1623009-01-7Relevant articles and documents
Palladium-Catalyzed Site-Selective Benzocylization of Aromatic Acids with o-Fluoro-Substituted Diaryliodonium Salts toward 3,4-Benzocoumarins
Pan, Cheng,Wang, Limin,Han, Jianwei,Han, Jianwei
, p. 4776 - 4780 (2020)
By using 2-fluoro-substituted diaryliodonium salts, a novel benzocylization has been accomplished for the synthesis of 3,4-benzocoumarin derivatives via a cascade of ortho-arylation and defluorination in the presence of palladium catalysts. The reaction exhibits a broad compatibility of readily available aromatic acids with an excellent level of site-selectivity. Mechanistic investigations revealed a unique reactivity of carboxylic acid directed arylation by followed nucleophilic substitution of aromatic fluoride in the present system.
Green and Rapid Access to Benzocoumarins via Direct Benzene Construction through Base-Mediated Formal [4+2] Reaction and Air Oxidation
Mou, Chengli,Zhu, Tingshun,Zheng, Pengcheng,Yang, Song,Song, Bao-An,Chi, Yonggui Robin
, p. 707 - 712 (2016/03/09)
Benzocoumarin is an important structural motif widely found in natural products and synthetic molecules. Traditional methods for the synthesis of benzocoumarins and their derivatives require multiple steps, typically with an intramolecular ester forming reaction to make the lactone ring as the last step. Another major method involves transition metal-catalyzed coupling or carbon-hydrogen bond activation reactions starting with pre-existing aryl frameworks in the substrates. Here we report a new strategy for the green and rapid access to benzocoumarins and their derivatives. Our method uses readily available unsaturated aldehydes and coumarins as the substrates and air as the green oxidant. The overall reaction proceeds through a formal [4+2] process to construct a new benzene ring and thus to afford benzocoumarins in essentially a single step. No metal catalysts were used; no toxic or expensive reagents were involved. The power of our new approach is further demonstrated in a concise formal total synthesis of cannabinol, a bioactive natural product.
