Palladium-Catalyzed Heck/Suzuki Tandem Reaction of (Z)-1-Iodo-1,6-dienes and Organoboronic Acids

The Heck/Suzuki tandem reaction has emerged as an essential strategy for the synthesis of complex molecules. Herein, an efficient palladium-catalyzed Heck/Suzuki tandem reaction of (Z)-1-iodo-1,6-dienes with organoboronic acids is described, providing various tetrahydropyridines in good to excellent yields under mild reaction conditions. The key to the success of this approach is the avoidance of the intramolecular second Heck insertion occurring prior to the transmetalation step. In addition, the asymmetric version of this reaction is investigated to deliver chiral tetrahydropyridine in excellent yield with promising enantioselectivity.

Pd0 -Catalyzed Asymmetric Carbonitratation Reaction Featuring an H-Bonding-Driven Alkyl-PdII -ONO2 Reductive Elimination

Reductive elimination of alkyl-Pd^II -O is a synthetically useful yet underdeveloped elementary reaction. Here we report that the combination of an H-bonding donor [PyH][BF₄ ] and AgNO₃ additive under toluene/H₂ O biphasic system can enable such elementary step to form alkyl nitrate. This results in the Pd⁰ -catalyzed asymmetric carbonitratations of (Z)-1-iodo-1,6-dienes with (R)-BINAP as the chiral ligand, affording alkyl nitrates up to 96 % ee. Mechanistic studies disclose that the reaction consists of oxidative addition of Pd⁰ catalyst to vinyl iodide, anion ligand exchange between I^- and NO₃ ^- , alkene insertion and S_N 2-type alkyl-Pd^II -ONO₂ reductive elimination. Evidences suggest that H-bonding interaction of PyH⋅⋅⋅ONO₂ can facilitate dissociation of O₂ NO^- ligand from the alkyl-Pd^II -ONO₂ species, thus enabling the challenging alkyl-Pd^II -ONO₂ reductive elimination to be feasible.

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.

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...