Fulgimides yield

However, the synthesis of meta and para derivatives 195, as well as 197, from fulgimide 196 requires even more drastic conditions. The reaction occurred only at high pressure (10 kbar) the yield of para-substituted photochrome 195 was 57% the yield of the meta isomer was 34% the yield of hybrid 197 was 11%. Hybrid product 199, in which the photochromic fragments are directly linked to each other by an N-N bond, was synthesized similarly (06MI1) from fulgimide 198 (Scheme 58). 

Five years later, Gust s group [34] developed another triad incorporating a porphyrin (P) linked to a dithienylethene (DTE) and a fulgimide (FG) (Scheme 6). The main synthetic approach was still the Sonogashira coupling of dithienylethene and fulgimide-appended zinc porphyrin (FG-PZn-DTE). Trifluoroacetic acid-induced demetalation of FG-PZn-DTE produced FG-P-DTE in 57% yield. 

A wide range of aryl and heterocyclic fulgimides with structure 5 have been prepared. Their overall yields and melting points are summarized in Table 4.20. 

Table 4.20. Synthetic Overall Yield and Melting Point of Fulgimides 5...

Table 4.21. Quantum Yield of Photocyclization Reaction of Fulgides and Fulgimides in Solution and Polymer Matrix51 91...

Source Based on V, Deblauwe and G. Smets, Quantum yields of the photochromic reactions of heterocyclic fulgides and fulgimides, Makromol. Chem, 189, 2503-2512 (1988). 

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