PtCl2-catalyzed transannular cycloisomerization of 1,5-enynes:: A new efficient regio- and stereocontrolled access to tricyclic derivatives

(GRAPHICS) Transannular PtCL2-catalyzed cycloisomerizations open a new route to cyclopropanic tricyclic systems. Ketones A or C were efficiently prepared from the same cycloundec-5-en-1-yne precursor B, depending on the substituent at the propargylic position (either benzoate or methoxy).