{"query": "What is the primary product of photodimerization?", "pos": "sensitization is also the preferred way to promote coumarin and many of its derivatives into the excited state. in the absence of an external olefin, [ 2  +  2 ] photodimerization occurs with the hh cis-anti-cis product (rac-317, figure 15) being the major product. in benzene as the solvent and with benzophenone as triplet sensitizer, yields over 90% were achieved by ding and co-workers. compound rac-317 served as the starting material for the synthesis of new phosphane ligands."}
{"query": "What's a basic challenge in the [2 + 2] photocycloaddition reactions?", "pos": "the requirement of an aryl enone was a fundamental obstacle in the [ 2  +  2 ] photocycloaddition reactions, which limited the application of this methodology. in order to overcome this problem, the yoon group described a visible-light-induced [ 2  +  2 ] photocycloaddition reaction of,-unsaturated 2-imidazolyl ketones such as 483 (scheme 163, dbu = 1,8-diazabicyclo[5.4.0]undec-7-ene)."}
{"query": "Dry AMD causes photoreceptors to break down because the retinal pigment epithelium, which supports retinal neurons, isn't working properly.", "pos": "intravitreal anti-vegf therapies have emerged as a standard of care to treat wet amd ; however, there is currently no fda-approved treatment available for the dry form. thus, safe and effective treatment of dry amd remains a critical unmet need. atrophic (dry) form of amd represents a slowly progressing neurodegenerative disorder of the eye in which specialized retinal neurons (rod and cone photoreceptors) degenerate in the central part of the retina called macula. histopathological and clinical data suggest that photoreceptor degeneration in dry amd is triggered by abnormalities in the retinal pigment epithelium (rpe) that lies beneath photoreceptors and provides critical metabolic support to these light-sensing neuronal cells."}
