Enantiopure secondary alcohols are fundamental high-value synthetic building blocks.One of the most attractive ways to get access to this compound class is the catalytic hydroboration. We describe an ew concept for this reaction type that allowed for exceptional catalytic turnover numbers (up to 15 400), which were increased by around 1.5-3 orders of magnitude compared to the most active catalysts previously reported. In our concept an aprotic ammonium halide moiety cooperates with an oxophilic Lewis acid within the same catalyst molecule.C ontrol experiments reveal that both catalytic centers are essential for the observed activity.Kinetic, spectroscopic and computational studies show that the hydride transfer is rate limiting and proceeds via ac oncerted mechanism, in whichh ydride at Boron is continuously displaced by iodide,r eminiscent to an S N 2r eaction. The catalyst, whichi s accessible in high yields in few steps,w as found to be stable during catalysis,r eadily recyclable and could be reused 10 times still efficiently working.

Epoxide desymmetrizations by bromide are very rare despite the large synthetic potential of chiral bromohydrins. Herein we present a new concept for epoxide desymmetrizations in which a bifunctional Lewis acid/ammonium salt catalyst allows for efficient enantioselective epoxide ring openings by Br. With acetylbromide as a Br source bromohydrin esters are formed.

α-Amino acids are of fundamental importance for life. Both natural and artificial α-amino acids also play a crucial role for pharmaceutical purposes. The catalytic asymmetric Strecker reaction still provides one of the most attractive strategies to prepare scalemic α-amino acids. Here we disclose a new concept for Strecker reactions, in which an achiral Brønsted base cooperates with a Lewis acid and an aprotic ammonium salt, which are both arranged in the same chiral catalyst entity. The described method could successfully address various longstanding practical issues of this reaction type. The major practical advantages are that (1) the N-protecting group is readily removable, (2) acetone cyanohydrin is attractive as cyanation reagent in terms of atom economy and cost efficiency, (3) an excess of the cyanation reagent is not necessary, (4) the new method does not require additives and (5) is performed at ambient temperature.