3-Diazopiperidine-2,4-diones as Convenient Precursors to Rare Polysubstituted Spiro Bis-β,γ-lactams and 2-Oxopyrrolidine-3-carboxylic Acid Derivatives via the Thermally Promoted Wolff Rearrangement.

Herein, we describe a diastereoselective and straightforward synthetic approach to polysubstituted spirocyclic bis-lactams bearing both β- and γ-lactam cores with diverse substitution patterns. The method developed is based on a microwave-assisted Wolff rearrangement/Staudinger [2 + 2] cycloaddition sequence involving 3-diazopiperidine-2,4-diones and imines. The corresponding reaction tolerates a wide range of functionalities in both substrates, giving the target bis-lactams in generally high yields.

5-Diazo Dihydrouracils: Preparation and Some Transformations.

An approach to a new type of diazo reagents─diazo dihydrouracils─has been developed, and various transformations of the obtained diazo heterocycles have been studied, demonstrating their high synthetic potential for obtaining structurally diverse derivatives based on the privileged dihydrouracil scaffold. The X-H insertion reactions provide high yields of a variety of 5-substituted dihydrouracils. Cyclopropanation and 1,3-dipolar cycloaddition reactions involving a carbonyl ylide intermediate have been carried out to give spiro-annulated derivatives.

Azide-based preparation of fused heterocyclic imines and their multicomponent reactions.

Structurally diverse pyrroles, indoles and imidazoles bearing an -ω-azidoalkyl moiety and an aldehyde or ketone function were prepared and successfully introduced into imine generation the intramolecular Staudinger/aza-Wittig tandem reaction. Reduction of the generated imines led to medicinally relevant nitrogen-containing fused heterocycles such as tetrahydropyrrolo[1,2-]pyrazines and diazepines. Rare 8-membered hexahydropyrrolo[1,2-][1,4]diazocine and 9-membered dihydro-4,8-(metheno)pyrrolo[1,2-][1,4]diazacycloundecine were also synthesized.

Access to 2-oxoazetidine-3-carboxylic acid derivatives via thermal microwave-assisted Wolff rearrangement of 3-diazotetramic acids in the presence of nucleophiles.

In this work, we report an efficient approach to 2-oxoazetidine-3-carboxylic acid derivatives based on a thermally promoted Wolff rearrangement of diazotetramic acids in the presence of nucleophiles. The method allows easy variation of the substituent in the exocyclic acyl group by introducing different -, -, and -nucleophilic reagents into the reaction. The reaction of chiral diazotetramic acids leads exclusively to -diastereomeric β-lactams.

Entry to new spiroheterocycles via tandem Rh(II)-catalyzed O-H insertion/base-promoted cyclization involving diazoarylidene succinimides.

A facile approach to novel medicinally relevant spiro heterocyclic scaffolds (namely furan-2(5)-ones, tetrahydrofurans and pyrans spiro-conjugated with the succinimide ring) has been developed. The protocol consists of Rh(II)-catalyzed insertion of heterocyclic carbenes derived from diazoarylidene succinimides (DAS) into the O-H bond of propiolic/allenic acids or brominated alcohols, followed by base-promoted cyclization to afford the target spirocyclic compounds in good to high yields.