Copper-catalyzed reaction with phenyl magnesium bromide gave alcohol 3 in 71% yield, following the reported procedure. Michael-addition of the latter with methyl propiolate (4) in the presence of DABCO afforded the needed diene 1. We mentioned that compound 1 partially decomposed during column chromatography and even under storage at room temperature. Therefore on the scale, we generated crude diene 1 in situ (please, see SI) and used it directly in the photochemical step. A mixture of isomers 1a was obtained. After extensive experimentation, we found a solution on how to avoid column chromatography, and not lose the yield. The crude reaction mixture after irradiation (isomers 1a and benzophenone) was saponified with sodium hydroxide. Standard workup (removal of benzophenone) followed by crystallization from hexane-MeOtBu mixture (removal of the minor isomer) allowed isolation of pure major isomer 1b in 71% yield after three steps from alcohol 3. Product 1b was obtained on a tengram scale with no column purifications involved. Scope. Next, we studied the scope of the developed method. The photocyclization tolerated well various substituents on the aromatic core (Scheme 2). Among them were the alkyl groups (5a-8a), fluorine (9a-11a) and chlorine atoms (12a, 13a), methoxy groups (14a-16a) and trifluoromethyl groups (17a-19a). The reaction was also compatible with various substituted pyridines (20a-24a). In all cases, we isolated analytical quantities of intermediate esters 5a-24a by column chromatography to characterize them. On the gram scale, however, we directly used crude reaction mixtures with 5a-24a after photocyclization in the subsequent saponification step. In half of all cases, we could obtain the final carboxylic acids by simple crystallization of crude reaction mixtures from various solvents (Scheme 2). In another half of the cases, column chromatography was still needed. The structure of carboxylic acids 5b and 9b was confirmed by X-ray crystallographic analysis (Figure ). Chemical stability. We also checked the chemical stability of three representative carboxylic acids 1b, 19b and 22b (Scheme 2), because we suspected that some of them could decompose via a retro-Michael type reaction. Treatment of them with aq. 1M hydrochloric acid, or aq. 1M aq. sodium hydroxide at room temperature for one day did not lead to any decomposition. All products were crystalline solids, and we stored all of them in closed vials at room temperature on the shelf. 1 H-NMR, LC-MS inspection after three months did not reveal any decomposition either.