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Methylierung von 4‐Hydroxy‐4‐(2‐piperidyl)‐4 H ‐pyrazolo [1,5‐ a ]indol mit Formaldehyd und Ameisensäure. 11. Mitteilung über metallorganische Reaktionen und Folgeprodukte
Author(s) -
Rihs Grety,
Fuhrer Hermann,
Marxer Adrian
Publication year - 1981
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19810640316
Subject(s) - chemistry , formic acid , formaldehyde , ketone , ring (chemistry) , indole test , nuclear magnetic resonance spectroscopy , spectroscopy , stereochemistry , medicinal chemistry , organic chemistry , physics , quantum mechanics
In the 10 th communication of this series [1] the synthesis of 4‐hydroxy‐4‐(2‐piperidyl)‐4 H ‐pyrazolo[1,5‐ a ]indole ( 4 ) was described (Scheme) . Surprisingly enough, methylation of this compound with formaldehyde and formic acid led via ring closure and a subsequent rearrangement to a pentacyclic ketone. By means of 13 C‐NMR.‐spectroscopy and mass spectroscopy, this ketone could be identified as a indolizino‐pyrazolo‐indole ( 9 ). Its structure and configuration were determined by X‐ray structure analysis.