Ethyl propiolate → HCID 11845245, compound

Participants

Reaction Steps

ethyl propiolate (cont. 99%)(8.28 g) was added to the o-xylene (348 mL) solution of 5-(4-nitrobenzyloxycarbonyl)-3-oxo-3a,4,6,7-tetrahydro-3H-2-oxa-1,5-diaza-7a-azoniainden-3a-ide (22.3 g) under a nitrogen atmosphere and refluxed for 16 h. The solution was concentrated under reduced pressure, followed by silica-gel column chromatography 3 times (n-hexane/AcOEt=2/1–1/3). The titled compound was obtained as pale yellow crystals (16.78 g, 64%). Besides, 6,7-dihydro-4H-pyrazolo[1,5-a]pyrazine-3,5-dicarboxylic acid 3-ethyl ester 5-(4-nitrobenzyl) ester was obtained as pale yellow crystals (6.18 g, 24%).

Provenance & Evidence