# Spirobarbiturates with a pyrrolizidine moiety: synthesis, structure and biological evaluation

## TL;DR

This paper describes the synthesis and testing of new spirobarbiturate compounds with potential anti-cancer properties.

## Contribution

A novel one-pot method for synthesizing polycyclic spirobarbiturates with a pyrrolizidine moiety is introduced.

## Key findings

- The reaction stereoselectivity depends on the substituents in the maleimide.
- X-ray diffraction confirmed the configuration of stereocenters in two adducts.
- Some compounds showed antiproliferative effects against cancer cell lines.

## Abstract

Polycyclic spirobarbiturates containing a pyrrolizidine moiety were synthesized via a one-pot three-component 1,3-dipolar cycloaddition reaction of alloxan, ʟ-proline and N-substituted maleimides. The reaction stereoselectivity was found to depend on the nature of substituents in the maleimide: in most cases the endo-isomer is the main (or only) product, but for some N-arylmaleimides the exo-product is predominant. The proposed mechanism is discussed, and the products were characterized by detailed spectral analysis. The configuration of the stereocenters was determined by X-ray diffraction analysis (XRD) for two adducts, followed by Hirshfeld surface analysis. The antiproliferative effect of the synthesized compounds against cancer cell lines was assessed.