title: Cycloaddition across the benzofuran ring as an approach to the morphine alkaloids.
abstract: The intramolecular Diels-Alder reaction of several amidofurans tethered onto a benzofuran ring was examined as a strategy for the synthesis of morphine. Bromo substitution on the furan ring did not provide sufficient activation to allow the cycloaddition to take place across the aromatic benzofuran. However, the presence of a large o-methylbenzyl group on the amido nitrogen atom causes the reactive s-trans conformation of the amidofuran to be highly populated, thereby facilitating its Diels-Alder cycloaddition across a tethered benzofuran.
authors.affiliation: Department of Chemistry, Emory University, Atlanta, Georgia 30322, USA.
authors.forename: Stefan
authors.initials: S
authors.lastname: France
authors.forename: Jutatip
authors.initials: J
authors.lastname: Boonsombat
authors.forename: Carolyn A
authors.initials: CA
authors.lastname: Leverett
authors.forename: Albert
authors.initials: A
authors.lastname: Padwa
mesh_terms: D001572:Benzofurans / Q000737:chemistry*; D009020:Morphine / Q000138:chemical synthesis*
chemical_list: D001572:Benzofurans; D009020:Morphine; C105430:benzofuran