Thexylborane

Thexylborane
Identifiers
CAS Number	3688-24-2;
3D model (JSmol)	monomer: Interactive image;
ChemSpider	monomer: 4483657;
PubChem CID	monomer: 10877414;
	InChI Key: AAYWIXGLVAEPTP-UHFFFAOYSA-N; monomer: InChI=1S/C6H13B/c1-5(2)6(3,4)7/h5H,1-4H3;
	SMILES monomer: [B]C(C)(C)C(C)C;
Properties
Chemical formula	C12H30B2
Molar mass	195.99 g·mol−1
Appearance	colorless liquid
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
	Infobox references

Thexylborane is a borane with the formula [Me₂CHCMe₂BH₂]₂ (Me = methyl). A colorless liquid, it is a rare, easily accessed monoalkylborane. It is produced by the hydroboration of tetramethylethylene:[1]

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 atom-economical synthesis of ketones from a pair of alkenes:

Me₂CHCMe₂BH₂ + 2 RCH=CH₂ → Me₂CHCH(Me)CH₂B(CH₂CH₂R)₂

Me₂CHCH(Me)CH₂B(CH₂CH₂R)₂ + CO + H₂O → OC(CH₂CH₂R)₂ + ...

The main point is that the thexyl group does not migrate.[1]

References

Negishi, Ei-Ichi; Brown, Herbert C. (1974). "Thexylborane-A Highly Versatile Reagent for Organic Synthesis via Hydroboration". Synthesis. 1974 (2): 77–89. doi:10.1055/s-1974-23248.

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[syn-1] Negishi, Ei-Ichi; Brown, Herbert C. (1974). "Thexylborane-A Highly Versatile Reagent for Organic Synthesis via Hydroboration". Synthesis. 1974 (2): 77–89. doi:10.1055/s-1974-23248.