Maleates from diazoacetates and dilactones from head-to-head dimerisation of alkenyl diazoacetates using Grubbs 2nd-generation ruthenium carbene catalyst

Grubbsʹ 2nd-generation ruthenium carbene catalyst homocouples diazoacetates to maleates and also catalyses head-tohead dimerisation of alkenyl diazoacetates giving dienyl dilactones.