Facile Synthesis of Cyclic Polyphenylenes by Consecutive Inter- and Intramolecular Cycloadditions of ortho-, meta-, and para-Phenylene-Tethered Triynes

Abstract

Consecutive inter- and intramolecular [2+2+2] cycloadditions of various phenylene-tethered triynes were comprehensively studied by using chiral rhodium catalysts. <i>ortho</i>-Phenylene-tethered triynes gave chiral <i>o</i>,<i>o</i>,<i>o</i>,<i>o</i>-tetraphenylenes in high-to-excellent enantiomeric excess as dimers. <i>meta</i>-Phenylene-tethered triynes gave chiral <i>o</i>,<i>m</i>,<i>o</i>,<i>m</i>-tetraphenylenes in moderate enantiomeric excess as dimers along with hexaphenylenes as trimers. This is the first synthesis of <i>cis</i>-<i>o</i>,<i>m</i>,<i>o</i>,<i>m</i>-tetraphenylenes; one structure was ascertained by X-ray crystal structure analysis. <i>para</i>-Phenylene-tethered triynes gave <i>o</i>,<i>p</i>,<i>o</i>,<i>p</i>,<i>o</i>,<i>p</i>-hexaphenylenes as trimers along with the formation of <i>o</i>,<i>p</i>,<i>o</i>,<i>p</i>,<i>o</i>,<i>p</i>,<i>o</i>,<i>p</i>-octaphenylenes as tetramers. 1 Introduction 2 Results and Discussion 2.1 <i>ortho</i>-Phenylene-Tethered Triynes 2.2 Naphthylene-Tethered Triynes 2.3 <i>meta</i>-Phenylene-Tethered Triynes 2.4 <i>para</i>-Phenylene-Tethered Triynes 3 Conclusion