Diastereoselective ZnCl-Mediated Joullié-Ugi Three-Component Reaction for the Preparation of Phosphorylated -Acylaziridines from 2-Azirines.

We disclose a direct approach to the diastereoselective synthesis of phosphorus substituted -acylaziridines based on a one-pot ZnCl-catalyzed Joullié-Ugi three-component reaction of phosphorylated 2-azirines, carboxylic acids and isocyanides. Hence, this robust protocol offers rapid access to an array of -acylaziridines in moderate-to-good yields and up to 98:2 dr for substrates over a wide scope. The relevance of this synthetic methodology was achieved via a gram-scale reaction and the further derivatization of the nitrogen-containing three-membered heterocycle.

α-Hydroxy Ketones as Masked Ester Donors in Brønsted Base Catalyzed Conjugate Additions to Nitroalkenes.

The catalyst-controlled enantioselective direct addition reaction of enolizable esters and related carboxylic acid derivatives to π electrophiles remains a difficult synthetic transformation. In this study, the suitability of α-hydroxy ketones as ester equivalents capable of being activated by bifunctional Brønsted base catalysts in the context of conjugate addition reactions to nitroolefins is demonstrated. The scope of the reaction, which affords the corresponding Michael adducts with very high stereoselectivity (diastereomeric ratio (d.

β -Amino Acid N-Carboxyanhydrides Relying on Sequential Enantioselective C(4)-Functionalization of Pyrrolidin-2,3-diones and Regioselective Baeyer-Villiger Oxidation.

A catalytic enantioselective entry to β -amino acids enabling their direct coupling with nucleophiles is described. The approach is based upon an effective bifunctional Brønsted base catalyzed construction of a quaternary carbon stereocenter at C position of pyrrolidin-2,3-diones. Subsequent regioselective Baeyer-Villiger oxidation of the resultant adducts gives β -amino acid N-carboxyanhydrides as the reactive species, which can further react with nucleophiles.

Enantioselective construction of tetrasubstituted stereogenic carbons through Brønsted base catalyzed michael reactions: α'-hydroxy enones as key enoate equivalent.

Catalytic and asymmetric Michael reactions constitute very powerful tools for the construction of new C-C bonds in synthesis, but most of the reports claiming high selectivity are limited to some specific combinations of nucleophile/electrophile compound types, and only few successful methods deal with the generation of all-carbon quaternary stereocenters. A contribution to solve this gap is presented here based on chiral bifunctional Brønsted base (BB) catalysis and the use of α'-oxy enones as enabling Michael acceptors with ambivalent H-bond acceptor/donor character, a yet unreported design element for bidentate enoate equivalents. It is found that the Michael addition of a range of enolizable carbonyl compounds that have previously demonstrated challenging (i.