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36.12.9.1.3.1 Variation 1: Retro-Brook Rearrangements

DOI: 10.1055/sos-SD-036-00789

Morey, J. V.; Wheatley, A. E. H.Science of Synthesis, (2008361130.

Brook rearrangements and the reverse process, the retro-Brook rearrangement (trialkylsilyl migration from trialkylsilyl ethers to carbanion centers), have been thoroughly studied.[‌56‌] Retro-Brook transmetalation has been found to proceed in an intramolecular fashion without radical formation, driven by formation of the most stable alcoholate. In contrast to the inversion of configuration noted when rearrangement occurs in aryl-substituted compounds,[‌57‌,‌58‌] configuration is retained at the migratory terminus during the aliphatic retro-Brook process.[‌59‌] Exploration of the ring-closure of 4-(tert-butyldimethylsiloxy)hex-5-enyllithium has revealed that [2-(tert-butyldimethylsiloxy)cyclopentyl]methyllithium (91) undergoes facile retro-[1,4]-Brook rearrangement only in the syn-form to give lithium alcoholate 92, which on reaction with methanol gives the alcohol 93 (Scheme 33).[‌60‌]

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