Palladium-Catalyzed Direct Arylations, Alkenylations, and Benzylations through C−H Bond Cleavages with Sulfamates or Phosphates as Electrophiles

Abstract

A catalytic system comprised of Pd(OAc)(2) and bidentate ligand dppe enabled first direct arylations with moisture-stable aryl sulfamates as electrophiles, and proved applicable to unprecedented C-H bond functionalizations with easily accessible alkenyl phosphates as well as benzyl phosphates.

New Arylating Agents in Pd-Catalyzed C–H Bond Functionalization of 5-Membered Ring Heteroarenes

“…In 2010, Ackermann and co-workers introduced the use of aryl imidazolylsulfonates as aryl sources in the palladium-catalyzed C2-direct arylation of azoles (Scheme 19) [85]. These derivatives were not moisture sensitive and the generated side product (e.g., imidazolesulfonic acid) was nongenotoxic.…”

Aryl Imidazylates and Aryl Sulfates As Electrophiles in Metal-Free ArSN1 Reactions

“…5d Anal. Calcd for C 10 H 10 N 2 O 4 S: C,47.24;H,3.96;N,11.02. Found: C,47.2;H,4.0;N,phenyl 1H-Imidazole-1-sulfonate (1b).…”

“…Calcd for C 10 H 10 N 2 O 4 S: C,47.24;H,3.96;N,11.02. Found: C,47.2;H,4.0;N,phenyl 1H-Imidazole-1-sulfonate (1b). From 476 mg (3.47 mmol) of 4-(N,N-dimethylamino)phenol (2b), 16 1.375 g (6.94 mmol) of Im 2 SO 2 , and 565 mg (1.87 mmol) of Cs 2 CO 3 in THF (10 mL).…”

“…From 1a (508 mg, 2 mmol) and 0.21 mL (2 mmol) of MeOTf in dry ether (8 mL 3.74;N,9.74. Found: C,36.2;H,3.7;N,9.7. 1-[(4-tert-Butylphenoxy)sulfonyl]-3-methyl-1H-imidazol-3-ium Trifluoromethanesulfonate (9c). From 1c (561 mg, 2 mmol) and 0.21 mL (2 mmol) of MeOTf in dry ether (8 mL).…”

CH Bond Alkylation (Including Hydroarylation of Alkenes)

“…An alternative to the use of benzyl halides in direct C-H benzylations was disclosed by Ackermann and coworkers. These authors optimized conditions for the C-H arylation and alkenylation of (benz)oxazoles with phosphate and sulfamate electrophiles and extended their results to the C-2 benzylation of (benz)oxazoles with benzyl phosphate (Scheme 19.21) [35]. More recently, the same group reported the use of a palladium catalyst containing an air-and moisture-stable secondary phosphine oxide ligand for this reaction [36].…”