Unique reactivity of diphenylacetylene
has been uncovered through
weak chelation-assisted cobalt-catalyzed regioselective C(4)–H
activation of 3-pivolyl indole. α-Hydroxy ketone and α,β-unsaturated
ketone derivatives have been synthesized in good yields from indole
and alkynes. Notably, the indole C(4)–H-functionalized α,β-unsaturated
ketone product was obtained with high stereo- and regioselectivity
simply by changing the coupling partner from symmetrical alkynes to
unsymmetrical aromatic-aliphatic alkynes. Most importantly, trifluoroethanol
acts as a sole source of water for this conversion. Quantitative detection
of bis(2,2,2-trifluoroethyl) ether from dry trifluoroethanol through 19F NMR and LCMS studies indirectly confirms the in situ formation
of water. A six-membered cobaltacycle intermediate was detected in
HRMS, and also, this was further confirmed by the quantum mechanical
calculations, which accounts for the highly regioselective C(4)–H
functionalization.
This review focuses on providing comprehensive highlights of the recent advances in the field of cobalt-catalysed C−H functionalization and related synthetic concepts relying on these through oxygen atom coordination. In...
A ruthenium(II)-catalyzed cross dehydrogenative
annulation of N-(7-azaindole)benzamides with maleimides
has been demonstrated.
Herein, we have explored the use of N-amino-7-azaindole
as a new bidentate directing group for dehydrogenative [4 + 2] annulation.
This method works efficiently, affording a variety of pharmacologically
useful 7-azaindole-based isoquinolones and showing a wide functional
group tolerance.
The ruthenium(II)-catalyzed regioselective
annulation of N-(7-azaindole)amides with 1,3-diynes
has been demonstrated.
Bioactive N-amino-7-azaindole has been used as a
new bidentate directing group to furnish an array of 3-alkynylated
isoquinolones. Furthermore, the developed protocol works efficiently
for both aryl- and heteroaryl-substituted amides producing a range
of pharmacologically useful 7-azaindole-based isoquinolones with a
wide range of functionality.
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