Visible-Light-Promoted Synthesis of 1,3-Dicarbonyl Sulfoxonium Ylides

Visible photons as ideal reagents for the activation of coloured organic compounds

In recent decades, the traceless nature of visible photons has been exploited for the development of efficient synthetic strategies for the photoconversion of colourless compounds, namely, photocatalysis, chromophore activation, and the formation of an electron donor/acceptor (EDA) complex. However, the use of photoreactive coloured organic compounds is the optimal strategy to boost visible photons as ideal reagents in synthetic protocols. In view of such premises, the present review aims to provide its readership with a collection of recent photochemical strategies facilitated via direct light absorption by coloured molecules. The protocols have been classified and presented according to the nature of the intermediate/excited state achieved during the transformation.

Continuous flow reactions in the preparation of active pharmaceutical ingredients and fine chemicals

Herein, we present an overview of continuous flow chemistry, including photoflow and electroflow technologies in the preparation of active pharmaceutical ingredients (APIs) and fine chemical intermediates. Examples highlighting the benefits and challenges associated with continuous flow processes, mainly involving continuous thermal, photo- and electrochemical transformations, are drawn from the relevant literature, especially our experience and collaborations in this area, with emphasis on the synthesis and prospective scale-up.

Construction of α-Acyloxy Ketones via Photoredox-Catalyzed O-H Insertion of Sulfoxonium Ylides with Carboxylic Acids

Herein, a photoredox-catalyzed insertion of sulfoxonium ylides with carboxylic acids was advanced under mild and simple conditions, offering a practical approach for preparing α-acyloxy ketones with a broad scope of carboxylic acids. A combined experimental and computational study suggests that this reaction proceeds via a stepwise proton-assisted electron transfer mechanism.

Demethyl oxidative halogenation of diacyl dimethylsulfonium methylides

α-Halo-α-methylthio-β-ketosulfones containing a quaternary halocarbon stereocenter were prepared via selective demethyl oxidative halogenations of diacyl dimethylsulfonium methylides in moderate to excellent yields (39 examples; up to 98%). The current protocols directly and efficiently introduce a halogen atom into organic compounds with high functional group tolerance under metal-free conditions.

Synthesis of α-Carbonyl-α'-amide Sulfoxonium Ylides from Isocyanates with Complete Atom Economy

An efficient catalyst- and additive-free facile synthesis of α-carbonyl-α'-amide sulfoxonium ylides from isocyanates and β-ketosulfoxonium ylides with complete atom economy has been described. The β-ketosulfoxonium ylides and isocyanates adorned with various functional groups were well-tolerated and afforded moderate to high yields of the α-carbonyl-α'-amide sulfoxonium ylide derivatives. Finally, using large-scale reactions and converting the synthesized ylides into other valuable compounds, we demonstrated the practicality of this synthetic method.