The Barton-McCombie deoxygenation is one of the most important transformations in the toolbox of organic chemists which has been the subject of a number of methodological developments. In this study, we report a photocatalyzed redox deoxygenation of secondary and tertiary alcohols from thiocarbamate precursors under visible light activation. The iridium complex IrA C H T U N G T R E N N U N G (ppy) 3 proved to be the most efficient catalyst in the presence of Hünigs base as sacrifial electron donor. A mechanistic investigation is presented based on fluorescence quenching experiments and cyclic voltammetry.
Reported herein is the use of S-perfluoroalkyl sulfilimino iminiums as a new source of R radicals under visible-light photoredox catalysis (R =CF , C F , CF Br, CFCl ). These shelf-stable perfluoroalkyl reagents, readily prepared on gram scale from the corresponding sulfoxide using a one-pot procedure, allow the efficient photoredox-induced oxyperfluoroalkylation of various alkenes using fac-Ir(ppy) as the photocatalyst. Importantly, spin-trapping/electron paramagnetic resonance experiments were carried out to characterize all the radical intermediates involved in this radical/cationic process.
This article deals with the recent developments in radical cascade reactions with a special emphasis on their applications in natural product synthesis. Particular attention has been paid to the mechanisms of the cascade sequences and the involvement of original elementary steps. Section 2 is dedicated to cascades occurring via a purely radical chain mechanism, describing first intramolecular processes, then processes involving both inter‐ and intramolecular steps. Section 3 is devoted to cascade reactions combining radical and ionic steps. The reactions are classified according to the type of metal reagent used, such as, samarium, titane, manganese, cerium, iron, zinc, silver, and copper. In addition, newer developments in radical cascades triggered by visible light photoredox catalysis are discussed.
Visible-light photocatalytic oxidation of 1,3-dicarbonyl compounds, using Ru(bpy) 3 Cl 2 as a photocatalyst and combining molecular oxygen and triphenylcarbenium as a new sacrificial acceptor, has been developed for carbon-carbon bond formation giving access to dimerization, allylation and polycyclization products.Scheme 1 Photooxidation of 1,3-dicarbonyl compounds. † Dedicated to Professor Max Malacria on the occasion of his 65th birthday. ‡ Electronic supplementary information (ESI) available. See
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