Abstract The first cobalt‐catalyzed cross‐coupling of aryl tosylates with alkyl and aryl Grignard reagents is reported. The catalytic system uses CoF3and NHCs (NHC=N‐heterocyclic carbene) as ancillary ligands. The reaction proceeds via highly selective C−O bond functionalization, leading to the corresponding products in up to 98 % yield. The employment of alkyl Grignard reagents allows to achieve a rare C(sp2)−C(sp3) cross‐coupling of C−O electrophiles, circumventing isomerization and β‐hydride elimination problems. The use of aryl Grignards leads to the formation of biaryls. The C−O cross‐coupling sets the stage for a sequential cross‐coupling by exploiting the orthogonal selectivity of the catalytic system.
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Phosphine-Directed sp 3 C–H, C–O, and C–N Borylation
- Award ID(s):
- 1764307
- PAR ID:
- 10287435
- Date Published:
- Journal Name:
- The Journal of Organic Chemistry
- Volume:
- 85
- Issue:
- 22
- ISSN:
- 0022-3263
- Page Range / eLocation ID:
- 14795 to 14801
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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The iron-catalyzed C(sp 2 )–C(sp 3 ) cross-coupling provides a highly economical route to exceedingly valuable alkylated arenes that are widespread in medicinal chemistry and materials science. Herein, we report an operationally-simple protocol for the selective C(sp 2 )–C(sp 3 ) iron-catalyzed cross-coupling of aryl chlorides with Grignard reagents at low catalyst loading. A broad range of electronically-varied aryl and heteroaryl chlorides underwent the cross-coupling using challenging alkyl organometallics possessing β-hydrogens with high efficiency up to 2000 TON. A notable feature of the protocol is the use of environmentally-friendly cyclic urea ligands. A series of guidelines to predict cross-coupling reactivity of aryl electrophiles is provided.more » « less
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