Facile dihydroboration of 1-trimethylgermyl-1-alkynes with dichloroborane-dioxane complex

ORGN 444

Narayan G. Bhat, nbhat@panam.edu, Department of Chemistry, University of Texas-Pan American, 1201 West University Drive, Edinburg, TX 78541 and Aroldo Ibarra, Chemistry, University of Texas-Pan American, 1201 West University Drive, Edinburg, TX 78541.
1-Trimethylgermyl-1-alkynes easily prepared by the deprotonation of the terminal alkynes with n-butyllithium followed by reaction with trimethylgermanium bromide readily undergo dihydroboration with two equivalents of dichloroborane-dioxane complex in dichloromethane at room temperature for 12 h. The resulting dihydroborated products are reacted with water at 0 oC for half an hour to provide the corresponding boronic acids. These are then reacted with 1,3-propane diol in n-pentane to provide the corresponding boronate esters in good yields (72%-82%). The structures of these boronate esters are confirmed by NMR spectral data.