3‐Acetylpyrrolo[1,2‐ c ]Oxazoles, Bipyrrolo[1,2‐ c ]Oxazoles, and Pyrrolo[1,2‐ c ]Oxazole‐Oxetane Ensembles via Base‐Catalyzed [3 + 2]‐Cyclization of 2‐Acylethynylpyrroles With Diacetyl
Abstract
ABSTRACT A stereoselective, base‐catalyzed [3 + 2]‐cyclization of 2‐acylethynylpyrroles with diacetyl (DBU/benzene, room temperature) afforded bipyrrolo[1,2‐ c ]oxazoles or 3‐acetylpyrrolo[1,2‐ c ]oxazoles, both integrated with α,β ‐ethylenic ketones, in 51–76% and 23–74% yields, respectively. Switching between these products was controlled by the concentration of diacetyl. Replacing the catalyst with NaOH triggered an unexpected Paternò–Büchi dimerization of diacetyl, followed by a [3 + 2]‐cyclization to yield pyrrolo[1,2‐ c ]oxazole‐oxetane ensembles (21–29%) alongside the aforementioned pyrrolo‐ and bipyrrolo[1,2‐ c ]oxazoles.
Fields of Study & Subjects
Synthesis and Characterization of Pyrroles
Synthesis and Reactivity of Heterocycles
Cyclopropane Reaction Mechanisms
Publication details
- Journal / source
- Asian Journal of Organic Chemistry
- Publisher
- Wiley
- Volume
- 15
- Issue
- 4
- Publication date
- 31 March 2026
- Language
- EN