Herein is disclosed an efficient enantio- and diastereoselective spiroketalization of aromatic ketone tethered to -homoformyl and enone moiety via enol formation using quinine derived squaramide organocatalyst to access aromatic [6,5] spiroketals with complete atom economy. Furthermore, aromatic spiroketals undergo Brønsted acid catalyzed Piancatelli type rearrangement to provide dihydronaphtho[1,2-]furans with retention of the enantioselectivities.
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