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We disclose a direct approach to the diastereoselective synthesis of phosphorus substituted N -acylaziridines based on a one-pot ZnCl 2 -catalyzed Joullié-Ugi three-component reaction of phosphorylated 2 H -azirines, carboxylic acids and isocyanides. Hence, this robust protocol offers rapid access to an array of N -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. The diastereo- and regioselective ring expansion of the obtained N -acylaziridines to oxazole derivatives was accomplished in the presence of BF 3 ·OEt 2 as an efficient Lewid acid catalyst.

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.r.) ≥95:5, up to 99 % enantiomeric excess (ee)), and its limitations are explored, as is the aftermath elaboration of adducts into densely functionalized enantioenriched products., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A catalytic enantioselective entry to β 2, 2 -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 4 position of pyrrolidin-2,3-diones. Subsequent regioselective Baeyer-Villiger oxidation of the resultant adducts gives β 2, 2 -amino acid N-carboxyanhydrides as the reactive species, which can further react with nucleophiles. Following this strategy both, β 2, 2 -amino acid derivatives with different functionalities at the newly created stereocenter, and spirocyclic structures can be efficiently prepared., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

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.e., α-substituted 2-oxindoles, cyanoesters, oxazolones, thiazolones, and azlactones) to α'-oxy enones can afford the corresponding tetrasubstituted carbon stereocenters in high diastereo- and enantioselectivity in the presence of standard BB catalysts. Experiments show that the α'-oxy ketone moiety plays a key role in the above realizations, as parallel reactions under identical conditions but using the parent α,β-unsaturated ketones or esters instead proceed sluggish and/or with poor stereoselectivity. A series of trivial chemical manipulations of the ketol moiety in adducts can produce the corresponding carboxy, aldehyde, and ketone compounds under very mild conditions, giving access to a variety of enantioenriched densely functionalized building blocks containing a fully substituted carbon stereocenter. A computational investigation to rationalize the mode of substrate activation and the reaction stereochemistry is also provided, and the proposed models are compared with related systems in the literature.