Intramolecular and intermolecular Schmidt reactions of alkyl azides with aldehydes

Despite recent advances in the use of alkyl azides in ring expansion reactions of ketones, there has been little work done on the corresponding chemistry of aldehydes. In the present study, the Lewis acid-promoted reactions of alkyl azides with aldehydes were studied in both intermolecular and intra...

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Bibliographic Details
Published in:Tetrahedron 2007-09, Vol.63 (36), p.9007-9015
Main Authors: Lee, Huey-Lih, Aubé, Jeffrey
Format: Article
Language:English
Subjects:
Aldehyde
Alkyl azide
Schmidt reaction
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Summary:Despite recent advances in the use of alkyl azides in ring expansion reactions of ketones, there has been little work done on the corresponding chemistry of aldehydes. In the present study, the Lewis acid-promoted reactions of alkyl azides with aldehydes were studied in both intermolecular and intramolecular contexts. The intramolecular reactions of azidoalkyl aldehydes in which the azide and carbonyl groups were separated by 2–5 carbons were examined. Although the examples having the shortest tether failed (3-azidopropanals), each of the other systems gave good yields of either NH-substituted lactams (resulting from hydride migration in the initially formed azidohydrin adduct) or formamides (alkyl migration). The product formed was dependent on the chain length of the starting azido aldehyde. The intermolecular reactions were less efficient, requiring TiCl 4 promotion for even moderate yields, and in each case gave mixtures of products resulting from hydride and alkyl migration. [Display omitted] The acid-promoted reactions of alkyl azides to form amides were studied in both intramolecular and intermolecular settings.
ISSN:0040-4020
1464-5416
DOI:10.1016/j.tet.2007.05.079