SYNTHESIS OF ETHYNYL-SUBSTITUTED QUINQUEPHENYLS AND CONVERSION TO EXTENDED FUSED-RING STRUCTURES

An organometallic coupling, electrophile-induced cyclization strategy for the synthesis of p-terphenyl compounds has been extended to the sy nthesis of p-quinquephenyl systems. In this work we report the synthes is of various polycyclic aromatic systems containing nine annelated ri ngs including the synthesis of functionalized polycyclic aromatic syst ems. An interesting side reaction which leads to an indenyl spiro ring system is also described. This side reaction can be suppressed by cha nging the electrophile (from H+ to I+) or by modification of the cycli zation precursor. The UV-vis and fluorescence spectra of several of th ese polycyclic aromatics and the p-quinquephenyl precursors are also r eported.