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Pd- and Rh-Catalyzed Hydroarylation of γ-(2-Methoxycarbonylphenyl)propargylic Alcohols: Approaches to 4- or 5-Substituted Seven-Membered Benzolactones and 3,3-Disubstituted Phthalides
- Arcadi, Antonio, Fabrizi, Giancarlo, Goggiamani, Antonella, Marinelli, Fabio
- Journal of organic chemistry 2015 v.80 no.14 pp. 6986-6995
- acidification, alcohols, alkynes, iodides, phthalides, sodium hydroxide
- A study of the palladium-catalyzed hydroarylation/hydrovinylation reaction of γ-(2-methoxycarbonylphenyl)propargylic alcohols with aryl iodides/vinyl triflates and of the rhodium-catalyzed one with organoboron derivatives is described. The opposite regiochemical outcome of the two processes allows an easy selective approach to 5- or 4-substituted benzoxepin-1(3H)-ones by combining the hydroarylative/hydrovinylative step with cyclocondensation between −OH and −COOMe groups in the intermediate γ,γ-disubstituted or β,γ-disubstituted allylic alcohols. A one-flask procedure to give benzo[c]oxepin-1(3H)-ones directly from the starting alkyne has been also developed. Treatment of crude γ,γ-disubstituted allylic alcohols with NaOH, followed by acidification, affords 3,3-disubstituted phthalides.