Do both elimination reactions, E1 and E2, follow Zaitsev’s rule?
(1) Certain cyclohexane derivatives.
Some cyclohexane derivatives, such as menthyl chloride, form the Hofmann product instead:
Formation of the Zaitsev product requires antiperiplanar elimination at the 2-position, but the isopropyl group – not the proton – is in the antiperiplanar location.
But there is an antiperiplanar hydrogen at the 6-position, so elimination occurs there and produces only the Hofmann product.
(2) Bulky bases
A bulky base attacks the least sterically hindered proton to form the Hofmann product.