One-pot Pd/norbornene-catalyzed Synthesis of Dibenzo[c,e]oxepin Derivatives

One–pot Pd/Norbornene-Catalyzed Synthesis of Dibenz[c,e]Oxepin Derivatives We have recently reported the sequential Pd/norbornene catalyzed process leading to dibenzopyran derivatives starting from o-aryl iodides and o-bromobenzyl alcohols.1 An activated olefin added to the same reagents gives rise to seven-membered heterocycles belonging to the oxepin class. The equation below shows the reaction of an ortho-substituted aryl iodide with a secondary o-bromobenzyl alcohol and an electron-poor terminal olefin, i.e. an acrylate ester, that gives compound I, which undergoes an intra oxa-Michael reaction leading to dibenz[c,e]oxepin derivatives as a mixture of two diastereoisomers.