Domino reactions of diazodicarbonyl compounds with α,β-unsaturated δ-amino esters: a convenient way towards 2-oxopiperidines, dihydropyridinones and isoquinolinediones.

Thermal decomposition of a series of diazodicarbonyl compounds in the presence of α,β-unsaturated δ-amino esters and sodium hydride gives rise to a variety of nitrogenous heterocycles. The direction of these processes is highly dependent on the structure of the initial reagents giving rise to the formation of multi-functionalized 2-oxopiperidines, 5,6-dihydropyridin-2(1H)-ones or tetrahydroisoquinoline-1,6(2H,8aH)-diones. The reactions occur in domino processes involving the Wolff rearrangement of diazocarbonyl compounds, NaH-catalyzed anti-stereoselective intramolecular Michael addition to the α,β-unsaturated system of amino esters, and in some cases also cycloelimination and intramolecular Claisen condensation of the initial products formed.

On the strong difference in reactivity of acyclic and cyclic diazodiketones with thioketones: experimental results and quantum-chemical interpretation.

The 1,3-dipolar cycloaddition of acyclic 2-diazo-1,3-dicarbonyl compounds (DDC) and thioketones preferably occurs with Z,E-conformers and leads to the formation of transient thiocarbonyl ylides in two stages. The thermodynamically favorable further transformation of C=S ylides bearing at least one acyl group is identified as the 1,5-electrocyclization into 1,3-oxathioles. However, in the case of diazomalonates, the dominating process is 1,3-cyclization into thiiranes followed by their spontaneous desulfurization yielding the corresponding alkenes.

Domino [4 + 1]-annulation of α,β-unsaturated δ-amino esters with Rh(II)-carbenoids – a new approach towards multi-functionalized N-aryl pyrrolidines.

Catalytic decomposition of diazomalonates and other diazoesters using Rh(II)- and Cu(II)-complexes in the presence of α,β-unsaturated δ-(N-aryl)amino esters gives rise to the formation of multi-functionalized pyrrolidines with yields of up to 82%. The reaction apparently occurs as a domino process involving the initial N-ylide formation followed by intramolecular Michael addition to the conjugated system of amino esters to afford the pyrrolidine heterocycle. The whole process can also be classified as a [4 + 1]-annulation of the δ-amino α,β-unsaturated ester with the carbenoid intermediate.

Less reactive dipoles of diazodicarbonyl compounds in reaction with cycloaliphatic thioketones - First evidence for the 1,3-oxathiole-thiocarbonyl ylide interconversion.

Acyclic diazodicarbonyl compounds react at room temperature with cycloaliphatic thioketones, e.g. 2,2,4,4-tetramethyl-3-thioxocyclobutanе-1-one and adamantanethione, via a cascade process in which the key step is a 1,5-electrocyclization of the intermediate thiocarbonyl ylide leading to tetrasubstituted spirocyclic 1,3-oxathioles.

Cyclic and acyclic sulfonimides in reactions with Rh(II)-ketocarbenoids: a new access to chemoselective O-functionalization of the imidic carbonyl groups.

Catalytic decomposition of diazoacetylacetone, diazoacetoacetic, diazomalonic, and diazoacetic esters using dirhodium tetraacetate in the presence of isothiazol-3(2H)-one 1,1-dioxides and a number of N-(arenesulfonyl)carboxamides in solutions of methylene chloride or dichloroethane gives rise to O-alkylation of the imidic carbonyl groups by Rh(II)-carbenoids and the formation of O-alkylimidates as the final products. The reaction proceeds with high chemoselectivity via carbonyl ylides and offers a powerful method for the synthesis in good yields of the imidates with polyfunctional O-alkyl groups. On the basis of X-ray analysis and 1H- and 13C-NMR studies it was shown that the resulting acyclic O-alkylimidates have the E-configuration in the solid state and in solution.