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1,3‐Dipolar Cycloadditions to (5 Z )‐1‐Acyl‐5‐(cyanomethylidene)‐ imidazolidine‐2,4‐diones: Synthesis and Transformations of Spirohydantoin Derivatives
Author(s) -
Grošelj Uroš,
Drobnič Aleš,
Rečnik Simon,
Svete Jurij,
Stanovnik Branko,
Golobič Amalija,
Lah Nina,
Leban Ivan,
Meden Anton,
GoličGrdadolnik Simona
Publication year - 2001
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(20011114)84:11<3403::aid-hlca3403>3.0.co;2-g
Subject(s) - chemistry , hydantoin , isoxazole , aromatization , imidazolidine , ring (chemistry) , dipole , stereochemistry , pyrazole , cleavage (geology) , carboxylate , medicinal chemistry , organic chemistry , catalysis , geotechnical engineering , fracture (geology) , engineering
Cycloadditions of various 1,3‐dipoles to (5 Z )‐1‐acyl‐5‐(cyanomethylidene)‐3‐methylimidazolidine‐2,4‐diones 8 or 9 , prepared in 3 steps from hydantoin ( 1 ) ( Schemes 1 and 2 ), were studied. In all cases, reactions proceeded regio‐ and stereoselectively. The type of product depended on the 1,3‐dipole and/or dipolarophile employed as well as on reaction conditions. Thus, with stable dipoles under neutral conditions, spirohydantoin derivatives 12 – 16 were obtained ( Scheme 2 ), while under basic or acidic conditions, pyrazole‐ or isoxazole‐5‐carboxamides 18 and 23 – 26 and carboxylate 27 were formed via aromatization of the newly formed dihydroazole ring, followed by the simultaneous cleavage of the hydantoin ring ( Schemes 3 – 5 ).