Synthesis of the reported structure of piperazirum using a nitro-Mannich reaction as the key stereochemical determining step.
Piperazirum, isolated from Arum palaestinum Boiss, was originally assigned as r-3,c-5-diisobutyl-c-6-isopropylpiperazin-2-one. The reported structure was synthesised diastereoselectively using a key nitro-Mannich reaction to set up the C5/C6 relative stereochemistry. The structure was unambiguously assigned by single crystal X-ray diffraction but the spectroscopic data did not match those reported for the natural product. The structure of the natural product must therefore be revised.
Department of Chemistry, University College London, 20 Gordon Street, London, WC1H 0AJ, UK.
James C
JC
Anderson
Andreas S
AS
Kalogirou
Michael J
MJ
Porter
Graham J
GJ
Tizzard
alkaloid; aza-Henry; natural products; nitro-Mannich; piperazinone; stereoselective synthesis