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By irradiating a stirred mixture of several stilbazoles with solid oxalic acid dihydrate dispersed in a nonpolar (i.e., cyclohexane) or moderately polar (benzene, dichloromethane, dioxane) solvent, the corresponding dimeric cyclobutane adducts were obtained in high yields and excellent regio\u2010 and stereoselectivities. The strategy could also be applied successfully to oily, waxy, or even insoluble stilbazoles. Moreover, the oxalic acid loading could be lowered to substoichiometric amounts. When further optimizations were needed, our strategy was found to be highly flexible to identify other oligocarboxylic acids as alternative additives to improve, or even overturn, the regioselectivity. Oxalic acid and other oligocarboxylic acids were found to be capable of orienting more than 50 stilbazoles toward photodimerization under these conditions.<\/jats:p>","DOI":"10.1002\/chem.201905597","type":"journal-article","created":{"date-parts":[[2020,1,16]],"date-time":"2020-01-16T11:12:45Z","timestamp":1579173165000},"page":"4682-4689","update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":20,"title":["[2+2] Photodimerization of Stilbazoles Promoted by Oxalic Acid in Suspension"],"prefix":"10.1002","volume":"26","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-8779-9641","authenticated-orcid":false,"given":"Thanh Binh","family":"Nguyen","sequence":"first","affiliation":[{"name":"Institut de Chimie des Substances Naturelles, CNRS UPR 2301 Universit\u00e9 Paris-Saclay  1 avenue de la Terrasse 91198 Gif-sur-Yvette France"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Tuan 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