Synthesis of bridged medium-sized rings through the intramolecular Pauson-Khand reaction

by Lovely, Carl J.; Seshadri, Hemalatha; Wayland, Brian R.; Cordes, A. Wallace

[GRAPHICS] A series of aromatic enynes containing steric buttressing elements were prepared and evaluated in the NMO-mediated Pauson-Khand cyclization. O-Allyl systems led to the expected angularly fused products, whereas the O-butenyl and O-pentenyl derivatives afforded the unprecedented bridge systems.