Asymmetric Yttrium-Catalyzed C(sp3 )-H Addition of 2-Methyl Azaarenes to Cyclopropenes.

An enantioselective C-H addition to a C=C bond represents the most atom-efficient route for the construction of chiral carbon-carbon skeletons, a central research topic in organic synthesis. We herein report the enantioselective yttrium-catalyzed C(sp3 )-H bond addition of 2-methyl azaarenes, such as 2-methyl pyridines, to various substituted cyclopropenes and norbornenes. This process efficiently afforded a new family of chiral pyridylmethyl-functionalized cyclopropane and norbornane derivatives in high yields and high enantioselectivities (up to 97 % ee).