Decarboxylative Alkynyl Termination of Palladium-Catalyzed Catellani Reaction: A Facile Synthesis of α‑Alkynyl Anilines via <i>Ortho</i> C–H Amination and Alkynylation

A palladium-catalyzed synthesis of α-alkynyl anilines is reported. The reaction proceeds via Catellani <i>ortho</i> C–H amination followed by decarboxylative alkynylative amination. Different terminal alkyne precursors were screened, and it was found that alkynyl carboxylic acids were superior over other alkynes, which led to operationally simple reaction conditions (no gradual addition of alkynes) and broad substrate scope. The reactivity of three different components matched well; as a result, relatively higher reaction temperature could be used, greatly shortening the reaction time to 4 h from the previously reported 144 h

Palladium/Norbornene-Catalyzed <i>Ortho</i>-Acylation and <i>Ipso</i>-Selenation via C(O)–Se Bond Cleavage: Synthesis of α‑Carbonyl Selane

A palladium/norbornene-catalyzed synthetic method that combines selective <i>ortho</i> C–H bond activation with sequential reactions to form complex selenide compounds has been developed. The C­(O)–Se bond in selenoates is successfully cleaved, and various kinds of α-carbonyl selanes were synthesized in decent to excellent yields. The reaction has good functional group tolerance and broad substrate scope

A Catalyst-Free Synthesis of Phosphinic Amides Using <i>O</i>‑Benzoylhydroxylamines

A practical approach for the synthesis of phosphinic amides via the coupling of secondary phosphine oxides (SPOs) with <i>O</i>-benzoyl­hydroxyl­amines has been reported. Simply heating the mixture of SPOs and <i>O</i>-benzoylhydroxylamines in the presence of K₂CO₃ gave the phosphinic amides in moderate to excellent yields under an open air system. This method provides a practical and catalyst-free method for the synthesis of various synthetically valuable phosphinic amides

Enantioselective Synthesis of Biaryl Atropisomers via Pd/Norbornene-Catalyzed Three-Component Cross-Couplings

Three-component cross-coupling cocatalyzed by palladium and norbornene is reported for the synthesis of biaryl atropisomers. This domino reaction gave optimal yield and enantioselectivity with a P,C-type ligand bearing axial chirality and P chiral center. The process showed advantages over traditional cross-coupling because of its step economy and its compatibility with readily available <i>ortho</i>-substituted aryl halides, which could, therefore, be used instead of continuously trisubstituted aryl halides

Stereoselective Synthesis of 1,3-Amino Alcohols by the Pd-Catalyzed Cyclization of Trichloroacetimidates

The synthesis of 4-vinyl-5,6-dihydro-1,3-oxazines, precursors of 1,3-amino alcohols, using the palladium-catalyzed cyclization of trichloroacetimidates is reported. The reaction favors the formation of the 4,6-<i>cis</i>-isomers with up to >20:1 diastereoselectivity. Chemoselective hydrolysis of the resulting 5,6-dihydro-1,3-oxazines was also investigated

Enantioselective Synthesis of Biaryl Atropisomers via Pd/Norbornene-Catalyzed Three-Component Cross-Couplings

Three-component cross-coupling cocatalyzed by palladium and norbornene is reported for the synthesis of biaryl atropisomers. This domino reaction gave optimal yield and enantioselectivity with a P,C-type ligand bearing axial chirality and P chiral center. The process showed advantages over traditional cross-coupling because of its step economy and its compatibility with readily available <i>ortho</i>-substituted aryl halides, which could, therefore, be used instead of continuously trisubstituted aryl halides

Palladium-Catalyzed Heck-type Domino Cyclization and Carboxylation to Synthesize Carboxylic Acids by Utilizing Chloroform as the Carbon Monoxide Source

A palladium-catalyzed domino cyclization and carboxylation reaction for synthesis of a variety of carboxylic acids was developed, where chloroform was used as “carbon monoxide” source. The in situ generated neopentylpalladium species by Heck cyclization was efficiently trapped by dichlorocarbene to form a series of carboxylic acids. It was found that in this type of domino reaction CHCl₃ is a convenient and safe alternation for CO gas

BF₃·OEt₂‑Promoted Synthesis of 2,3-Metallocenocyclohexanones: A 1,2-Hydride Shift and Cationic Cyclization Strategy

A BF₃·OEt₂-promoted cyclization of metallocenyl enones to form cyclohexanone-fused metallocenes is reported. 2,3-Metallocenocyclohexanones were formed exclusively, and no normal Nazarov-type cyclopentanone analogues were detected. The reaction possibly proceeded via an unusual cationic 1,2-hydride shift followed by Friedel–Crafts alkylative cyclization process. During the studies of the alkylation reaction of these keto esters, an unusual and rare facial selectivity was observed. The electrophiles would be attacked from the same face as the second Cp ring

Total Synthesis of Maoecrystal V: Early-Stage C–H Functionalization and Lactone Assembly by Radical Cyclization

A total synthesis of the unusual <i>ent</i>-kaurane maoecrystal V is described. The synthesis strategy features a counterintuitive early disconnection of the lactone subunit to a polycyclic enol ether intermediate in order to preserve the central tetrahydrofuran ring until the beginning stages of the synthesis. This strategy enables an application of C–H functionalization at the early phase of the synthesis during the construction of a dihydrobenzofuran intermediate

Pd-Catalyzed Heck-Type Cascade Reactions with <i>N</i>‑Tosyl Hydrazones: An Efficient Way to Alkenes via in Situ Generated Alkylpalladium

A palladium-catalyzed Heck-type cascade reaction of aryl halides and <i>N</i>-tosyl hydrazones is reported. The neopentylpalladium species, generated from an intramolecular Heck-type insertion reaction of aryl halides, could efficiently react with carbenes to form highly functionalized alkenes. The synthesis of spiro compounds was also explored via a multiple Heck-type insertion reaction with <i>N</i>-tosyl hydrazone