Palladium-catalyzed 1,2-addition of organic halides and terminal alkynes to 7-oxabenzonorbornadiene: An efficient route to polyaromatic hydrocarbons

A three-component coupling reaction of organic halides with oxabicyclic alkenes and terminal alkynes was catalyzed by a palladium complex and a phase-transfer agent in the presence of aqueous NaOH. The reaction gave a series of 5,6-disubstituated 7-oxabenzonorbornene derivatives in good yields. The disubstituted products from oxabenzonorbornadiene can be readily converted into polyaromatic hydrocarbons by a Lewis acid mediated deoxyaromatization reaction. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008).