A practical cobalt-catalyzed cross-coupling of benzylic zinc reagents with aryl and heteroaryl bromides or chlorides

Abstract

A catalytic system consisting of 5 mol% CoCl2 and 10 mol% isoquinoline allows a convenient cross-coupling of benzylic zinc reagents with various aryl and heteroaryl bromides or chlorides leading to polyfunctionalized diaryl- and aryl-heteroaryl-methane derivatives.

Nickel‐Catalyzed Cross‐Electrophile Coupling with Organic Reductants in Non‐Amide Solvents

“…We adapted conditions from our previous work, [7b, 16] but for convenience and cost considerations, we used the pre-formed catalyst (dtbbpy)NiBr 2 (dtbbpy = 4,4'-ditert-butyl-2,2'-bipyridine). We chose this reactiont os tart with because diarylmethanes are found in many pharmaceutically active molecules [17,18] and the cross-electrophile coupling of benzylic halidesw ith aryl halidesh ad proven difficult, [17b, 19, 20] possibly because they can react directly with zinc.…”

One-pot nickel-catalyzed cross-coupling of (Het)arylammonium salts prepared in situ and organozinc reagents

“…), and THF (2 mL) and was flushed with Ar 3 times. After stirring at 25 °C for 2 h, Ni(COD) 2 /L2 (0.5 mol%) and the arylzinc reagent [13][14][15] (2a, 1.5 equiv.) in NMP (1 mL) were added to the reaction mixture.…”

Recent Advances in Cobalt-Catalyzed Csp2 and Csp3 Cross-Couplings

“…Thus, all three iodobenzonitriles (ortho, meta, and para) 26a-c react with p-anisylzinc pivalate (27) to give the expected cross-coupling products 28a-c in 71-75% yield using only 5 mol% CoCl 2 in the absence of any additional ligand (40 °C, 16 h; Scheme 12). 7 Various heterocyclic bromides such as 29-32 undergo smooth cross-couplings under mild conditions.…”

“…In a typical example, the ester-substituted benzylic zinc reagent 68 reacts with 4-bromo benzonitrile 69 in the presence of 5 mol% CoCl 2 and 10 mol% isoquinoline 67 to furnish, after 18 hours at 50 °C, the expected cross-coupling product 70 in 62% yield (Scheme 23). 27 Scheme 23 Cobalt-catalyzed cross-coupling of benzylic zinc reagents…”