Ortho-carborane is prepared by the addition of acetylenes to decaborane(14). Modern syntheses involve two stages, the first involving generation of an adduct of decaborane:
:BH + 2 SEt  →  BH(SEt) + H
In the second stage, the alkyne is installed as the source of two carbon vertices:
:BH(SEt) + CH  →  CBH +  2 SEt + H
Substituted acetylenes can be employed more conveniently than acetylene gas. For example bis(acetoxymethyl)acetylene adds to the decarborane readily.
:BH(SEt) + C(CHOCCH)  →  CBH(CHOCCH) +  2 SEt + H
The organic substituents are removed by ester hydrolysis followed by oxidation:
:3 CBH(CHOCH) + 10 KOH  +  + 8 KMnO  →  3 CBH + 6 CHCOK +  8 MnO +  6 KCO + 8 HO