38 research outputs found
Sequential Insertion of Carbon Monoxide and Imines into Nickel−Methyl Bonds: A New Route to Imine Hydroacylation
Novel Coupling of Two Mechanistically Distinct Polymerizations on a Single Metal Center: Palladium-Mediated Synthesis of Poly(norbornene)−Poly(THF) Block Copolymers
Palladium-Catalyzed Multicomponent Synthesis of 2-Imidazolines from Imines and Acid Chlorides
We describe the palladium-catalyzed multicomponent synthesis of 2-imidazolines. This reaction proceeds via the coupling of imines, acid chlorides and carbon monoxide to form imidazolinium carboxylates, followed by a decarboxylation. Decarboxylation in CHCl3 is found to result in a mixture of imidazolinium and imidazolium salts. However, the addition of benzoic acid suppresses aromatization, and generates the trans-disubstituted imidazolines in good yield. Combining this reaction with subsequent nitrogen deprotection provides an overall synthesis of imidazolines from multiple available building blocks
An Electrophilic Approach to the Palladium-Catalyzed Carbonylative C–H Functionalization of Heterocycles
A palladium-catalyzed
approach to intermolecular carbonylative
C–H functionalization is described. This transformation is
mediated by P<sup><i>t</i></sup>Bu<sub>3</sub>-coordinated
palladium catalyst and allows the derivatization of a diverse range
of heterocycles, including pyrroles, indoles, imidazoles, benzoxazoles,
and furans. Preliminary studies suggest that this reaction may proceed
via the catalytic formation of highly electrophilic intermediates.
Overall, this provides with an atom-economical and general synthetic
route to generate aryl-(hetero)Âaryl ketones using stable reagents
(aryl iodides and CO) and without the typical need to exploit pre-metalated
heterocycles in carbonylative coupling chemistry
A Palladium-Catalyzed Carbonylation Approach to Acid Chloride Synthesis
We describe a new approach to acid
chloride synthesis via the palladium-catalyzed
carbonylation of aryl iodides. The combination of sterically encumbered
phosphines (P<sup><i>t</i></sup>Bu<sub>3</sub>) and CO coordination
has been found to facilitate the rapid carbonylation of aryl iodides
into acid chlorides via reductive elimination from (<sup><i>t</i></sup>Bu<sub>3</sub>P)Â(CO)ÂPdÂ(COAr)ÂCl. The formation of acid chlorides
can also be exploited to perform traditional aminocarbonylation reactions
under exceptionally mild conditions (ambient temperature and pressure),
and with a range of weakly nucleophilic substrates
Chiral Phosphorus-Based 1,3-Dipoles: A Modular Approach to Enantioselective 1,3-Dipolar Cycloaddition and Polycyclic 2‑Pyrroline Synthesis
The design of a new class of chiral
1,3-dipoles for enantioselective
cycloaddition reactions is reported. These phosphorus-based dipoles
are easily formed (from imines, acid chlorides, and chiral phosphites),
rigidly chiral, and undergo intramolecular alkene cycloaddition with
high enantioselectivity. Overall, this provides a straightforward
and modular approach to synthesize chiral 2-pyrrolines and pyrrolidines
in up to 99% ee