1-Bromo-2-(diphenylphosphinoyl)ethyne and 1-bromo-2-(p-tolylsulfinyl)ethyne: versatile reagents eventually leading to benzocyclotrimers

The title compounds form Diels-Alder cycloadducts with a number of dienes, which can be transformed into vic-bromo(trimethylstannyl)olefins, ultimate precursors for the synthesis of benzocyclotrimers via copper-mediated cyclotrimerization. The overall result is a formal condensation of three diatomic carbons with three dienes. (C) 2009 Elsevier Ltd. All rights reserved.