Direct Arylation of Tautomerizable Heterocycles with Aryl Boronic Acids

Multistep versus Single-Step Synthesis of 6-Arylpurine Ribonucleosides

Possible Mechanism of the Pd-Catalyzed Direct Arylation via C-OH Bond Activation Using PyBroP

General Procedure for the Pd-catalyzed Direct Arylation of Tautomerizable Heterocycles with Aryl Boronic Acids via C-OH Bond Activation using PyBroP

A mixture of the tautomerizable heterocycle (0.5 mmol), PyBroP (1.2 eq) and Et3N (3 eq) in 1,4-dioxane (4 mL) was stirred in a sealed tube at rt for 2h. Then, the aryl boronic acid (2 eq), Na2CO3 (5 eq), PdCl2(PPh3)2 (5 mol%) and water (1 mL) were added, and the mixture was stirred at 100 °C in the sealed tube for 4h. After the mixture was cooled to rt, it was diluted with EtOAc, washed with water, and dried with brine and Na2SO4. Flash chromatography using an EtOAc/hexane mixture or HPLC using a MeCN/water mixture gave the biaryl product.

Ref:

J. Am. Chem. Soc. 2008, 130, 34, 11300–11302