4 research outputs found
Palladium-Catalyzed Decarboxylative <i>ortho</i>-Amidation of Indole-3-carboxylic Acids with Isothiocyanates Using Carboxyl as a Deciduous Directing Group
Palladium-catalyzed <i>ortho</i>-amidation of indole-3-carboxylic
acids with isothiocyanates by using the deciduous directing group
nature of carboxyl functionality to afford indole-2-amides is demonstrated.
Both C–H functionalization and decarboxylation took place in
one pot, and hence, this carboxyl group served as a unique, deciduous
(or traceless) directing group. This reaction offers a broad substrate
scope as demonstrated for several other heterocyclic carboxylic acids
like chromene-3-carboxylic acid, imidazoÂ[1,2-<i>a</i>]Âpyridine-2-carboxylic
acid, benzofuran-2-carboxylic acid, pyrrole-2-carboxylic acid, and
thiophene-2-carboxylic acid. In the reaction using 2-naphthoic acid,
of the two possible isomers, only one isomer of the amide was exclusively
formed. The indole-2-amide product underwent palladium-catalyzed C–H
functionalization to afford the diindole-fused 2-pyridones by combining
two molecules of the indole moiety, with the elimination of an amide
group from one of them, attached at the C3-position for the C–C/C–N
bond formation. The structures of key products are confirmed by 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 2<i>H</i>-chromene-3-carboxamides with alkynes has been
achieved by using
the directing group nature of amide in the presence of CuÂ(OAc)<sub>2</sub>·H<sub>2</sub>O as an oxidant and AgNTf<sub>2</sub> 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
Palladium-Catalyzed Decarboxylative <i>ortho</i>-Amidation of Indole-3-carboxylic Acids with Isothiocyanates Using Carboxyl as a Deciduous Directing Group
Palladium-catalyzed <i>ortho</i>-amidation of indole-3-carboxylic
acids with isothiocyanates by using the deciduous directing group
nature of carboxyl functionality to afford indole-2-amides is demonstrated.
Both C–H functionalization and decarboxylation took place in
one pot, and hence, this carboxyl group served as a unique, deciduous
(or traceless) directing group. This reaction offers a broad substrate
scope as demonstrated for several other heterocyclic carboxylic acids
like chromene-3-carboxylic acid, imidazoÂ[1,2-<i>a</i>]Âpyridine-2-carboxylic
acid, benzofuran-2-carboxylic acid, pyrrole-2-carboxylic acid, and
thiophene-2-carboxylic acid. In the reaction using 2-naphthoic acid,
of the two possible isomers, only one isomer of the amide was exclusively
formed. The indole-2-amide product underwent palladium-catalyzed C–H
functionalization to afford the diindole-fused 2-pyridones by combining
two molecules of the indole moiety, with the elimination of an amide
group from one of them, attached at the C3-position for the C–C/C–N
bond formation. The structures of key products are confirmed by X-ray
crystallography