Co-catalyzed ortho-C–H functionalization/annulation of arenes and alkenes with alkynylsilanes: access to isoquinolone and pyridone motifs

Abstract

A method for cobalt-catalyzed ortho-C–H functionalization annulation of arenes and alkenes with alkynylsilanes assisted by 8-aminoquinolyl auxiliary.

Isoquinolone Syntheses by Annulation Protocols

“…In the presence of NaOPiv•H 2 O, Co(OAc) 2 •4H 2 O/Ag 2 O-catalyzed decarboxylative C-H/N-H activation/annulation of N-PyO benzamides with alkynyl carboxylic acids under air in TFE also affords 3-substituted isoquinolones with high regioselectivity [67]. Similarly, 3-substituted isoquinolones can be obtained using Co(OAc) 2 •4H 2 O as catalyst from the reactions of N-(quinolin-8-yl)benzamides with alkynylsilanes with desilylation under oxygen in the same solvent, with the use of Mn(acac) 2 and CsF [68].…”

20 Years of Forging N-Heterocycles from Acrylamides through Domino/Cascade Reactions

“…Recently, Lin and Shen introduced alkynylsilanes 104 as substrate to provide pyridones 89g-h. 102 Following their work on the cobalt-catalyzed C-H functionalization / cyclization of acrylamides 1s with alkynes, Daugulis' group reported an expansion of the scope to alkenes to afford dihydroisoquinolinones and dihydropyrid-2-ones 89i (Scheme 32). 103 The procedure was slightly modified by swapping the catalyst from Co(OAc)2 (10 mol%) to Co(acac)2 (20…”

“…Recently, Lin and Shen introduced alkynylsilane 104 as a substrate to provide pyridones 89g,h. 102 Their initial catalyst system consisted of Co(OAc) 2 •4H 2 O (20 mol%) with Mn(OAc) 2 as a co-oxidant, and required CsF (1.2 equiv) as a silaphilic base to remove silicon. Trimethylsilyl phenylacetylene 104 was used as a benchmark alkyne and coupling with several -and/or -substituted acrylamides was successfully achieved in trifluoroethanol at 100 °C under an oxygen atmosphere (Scheme 31, Conditions A), affording pyridones 89g in moderate to excellent yields.…”

Comprehensive Strategies for the Synthesis of Isoquinolines: Progress Since 2008

“…The present protocol was realized using benzamides 106 with alkynylsilanes 107 affording the corresponding isoquinolones 108 (Scheme 59). [87] Recently, Liu et al established Cp*-free cobaltcatalyzed CÀ H activation/annulation reaction using 2-(hydroxymethyl)pyridine as the traceless directing group (Scheme 60). [88]…”

“…The present protocol was realized using benzamides 106 with alkynylsilanes 107 affording the corresponding isoquinolones 108 (Scheme 59). [87] …”