Cobalt(iii) catalyzed C-8 selective C–H and C–O coupling of quinoline N-oxide with internal alkynes via C–H activation and oxygen atom transfer

Abstract

An efficient, scalable, atom-economical, regio-selective air stable Cp*Co(iii) catalyzed C-H and C-O coupling via a C-H activation/oxygen atom transfer reaction of quinoline N-oxide and an internal alkyne is reported. Such a catalytic transformation is witnessed for the first time with a cobalt catalyst and using N-oxide as a traceless directing group, in contrast to the existing literature. The developed synthetic methodology is straightforward and possesses various functional group tolerances, including heterocycles.

Cobalt catalyzed carbonylation of unactivated C(sp3)–H bonds

“…16 n We have previously demonstrated the activation of C(sp 3 )–H bonds using Cp*Co( iii ) for C–H alkenation with alkynes and C–H amidation with oxazolone. 18 Inspired by these results and based on our continuous efforts on the development of cobalt catalyzed C–H bond functionalization, 19 we report herein the first regio- and site-selective cobalt catalyzed carbonylation of unactivated C(sp 3 )–H bonds including terminal and internal C–H bond connected α-1°, 2° and 3° carbons (Scheme 1c). …”

Direct Functionalization of C−H Bonds by Iron, Nickel, and Cobalt Catalysis

“…Other Cp*Co III ‐catalyzed reactions involving an initial alkenylation step with alkynes were the synthesis of indenones from benzoates, the synthesis of spiro indenyl benzosultams, and an interesting ketone synthesis on the quinoline scaffold starting from quinoline N‐oxide …”

Theoretical prediction on the synthesis of 2,3‐dihydropyridines through Co(III)‐catalysed reaction of unsaturated oximes with alkenes

“…So far, the majority of developed CH activation methods employ catalysts based on noble transition metals such as Ru, Rh, Pd, or Ir . More recently, earth‐abundant and cost‐efficient first‐row transition metals, especially Co, have emerged as attractive alternatives to the noble metals . Among them, the Cp*Co(III) catalysts not only emulate the known catalytic capabilities of Cp*Rh(III) efficiently, but also exhibit other unique reactivities .…”