Brook Rearrangement

Sasaki, Michiko; Takeda, Kazuya

doi:10.1002/9781118939901.ch6

Cited by 13 publications

(5 citation statements)

References 127 publications

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“…Penta- and hexa-coordinate silicon are known to be crucial intermediates in many reactions. A representative reaction involving a pentavalent silicon intermediate is the Brook rearrangement . This process generally requires base, and its putative reaction mechanism is an intramolecular anionic migration of the silyl group from carbon to oxygen.…”

Section: Introductionmentioning

confidence: 99%

Enantioselective 1,2-Anionotropic Rearrangement of Acylsilane through a Bisguanidinium Silicate Ion Pair

et al. 2018

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Highly enantioselective bisguanidinium-catalyzed tandem rearrangements of acylsilanes are reported. The acylsilanes were activated via an addition of fluoride on the silicon to form a penta-coordinate anionic silicate intermediate. The silicate then underwent alkyl or aryl group migration from the silicon atom to the neighboring carbonyl carbon atom (1,2-anionotropic rearrangement), followed by [1,2]-Brook rearrangement to provide the secondary alcohols in high yields with excellent enantioselectivities (up to 95% ee). The isolation of an α-silylcarbinol intermediate as well as DFT calculations revealed that the 1,2-anionotropic rearrangement occurred via a bisguanidinium silicate ion pair, which is the stereodetermining step. The chiral center formed is then retained without inversion through the subsequent [1,2]-Brook rearrangement. Crotyl acylsilanes were smoothly transformed into homoallylic linear crotyl alcohols with retention of E/Z geometry, and no branched alcohols were detected. This clearly suggested that the 1,2-anionotropic rearrangement occurred through a three-membered instead of a five-membered transition state.

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Section: Introductionmentioning

confidence: 99%

Enantioselective 1,2-Anionotropic Rearrangement of Acylsilane through a Bisguanidinium Silicate Ion Pair

et al. 2018

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“…This was later extended to structures where the migrating silyl unit is more distal from the oxygen atom (Scheme , path a) . Such [1,2]- and [1, n ]-rearrangements are used in sequential relay processes, with the ability to generate C–C bonds through in situ functionalization of the carbanionic intermediate. In this context, we have recently been interested in the Zn-Brook rearrangement to generate configurationally stable chiral allenylzinc compounds, as well as their enantiomerically enriched variants (Scheme , path b).…”

Section: Introductionmentioning

confidence: 99%

Brook Rearrangement as Trigger for Carbene Generation: Synthesis of Stereodefined and Fully Substituted Cyclobutenes

Zhang

Marek

2017

J. Am. Chem. Soc.

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Through a sequence that can be performed in a single vessel, involving regio- and diastereoselective copper-catalyzed carbomagnesiation of cyclopropenes, reaction with acylsilanes, and addition of THF as cosolvent, Brook rearrangement can be triggered to furnish a wide range of cyclobutenes with exceptional diastereoselectivity. Accordingly, stereodefined and highly substituted cyclobutenes with contiguous quaternary carbon centers can be synthesized easily and in high yield. The new strategy constitutes an unprecedented application of Brook rearrangement, one which involves the intermediacy of carbene species.

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“…The driving force for Brook rearrangements depends on the balance between bond energy values (Si–C = 76 kcal/mol; Si–O = 108 kcal/mol) and the higher stability of the oxyanion relative to that of the carbanion . The Brook rearrangement is an umpolung-type reaction, which is characterized by its high stereoselectivity and stereospecificity, features that have made it a highly popular tool in the area of synthetic organic chemistry …”

Section: Introductionmentioning

confidence: 99%

A Qualitative Analysis of a “Bora-Brook Rearrangement”: The Ambident Reactivity of Boryl-Substituted Alkoxide Including the Carbon-to-Oxygen Migration of a Boryl Group

et al. 2016

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A bora-Brook rearrangement, i.e., the migration of boryl group from a carbon to an oxygen atom in an isolated α-boryl-substituted alkoxide, was examined, and decisive factors for the acceleration of this reaction are disclosed. In this rearrangement, the boryl-substituted alkoxide exhibited ambiphilic reactivity toward electrophiles to afford two types of products, which are electrophiles bound either at the oxygen or at the carbon atom. Using polar solvents, a saturated backbone of the boron-containing heterocycle, or larger alkali metal cations resulted in a significantly increased reaction rate of base-catalyzed isomerization of α-borylbenzyl alcohol including the bora-Brook rearrangement.

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Brook Rearrangement

Cited by 13 publications

References 127 publications

Enantioselective 1,2-Anionotropic Rearrangement of Acylsilane through a Bisguanidinium Silicate Ion Pair

Enantioselective 1,2-Anionotropic Rearrangement of Acylsilane through a Bisguanidinium Silicate Ion Pair

Brook Rearrangement as Trigger for Carbene Generation: Synthesis of Stereodefined and Fully Substituted Cyclobutenes

A Qualitative Analysis of a “Bora-Brook Rearrangement”: The Ambident Reactivity of Boryl-Substituted Alkoxide Including the Carbon-to-Oxygen Migration of a Boryl Group

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