Diversity diarylethenes

The photoinduced reaction of chloranil with various 1,1-diarylethenes is another example of an intramoleclar [2 -I- 2] cycloaddition as reported by Xu and co-workers [86]. Although not interesting from the preparative point of view, the diverse reaction outcomes caused by parallel reaction pathways with and without single-electron transfer and various secondary reactions of the primary products show that the photochemistry involving haloquinones is far from being explored. Another interesting example in this context is the reaction of dichlorobenzoqui-none with various diarylacetylenes in the solid phase via photoinduced electron transfer as reported by Kochi and co-workers [87]. Here, time-resolved spectroscopy revealed the radical ion pair of the two reactants to be the first reactive intermediate that then underwent coupling. 

Scheme 5.8 Programmable and diversity oriented synthesis of diarylethenes 43 and triarylethenes 44 (a) [Pd2(dba3)], P(2-furyl)3, NEt3, THF, 60°C (b) PdCI2(PhCN)2, Bu4NF, THF, 60°C.

Photochromic LC polymers are usually synthesized via the copolymerization of mesogenic monomers with photochromic mesogenic or nonmesogenic monomers similar to the synthesis of chiral LC polymers (Figure 19), hut, instead of a chiral monomer, a photochromic monomer is used as a mle, its concentration varies from 10 to 60mol.%. Diverse derivatives of azobenzene, spiropyran, diarylethenes, dnnamates, and coumarin-containing derivatives are used as photoactive fragments. 

Diverse Studies from Japanese Project Cluster 11.4.14.1 Synthesis of Photochromic Diarylethenes... 

---