Enantioselective Synthesis of Nine- to Eleven-Membered Cyclic Polyphenylenes Containing Heteroatoms by Catalytic Intramolecular [2+2+2] Cycloaddition

Rh-catalyzed enantioselective intramolecular reactions of triynes consisting of 1,6-diyne and 1,10-diyne moieties tethered by sulfur or oxygen and ortho-phenylene moieties proceeded to give chiral tetrabenzoheteronines possessing a nine-membered ring system as [2+2+2] cycloadducts. In the reaction of triynes consisting of 1,6-diyne and 1,11-diyne moieties, sulfur-tethered substrates gave chiral metacyclophanes with an eleven-membered ring system, whereas an oxygen- and sulfur-tethered substrate afforded a tetrabenzo-1,4-oxathiecine with a ten-membered ring system. The mechanisms of the different reaction pathways depending on the heteroatom of the tether are discussed.