Tandem cobalt mediated rearrangement and Pauson–Khand reaction for the synthesis of functionalised polycyclic systemsElectronic supplementary information (ESI) available: experimental procedures and data for all new compounds. See http://www.rsc.org/suppdata/cc/b2/b204616b/

Abstract

The cobalt mediated rearrangement of enol ether complex 2 furnishes cyclic ketone 6, which undergoes an intramolecular Pauson-Khand reaction allowing access to functionalized polycyclic systems.

Investigation of a Stereoselective Co-Mediated Rearrangement Reaction

“…Isomerization can be slowed by maintaining low reaction temperatures; however, this is usually at the expense of reaction efficiency. This was particularly evident in the but-1-enyl-substituted enol ether 17 rearrangement (entry 7, Table ) which must be carried out at −78 °C over a short reaction time because of its tendency to undergo Lewis acid mediated Prins cyclization reactions . Nonetheless, the fact that similar stereochemical trends to the Ti-mediated reaction can be observed at lower temperatures suggests that the reaction proceeds in a manner analogous to that mediated by TiCl 4 before epimerization processes take over.…”