Reactivity of Vinyl Epoxides/Oxetanes/Cyclopropanes toward Arynes: Access to Functionalized Phenanthrenes

Abstract

The reactivity of vinyl epoxides/oxetanes/cyclopropanes toward arynes has been demonstrated under mild conditions to give the corresponding phenanthrenes in moderate to good yields. This transition-metal-free cascade process involves a series of Diels–Alder reaction, ring-opening aromatization, and ene reaction. Various functionalized phenanthrenes could be synthesized utilizing the versatile hydroxy group. Interestingly, vinyl epoxides/oxiranes experience preferentially the Diels–Alder reaction toward arynes over nucleophilic attack of epoxides/oxiranes.

Palladium-Catalyzed Regioselective [5 + 1] Annulation of Vinyl Aziridines/Epoxides with ClCF2COONa

“…Interestingly, carbonylative ring expansion reactions involving π-allyl Pd II complexes displayed regioselectivity, resulting in [3 + 1] annulation products using no silyl-substituted vinyl aziridines or vinyl epoxides, alternative [5 + 1] annulation products with 5-vinyloxazolidin-2-ones, vinyl cyclic carbonates, or silyl-substituted vinyl aziridine . In our ongoing interest in ring-opening functionalization of vinyl aziridines/epoxides involving reactive intermediates, we develop an effective method for the synthesis of δ-lactams and δ-lactones from vinyl aziridines/epoxides employing ClCF 2 COONa as a carbonyl source . To the best of our knowledge, a difluorocarbene-involved annulation reaction of π-allyl Pd II complexes has remained undiscovered until now.…”