An efficient synthesis of N-fused
polycyclic and 2,3-disubstituted
indoles by copper-catalyzed direct annulation/acyl migration reaction
of enaminones is reported. This strategy features cheap and low loading
of the catalyst/ligand, readily available starting materials, and
good functional group compatibilities. Notably, allyl-containing substrates
are also tolerated, which allows the downstream derivatization toward
indole alkaloids.
An efficient synthesis
of N-fused polycyclic indoles
by a palladium-catalyzed annulation/acyl migration cascade reaction
is described. The reaction is ligand-free, scalable, and provides
access to a diverse range of useful indole scaffolds from readily
available starting materials. Supporting mechanistic studies indicate
that the reaction likely proceeds via an intramolecular α-arylation
mechanism. The synthetic utility of this protocol is demonstrated
by a gram-scale reaction and syntheses toward indole alkaloids and
a HSP90 inhibitor.
A copper-catalyzed annulation of alkyne-tethered enaminones
for
the synthesis of 2,3-ring fused pyrroles is reported. The 5-exo-dig cyclization/olefin migration reaction delivers the
multisubstituted pyrroles in 59–99% yields with 16 examples.
This strategy features easily available starting materials, mild reaction
conditions, and a cheap ligand-free copper catalyst. The atom-economic
transformation provides a simple access to a variety of synthetic
useful pyrroles and their derivatives.
A two-component and metal-free azidotrifluoromethylation of alkenes is realized using readily synthesized trifluoromethanesulfonyl azide (N3SO2CF3) as a bifunctional reagent for both CF3 and N3 groups.
An efficient aminochlorination reaction
of stryenes is described
using N3SO2CF3 as an amination reagent
and FeCl2 as a chloride source. The operationally simple
procedure features mild reaction conditions, good functional group
compatibility, and high regioselectivity. An example of aminobromination
using FeBr2 is also realized. Additionally, a one-pot aminoazidation
of styrenes is achieved by adding sodium azide to the reaction. The
gram-scale synthesis and downstream derivatization of the products
are showcased as well.
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