Search

Using newly designed α-imino amide surrogates and azlactones as amphiphilic reactants, catalyzed by a chiral bifunctional guanidine, the construction of chiral 3,4-diaminopyrrolidine-2,5-diones and their derivatives was realized via formal [3+2]-cyclization. The role of guanidine as a multiple hydrogen bond donor was demonstrated by DFT calculations. [ABSTRACT FROM AUTHOR]

A chiral Lewis acid-catalyzed enantioselective formal [2 + 2 + 2] cycloaddition of 1,3,5-triazinanes with azlactones or β,γ-unsaturated pyrazole amides was developed to synthesize chiral tertiary/quaternary tetrahydropyrimidin-4-one derivatives with good yields and enantioselectivities. Two competitive reaction pathways were proposed based on experiments. [ABSTRACT FROM AUTHOR]

Chiral Lewis acid-promoted enantioselective α-alkylation of β-ketoamides with phenyliodonium ylide was developed. In the presence of a chiral N,N′-dioxide/Ni(ii) complex, the corresponding 1,4-dicarbonyl compounds were obtained with good results (up to 91% yield and 97% ee). Control experiments and EPR studies supported a radical process. [ABSTRACT FROM AUTHOR]

Chiral Ni(ii)-complexes of N,N′-dioxides show high catalytic activity and enantioselectivity in catalysing the asymmetric Friedel–Crafts C3-alkylation of 2,5-dimethyl pyrrole to β,γ-unsaturated α-ketoesters. A dramatic reversal of enantioselectivity is realized with ligands derived from the same type of chiral source of l-ramipril, by slightly tuning the amide units. [ABSTRACT FROM AUTHOR]

A series of amide-based bifunctional organocatalysts have been utilized in asymmetric reactions. Prolinamide analogues have been designed to catalyze asymmetric reactions viaenamine intermediates with the assistance of tunable hydrogen bonding. In addition, the combination of various Lewis base functional groups, such as guanidine, N-oxide and phosphane, with an amide moiety have also constituted efficient bifunctional organocatalysts with unique reactivity and selectivity. [ABSTRACT FROM AUTHOR]

An efficient lanthanide(iii)-catalyzed diastereo- and enantioselective Michael addition of 3-substituted benzofuran-2(3H)-ones to 4-oxo-enoates was developed. The desired adducts with contiguous quaternary–tertiary stereocenters were obtained in up to 99% yield with up to >95/5 dr and 98% ee. [ABSTRACT FROM AUTHOR]

An efficient catalytic enantioselective aza-ene-type reaction of glyoxal derivatives with enamides and enecarbamates has been realized using a nickel(ii)-N,N′-dioxide complex as the catalyst. [ABSTRACT FROM AUTHOR]