers [155] reported efficient bis(phosphine)nickel-catalyzed cross-couplings of diarylboronic acids with aryl chlorides, tosylates, and sulfamates catalyzed by NHC (C175-C178) (Fig. 12) generated in situ from N,N 0 -dialkylimidazoliums in toluene using K 3 PO 4 •H 2 O base.…”

“…Zende et al [178] reported the formation of novel pincertype NHC ligands (L118) from 2,6-dibromopyridine (155) in 56-79% yields as shown in Scheme 148. The ligands had proved to be highly effective toward Pd-catalyzed Suzuki cross-coupling of bromoanthracene to afford 66-88% yields at a very low catalyst loading of 0.1 mol% of the products and easy synthesis of molecules for organic light-emitting diode applications.…”

Designing Pd and Ni Catalysts for Cross-Coupling Reactions by Minimizing Off-Cycle Species

“…Nickel catalysts are capable of activating aryl sulfamates, 136,137,138 which are especially appealing because they can be diversified by selective functionalization prior to cross-coupling. 139,140,141 However, nickel catalysts also have disadvantages -the conditions required to achieve high yields are harsher than those of palladium, including the need for higher temperatures and catalyst loadings.…”