Abstract
AbstractPhotoredox‐catalyzed methylcyclobutanations of alkylboronic esters are described. The reactions proceed through single‐electron transfer induced deboronative radical addition to an electron‐deficient alkene followed by single‐electron reduction and polar 4‐exo‐tet cyclization with a pendant alkyl halide. Key to the success of the methodology was the use of easily oxidizable arylboronate complexes. Structurally diverse cyclobutanes are shown to be conveniently prepared from readily available alkylboronic esters and a range of haloalkyl alkenes. The mild reactions display excellent functional group tolerance, and the radical addition‐polar cyclization cascade also enables the synthesis of 3‐, 5‐, 6‐, and 7‐membered rings.
Highlights
Photoredox-catalyzed methylcyclobutanations of alkylboronic esters are described
The reactions proceed through single-electron transfer induced deboronative radical addition to an electron-deficient alkene followed by singleelectron reduction and polar 4-exo-tet cyclization with a pendant alkyl halide
Key to the success of the methodology was the use of oxidizable arylboronate complexes
Summary
Photoredox-catalyzed methylcyclobutanations of alkylboronic esters are described. The reactions proceed through single-electron transfer induced deboronative radical addition to an electron-deficient alkene followed by singleelectron reduction and polar 4-exo-tet cyclization with a pendant alkyl halide. The importance of anhydrous conditions was highlighted by the complete reversal of selectivity from cyclobutane to Giese product formation upon addition of water to the reaction (entry 8). Submitting enoate 7 a to the optimized Giese reaction conditions reported by Akita (with BF3K salt)[14a] and Ley (with Bpin and DMAP)[15b] resulted in no cyclobutane formation.[13] These results highlight the benefits on reactivity of using oxidized arylboronate complexes such as 5.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
