Scalable organocatalytic asymmetric Strecker reactions catalysed by a chiral cyanide generator

Asymmetric organocatalytic Strecker-type reactions of aliphatic N,N-dialkylhydrazones.

The enantioselective organocatalytic Strecker-type reaction of aliphatic N,N-dialkylhydrazones is presented. Using trimethylsilyl cyanide (TMSCN) as the cyanide source, the reaction can be efficiently catalyzed by a tert-leucine-derived bifunctional thiourea to afford the corresponding hydrazino nitriles in good to excellent yields (50-96%) and moderate to good enantioselectivities, up to 86% e...

Asymmetric strecker reactions.

Organocatalytic direct asymmetric aldol reactions in water.

We have developed direct asymmetric cross-aldol reactions that can be performed in water without addition of organic solvents. A bifunctional catalyst with a long hydrophobic alkyl chain efficiently catalyzed the reactions and afforded the desired aldol products in excellent yield with high enantiomeric excess, even when only an equal molar ratio of the donor and acceptor was used. These result...

First asymmetric cascade reaction catalysed by chiral primary aminoalcohols.

Readily available chiral primary 1,2-aminoalcohols and diamines have been explored as organocatalysts for a domino Michael-aldol reaction. Their application in this organocascade process afforded cyclohexanone A with high levels of reactivity (up to 91% yield) and stereoselectivity (>97 : 3 d.r., up to 93% ee). Depending on the acid cocatalyst different chiral species (cyclic secondary amines v...

Asymmetric Addition of Cyanide to β-Nitroalkenes Catalysed by Chiral Salen Complexes of Titanium(IV) and Vanadium(V)

Structurally well-defined bimetallic titanium(IV) (salen) and monometallic vanadium(V) (salen) complexes have been used as catalysts for the asymmetric addition of trimethylsilyl cyanide to β-nitroalkenes to produce chiral nitronitriles with ee values in the range of 79-89 % and conversions up to 100 % at 0 °C. The reaction conditions (solvent, temperature, time and vanadium complex counter-ion...