Transition metal catalyzed ring opening reactions of 2-phenyl-3-vinyl substituted 2H-azirines

Synthesis of azirines containing aldehyde functionality and their utilization as synthetic tools for five membered oxazoles and isoxazoles

“…In recent years, considerable interest has been given in the use of both organometallic reagent and catalysts for effecting ring cleavage of small ring systems [13]. Recently Padwa et al reported several transition metal catalyzed ringopening reactions of 2-phenyl-3-vinyl substituted 2H-azirines [14]. By comparison with the extensive studies carried out photochemically with 2H-azirines ring system, [15][16][17][18] its behavior toward organometallic reagent and other catalysts have been relatively unexplored.…”

Three‐Membered Heterocycles. Structure and Reactivity

“…Thus, the azirinyl aldehyde 272 is transformed cleanly into the isoxazole 273 at room temperature. Similarly, vinyl azirine 274 undergoes thermal rearrangement to form exclusively the 2,5-disubstituted pyrrole 276, which is complementary to photolytic rearrangement, a process providing only the 2,3-product 275 [311,312]. Finally, Taber has reported on the high-yielding synthesis of indoles (e.g., 278) from arylazirines 277, which are themselves synthesized from the oximes of aryl ketones [313].…”

“…Incorporation of an electron-withdrawing fluoro substituent at the a-position enhanced the catalytic reactivity. Enan-tiomeric excesses tend to be modest, but occasionally are quite good, as seen in the epoxidation of phenylstilbene (312), which takes place in quantitative yield and with 83% ee [366]. The impact of these electronic effects is intriguing, and can be quite dramatic.…”

Five‐Membered Heterocycles: 1,2‐Azoles. Part 2. Isoxazoles and Isothiazoles

“…Baker's Yeast 52-82% The thermolysis of 3-phenyl-2H-azirine-2-carbaldehyde at 200 C leads to 3-phenylisoxazole in high yield [178]. The same isoxazole can also be obtained in 90% yield by treatment of 3-phenyl-2H-azirine-2-carboxaldehyde at 25 C with Grubbs' catalyst [179]. Furthermore, 2-benzoyl-3-phenyl-2H-azirine affords the corresponding isoxazole upon heating in non-hydroxylic solvents [180] (Scheme 9.22).…”