Brook rearrangement

The Brook rearrangement is a type of reaction in organic chemistry that involves the migration of a silyl group from a carbon atom to an oxygen atom. This rearrangement was first observed in the late 1950s by Canadian chemist Adrian Gibbs Brook, after whom the reaction is named[1].

The reaction mechanism for the Brook rearrangement depends on the conditions employed. Anionic rearrangements are the most common Brook rearrangements observed, and their mechanisms can be broken into two general categories. The first category starts with proton abstraction of a nearby hydroxyl group by a base. This generates an alkoxide which then acts as a nucleophile and attacks the silicon atom, with the methylene group acting as the leaving group. The generated carbanion is then protonated by the H-B species to form the product[1].

These silyl migrations can be promoted in a number of different ways, including thermally, photolytically, or under basic/acidic conditions. In the forward direction, these silyl migrations produce silyl ethers as products, which is driven by the stability of the resulting structures[1].

The Brook rearrangement has been shown to occur with retention of configuration at the silicon atom. By starting with a chiral silicon of known configuration, the stereochemistry of the reaction could be determined by looking at the specific rotation of the product[1].

The Brook rearrangement has been extensively applied to develop numerous useful transformations of diverse organosilanes. Some representative examples include formal [3 + 2] and [4 + 3] annulations to construct diverse ring systems, syntheses of configurationally defined silyl enol ethers, multi-component reactions by Brook rearrangement-based ARC (anion relay chemistry), and various umpolung processes such as silyl benzoin condensations and sila-Stetter reactions[8].

Citations:

[1] https://en.wikipedia.org/wiki/Brook_rearrangement

[2] https://www.sciencedirect.com/topics/chemistry/brook-silaketone-rearrangement

[3] https://www.youtube.com/watch?v=TQscofpz0JY

[4] https://www.slideshare.net/AnusreeAnu11/brook-rearrangement

[5] https://onlinelibrary.wiley.com/doi/10.1002/anie.202205671

[6] https://www2.chemistry.msu.edu/faculty/reusch/virttxtjml/rearang2.htm

[7] https://www.youtube.com/watch?v=Po7ZYtv0vD4

[8] https://www.organicreactions.org/pubchapter/the-brook-rearrangement/

[9] https://onlinelibrary.wiley.com/doi/abs/10.1002/0471264180.or102.01

[10] https://pubmed.ncbi.nlm.nih.gov/23963407/

[11] https://academic-accelerator.com/encyclopedia/brook-rearrangement