Cascade cyclization, dipolar cycloaddition to bridged tricyclic amines related to the Daphniphyllum alkaloids

A tandem one-pot reaction of an aldehyde with a primary amine involving condensation and then cyclization (N-alkylation), followed by intramolecular dipolar cycloaddition of the resulting nitrone or azomethine ylide, provides a synthesis of bridged tricyclic amines. The reaction was most successful using hydroxylamine, and when the dipolarophile was an unsaturated ester, subsequent reduction of the N-O bond and cyclization to the lactam provided the core ring system of the yuzurimine, daphnilactone B, and bukittinggine type Daphniphyllum alkaloids.     

Cascade cyclization, dipolar cycloaddition of azomethine imines for the synthesis of pyrazolidines

A tandem multi-step, one-pot reaction of aldehydes with hydrazines has been used for the preparation of tetrahydropyrazoles and dihydropyrazoles. The chemistry involves condensation then cyclization, followed by inter- or intramolecular dipolar cycloaddition of the resulting azomethine imine intermediates. The intramolecular cycloaddition gives fused tricyclic compounds as single diastereoisomers. The intermolecular cycloaddition was successful with a variety of activated alkene and alkyne dipolarophiles.     

Borylation of Unactivated Aryl Chlorides under Mild Conditions by Using Diisopropylaminoborane as a Borylating Reagent

The synthesis of arylboronic ester derivatives from aryl chlorides by using aryl(amino)boranes is described. Palladium‐catalyzed coupling between aryl chlorides and diisopropylaminoborane leads to the formation of a C?B bond under mild conditions. A wide range of functional groups are tolerated, making this method particularly useful for the borylation of functionalized aromatics.     

Sequential dehydrogenation–arylation of diisopropylamine–borane complex catalyzed by palladium nanoparticles

Palladium nanoparticles have been prepared using different techniques, CO₂-assisted microfluidics coflow or thermolysis using ionic liquids. Both techniques displayed interesting activities in dehydrogenation of diisopropylamine–borane complex, and allowed performing a dehydrogenation–arylation sequence with the creation of a carbon–boron bond.