Codimerisation of styrene and α-methylstyrene in the presence of zeolites

Lewis base-assisted Lewis acid-catalyzed selective alkene formation via alcohol dehydration and synthesis of 2-cinnamyl-1,3-dicarbonyl compounds from 2-aryl-3,4-dihydropyrans

“…The AlCl3-catalyzed dehydration of 1a suffered mainly from the formation of the undesirable by-product 3a. The dimerization tri-substituted alkene mechanism of formation is known to proceed in the presence of an acid catalyst through the following two pathways: (1) coupling of benzylic alcohols and styrenes, in which the styrene components act as π-type nucleophiles [46,47]; (2) dimerization of 2a [48]. The two reaction pathways described to form 3a and the dehydration of 1a to 2a have been reported to be associated with the formation of a benzyl cation (I) (Scheme 2) [49,50].…”