New strategies for the synthesis of 1- and 2-azetines and their applications as value-added building blocks.

Four-membered nitrogen-containing heterocycles are highly desirable functional groups with synthetic and biological applications. Unsaturated four-membered N-heterocycles, 1- and 2-azetines, are historically underexplored, but have recently been gaining interest due to the development of new synthetic methods to access these compounds, and to their potential as reactive intermediates. This review covers both the synthesis and applications of azetines, with a focus on synthetic methods to access azetines developed since 2018, and a comprehensive review of the reactivity and applications of azetines as starting materials or intermediates to access both other heterocycles and complex products.

A general alkene aminoarylation enabled by N-centred radical reactivity of sulfinamides.

Arylethylamines are popular structural elements in bioactive molecules but are often made through a linear series of synthetic steps. A modular protocol to assemble arylethylamines from alkenes in one step would represent a useful advance in discovery chemistry, though current limitations preclude a generally applicable method. In this work we disclose an aminoarylation of alkenes using aryl sulfinamide reagents as bifunctional amine and arene donors. This reaction features excellent regioselectivity and diastereoselectivity on a variety of activated and unactivated substrates. Using a weakly oxidizing photocatalyst, a nitrogen radical is generated under mild conditions and adds to an alkene to form a new C-N bond. A desulfinylative aryl migration event known as a Smiles-Truce rearrangement follows to form a new C-C bond. In this manner, arylethylamines can be rapidly assembled from abundant alkene feedstocks. Moreover, chiral information from the sulfinamide can be transferred via rearrangement to a new carbon stereocentre in the product, thus advancing the development of traceless asymmetric alkene difunctionalization.