A quantitative approach to nucleophilic organocatalysis

A quantitative approach to nucleophilic organocatalysis

The key steps in most organocatalytic cyclizations are the reactions of electrophiles with nucleophiles. Their rates can be calculated by the linear free-energy relationship log k(20 °C) = s(N)(E + N), where electrophiles are characterized by one parameter (E) and nucleophiles are characterized by the solvent-dependent nucleophilicity (N) and sensitivity (s(N)) parameters.Electrophilicity param...

Theoretical Studies in Nucleophilic Organocatalysis

Chiral phosphines in nucleophilic organocatalysis

This review discusses the tertiary phosphines possessing various chiral skeletons that have been used in asymmetric nucleophilic organocatalytic reactions, including annulations of allenes, alkynes, and Morita-Baylis-Hillman (MBH) acetates, carbonates, and ketenes with activated alkenes and imines, allylic substitutions of MBH acetates and carbonates, Michael additions, γ-umpolung additions, an...

Cyclization of ortho-hydroxycinnamates to coumarins under mild conditions: A nucleophilic organocatalysis approach

(E)-Alkyl ortho-hydroxycinnamates cyclize to coumarins at elevated temperatures of 140-250 °C. We find that the use of tri-n-butylphosphane (20 mol %) as a nucleophilic organocatalyst in MeOH solution allows cyclization to take place under much milder conditions (60-70 °C). Several coumarins were prepared, starting from ortho-hydroxyarylaldehydes, by Wittig reaction with Ph(3)P=CHCO(2)Me to (E)...

Cooperative nucleophilic–electrophilic organocatalysis by ionic liquidsw

The anionic and the cationic partners of ionic liquids may act cooperatively and independently as nucleophilic and electrophilic catalysts. This ambiphilic propensity was demonstrated by kinetically discriminating the contributions of the anion (nucleophilic catalyst) and of the cation (electrophilic catalyst) to the solvent-free Baylis– Hillman dimerization of cyclohexenone catalysed by ionic ...