Dichotomies in microwave-assisted propargyl-isomerization-Claisen domino sequences dependent on base strengths

Microwave-assisted unimolecular isomerization-Claisen domino reactions of 1,3-di(hetero)aryl propargyl trityl ethers lead, depending on the basicity of the amine, either to the formation of tricyclo[3.2.1.0(2.7)]oct-3-enes (with triethylamine) or to indanes (with DBU). Based upon product analyses and computations, this base dependent dichotomy can be rationalized as a sequel of pericyclic reactions with intermediate protonation and deprotonation.