Rhodium- or Copper-Catalysed CH-Insertion of Carbenoids into Dihydro­aromatic Compounds and Acyclic 1,4-Dienes

A straightforward reaction sequence consisting of a cobalt-catalysed Diels-Alder reaction for the generation of dihydro­aromatic compounds and a rhodium- or alternatively a copper-catalysed CH-insertion reaction of carbenoids from diazo esters generates highly substituted benzene derivatives. When acyclic 1,4-dienes are synthesised by a cobalt-catalysed 1,4-hydrovinylation reaction, the rhodium-catalysed conversion with diazo esters leads to cyclopropanation rather than CH-insertion products.