Thexylborane is a borane with the formula [Me2CHCMe2BH2]2 (Me = methyl). The name derives from "t-hexylborane" (although the group is not the standard tert-hexyl group), and the formula is often abbreviated ThxBH2. A colorless liquid, it is a monoalkylborane. It is produced by the hydroboration of tetramethylethylene: B2H6 + 2 Me2C=CMe2 → [Me2CHCMe2BH2]2
Reactions Thexylborane is generated in situ. In solution, it isomerizes over the course several days to the 2,3-dimethyl-1-butyl derivative, shown as the monomer here: Me2CHCMe2BH2 → Me2CHCH(Me)CH2BH2
Thexylborane allows the synthesis of ketones by coupling a pair of alkenes with carbon monoxide, which serves as a carbonyl linchpin: Me2CHCMe2BH2 + 2 RCH=CH2 → Me2CHCH(Me)CH2B(CH2CH2R)2 Me2CHCH(Me)CH2B(CH2CH2R)2 + CO + H2O → O=C(CH2CH2R)2 + ... An important feature of this reagent is that the thexyl group almost never undergoes anionotropic 1,2-migration from boron to a neighboring atom.
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