Fluorenylidene biphenylene

Miyatake et al. have combined two strategies in a single polymer architecture (multiblock copolymers containing sulfonic acid clusters in their hydrophilic blocks) [62]. They have successfully synthesized a series of multiblock poly (arylene ether sulfone ketone)s (SPESKs) containing fully sulfonated fluorenylidene biphenylene units (Fig. 7.23) [63, 64]. The well-controlled post-sulfonation reaction of the precursor polymers enabled preferential sulfonation on... 

Fig. 7.23 Multiblock poly(arylene ether sulfone ketone)s (SPESKs) containing fully sulfonated fluorenylidene biphenylene units...

The formation of reactive carbenes from alkylidene Meldrum s acids has also been observed. Thus pyrolysis of 1-indanylidene Meldrum s acid at 640 °C gave the corresponding carbene which further rearranged to benzofulvene and naphthalene (Scheme 12) <1998JA8315>. Similarly, EVP of 9-fluorenylidene Meldrum s acid at 1100°C provided a mixture of phenanthrene and biphenylene <1996TL6819>. 

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