The liquid phase alkylation of naphthalene with isopropanol has been studied over various large pore zeolites with intermediate aluminum content. While H-Y zeolite exhibits the best activity. and shows a high selectivity in 2,6- and 2,7-diisopropylnaphthalenes, in agreement with previous studies, H-Beta displays a peculiar behavior under the same conditions. The latter produces little diisopropylnaphthalenes; instead, a series of unexpected compounds. consisting of (cyclopentyl)naphthalene derivatives (so-called cyclizates), are formed in high yields. H-Mordenite, which features low activity, also demonstrates such an unexpected behavior towards formation of multialkylated products. The results obtained over H-Beta are more particularly reported, and the identification of the cyclizates is confirmed. A mechanism is proposed to explain the formation of these compounds depending on the various catalytic materials used, and the impact of the pore structure on activity and product distribution is discussed.