Accessing Dihydro-1,2-oxazine via Cloke-Wilson-Type Annulation of Cyclopropyl Carbonyls: Application toward the Diastereoselective Synthesis of Pyrrolo[1,2-b][1,2]oxazine.
J Org Chem
; 85(10): 6535-6550, 2020 05 15.
Article
en En
| MEDLINE
| ID: mdl-32329340
ABSTRACT
A convenient additive-free synthesis of dihydro-4H-1,2-oxazines via a Cloke-Wilson-type ring expansion of the aryl-substituted cyclopropane carbaldehydes with the hydroxylamine salt is introduced. Comparatively less active cyclopropyl ketones also follow a similar protocol if supplemented by catalytic p-toluene sulfonic acid monohydrate. The transformation is performed in an open-to-air flask as it shows negligible sensitivity toward air/moisture. Dihydro-4H-1,2-oxazines when subjected to cycloaddition with the cyclopropane diester afford a trouble-free formulation of the valued hexahydro-2H-pyrrolo[1,2-b][1,2]oxazine derivatives. A cascade one-pot variant of this two-step strategy offers a comparable overall yield of the final product.
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1
Colección:
01-internacional
Banco de datos:
MEDLINE
Idioma:
En
Revista:
J Org Chem
Año:
2020
Tipo del documento:
Article
País de afiliación:
India