Cyclization of 1-phenyl-2-propen-1-ones into 1-indanones using H-zeolite and other solid acids. The role of mono- and dicationic intermediates

Available solid acids such as HUSY-zeolite, sulfated zirconia or heteropolyacid, H3PW12O40 are successfully applied instead of superacids in cyclization of aryl vinyl ketones into 1-indanones. The cases, when the effective excess of acidic sites of the solid is required to carry out the reaction, are interpreted in terms of key dicationic (superelectrophilic) intermediacy.