The reaction of 4-amino-2-oxazolines with isocyanates and isothiocyanates. Synthesis and X-ray structures of polysubstituted 2-imidazolidinones, 1,3-oxazolidines and 1,3-thiazolidines |
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Authors: | Antonio Guirado Raquel Andreu Delia Bautista Peter G Jones |
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Institution: | a Departamento de Química Orgánica, Facultad de Química, Universidad de Murcia, Campus de Espinardo, 30071 Murcia, Apartado 4021, Spain b Departamento de Química Orgánica, Universidad de Valencia, 46100 Valencia, Spain c Institut für Anorganische und Analytische Chemie, Technische Universität Braunschweig, Postfach 3329, 38023 Braunschweig, Germany |
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Abstract: | Reactions of 4-alkylamino-2-phenyl-2-oxazolines 1 with isocyanates and isothiocyanates provide unprecedented efficient and regioselective heterocycle-heterocycle transformations. Compounds 1 reacted rapidly with tosyl isocyanate yielding directly 3-alkyl-4-benzamido-1-tosyl-2-imidazolidinones 4 in almost quantitative yields. The corresponding ureido intermediates 2 were not isolable species. However, the reactions with non-sulfonylated isocyanates or isothiocyanates were slower, leading to the expected ureido and thioureido derivatives 5, which were easily and efficiently transformed to either polysubstituted 2-imino-1,3-oxazolidine or 2-imino-1,3-thiazolidine hydrochlorides 7, respectively, by treatment with hydrochloric acid. The possible reasons for this disparity in chemical behaviour are discussed. X-ray crystallographic structures for 4-benzamido-3-methyl-1-tosyl-2-imidazolidinone 4b, 4-1-isopropyl-3-(4-nitrophenyl)ureido]-2-phenyl-2-oxazoline 5e, (Z)-3-benzyl-4-benzamido-2-phenylimino-1,3-oxazolidine hydrochloride 7a and (Z)-3-benzyl-4-benzamido-2-phenylimino-1,3-thiazolidine hydrochloride 7b have been determined. |
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Keywords: | Oxazolines Ureas Thioureas Imidazolidinones Oxazolidines Thiazolidines |
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