Cu-Catalyzed Direct C-P Bond Formation through Dehydrogenative Cross-Coupling Reactions between Azoles and Dialkyl Phosphites.

A direct dehydrogenative cross-coupling of azoles [C(sp2)-H] with dialkyl phosphites [P(O)-H] to access 2-phosphonated azoles using Cu(I)/Cu(II) as catalyst and K2S2O8/di- tert-butylperoxide as oxidant has been achieved. A remarkable advantage over reported procedures includes that oxazoles, imidazoles, benz(ox/othi/imid)azoles, and indole are found to react under optimized reaction conditions to provide corresponding adducts in high yields. The mechanistic insight of cross-coupling was obtained by deuterium kinetic isotope effect studies.