The palladium-catalyzed coupling reaction of N-hydroxyphthalimide esters and styrenes to deliver exclusively (E)-substituted olefins under irradiation with visible light is reported. This method tolerates N-hydroxyphthalimide esters derived from primary, secondary, tertiary as well as benzylic carboxylic acids. Notably, Pd(PPh ) is employed as an inexpensive palladium source and no addition of base or classical photocatalyst is required. Mechanistic studies suggest a light-mediated single-electron reduction of the activated acid by a photoexcited palladium(0) species to access alkyl radicals through decarboxylation.

Carbene insertion reactions with B−H bonds are a challenging but promising method for the synthesis of organoboranes. Herein, we report visiblelight-induced B−H insertions of HBpin with acylsilane. This metal-free and operationally simple reaction proceeds in an atom-economical way with broad substrate scope under mild reaction conditions, affording a variety of important α-alkoxyorganoboronate esters in quantitative yields. Control experiments and density functional theory calculations suggest that the siloxycarbene generation from the T 1 state of acylsilane and the carbene insertion into the B−H bond occurred in a concerted manner.

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Herein, we present a dual catalytic strategy to efficiently obtain mono-protected homoallylic 1,2-diols by coupling abundant aldehydes with simple (silyl) enol ethers, thus providing direct access to this important motif without the (super)stoichiometric use of prefunctionalized metal-allyl species. The modularity of our approach is shown by the introduction of several silyl-and alkyl-based protecting groups, enabling a diverse protecting group strategy. To highlight functional group tolerance and chemoselectivity, we demonstrate the functionalization of a variety of aliphatic, aromatic and heteroaromatic aldehydes, even in presence of ketones and esters. The applicability was further supported by a large scale experiment and a robustness screening. Mechanistic studies support a radical mechanism, starting from the single electron oxidation of the silyl enol ether, facilitated by the β-silicon effect.

No abstract

Hydrofunctionalization of unactivated alkenes is an indispensable mean in synthetic chemistry. Given that addition of electrophilic species into alkenes intrinsically follows the Markovnikov rule, a regioselectivity switch presents a major challenge. Herein, we present a visible-light-promoted strategy for the selective anti-Markovnikov hydrooxygenation of unactivated alkenes. Therefore, an innovative reagent was carefully designed to release a highly reactive and strongly underdeveloped alkoxycarbonyloxyl radical upon reduction, which selectively adds into alkenes. Hydrogen atom abstraction from 2-phenylmalononitrile is the key to form the product. We believe that this methodology enlarges the toolbox for regioselective hydrofunctionalization and could serve as a complementary strategy to the established hydroboration/ oxidation protocol.

<p>A dual catalytic strategy enables the efficient synthesis of mono-protected homoallylic 1,2-diols by coupling abundant aldehydes with simple (silyl) enol ethers, thus providing direct access to this important motif without the (super)stoichiometric use of prefunctionalized metal-allyl species. A variety of silyl- and alkyl-based protecting groups is shown and functional group tolerance, chemoselectivity and scalability are highlighted. </p>

<p>A dual catalytic strategy enables the efficient synthesis of mono-protected homoallylic 1,2-diols by coupling abundant aldehydes with simple (silyl) enol ethers, thus providing direct access to this important motif without the (super)stoichiometric use of prefunctionalized metal-allyl species. A variety of silyl- and alkyl-based protecting groups is shown and functional group tolerance, chemoselectivity and scalability are highlighted. </p>