Unique regioselectivity in the C(sp3)-H α-alkylation of amines: the benzoxazole moiety as a removable directing group

Org Lett. 2014 Aug 15;16(16):4201-3. doi: 10.1021/ol501935d. Epub 2014 Jul 24.

Abstract

The benzoxazol-2-yl- substituent was found to act as a removable activating and directing group in the Ir-catalyzed alkylation of C(sp(3))-H bonds adjacent to nitrogen in secondary amines. It can be easily introduced by oxidative coupling or by an SNAr reaction, and it can be removed by hydroxide or by hydride reduction. For 1,2,3,4-tetrahydroisoquinolines, activation exclusively takes place in the 3-position. A variety of activated as well as unactivated terminal olefins are suitable reaction partners.