Cyclic enaminones. Part II: applications as versatile intermediates in alkaloid synthesis

One-Pot Synthesis of Benzo[b][1,4]oxazins via Intramolecular Trapping Iminoenol

A highly atom-efficient "one-pot" protocol has been developed to construct multisubstituted 2-hydroxy-benzo[b][1,4]oxazins starting from N-(2-hydroxylaryl)enaminones. This procedure comprises a PIDA-mediated intramolecular iminoenol tautomer trapping reaction, followed by Et₃N-promoted aerobic oxidative ring construction. In particular, an O₂ molecule from air served as the oxygen source of the hydroxyl group in the titled products. This reaction proceeded smoothly at room temperature under air atmosphere and metal-free conditions.

A copper-catalyzed three component reaction of aryl acetylene, sulfonyl azide and enaminone to form iminolactone via 6π electrocyclization

We developed a copper-catalyzed three component reaction of aryl acetylene, enaminone and sulfonyl azide to construct iminolactone via copper-catalyzed alkyne–azide cycloaddition (CuAAC), Michael addition of metalated ketenimine followed by elimination and 6π electrocyclization.

Stereoselective synthesis of enamino ketones through an aza-Michael/hydrolysis cascade reaction

Highly functionalized (Z)-β-enamino ketones have been prepared from readily available 3,4-dihydroisoquinoline imines and ynones through an aza-Michael/hydrolysis cascade reaction.

Iodine-mediated synthesis of sulfur-bridged enaminones and chromones via double C(sp2)–H thiolation

The synthesis of sulfur-bridged enaminones and chromones has been readily achieved via double vinyl C–H thiolation under metal-free conditions by using enaminones and elemental sulfur.

Cyclic enaminones. Part I: stereocontrolled synthesis using diastereoselective and catalytic asymmetric methods

Cyclic enaminones are versatile intermediates to construct a variety of azacyclic frameworks and have been widely used in alkaloid synthesis. Here, we summarize three approaches for stereoselective syntheses of cyclic enaminones and their functionalized derivatives. These include chiral substrates (chirons) as starting materials, syntheses employing non-catalytic (stoichiometric) reagents, and catalytic asymmetric methods.

The base-promoted synthesis of multisubstituted benzo[b][1,4]oxazepines

A variety of substituted benzo[b][1,4]oxazepines have been prepared via base-promoted intramolecular O-arylation from N-(2-haloaryl)enaminones under metal-free conditions.

Gold nanoparticles on OMS-2 for heterogeneously catalyzed aerobic oxidative α,β-dehydrogenation of β-heteroatom-substituted ketones

In the presence of Au/OMS-2, various kinds of β-heteroatom-substituted α,β-unsaturated ketones can be synthesized through aerobic oxidative dehydrogenation of the corresponding saturated ketones.

Base-mediated regiospecific cascade synthesis of N-(2-pyridyl)pyrroles from N-propargylic β-enaminones

Two birds with one stone: two classical heterocycles, pyrrole and pyridine, were simultaneously installed from one acyclic enaminone precursor for the preparation of N-(2-pyridyl)pyrroles.

Synthesis of β,β-diaryl propiophenones via palladium-catalyzed domino arylboronation, elimination and enone hydroarylation of enaminones

The first example of a domino reaction involving enaminone C–N conversion-based arylation has been realized as an efficient new route toward the synthesis of β,β-diaryl propiophenones.