Premium
Applications of Aziridinium Ions: Selective Syntheses of Pyrazolidin‐3‐ones and Pyrazolo[1,2‐ a ]pyrazoles
Author(s) -
Chuang TsungHsun,
Sharpless K. Barry
Publication year - 2000
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 - 10.1002/1522-2675(20000809)83:8<1734::aid-hlca1734>3.0.co;2-e
Subject(s) - chemistry , cycloaddition , intramolecular force , hydrazine (antidepressant) , ion , medicinal chemistry , catalysis , organic chemistry , stereochemistry , chromatography
Reaction of ethyl (2 S *,3 R *)‐3‐chloro‐2‐(dialkylamino)‐3‐phenylpropanoates ( 4 ) with hydrazine monohydrate gave pyrazolidin‐3‐ones ( 5 ) via selective opening of the in situ generated aziridinium ions, followed by intramolecular amidation. (1 Z ,4 S *,5 S *)‐1‐Arylmethylidene‐4‐(dialkylamino)‐3‐oxo‐5‐phenylpyrazolidinium‐1‐ide ( 6 ), prepared from pyrazolidin‐3‐ones ( 5 ) and aromatic aldehydes under acid catalysis, reacted with a variety of 1,3‐dipolarophiles to afford good yields of pure cycloadducts 7 – 11 . The cycloaddition regio‐ and/or stereoselectivities, in all relevant cases, were also high.