Newly prepared, stable aroyldiaziridines of 3,4-tetrahydroisoquinolines undergo regioselective
cycloaddition reactions with a number of both mono and disubstituted alkynes, affording
five-membered ring products which, after oxidative aromatization of the pyrazoline
ring, lead to the efficient preparation of pyrazolo[5,1-a]isoquinolines. The overall transformation is base-catalyzed and occurs more rapidly
in the presence of oxygen, in halogenated solvents and in dioxane.
isoquinolines - diaziridines - cycloadditions - alkynes - oxidations