3-Oxabicyclo[4.1.0]heptane, 7-[3-methyl-1-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1,2-butadien -1-yl]-7-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-