The Scope and Limitations of Intramolecular Radical Cyclizations of Acylsilanes with Alkyl, Aryl, and Vinyl Radicals
摘要:
5-Exo cyclizations of primary and secondary radicals with acylsilanes successfully give cyclopentyl silyl ethers. The corresponding 6-exo cyclizations are sensitive to changes of the size of silyl groups. Secondary radicals undergo 6-exo cyclizations with acylsilanes more slowly. Reaction of aryl radical with acylsilane proceeds well for 5-exo cyclization but not for 6-exo cyclization. Vinyl radicals give best results in 5-exo cyclizations with acylsilanes but give low yields (similar to 30%) in 6-exo cyclizations. Intramolecular cyclizations of vinyl radicals with acylsilanes give enol silyl ethers regiospecifically.
Intramolecular free radical cyclizations using acylsilanes as radicalphiles
摘要:
Carbon radicals add intramolecularly to acylsilanes at the carbonyl carbon followed by radical Brook rearrangement to give silylated cyclopentanols or cyclohexanols in good yields.
Carbeneinsertionreactions with B-H bonds are a challenging but promising method for synthesis of organoboranes. Herein, we report visible-light-induced B-H insertions of HBpin with acylsilane. This metal-free and operationally simple reaction pro-ceeds in an atom-economical way with broad substrate scope under mild reaction conditions, affording a variety of important α-alkoxyorganoboronate esters