Synthesis of 3‑(Hetero)aryl Tetrahydropyrazolo[3,4‑<i>c</i>]pyridines by Suzuki–Miyaura Cross-Coupling Methodology

Abstract

A new synthetic route to 3-(heteroaryl) tetrahydropyrazolo­[3,4-<i>c</i>]­pyridines has been developed that uses the Suzuki–Miyaura cross-coupling of a triflate <b>6</b> with (hetero)­aryl boronic acids or esters. Using Pd­(OAc)₂ and XPhos or an XPhos precatalyst, a diverse range of substituents at the C3 position of the tetrahydropyrazolo­[3,4-<i>c</i>]­pyridine skeleton were prepared. The use of pivaloyloxymethyl and benzyl protection also offers the potential to differentially functionalize the pyrazole and tetrahydropyridine nitrogens