反应详情

When phenylmagnesium bromide (a) or phenyllithium (b) is used in place of 3-pyridylmagnesium bromide, the phenylcarbinol enol ether 13 arises (Scheme 3). This is refluxed with acetic anhydride (c) or dehydrated with phosphorous oxychloride and pyridine (d) and hydrolyzed with aqueous hydrochloric acid (e) to give 2-phenyl-2-cyclohexenone (14). Reduction of 14 with sodium borohydride and cerium chloride in methanol (f) provides the allylic alcohol 15 which is dehydrated (d) to 2-phenyl-1,3-cyclohexadiene 16. Reaction of 16 with tertiary butyl nitrosoformate (2) as in Scheme 1, provides the Diels-Alder cycloadduct 17, which can be converted in four steps to (±) exo-2-phenyl-7-azabicyclo[2.2.1]heptane (18), the phenyl analog of epibatidine. ##STR6##