- Metalation of Isoxazolyloxazolines, a Facile Route to Functionally Complex Isoxazoles: Utility, Scope, and Comparison to Dianion Methodology
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2-(5'-Alkylisoxazol-4'-yl)-Δ2-oxazoline was metalated at the C-5' alkyl group, and the lithio anion was quenched with a variety of electrophiles.Alkyl halides, aldehydes, and acylpyridinium salts were used as electrophiles.The lithio anion was oxygenated with MOOPH or N-(phenylsulfonyl)oxaziridene.The isoxazolyloxazoline system was converted to the isoxazolyl carboxylic acid, aldehyde, ketone, and chiral oxazoline.The isoxazolyloxazoline was formed, metalated, and deprotected in synthetically useful yields and represents a facile entry into functionally complex isoxazoles.To determine the necessity of the oxazoline protection/deprotection scheme, dianions of isoxazole-4-carboxylic acids were studied.The dianion method was found to be more efficient for simple alkyl halides, but limited in scope.
- Natale, N. R.,McKenna, John I.,Niou, Chorng-Shyr,Borth, Mark,Hope, Hakon
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p. 5660 - 5666
(2007/10/02)
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- A FACILE SYNTHESIS OF FUNCTIONALLY COMPLEX ISOXAZOLE DERIVATIVES
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Metalation of 2(4'-Isoxazolyl)-Δ2-oxazolines takes place initially and selectively on the C-5'-alkyl group.Subsequent metalation also proceeds at this position.Selective deprotection of the oxazoline was accomplished without disturbing the izox
- Natale, N. R.,Niou, Chorng-Shyr
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p. 3943 - 3946
(2007/10/02)
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