Palladium-catalyzed cascade cyclization of allenamide with 2-iodoanilines to access functionalized indoloquinolines

A novel and efficient palladium-catalyzed cascade cyclization to indoloquinoline derivatives in one pot has been developed by using allenamide derivatives and 2-iodoanilines as the key building blocks. The process involved two cyclizations: intramolecular cyclization/π-allylic substitution and intramolecular 6-endo Heck cyclization. Furthermore, dihydrobenzofuro[2,3-b]quinoline derivatives could also be achieved via this strategy using allenyl ethers instead of allenamides. The readily available substrates, mild conditions, high efficiency and step economy make this strategy a promising method in the synthesis of polycyclic motifs.

One-Pot anti-Michael Regio- and Stereoselective Hydroamination of Activated N-Allenamides

N-Allenamides, substituted by an ester at the γ-position, were obtained through addition of terminal ynamides with ethyl diazoacetate under copper catalysis for the first time. Regio- and stereoselective hydroamination of those activated N-allenamides provided exclusively E-configured captodative enamimes through a one-pot anti-Michael addition. Numerous ynamides as well as various secondary amines were adapted in this process.

Palladium-catalyzed regiodivergent arylamination/aryloxygenation of allenamide

In regiodivergent arylamination/aryloxygenation of allenamides, use of Cy2NMe caused 2,1-arylamination and the corresponding alkenes were formed with excellent Z configuration. Whereas, utilizing Ag2CO3 caused 2,3-aryloxygenation via an unexpected CO2 insertion from Ag2CO3.

Highly Diastereoselective Synthesis of Octahydro-1H-cyclpenta[c]pyridine Skeleton via Pd/Au-Relay Catalyzed Cascade Reaction of (Z)-1-Iodo-1,6-diene and Alkyne

The Octahydro-1H-cyclopenta[c]pyridine Skeletons exist in a broad spectrum of bioactive natural products, and the development of efficient and convenient protocols to construct this skeleton remains a challenging task. Herein, we...

Ligand-Regulated Palladium-Catalyzed Regiodivergent Hydroarylation of the Distal Double Bond of Allenamides with Aryl Boronic Acid

The ligand-regulated regiodivergent hydroarylation of the distal double bond of allenamides with aryl boronic acid was achieved in the presence of palladium(II) catalysts, delivering a variety of functionalized enamide with excellent E selectivity and Markovnikov/anti-Markovnikov selectivity. Two possible coordination intermediates were proposed to be responsible for the regiodivergent hydroarylation: (1) The coordination Intermediate I, which was proposed to be formed through the coordination of MeCN, distal double bond, phenyl to palladium, led to the aryl group away from the Intermediate I, inducing excellent E selectivity and anti-Markovnikov selectivity. (2) A switch of regioselectivity to 1,2-Markovnikov hydroarylation was obtained using bidentate phosphine ligand (dppf or Xantphos). The formed coordination Intermediate II led to the N-tether away from the Intermediate II and at the trans position of aryl, resulting in excellent E selectivity and Markovnikov selectivity. Meanwhile, tentative investigation on the mechanism proved that the hydron source of this hydroarylation is more likely to be boronic acid. The transmetallation between aryl boronic acid and palladium catalyst was the initial step of this transformation.

Dehydrogenative Aza-[4 + 2] Cycloaddition of Amines with 1,3-Dienes via Dual Catalysis

We describe a synergistic utilization of copper catalysis and proton-transfer catalysis that enables an atom- and step-economical aza-[4 + 2] cycloaddition reaction of readily available N-arylamino carbonyl compounds with simple 1,3-dienes. The reaction proceeds smoothly under an air atmosphere and produces water as the sole side product. Whereas the amines can directly serve as the C- and N-atom donors, this operationally simple protocol provides green, rapid, and efficient access to 1,2,3,6-tetrahydropyridines with a broad scope.

Palladium/Norbornene Catalyzed ortho Amination/Cyclization of Aryl Iodide: Process to 3-Methyl-indole Derivates and Controllable Reductive Elimination against the Second Amination

A palladium/norbornene cooperative catalyzed selective C-H bond amination of aryl iodides was explored, providing an efficient tool for constructing benzocyclic molecules. When ortho-substituted iodobenzene was involved, the C-H bond amination and following Heck cyclization efficiently delivered a 3-methyl-indole scaffold. On the other hand, we realized the controllable synthesis of monoaminated benzo-cyclobutanyl scaffold. The possible coordination of an installed terminal alkenyl group with palladium and steric hindrance were proposed to be responsible for the monoamination selectivity.