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C‐Glycosides VI . Modalités de l'élaboration de cycles pyrazoliques à partir d'une hydrazone d' aldéhydo ‐sucre
Author(s) -
Tronchet J. M. J.,
Jotterand A.
Publication year - 1971
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.19710540423
Subject(s) - chemistry , hydrazone , glycosyl , bromide , pyrazole , sugar , nucleophilic substitution , medicinal chemistry , nucleophile , glycoside , stereochemistry , organic chemistry , catalysis
The reaction of an aldehydo ‐sugar hydrazonoyl bromide with ethynylmagnesium bromide led mainly to an α‐ethynyl‐hydrazone whose cyclisation to a pyrazole is catalysed by bases. Thus the nucleophilic substitution – nucleophilic cyclisation mechanism of the Grünanger pyrazole synthesis is confirmed. 3‐Glycosyl‐pyrazoles can also be prepared from aldehydo ‐sugar hydrazonoyl bromides by 1,3‐dipolar cyclo‐addition. All these reactions take place without change in the configuration of the initial aldehydo ‐sugar.