Ruthenium-Catalyzed Oxidative Annulation Research Articles

N-Amino-7-azaindole as the N,N'-Bidentate Directing Group: Ruthenium-Catalyzed Oxidative Annulation of N-(7-Azaindole)benzamides with Alkynes via C-H Bond Activation.

We report a new application of N-amino-7-azaindole as a new bidentate-directing group for [Ru(p-cymene)Cl2]2-catalyzed C(sp2)-H alkenylation/annulation of N-(1H-pyrrolo[2,3-b]pyridin-1-yl)benzamides with internal alkynes to afford N-isoquinolono-7-azaindole via the formation of C-C and C-N bonds. The reaction shows a wide range of substrate scope with different symmetrical and unsymmetrical alkynes, affording the desired product in good to excellent yields. In the case of unsymmetrical alkynes, a highly regioselective product was obtained, which was confirmed by single-crystal X-ray crystallography. A new ruthenium-4-methyl-N-(1H-pyrrolo[2,3-b]pyridin-1-yl)benzamide complex was isolated, and its structure was confirmed by single-crystal X-ray crystallography.

Ruthenium-Catalyzed Oxidative Annulation and Hydroarylation of Chromene-3-carboxamides with Alkynes via Double C-H Functionalization.

Ruthenium-catalyzed oxidative annulation of 2H-chromene-3-carboxamides with alkynes has been achieved by using the directing group nature of amide in the presence of Cu(OAc)2·H2O as an oxidant and AgNTf2 as an additive. This reaction offers a broad substrate scope, and both symmetrical and unsymmetrical alkynes can be harnessed. High regioselectivity was achieved in the case of unsymmetrical alkynes. In addition, we have also accomplished double C-H activation by employing an excess of alkyne, where both annulation and hydroarylation took place regio- and stereoselectively in one pot, with the catalyst playing a dual role. While the first C-H functionalization could involve Ru-N covalent bond, the second C-H functionalization most likely involves Ru-O coordinate bond. The structures of key products are confirmed by X-ray crystallography.

ChemInform Abstract: Ruthenium‐Catalyzed Synthesis of Isoquinolones with 8‐Aminoquinoline as a Bidentate Directing Group in C—H Functionalization.

Ruthenium-catalyzed oxidative annulation of N-quinolin-8-yl-benzamides with alkynes in open air has been achieved using 8-aminoquinolinyl moiety as a bidentate directing group in the presence of Cu(OAc)2·H2O as an oxidant. This reaction offers a broad substrate scope, and both symmetrical and unsymmetrical alkynes can be applied. High regioselectivity was achieved in the case of unsymmetrical (aryl)alkynes. Reaction with heteroaryl amides was also successful in this catalytic process. A ruthenium-N-quinolin-8-yl-benzamide complex was isolated in the absence of alkyne; in the absence of both N-quinolin-8-yl-benzamide and alkyne, in contrast to literature, only the monoacetate complex RuCl(OAc)(p-cymene), but not the bis-acetate complex Ru(OAc)2(p-cymene), was isolated. These data suggest that this reaction may proceed via N,N-bidentate chelate complex. Key products were characterized by X-ray crystallography.

Ruthenium-catalyzed synthesis of isoquinolones with 8-aminoquinoline as a bidentate directing group in C-H functionalization.

Ruthenium-catalyzed oxidative annulation of N-quinolin-8-yl-benzamides with alkynes in open air has been achieved using 8-aminoquinolinyl moiety as a bidentate directing group in the presence of Cu(OAc)2·H2O as an oxidant. This reaction offers a broad substrate scope, and both symmetrical and unsymmetrical alkynes can be applied. High regioselectivity was achieved in the case of unsymmetrical (aryl)alkynes. Reaction with heteroaryl amides was also successful in this catalytic process. A ruthenium-N-quinolin-8-yl-benzamide complex was isolated in the absence of alkyne; in the absence of both N-quinolin-8-yl-benzamide and alkyne, in contrast to literature, only the monoacetate complex RuCl(OAc)(p-cymene), but not the bis-acetate complex Ru(OAc)2(p-cymene), was isolated. These data suggest that this reaction may proceed via N,N-bidentate chelate complex. Key products were characterized by X-ray crystallography.

Ruthenium-Catalyzed Pyrrole Synthesis via Oxidative Annulation of Enamides and Alkynes

An efficient and regioselective ruthenium-catalyzed oxidative annulation of enamides with alkynes via the cleavage of C(sp(2))-H/N-H bonds is reported. The reactions can afford N-acetyl substituted or N-unsubstituted pyrroles by altering the reaction conditions slightly.