Synthesis of Heterocyclic Monomers via Reissert Chemistry

The chemistry of Reissert compounds has been used to synthesize activated difluorotetraketone monomers containing two coupled isoquinolyl moieties, linked at either the 1,1'- or 4,4'-positions. These monomers offer routes to novel families of poly(heteroarylene ether)s. New 4,4'-coupled bis(Reissert compound) 9 containing 4,4'-diketo moieties failed to afford the desired difluorotetraketo monomer upon attempted rearrangement. However, analogous bis(Reissert compound) 19 containing 4,4'-dibenzyl units did so, via aldehyde condensation, hydrolysis of the intermediate ester and oxidation of the four benzylic moieties to keto groups; thus the novel difluorotetraketone monomer 10 was prepared. Novel bis(Reissert compound)s 24, 28, and 35 were synthesized from diacid chlorides and 4-(p-fluorobenzyl)isoquinoline. Rearrangement of 24 to the diketone 29, followed by oxidation of the 4-benzyl moieties resulted in difluorotetraketone monomer 30 containing a 1,1'-linked bisisoquinoline. The 1,1'-linked bis(isoquinolylfluorodiketo) monomer 38, isomeric with 10, was prepared from 4-(p-fluorobenzyl) Reissert compound 36 by condensation with terephthaldehyde, ester hydrolysis to diol 37, and oxidation. In the course of this effort, a number of new isoquinoline Reissert compounds were synthesized as model systems. (C) 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3856-3867, 2010