Chemo- and Regioselective Alkylation of Pyridine N-Oxides with Titanacyclopropanes

Org Lett. 2023 Dec 8;25(48):8640-8644. doi: 10.1021/acs.orglett.3c03469. Epub 2023 Nov 28.

Abstract

While titanacyclopropanes are used to react mainly with ester, amide, and cyano to undergo cyclopropanation, herein they react preferentially with pyridine N-oxide to accomplish C2-H alkylation beyond these functionalities with double regioselectivity. After being pyridylated at the less hindered C-Ti bond, the remaining C-Ti bond of titanacyclopropanes can be further functionalized by various electrophiles, allowing facile introduction of complex alkyls onto the C2 of pyridines. Its synthetic potential has been demonstrated by late-stage diversification of drugs.