Catalytic 4-exo-dig carbocyclization for the construction of furan-fused cyclobutanones and synthetic applications.

ABSTRACT: Cyclobutanone is a strained motif with broad applications, while direct assembly of the aromatic ring fused cyclobutanones beyond benzocyclobutenone (BCB) skeletons remains challenging. Herein, we report a Rh-catalyzed formal [3+2] annulation of diazo group tethered alkynes involving a 4-exo-dig carbocyclization process, providing a straightforward access to furan-fused cyclobutanones. DFT calculations disclose that, by comparison to the competitive 5-endo-dig process, 4-exo-dig carbocyclization is mainly due to lower angle strain of the key sp-hybridized vinyl cationic transition state in the cyclization step. Using less reactive catalysts Rh₂(carboxylate)₄ is critical for high selectivity, which is explained as catalyst-substrate hydrogen bonding interaction. This m

SUBMITTER: Hong K 

PROVIDER: S-EPMC10567718 | biostudies-literature | 2023 Oct

REPOSITORIES: biostudies-literature