Palladium‐Catalyzed Chemo‐ and Regioselective Oxidative Cross‐Dehydrogenative Coupling of Acetanilides with Benzothiazole

Abstract

A practical, versatile, and efficient method for the palladium‐catalyzed direct heteroarylation of acetanilides was developed. In this method, a wide range of acetanilides bearing electron‐donating and electron‐withdrawing groups are well tolerated, and the desired 2‐arylbenzothiazoles are generated in good to high yields through a cross‐dehydrogenative coupling process.

Palladium-catalyzed cross-dehydrogenative coupling of (hetero)arenes

“…Interestingly, this approach was exploited by Kianmehr and co-workers, who reported in 2017 the development of a versatile method for the regioselective Pd-catalyzed CDC of benzothiazoles with acetanilides (Scheme 37). 79 Reactions were carried out by treating 1.5 equiv. of benzothiazoles and 1.0 equiv.…”

Direct Arylation of C(sp2)–H Bonds in Anilines

“…56 The process could further be extended to the use of sodium and ammonium peroxydisulfates as the oxidant, 57 or heteroarenes as coupling partners. 58 Although highly efficient, this method however suffers from strong regioselectivity issues regarding the C-H bond that is actually activated in the unactivated arene coupling partner. This limitation could be later overcome by the addition of a pyridine ligand substituted at the C3-position with an acetate group, 59 the use of mechanochemistry 60 or Selectfluor™ as the oxidant in combination with D-camphorsulfonic acid.…”

Nickel-Catalyzed Regioselective Thiolation of Anilides with Thiols

“…NiBr 2 and Ni(OAc) 2 were ineffective in enhancing the reaction yield and diminished the reaction progress (entries 13,14). Other first-row metal catalysts such as FeCl 2 and CoCl 2 were found to be inferior (entries 15,16). The reaction was not also successful with PdCl 2 and Cu(OAc) 2 (entries 17, 18), and no desired product was achieved in the absence of nickel catalyst (entry 19).…”

“…Anilides are an important class of organic compounds due to their biological activity as fundamental structural motifs in various natural products, medicinal chemistry, and materials science. 10 C–H functionalization of anilides such as alkenylation, 11 alkylation, 12 alkoxylation, 13 arylation, 14 heteroarylation, 15 nitration, 16 halogenation, 17 acylation, 18 and thiolation (Scheme 1 , eq. 1, 2, and 3) 19 have been reported recently.…”