2-Bromo-2-methylbutane is treated with $(\mathrm{CH}{}_3){}_3\mathrm{COK}$ in $(\mathrm{CH}{}_3){}_3\mathrm{COH}$. The major alkene is

tert-Butoxide is a bulky strong base. It reaches the six unhindered methyl hydrogens more readily than the hindered methylene hydrogens, so the Hofmann alkene 2-methylbut-1-ene is the major product (about 70 percent). Substitution is not possible by SN2 at the tertiary carbon.