Copper-Catalyzed Chan-Lam Cyclopropylation of Phenols and Azaheterocycles

Small molecules containing cyclopropane-heteroatom linkages are commonly needed in medicinal chemistry campaigns yet are problematic to prepare using existing methods. To address this issue, a scalable Chan-Lam cydopropylation reaction using potassium cydopropyl tri-fluoroborate has been developed. With phenol nucleophiles, the reaction effects O-cyclopropylation, whereas with 2-pyridones, 2-hydroxybenzimidazoles, and 2-aminopyridines the reaction brings about N-cydopropylation. The transformation is catalyzed by Cu(OAc)(2) and 1,10-phenanthroline and employs 1 atm of O-2 as the terminal oxidant. This method is operationally convenient to perform and provides a simple, strategic disconnection toward the synthesis of cydopropyl aryl ethers and cydopropyl amine derivatives bearing an array of functional groups.