The thermal rearrangements of 3-acylamino-5-methylisoxazoles 1 have been investigated under basicand neutral conditions and interpreted with the support of computational data. The density functionaltheory (DFT) study on the competitive routes available for the base-catalyzed thermal rearrangement ofisoxazoles 1 showed that the Boulton-Katritzky (BK) rearrangement, producing the less stable 3-acetonyl-1,2,4-oxadiazoles 5, is a much more favored process than either the migration-nucleophilic attack-cyclization(MNAC) or the ring contraction-ring expansion (RCRE). In turn, an increase in reaction temperaturewill promote the MNAC of oxadiazoles 5, producing the more stable 2-acylaminooxazoles 8. The thermalrearrangement of 3-acylaminoisoxazoles 1 into oxazoles 8 can therefore be interpreted in terms of acascade BK-MNAC rearrangement involving 3-acetonyl-1,2,4-oxadiazoles 5 as ancillary intermediates.
|Numero di pagine||8|
|Rivista||Journal of Organic Chemistry|
|Stato di pubblicazione||Published - 2009|
All Science Journal Classification (ASJC) codes
- Organic Chemistry