Synthesis of Pyrazolone Derivatives. XXXVIII. [1, 5] Sigmatropic Rearrangement during the Cycloaddition of (1R, 4S)-3-Diazobornane-2-one to Activated Acetylenes
Open Access
- 1 January 1979
- journal article
- research article
- Published by Pharmaceutical Society of Japan in YAKUGAKU ZASSHI
- Vol. 99 (7) , 705-710
- https://doi.org/10.1248/yakushi1947.99.7_705
Abstract
(1R,4S)-3-Diazobornane-2-one was reacted with dimethyl acetylenedicarboxylate and methyl propiolate to give (4S,7R)-4,7-methano-8H-pyrazolo[1,5-a]azepines (3a, b) (5R,8S)-5,8-methano-1H,4H-cycloheptapyrazole (5) via a spiropyrazole intermediate (6). The reaction from 6 to 3a, b and 5 is interpreted as a [1,5]sigmatropic acyl rearrangement. Compound 3a was converted to (8R,11S)-8,11-methano-7H-benzo[3,4]yrazolo[1,5-a]-azepine and (8R,11S)-8,11-methano-7H-pyridazino[4'',5'':4,3]pyrazolo[1,5-a]azepine. Treatment of 3a, b with sodium methoxide in methanol resulted in cleavage of amido linkage to yield (1R,3S)-(pyrazol-5-yl)cyclopentanes. These compounds exhibited CNS stimulatory action in mice.Keywords
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