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1,3‐Dipolar cycloadditions of (4 R *,5 R *)‐1‐alkylidene‐4‐(benzoylamino)‐5‐phenyl‐3‐pyrazolidinon‐1‐azomethine imines
Author(s) -
Pezdirc Lidija,
Grošelj Uroš,
Meden Anton,
Stanovnik Branko,
Svete Jurij
Publication year - 2008
Publication title -
journal of heterocyclic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.321
H-Index - 59
eISSN - 1943-5193
pISSN - 0022-152X
DOI - 10.1002/jhet.5570450121
Subject(s) - chemistry , diastereomer , acetone , nuclear magnetic resonance spectroscopy , stereochemistry , two dimensional nuclear magnetic resonance spectroscopy , diazomethane , spectroscopy , medicinal chemistry , organic chemistry , physics , quantum mechanics
1,3‐Dipolar cycloadditions of azomethine imines 3a and 3b , available by acid‐catalyzed treatment of 3‐pyrazolidinone 1 with acetone ( 2a ) and butyraldehyde ( 2b ), respectively, were studied. Reactions of 3a with DMAD ( 4 ) afforded a mixture of products 9 and 10a , whilst treatment of 3b with DMAD ( 4 ) gave a mixture of compound 9 and epimeric cycloadducts 10 / 10′b . On the other hand, cycloadducts 13a,b‐16a,b were isolated as single diastereomers in 9–37% yields upon reactions of 3a,b with olefinic dipolarophiles 5–8 . The structures of cycloadducts 9, 10a, 10/10′b , and 13a,b‐16a,b were determined by 1 H nmr and NOESY spectroscopy. The structure of compound 13a was confirmed by X‐ray diffraction.