Bromonitroalkenes as efficient intermediates in organic synthesis

Bromonitroalkenes are useful molecules in synthetic organic chemistry. They are mainly prepared from nitroalkenes via bromination reactions. In this review, the application of bromonitroalkenes as partners in the reaction with a diversity of mono- and bi-functional molecules, including aldehydes and ketones, active methylene compounds, 1,2-dicarbonyls, enamines, enols, electron-rich arenes, amidines, azomethine ylides, azirines, diazo compounds, and many others, is reviewed. By using these substrates, various biologically active scaffolds, such as heterocycles, carbocycles, spirocycles, polycyclic systems, natural products, and other useful acyclic compounds, were prepared. In addition, due to their dielectrophilic character, electrophilic and nucleophilic character, and ability to participate in cycloaddition reactions, bromonitroalkenes were efficiently applied in asymmetric cascade/domino/tandem reactions catalyzed by chiral catalysts. In this manuscript, around 55 papers are summarized and discussed during the years 2000-2023.

Organocatalytic enantioselective synthesis of dihydronaphthofurans and dihydrobenzofurans: reaction development and insights into stereoselectivity

Squaramide/cinchona alkaloid-derived bifunctional organocatalysts are in high demand in asymmetric transformations.

Stereoselective Synthesis of Dihydrofuranoindoles via the Friedel-Crafts Alkylation/Annulation Cascade Process

A stereoselective annulation protocol was developed to construct dihydrofuranoindoles from readily available starting materials. In the presence of a bifunctional squaramide, the Friedel-Crafts alkylation/annulation cascade process occurred smoothly to provide dihydrofuranoindoles in 26-95% isolated yields exclusively as trans-diastereomers (38-99% ee). This catalytic protocol was compatible with a range of structurally distinct hydroxyindoles bearing the hydroxyl group at different positions, providing four kinds of dihydrofuranoindoles. Moreover, gram-scale synthesis and further synthetic manipulation of the product were also demonstrated.