Cu(II)-Catalyzed Decarboxylative (4 + 2) Annulation of Coumarin-3-Carboxylic Acids with In Situ Generated α,β-Unsaturated Carbonyl Compounds from tert-Propargylic Alcohols

Cu(II)-catalyzed decarboxylative oxidative (4 + 2) annulation of coumarin-3-carboxylic acids with tert-propargylic alcohols, via the in situ generated α,β-unsaturated carbonyl compounds by the Meyer-Schuster rearrangement, has been developed. This protocol involving indirect C-H functionalization offers access to diverse naphthochromenone architectures with good to excellent yields.

Construction of 3,12-Diazatetracyclododecane-dienes through Unexpected Visible-Light-Induced Radical Cascade Cyclization

A novel visible-light-induced cascade radical cyclization reaction of 3-cyano-4-aryl-1,4-dihydropyridines for the construction of 3,12-diazatetracyclododecane-diene derivatives is reported for the first time. In the presence of 410 nm blue LED lamp as the light source and ethanol as the solvent, the reactions proceed smoothly to afford photocyclization products in good yields. The process is carried out through the breaking of original C═C double bonds and the formation of three new single bonds in one pot and proved to be able to tolerate different substituents.

Recent advances in the synthesis of indolizine and its derivatives by radical cyclization/cross-coupling

Indolizine is a nitrogen-containing heterocycle that has a variety of potential biological activities, and some indolizine derivatives with excellent fluorescence properties can even be used as organic fluorescent molecules for biological and material applications. Thus, many approaches for their synthesis have been developed. Among them, radical-induced synthetic approaches are receiving increasing attention owing to their unique advantages, such as efficient heterocycle construction, efficient C-C or C-X bond construction, and high atom- and step-economy. This review systematically examines the current and latest synthetic strategies using radical species or radical intermediates for synthesizing indolizines and their derivatives. This review is classified into two parts based on the type of building blocks used for indolizine ring construction and the type of radical trigger for indolizine derivative construction. We anticipate that this review will provide a deep understanding of this topic, and ultimately help researchers to develop novel approaches for the synthesis of indolizine and its derivatives.

Indolizine synthesis via radical cyclization and demethylation of sulfoxonium ylides and 2-(pyridin-2-yl)acetate derivatives

A novel radical cross-coupling/cyclization of 2-(pyridin-2-yl)acetate derivatives and sulfoxonium ylides is developed, which provides a straightforward access to structurally diverse methylthio-substituted indolizine.