# One-Pot Synthesis and Photochemical Diversification of Pyrazolo[1,2‑a]pyridazinones into 3D-Rich Scaffolds

## TL;DR

A new method for making complex chemical structures called pyrazolo[1,2-a]pyridazinones using light and simple conditions.

## Contribution

A one-pot synthesis and light-driven diversification of pyrazolo[1,2-a]pyridazinones into 3D-rich scaffolds without photocatalysts.

## Key findings

- A one-pot synthesis of pyrazolo[1,2-a]pyridazinones from tetrahydropyridazines was developed.
- Photoinduced transformations produce diverse derivatives like tricyclic cyclobutenes and γ-(pyrazol-1-yl)butanals.
- The method is efficient and atom-economical under mild conditions.

## Abstract

We report a one-pot,
three-component synthesis of pyrazolo­[1,2-a]­pyridazinones
from tetrahydropyridazines, a transformation
that was historically challenging due to competing ring contractions.
The resulting compounds undergo photoinduced transformations, without
the need for external photocatalysts, to afford diverse 3D-rich derivatives,
including tricyclic cyclobutenes and γ-(pyrazol-1-yl)­butanals.
Enabled by mild conditions, this strategy offers an efficient, atom-economical
route to structurally diverse pyrazolo­[1,2-a]­pyridazinones
and their derivatives.