NHC-catalyzed activation of α,β-unsaturated N-acyltriazoles: an easy access to dihydropyranones

Employing the NHC-catalyzed activation of α,β-unsaturated N-acyltriazoles an efficient enantioselective synthesis of dihydropyranones via a formal [3+3] cycloaddition with 1,3-dicarbonyl compounds is described.

Highly stereoselective synthesis of functionalized pyrrolo[3,2-c]quinolines via N-heterocyclic carbene catalyzed cascade sequence

An N-heterocyclic carbene-catalyzed stereoselective Michael-Mannich-lactamization cascade reaction of tosyl-protected o-amino aromatic aldimines and 2-bromoenals for the construction of functionalized pyrrolo[3,2-c]quinolines with three consecutive stereocenters was achieved in good yields with excellent diastereo- and enantioselectivities.

Palladium(0)-catalyzed cyclopropanation of benzyl bromides via C(sp3)–H bond activation

A novel Pd(0)-catalyzed domino cyclopropanation reaction was established. The process involves a Heck-type coupling reaction and a C(sp³)–H activation.

Stereospecific synthesis of highly functionalized benzo[3.1.0]bicycloalkanes via multistep cascade reactions

A facile approach for the synthesis of benzo[3.1.0]bicycloalkanesviaalkylation/cyclopropanation cascade reactions of benzyl bromide with triphenylphosphonium bromide.

A sidearm-assisted phosphine for catalytic ylide intramolecular cyclopropanation

The first phosphine-catalyzed cyclopropanation reactionviacovalent ylide catalysis has been realized with high efficiency in the presence of sidearm-assisted phosphine catalysts.

N-heterocyclic carbene catalysed oxidative esterification of aliphatic aldehydes

Aliphatic aldehydes are readily transformed to the corresponding esters by oxidative carbene catalysis.

Divergent NHC-catalyzed oxidative transformations of 3-bromoenal: selective synthesis of 2H-pyran-2-ones and chiral dihydropyranones

A selective synthesis of either 2H-pyran-2-ones (4) or chiral dihydropyranones (6) from the same substrates of 3-bromoenals and 1,3-dicarbonyl compounds upon oxidative N-heterocyclic carbene catalysis is presented. It is shown that the oxidative transformation of 3-bromoenals under NHC catalyst can be well controlled to proceed through two pathways, i.e., elimination of reducible β-bromide or by an external oxidant 3, allowing the selective generation two sorts of unsaturated acyl azoliums, respectively.

An efficient organocatalytic enantioselective synthesis of spironitrocyclopropanes

An organocatalytic asymmetric synthesis of spironitrocyclopropanes has been demonstrated starting from 2-arylidene-1,3-indandiones and bromonitroalkanes catalyzed by a cinchona-derived bifunctional organocatalyst. The products were obtained with excellent enantioselectivities, diastereoselectivities and with good yields.

N-heterocyclic carbene-catalyzed Ireland-Coates Claisen rearrangement: synthesis of functionalized β-lactones

The N-heterocyclic carbene (NHC)-catalyzed Claisen rearrangement of hybrid Ireland-Coates structures has been achieved, allowing the stereoselective synthesis of highly functionalized β-lactones. The reaction proceeds with high diastereoselectivity (>20:1) and affords a diverse range of β-lactone fused cyclopentanes. Mechanistic studies are detailed.

Direct α-functionalization of simple aldehydes via oxidative N-heterocyclic carbene catalysis

A direct α-functionalization of simple aldehydes under N-Heterocyclic Carbene (NHC) catalysis and direct generation of ester enolate equivalents from nonfunctionalized aldehydes are disclosed. The catalysis involves selective enolate generation from an oxidatively generated NHC-bounded ester intermediate as a key step. The ester enolate intermediates undergo stereoselective reactions with enones and trifluoromethyl ketones.