Stereoselective Synthesis of 7-(E)-Arylidene-2-chloro-6-azabicyclo[3.2.1]octanes via Aluminum Chloride-Promoted Cyclization/Chlorination of Six-Membered Ring 3-Enynamides

An efficient stereoselective synthesis of 7-(E)-arylidene-2-chloro-6-azabicyclo[3.2.1]octanes is described. The aluminum chloride-promoted cyclization/chlorination of six-membered ring 3-enynamides enables a straightforward approach to the 6-azabicyclo[3.2.1]octane nucleus that is incorporated in many biologically active compounds. Acid treatment of the resultant chlorinated arylideneazabicyclooctanes furnishes 3-alkanoyl-4-chlorocyclohexanamines in excellent yields and high stereoselectivity. (Figure presented.).