Palladium-Catalyzed Selective α-Arylation of ortho-Bromoacetophenones

Abstract

Synthesis of 1-(2-bromophenyl)-2-phenylethanones via an intermolecular Pd-catalyzed α-arylation of 1-(2-bromophenyl)ethanones is presented. The method relies on selective C-H activation (α-arylation) of relatively more reactive external iodo-arenes as coupling partners without affecting the bromo-substituent. Moreover, the scope and generality of the method has been well studied by employing the reaction with iodo-arenes as coupling partners bearing electron-withdrawing, simple, and electron-donating groups on the aromatic ring.

GRAPHICAL ABSTRACT

Keywords:

• α-Arylation
• 1-(2-bromophenyl)ethanones
• C-H activation
• iodo-arenes
• Pd-catalysis

Notes

^a All reactions are carried out on 0.5-mmol scale of iodo-arenes in 4 mL of toluene (0.12 M).

^b Yields in the parentheses are isolated yields of chromatographically pure products.

^c For compounds 3ac–3cf the first letter refers to the 2-bromoacetophenes 1a–1c, whereas the second letter indicates the aromatic ring coming from iodo-arenes 2a–2f.