Practical synthesis of 1,4-dioxane derivative of the closo-dodecaborate anion and its ring opening with acetylenic alkoxides

Practical method of synthesis of the 1,4-dioxane derivative of the closo-dodecaborate anion was developed. The cleavage of the dioxonium ring in [B12H11O(CH2CH2)2O]− with acetylenic alcohols gave rise to the preparation of closo-dodecaborate derivatives with terminal acetylene group. These compounds can be introduced into click reactions with phenylazide leading to the corresponding triazoles. The structures of (Bu4N)[B12H11O(CH2CH2)2O] and (Bu4N)2[B12H11(OCH2CH2)2OCH2Ctriple bond; length of mdashCH] · 0.5HOCH2Ctriple bond; length of mdashCH were determined by single-crystal X-ray diffraction.