An efficient, one-pot, and cheap metal-catalyzed tandem Chan-Lam coupling/deprotection/oxidation reaction to access unsymmetrical azobenzenes is disclosed. In this protocol, phthaloyl is automatically fallen off under this basic catalytic system, without...
An
anhydride-promoted traceless hydrazine–I/Br exchange
strategy is reported, where hydrazine hydrate and cyclic/linear iodonium,
including rarely explored cyclic bromonium, are converted to benzo[c]cinnolines/azobenzenes in one pot. The reaction proceeds
through diacylation (first and second CN formation), N,N′-diarylation (third and fourth
CN formation), and deacylation/oxidation (2 CN cleavages
and 1 NN formation). The reaction mechanism is investigated
by isolating multiple intermediates and kinetic studies. Furthermore,
time-dependent electrospray ionization mass spectrometry (TD ESI-MS)
was applied to track the process by detecting most intermediates.
The complex [CuIII(iodobiphenyl)(bipy)I]+ (Int-C) was detected for the first time, giving evidence for
oxidative addition of cyclic iodonium to Cu catalyst. Another complex
[CuI(PHA)(bipy)] (Int-B) via ligand-exchange
between the hydrazide and Cu catalyst was also detected, indicating
a two-path initial activation process.
Multidentate
ligands are highly important but difficult to access.
Herein we disclose an atom- and step-economic synthesis of highly
substituted 1,1′-biisoquinolines by a C–H activation/bididirecting
group strategy. Through rational design of a bididirecting group to
“N–OH + N–OAc”, selective unsymmetrical
diannulation with two different alkynes in a one-pot reaction has
been achieved for the first time to access unsymmetrical biisoquinolines.
Moreover, the resultant biisoquinolines show tunable photoluminescence
and serve as aggregation-induced emission (AIE) systems.
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