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High Resolution Image Download MS PowerPoint Slide We report the discovery of an example of oxidative bicyclo1.1.0butane activation. This reactivity stands in contrast to well-established strain-release nucleophile addition and reductive activation and opens up further possibilities for exploiting bicyclo1.1.0butanes in synthesis. Using a strongly oxidizing acridinium organophotocatalyst, the formal 2σ+2π cycloaddition between bicyclo1.1.0butanes and alkenes or aldehydes leads to the corresponding bicyclo2.1.1hexanes or oxabicyclo2.1.1hexanes. The subtle interplay between bicyclo1.1.0butane and alkene identity dictates the mechanism of the reaction, with regiodivergent pathways providing complementary reaction products in up to >20:1 regioselectivity. A mechanistic investigation including electrochemical, photophysical, radical trapping, and computational studies support the oxidative mechanisms proposed.
Golfmann et al. (2024) studied this question.