A strategy for expedient
synthesis of 3-substituted chromones from
easily available o-hydroxyarylenaminones and
diazo compounds has been developed. Carefully conducted experimental
and computational studies led us to propose an uncommon mechanistic
pathway involving the hydroxyl group assisted alkylation of enaminones
with in situ generated gold carbenes.
Palladium nanoparticles
ligated with inexpensive triphenylphosphine
and amphiphile PS-750-M are suitable for exploring the reactivity
of carbenes in aqueous nanomicelles. Nanocatalyst is highly selective
for metal–carbene migratory insertion, and micelle of PS-750-M
shields the in situ generated carbene to prevent the dimerization.
In addition to a broad substrate scope, the nanocatalyst is thoroughly
characterized by NMR, scanning electron microscopy, high-resolution
transmission electron microscopy, X-ray photoelectron spectroscopy,
and thermogravimetric analysis. The sustainability of the reaction
system is demonstrated by the recyclability of both the catalyst and
the micellar reaction medium at variable reaction scales. NMR and
kinetics studies with the recycled catalyst revealed the retention
of catalyst integrity. Control experiments including the dynamic light
scattering study demonstrate the importance of PS-750-M.
Reported herein, for the first time, is a copper-promoted intramolecular [4+2]-cycloaddition cascade to access ionic N-doped polycyclic aromatic hydrocarbons (PAHs) with tunable emission wavelengths.
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