Trending

A catalytic asymmetric aldol addition/cyclization reaction of unactivated ketones with isocyanoacetate pronucleophiles has been developed. A quinine-derived aminophosphine precatalyst and silver oxide were found to be an effective binary catalyst system and promoted the reaction to afford chiral oxazolines possessing a fully substituted stereocenter with good diastereoselectivities and excellent enantioselectivities.

A stereoselective aldol reaction of unactivated ketones and isocyanoacetate pronucleophiles is catalyzed by a binary catalyst system consisting of an aminophosphine precatalyst and silver(I) oxide and affords oxazoline products with a fully substituted β-carbon atom. The reaction is efficient and broad in scope and proceeds with high diastereo- and enantioselectivity.

A convergent, organocatalytic asymmetric aminomethylation of α,β-unsaturated aldehydes by N-heterocyclic carbene (NHC) and (in situ generated) Brønsted acid cooperative catalysis is disclosed. The catalytically generated conjugated acid from the base plays dual roles in promoting the formation of azolium enolate intermediate, formaldehyde-derived iminium ion (as an electrophilic reactant), and methanol (as a nucleophilic reactant). This redox-neutral strategy is suitable for the scalable synthesis of enantiomerically enriched β²-amino acids bearing various substituents.

Harmonious cooperation: An N-heterocyclic carbene (NHC) and (in situ generated) Brønsted acid cooperatively catalyze the aminomethylation of α,β-unsaturated aldehydes. This cooperative catalytic reaction provides a redox neutral strategy for quick access to β²-amino esters in an enantioselective manner.

A three-component carboetherification of unactivated alkenes has been developed allowing the rapid building of complexity from simple starting materials. A wide range of α-substituted styrenes underwent smooth reactions with unactivated alkyl nitriles and alcohols to afford γ-alkoxy alkyl nitriles with concomitant generation of a quaternary carbon center. A radical clock experiment provided clear-cut evidence that the reaction proceeds through a tertiary alkyl radical intermediate.

Three-component coupling of alkenes, alcohols, and alkyl nitriles catalyzed by copper triflate afforded 4-alkoxyalkyl nitriles in good to excellent yields. The reaction forms a CC and a CO bond with concomitant creation of a quaternary carbon center. The involvement of a radical intermediate was proven by a radical clock experiment.