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Stronger acid, higher speed: The pKa  values of a range of binol-derived Brønsted acids of three different types were measured and found to correlate directly with the catalytic properties of the acids: higher rate constants kI were observed for more acidic Brønsted acid catalysts (see plot; binol=1,1'-bi-2-naphthol).

Direct, oxidative metal-catalyzed C-H functionalizations of arenes are important in synthetic organic chemistry. Often, (over-)stoichoimetric amounts of organic or inorganic oxidants have to be used in these reactions. The combination of rhodium and photoredox catalysis with visible light allows the direct C-H olefination of arenes. Small amounts (1 mol%) of a photoredox catalyst resulted in the efficient C-H functionalization of a broad range of substrates under mild conditions.

An efficient method for the highly enantioselective synthesis of chiral chromanes bearing multiple stereogenic centers was developed. A chiral BINOL-based N-triflylphosphoramide proved to be an effective catalyst for the in situ generation of ortho-quinone methides (o-QMs) and their subsequent cycloaddition reaction with unactivated alkenes provided chromanes with excellent diastereo- and enantioselectivity.

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A new asymmetric Brønsted acid-catalyzed cascade reaction involving a 1,4-addition, enantioselective protonation and 1,2-addition has been developed. This organocatalytic cascade not only provides for the first time 3-and 2,3-substituted tetrahydroquinolines and octahydroacridines in good yields with high dia-and enantioselectivities under mild reaction conditions but additionally represents the first example of a chiral Brønsted acidcatalyzed protonation reaction in an organocatalytic domino reaction. Furthermore, the new Brønsted acid-catalyzed hydride-proton-hydride transfer cascade can be applied to prepare new molecular scaffolds with up to three new stereocenters in an efficient one-pot reaction sequence.Keywords: BINOL phosphate; enantioselective isomerization; Hantzsch dihydropyridine; organocatalytic cascade reaction; transfer hydrogenationThe hydrogenation of unsaturated organic compounds, such as olefins, carbonyls, imines as well as aromatic and heteroaromatic compounds is one of the most important and utilized transformations in both academia and chemical industry.[1] Due to the constantly increasing number of optically and biologically active substances asymmetric reductions have become a central research area in enantioselective catalysis. So far, most of these enantioselective reductions rely on chiral transition metal catalysts and highly enantioselective hydrogenations of ketones, ketimines and alkenes are known.[2] However, most of these metal catalysts failed to give satisfactory results for the asymmetric hydrogenation of aromatic and heteroaromatic compounds and examples of efficient and highly selective transformations are rare. [3] Within this context, and based on our previous work on organocatalytic transfer hydrogenations [4] we recently developed new highly enantioselective partial reductions of pyridines [5] and quinolines.[6] The corresponding products are not only of great synthetic importance in the preparation of pharmaceuticals, agrochemicals, and in materials science, but additionally many interesting alkaloid natural products contain these structural key elements.With the newly developed enantioselective Brønst-ed acid-catalyzed transfer hydrogenation we were, for instance, able to reduce quinolines to the corresponding 2-or 4-substituted tetrahydroquinolines,[6] which we isolated in good yields and with excellent enantioselectivities [Scheme 1, Eq. (1)].In this first organocatalytic transfer hydrogenation, the activation of the quinolines is achieved by a catalytic protonation through a chiral Brønsted acid which subsequently allows a cascade hydrogenation involving a 1,4-hydride addition, proton transfer and Scheme 1. Brønsted acid-catalyzed enantioselective transfer hydrogenation of quinolines using Hantzsch dihydropyridine as the hydride source.

A new enantioselective Brønsted acidcatalyzed Friedel-Crafts reaction of indole with cyclic imines has been develeoped. This organocatalytic reaction provides for the first time optically active indolindolinone derivatives in high yields and with excellent enantioselectivities (up to 91% ee) under mild reaction conditions.

A highly stable lipase from Geobacillus thermocatenolatus (BTL2) and the enhanced green fluorescent protein from Aquorea victoria (EGFP) were recombinantly produced N-terminally tagged to the lectin domain of the hemolytic pore-forming toxin LSLa from the mushroom Laetiporus sulphureus. Such a domain (LSL150), recently described as a novel fusion tag, is based on a β-trefoil scaffold with two operative binding sites for galactose or galactose-containing derivatives. The fusion proteins herein analyzed have enabled us to characterize the binding mode of LSL150 to polymeric and solid substrates such as agarose beads. The lectin-fusion proteins are able to be quantitatively bound to both cross-linked and non-cross-linked agarose matrixes in a very rapid manner, resulting in a surprisingly dynamic protein distribution inside the porous beads that evolves from heterogeneous to homogeneous along the postimmobilization time. Such dynamic distribution can be related to the reversible nature of the LSL150–agarose interaction. Furthermore, this latter interaction is temperature dependent since it is 4-fold stronger when the immobilization takes place at 25 °C than when it does at 4 °C. The strongest lectin–agarose interaction is also quite stable under a survey of different conditions such as high temperatures (up to 60 °C) or high organic solvent concentrations (up to 60% of acetonitrile). Notably, the use of cross-linked agarose would endow the system with more robustness due to its better mechanical properties compared to the noncross-linked one. The stability of the LSL150–agarose interaction would prevent protein leaching during the operation process unless high pH media are used. In summary, we believe that the LSL150 lectin domain exhibits interesting structural features as an immobilization domain that makes it suitable to reversibly immobilize industrially relevant enzymes in very simple carriers as agarose.