CAS 219488-99-0 appears in our catalog under these names: 3-METHYL-2-BUTEN-2-YLBORONIC ACID PINAC&, 4,4,5,5-Tetramethyl-2-(3-methylbut-2-en-2-yl)-1,3,2-dioxaborolane, 95%, 95%. Offered by: Sigma-Aldrich, Chemat. Available pack sizes: 1G, 100mg, 250mg.