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Photoredox‐Catalyzed Cyclobutane Synthesis by a Deboronative Radical Addition–Polar Cyclization Cascade
Author(s) -
Shu Chao,
Noble Adam,
Aggarwal Varinder K.
Publication year - 2019
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201813917
Subject(s) - cyclobutanes , cyclobutane , chemistry , alkene , photoredox catalysis , alkyl , radical cyclization , cascade , catalysis , halide , photochemistry , polar , electron transfer , combinatorial chemistry , stereochemistry , organic chemistry , ring (chemistry) , photocatalysis , astronomy , physics , chromatography
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 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.