A Simple and Mild Synthesis of 1H-Isochromenes and (Z)-1-Alkylidene-1,3-dihydroisobenzofurans by the Iodocyclization of 2-(1-Alkynyl)benzylic AlcoholsThe Journal of Organic Chemistry
Publication VersionPublished Version
AbstractA variety of iodo-substituted isochromenes, dihydroisobenzofurans, and pyranopyridines are readily prepared in good to excellent yields under mild conditions by the iodocyclization of readily available 2-(1-alkynyl)benzylic alcohols or 2-(1-alkynyl)-3-(hydroxymethyl)pyridines. Reactions are carried out in MeCN at 25 °C with 3 equiv of I2 as the iodine source and NaHCO3 (3 equiv) as the base. The regiochemical outcome of the reaction strongly depends on the substitution pattern of the starting material. In particular, the 5-exo-dig cyclization mode, leading to dihydroisobenzofurans, is observed in the case of substrates bearing a tertiary alcoholic group, owing to the gem-dialkyl effect, while the 6-endo-dig cyclization mode, leading to isochromene or pyranopyridines, is the usually preferred pathway in the case of substrates bearing a primary or secondary alcoholic group.
Copyright OwnerAmerican Chemical Society
Citation InformationRaffaella Mancuso, Saurabh Mehta, Bartolo Gabriele, Giuseppe Salerno, et al.. "A Simple and Mild Synthesis of 1H-Isochromenes and (Z)-1-Alkylidene-1,3-dihydroisobenzofurans by the Iodocyclization of 2-(1-Alkynyl)benzylic Alcohols" The Journal of Organic Chemistry Vol. 75 Iss. 3 (2009) p. 897 - 901
Available at: http://works.bepress.com/william_jenks/11/