Palladium-Catalyzed Cascade Double C-N Bond Activation: A New Strategy for Aminomethylation of 1,3-Dienes with Aminals

Palladium-Catalyzed Aminoalkylative Cyclization Enables Modular Synthesis of Exocyclic 1,3-Dienes

A novel and efficient palladium-catalyzed regioselective and stereodivergent ring-closing reaction of aminoenynes with aldehydes and boronic acids or hydrosilane is developed. This three-component reaction allows for the modular synthesis of a series of exocyclic 1,3-dienes bearing 5- to 8-membered saturated N-heterocycles. The reactions utilize a simple Pd-catalyst and work with broad range of aminoenynes, aldehydes and organometallic reagents under mild reaction conditions. The products represent useful intermediates for chemical synthesis due to the versatility of the conjugated diene. Preliminary mechanistic details of the method are also revealed.

Palladium-Catalyzed Regioselective Intermolecular Hydroalkoxylation of 1-Arylbutadienes

An efficient method for the synthesis of (E)-(3-alkoxybut-1-enyl)benzenes by Pd-catalyzed regioselective intermolecular hydroalkoxylation of 1-arylbutadienes has been developed. This method can be executed in a simple operation with no dry reaction conditions required and having tolerance to a wide range of substrates. Chloromethyl methyl ether (MOMCl) as an additive was found to be essential for the success of the reaction.

Highly Regioselective and Ligand-Controlled Diastereodivergent Aminomethylative Annulation of Dienyl Alcohols Enabled by Hydrogen-Bonding Assisting Effect

A ligand-controlled palladium-catalyzed highly regioselective and diastereodivergent aminomethylative annulation of dienyl alcohols with aminals has been established, which allows for producing either cis- or trans-disubstituted isochromans in good yields with...

Palladium-Catalyzed Aminomethylation and Cyclization of Enynol to O-Heterocycle Confined 1,3-Dienes

The rational tuning of the electrophilicity of the allylpalladium intermediates enables the regioselectively intramolecular 1,2-addition of enynol in the presence of aminal. This aminomethylation and cyclization reaction via C-N bond activation and intramolecular nucleophilic addition provides a rare example for the synthesis of O-containing heterocycle-confined 1,3-dienes, which is of synthetic potential for further derivatization. The method possesses broad substrate generality as well as functional group compatibility and efficiently affords a wide range of desired products with 5-, 6-, and 8-membered O-containing heterocycles with various functional groups.

Copolymerization of 1,3-butadiene with phenyl/phenethyl substituted 1,3-butadienes: a direct strategy to access pendant phenyl functionalized polydienes

Copolymerization of 1,3-butadiene with various types of phenyl substituted 1,3-butadiene derivatives, including (E)-1-phenyl-1,3-butadiene (PBD), 1-phenethyl-1,3-butadiene (PEBD), 1-(4-methoxylphenyl)-1,3-butadiene (p-MEPBD), 1-(2-methoxylphenyl)-1,3-butadiene (o-MEPBD) and 1-(4-N,N-dimethylaminophenyl)-1,3-butadiene (p-DMPBD), by using a coordination polymerization system of CpTiCl₃/MAO is reported herein. Comonomers PBD and PEBD can be copolymerized with 1,3-butadiene in a large range of comonomer feed ratios (0–44.6% for PBD, 0–30.2% for PEBD), affording the targeted copolymers with well-controlled comonomer incorporations, molecular weights, polydispersities and microstructure, whereas no corresponding copolymer products were obtained under identical conditions when p-MEPBD, o-MEPBD and p-DMPBD were employed. Moreover, different polymerization parameters, including temperature, Al/Ti ratio, etc., posed a significant influence on the polymerization behaviors, as well as the properties of the resultant copolymers. Microstructure analysis by NMR spectra revealed high 1,4-selectivities of the catalysts, and the glass transition temperature (T_g) of the resulted copolymer was found to be highly dependent on the incorporation content of the comonomers; with an increasing comonomer content, a gradually increasing T_g was demonstrated.

Copolymerization of 1,3-butadiene with various phenyl substituted 1,3-butadiene derivatives to access pendant phenyl functionalized polydiene elastomers is reported.

Palladium-catalyzed formal insertion of carbenoids into N,O-aminals: direct access to α-alkoxy-β-amino acid esters

A new and efficient reaction has been developed to synthesize α-alkoxy-β-amino acid esters via palladium-catalyzed formal insertion of carbenoids into N,O-aminals.