An intramolecular Li-Si exchange was observed on various lithiated ferrocenylbenzyl silyl ethers. The thermodynamically more stable C-silylated isomers were isolated in good yields and fully characterized. The reaction mechanism of the [1,4] retro-Brook rearrangement was investigated by DFT calculations. Two distinct reaction routes were proposed and a possible stabilization effect of the ferrocenyl fragment on the C-silylated isomers was described. The diastereoselective rearrangement of the trimethylsilyl group to the ortho position of the ferrocenyl cyclopentadienyl ring was also accomplished and the absolute configuration of the product was determined.
Keywords: carbanions; ferrocene; organosilanes; rearrangement; silyl transfer.
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