Ethynylbenziodoxolones (EBXs) are commonly used as radical traps in photocatalytic alkynylations. Herein, we report that aryl‐substituted EBX reagents can be directly activated by visible light irradiation. They act as both oxidants and radical traps, alleviating the need for a photocatalyst in several reported EBX‐mediated processes, including decarboxylative and deboronative alkynylations, the oxyalkynylation of enamides and the C−H alkynylation of THF. Furthermore, the method could be applied to the synthesis of alkynylated quaternary centers from tertiary alcohols via stable oxalate salts and from tertiary amines via aryl imines. A photocatalytic process using 4CzIPN as an organic dye was also developed for the deoxyalkynylation of oxalates.

The enantioselective functionalization of nonactivated enantiotopic secondary CÀHbonds is one of the greatest challenges in transition-metal-catalyzed C À Ha ctivation proceeding by an inner-sphere mechanism. Suchr eactions have remained elusive within the realm of Pd 0 catalysis.R eported here is the unique reactivity profile of the IBiox ligand family in the Pd 0-catalyzed intramolecular arylation of such nonactivated secondary CÀHb onds.C hiral C 2-symmetric IBiox ligands led to high enantioselectivities for ab road range of valuable indane products containing atertiary stereocenter,as well as the arylation of secondary C À Hb onds adjacent to amides.Depending on the amide substituents and upon control of reaction time,indanes containing labile tertiary stereocenters were also obtained with high enantioselectivities.A nalysis of the steric maps of the IBiox ligands indicated that the level of enantioselectivity correlates with the difference between the two most occupied and the two less occupied space quadrants,and provided ab lueprint for the design of even more efficient ligands.

The two sulfonyl-bridged Geländer helices 1a and 2a are obtained by oxidation of the corresponding sulfide bridged precursors 1b and 2b. Both Geländer structures are fully characterized by NMR, high-resolution mass spectrometry, and optical spectroscopies. X-ray diffraction with a single crystal of 2a provides its solid-state structure. Both Geländer helices 1a and 2a are separated into enantiomers, and their racemizations are monitored by circular dichroism. For 1a, consisting of two equally sized macrocycles, a substantial increase in the enantiomerization barrier is observed upon going from the sulfide to the sulfone, and only a subtle rise is detected for the constitutional isomer 2a with two macrocycles of different size during the same transformation. This results not only in 1a with the highest configurational stability in the series of hitherto investigated Geländer structures but also challenges the so far hypothesized correlations between bridging structures and the Gibbs free energy of enantiomerization. The simulation of the enantiomerization process in the macrocyclic subunits suggests the proximity of the endotopic hydrogens as parameter responsible for the heights of the enantiomerization barrier.

The enantioselective functionalization of nonactivated enantiotopic secondary C−H bonds is one of the greatest challenges in transition‐metal‐catalyzed C−H activation proceeding by an inner‐sphere mechanism. Such reactions have remained elusive within the realm of Pd0 catalysis. Reported here is the unique reactivity profile of the IBiox ligand family in the Pd0‐catalyzed intramolecular arylation of such nonactivated secondary C−H bonds. Chiral C2‐symmetric IBiox ligands led to high enantioselectivities for a broad range of valuable indane products containing a tertiary stereocenter, as well as the arylation of secondary C−H bonds adjacent to amides. Depending on the amide substituents and upon control of reaction time, indanes containing labile tertiary stereocenters were also obtained with high enantioselectivities. Analysis of the steric maps of the IBiox ligands indicated that the level of enantioselectivity correlates with the difference between the two most occupied and the two less occupied space quadrants, and provided a blueprint for the design of even more efficient ligands.

Ethynylbenziodoxolones (EBXs) are commonly used as radical traps in photocatalytic alkynylations.H erein, we report that aryl-substituted EBX reagents can be directly activated by visible light irradiation. They act as both oxidants and radical traps,a lleviating the need for ap hotocatalyst in several reported EBX-mediated processes,i ncluding decarboxylative and deboronative alkynylations,t he oxyalkynylation of enamides and the C À Ha lkynylation of THF.F urthermore,t he method could be applied to the synthesis of alkynylated quaternary centers from tertiary alcohols via stable oxalate salts and from tertiary amines via aryl imines.A photocatalytic process using 4CzIPN as an organic dye was also developed for the deoxyalkynylation of oxalates.

EthynylBenziodoXolones (EBXs) are commonly used as radical traps in photocatalytic alkynylations. Herein, we report their application in two complementary deoxygenation strategies allowing the synthesis of valuable alkynylated all-carbon quaternary centers from tertiary alcohols via stable oxalate salts. Our first approach involves a photocatalytic process using 4CzIPN as an organic dye to promote oxidative degradation of the oxalate and EBXs to trap the formed radical. In our second approach, we demonstrate the direct photoexcitation of an EBX, which then acts as both oxidant and radical trap, alleviating the need for a photocatalyst in several EBX-mediated alkynylation processes.

EthynylBenziodoXolones (EBXs) are commonly used as radical traps in photocatalytic alkynylations. Herein, we report their application in two complementary deoxygenation strategies allowing the synthesis of valuable alkynylated all-carbon quaternary centers from tertiary alcohols via stable oxalate salts. Our first approach involves a photocatalytic process using 4CzIPN as an organic dye to promote oxidative degradation of the oxalate and EBXs to trap the formed radical. In our second approach, we demonstrate the direct photoexcitation of an EBX, which then acts as both oxidant and radical trap, alleviating the need for a photocatalyst in several EBX-mediated alkynylation processes.In addition, we would like to thank members of the Laboratory of Supramolecular Chemistry-Ecole Polytechnique Fédérale de Lausanne LCS-EPFL: Cristian Pezzato and Cesare Berton for enabling us to run our absorption and fluorescence studies and Ophélie Planes who also helped greatly for the cyclic voltammetry studies.