The application of intramolecular radical cyclizations of acylsilanes in the regiospecific formation of cyclic silyl enol ethers

Radical Brook rearrangement: past, present, and future

The Brook rearrangement has emerged as one of the most pivotal transformations in organic chemistry, with broad applications spanning organic synthesis, drug design, and materials science. Since its discovery in the 1950s, the anion-mediated Brook rearrangement has been extensively studied, laying the groundwork for the development of numerous innovative reactions. In contrast, the radical Brook rearrangement has garnered comparatively less attention, primarily due to the challenges associated with the controlled generation of alkoxyl radicals under mild conditions. However, recent advancements in visible-light catalysis and transition-metal catalysis have positioned the radical Brook rearrangement as a promising alternative synthetic strategy in organic synthesis. Despite these developments, significant limitations and challenges remain, warranting further investigation. This review provides an overview of the radical Brook rearrangement, tracing its development from past to present, and offers perspectives on future directions in the field to inspire the creation of novel synthetic tools based on this transformation.

Tuning the reactivity of alkoxyl radicals from 1,5-hydrogen atom transfer to 1,2-silyl transfer

Controlling the reactivity of reactive intermediates is essential to achieve selective transformations. Due to the facile 1,5-hydrogen atom transfer (HAT), alkoxyl radicals have been proven to be important synthetic intermediates for the δ-functionalization of alcohols. Herein, we disclose a strategy to inhibit 1,5-HAT by introducing a silyl group into the α-position of alkoxyl radicals. The efficient radical 1,2-silyl transfer (SiT) allows us to make various α-functionalized products from alcohol substrates. Compared with the direct generation of α-carbon radicals from oxidation of α-C-H bond of alcohols, the 1,2-SiT strategy distinguishes itself by the generation of alkoxyl radicals, the tolerance of many functional groups, such as intramolecular hydroxyl groups and C-H bonds next to oxygen atoms, and the use of silyl alcohols as limiting reagents.