Synthesis and stereochemistry of dispiro substituted pyridazines: application of ellipticity-absorbance ratio spectra for proving enantiomeric relationship by HPLC-CD/UV detection.

The aim of our study was to synthesize vinylic and pyrido-fused pyridazines with a spirano moiety and to investigate their stereochemistry by spectroscopic and HPLC analyses. The vinylic compounds 5 were obtained by Knoevenagel condensation of cyclohexylidene malonates 1 with pyridazinecarbaldehyde 2. Compound 5b exhibits geometric isomerism identified by NMR, HPLC, and X-ray methods.