SYNTHETIC ROUTES TO BRIDGED DICYCLOOCTATETRAENES AND ALKYNYLCYCLOOCTATETRAENES

Dicyclooctatetraenylethyne, (E)-1,2-dicyclooctatetraenylethylene and 1,4-dicyclooctatetraenylbenzene (3a-c) have been prepared through a convergent synthesis by the palladium-catalyzed couPling of 1,2-bis(tributylstannyl)ethyne, (E)-1,2-bis(tributylstannyl)ethylene, and 1,4-bis(tributylstannyl)benzene (2a-c), respectively, with bromocyclooctatetraene (1). Modified Stille coupling conditions with tri(2-furyl)phosphine and triphenylarsine as ligands were employed. Alkynylcyclooctatetraenes, including 3a, have been prepared by the palladium/copper-catalyzed coupling of terminal alkynes with 1. Bridged dicyclooctatetraenes 3a and 3c were also prepared through a linear synthesis starting from 2,6-cyclooctadien-1-one.