Divergent Access to (1,1) and (1,2)‐Azidolactones from Alkenes using Hypervalent Iodine Reagents

Abstract

A versatile synthesis of azidolactones through azidation and cyclization of carboxylic acids onto alkenes has been developed. Based on either photoredox or palladium catalysis, (1,1) and (1,2) azido lactones can be selectively synthesized. The choice of catalyst and benziodoxol(on)e reagent serving as azide source was essential to initiate either a radical or Lewis acid mediated process with divergent outcome. These transformations were carried out under mild conditions using a low catalyst loading and gave access to a large scope of azido lactones.

Recent Synthetic Applications of the Hypervalent Iodine(III) Reagents in Visible-Light-Induced Photoredox Catalysis

“…In 2017, the Waser's group reported a method of synthesis of azidolactones starting from alkene-containing carboxylic acids (Alazet et al, 2017 ) ( Figure 4C ). Using Zhdankin reagent as the azide-transfer reagent and only 0.5 mol% Cu(dap) 2 Cl as photoredox catalyst, (1,2)-azidolactones were achieved under visible light irradiation.…”

Bench‐Stable Electrophilic Indole and Pyrrole Reagents: Serendipitous Discovery and Use in C–H Functionalization

“…Based on these results, our initial aim was to expand the scope of domino transformations to other hypervalent iodine reagents, in particular azidobenziodoxol(on)es (ABX) . Our choice of ABX was justified by the large number of applications and chemical modifications related to azides, such as reduction to amines or cycloaddition with alkynes and the recent success reported with this reagent for azide transfer reactions . Best results in the domino cyclization‐alkynylation reactions had been obtained with hexafluoroisopropanol‐derived reagent 6 .…”

Transition Metal Catalyzed Azidation Reactions

“…A and B of Scheme 53 follow a radical mechanism based on an initial azidation at the indolyl C3-position and subsequent intramolecular nucleophilic attack at C2-position to obtain the desired product. Two years later, Waser and co-workers also investigated the cyclization/azidation of carboxylic acids to convert alkene-containing carboxylic acids into lactones using azidoiodinanes (ABX or ADBX) as the azide source [114]. The reaction can be performed in the presence of a Cu-catalyst combined with photoredox conditions or a Pd-catalyst giving access to (1,1)-or (1,2)-azidolactones, respectively (Scheme 55).…”