Probing the Reactivity of Cyclic N,O-Acetals versus Cyclic O,O-Acetals with NaBH4 and CH3MgI
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James A. Ciaccio [1] ; Shahrokh Saba [1] ; Samantha M. Bruno [1] ; John H. Bruppacher [1] ; Alexa G. McKnight [1]
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[1] Fordham University
Fordham University
Estados Unidos
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- Localización: Journal of chemical education, ISSN 0021-9584, Vol. 95, Nº 6, 2018, págs. 1045-1049
- Idioma: inglés
- Texto completo no disponible (Saber más ...)
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Resumen
An operationally straightforward, project-like laboratory experiment has been developed in which students directly compare the reactivity of two heterocycles, a cyclic O,O-acetal (standard C═O protecting group) and a cyclic N,O-acetal (oxazolidine), toward sodium borohydride and methylmagnesium iodide. Students synthesize a substrate containing both structural features, and then experimentally establish the chemo- and regioselective ring-opening of the N,O-acetal by identifying their 2-amino-1-alkanol products through spectral analysis. This experiment demonstrates that nonaromatic N- and O-heterocycles beyond those usually encountered by students in introductory organic textbooks, such as O,O-acetals and epoxides, are also reactive to nucleophiles, and it emphasizes the great effect on chemical reactivity of a seemingly minor structural alteration: exchanging O for N in a heterocycle.
