Synthesis of Chiral and Cyclic pai-Conjugated System Using Cycloaddition

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We achieved an easy-to-use protocol for the synthesis of substituted o,o,o,o-tetraphenylenes: two triynes with phenylene-bridged 1,5-diyne moiety was homo-coupled by consecutive inter- and intramolecular [2+2+2] cycloadditions, and tetraphenylenes were obtained with good to excellent enantiomeric excess. We further examined meta-phenylene tethered triynes and achieved the first construction of o,m,o,m-tetraphenylenes in cis-form. In addition to the tetraphenylenes as dimers, o,m,o,m,o,m-hexaphenylenes were also obtained as trimers. In the reaction of para-phenylene tethered triynes, o,p,o,p,o,p-hexaphenylenes were major products along with the formation of o,p,o,p,o,p,o,p-octaphenylenes as tetramers.