Stereoselective aza-Henry Reaction Research Articles

Stereoselective Aza-Henry Reaction of 3-Nitro-dihydro-2(1H)-quinolones with N-Boc-Aldimines under the Catalysis of Chiral Ammonium Betaines

Stereoselective Aza-Henry Reaction of 3-Nitro-dihydro-2(1H)-quinolones with N-Boc-Aldimines under the Catalysis of Chiral Ammonium Betaines

Development of an Intermittent-Flow Enantioselective Aza-Henry Reaction Using an Arylnitromethane and Homogeneous Brønsted Acid-Base Catalyst with Recycle.

A stereoselective aza-Henry reaction between an arylnitromethane and Boc-protected aryl aldimine using a homogeneous Brønsted acid-base catalyst was translated from batch format to an automated intermittent-flow process. This work demonstrates the advantages of a novel intermittent-flow setup with product crystallization and slow reagent addition which is not amenable to the standard continuous equipment: plug flow tube reactor (PFR) or continuous stirred tank reactor (CSTR). A significant benefit of this strategy was the integration of an organocatalytic enantioselective reaction with straightforward product separation, including recycle of the catalyst, resulting in increased intensity of the process by maintaining high catalyst concentration in the reactor. A continuous campaign confirmed that these conditions could effectively provide high throughput of material using an automated system while maintaining high selectivity, thereby addressing nitroalkane safety and minimizing catalyst usage.

ChemInform Abstract: Chiral Ammonium Betaine‐Catalyzed Highly Stereoselective Aza—Henry Reaction of α‐Aryl Nitromethanes with Aromatic N‐Boc Imines.

AbstractVarious substituted aryl groups for both imines (I) and nitromethanes (II) are tolerated in the reaction.

Vinylogy in nitronates: utilization of α-aryl conjugated nitroolefins as a nucleophile for a highly stereoselective aza-Henry reaction.

The vinylogous reactivity of α,β-disubstituted nitroolefins was uncovered through the facile generation of the corresponding α-substituted vinylogous nitronates and their use in the development of a highly diastereo- and enantioselective aza-Henry reaction with N-Boc aldimines under the catalysis of chiral ammonium betaines. The novel vinylogous nitronates undergo stereoselective bond formation at the sterically encumbered α-position exclusively, allowing the construction of contiguous tertiary-quaternary stereogenic carbon centers.

Chiral ammonium betaine-catalyzed highly stereoselective aza-henry reaction of α-aryl nitromethanes with aromatic N-Boc imines.

A highly stereoselective aza-Henry reaction of α-aryl nitromethanes with aromatic N-Boc imines was established by using C1 -symmetric chiral ammonium betaine as a bifunctional organic base catalyst. Various substituted aryl groups for both imines and nitromethanes were tolerated in the reaction, and a series of precursors for the synthesis of unsymmetrical anti-1,2-diaryl ethylenediamines was provided.

ChemInform Abstract: Nitroolefins as a Nucleophilic Component for Highly Stereoselective Aza Henry Reaction under the Catalysis of Chiral Ammonium Betaines.

AbstractThe ammonium‐betain catalyzed aza Henry reaction of in situ generated chiral vinylogous nitronates with N‐Boc imines is reported.

Nitroolefins as a Nucleophilic Component for Highly Stereoselective Aza Henry Reaction under the Catalysis of Chiral Ammonium Betaines

The ammonium-betain catalyzed aza Henry reaction of in situ generated chiral vinylogous nitronates with N-Boc imines is reported.

Zwitterionic-type molten salt-catalyzed syn-selective aza-Henry reaction: solvent-free one-pot synthesis of β-nitroamines

Zwitterionic imidazolium sulfonates are excellent catalysts for stereoselective aza-Henry reaction under solvent-free conditions. The major syn-β-nitroamine is obtained in high yields. This three-component condensation reaction catalyzed by zwitterionic-type molten salt deserves attention in its own right as a useful method.

Asymmetric aza‐Henry reaction of N‐tosyl imine

An efficient stereoselective aza-Henry reaction of N-tosyl imine, catalyzed by the coordination of diethylzinc with a chiral semi-aza-crown ligand, with moderate to high ee (up to 83%) is reported.