“…Precipitated material was filtered off and the filtrate was purified by means of chromatography (silica gel, ethyl acetate/hexanes 1:3) yielding 20 as a colorless solid (1.74 g, 60 %, R f = 0.55). 1- 3,4,5,6,7,8,9,10,]-1'-[closo -2,3,4,5,6,7,8,9,10,11-decamethyl-1,12-dicarbadodecaboranyl(12) 1- 3,4,5,6,7,8,9,10,]-1'-[closo -2,3,4,5,6,7,8,9,10,11-decamethyl-1,12-dicarbadodecaboranyl(12)]-1,4-butadiyne (23) 1- 3,4,5,6,7,8,9,10,]-1'-[closo -2,3,4,5,6,7,8,9,10,11-decamethyl-1,12-dicarbadodecaboranyl(12)]-1,4-butadiyne (24) and 1-[12-(methyl propiolyl)-closo-2,3,4,5,6,7,8,9,10,11-decamethyl-1,12-dicarbadodecaboranylene(12)]-1'-[closo -2,3,4,5,6,7,8,9,10,11-decamethyl-1,12-dicarbadodecaboranyl(12) 12,12 3,4,5,6,7,8,9,10,]-1,4-butadiynediyl}}-{1,1'-{bis [closo-2,3,4,5,6,7,8,9,10,11-decamethyl-1,12-dicarbadodecaboranylene(12)]}-1,4-butadiyne} (26): A mixture of 24 (0.900 g, 1.4 mmol), CuCl (1.00 mg, 0.10 mmol), and DBU (0.100 mL, 0.600 mmol) in anhydrous pyridine (25 mL) was reacted according to the procedure described for the synthesis of 19. The product was extracted with hot toluene.…”