An efficient cobalt catalyst for the neutral Diels–Alder reaction of acyclic 1,3-dienes with internal alkynes

The efficiently cobalt(I)-catalysed neutral Diels–Alder type reactions of internal alkynes with substituted 1,3-dienes is described. The regiochemistry for the dihydroaromatic products of reactions of isoprene with unsymmetrical reaction partners (2-alkynes and 1-trimethylsilyl-1-hexyne) is investigated. The dihydroaromatic reaction products are easily oxidised electrochemically to the corresponding functionalised durene and isodurene derivatives.