A novel one-pot, three-component access to hexahydropyrrolo[2,1-a]isoquinolines by an alkylation-dehydrohalogenation-1,3-dipolar cycloaddition sequence

A simple one-pot process for the alkylation of isoquinolines followed by a dehydrohalogenation of the quaternary salts formed and by an in situ trapping of azomethine ylides with appropriate dipolarophiles is described. This method has successfully been applied to the synthesis of benz[5,6]azepino[2, 1-a]isoquinolines and 5,6-dihydroindazolo[3,2-a]isoquinoline 8-oxides via an 1.7-electrocyclization process of similar type azomethine ylides.