2-(2'-bromo-beta-phenethyl)isoquinolinium bromides 6 and their nor- and homoanalogues (10,11) induced 6-, 5-, and 7-exo radical closures in a one-pot manner to give protoberberines 2, dibenzo[b,g]indolizidine 14a and, dibenzo[a, h]-1-azabicyclo[5.4.0]undecane 15a, respectively. A one-pot radicalcyclization of 1-(2'-bromobenzyl)isoquinoline methiodide 18a gave a pavine alkaloid, (+/-)-algemonine (19a).
The affinities of tetrahydroprotoberberines for dopaminereceptors dramatically decrease after cleaving the central C‐N bond to the analogous ten‐membered dibenzo[c,g]azecines [1]. In the present work, we also synthesized eleven‐membered homologues of these heterocycles and measured the affinities of the resulting dibenzazaundecenes and their underlying homoberberines for human dopaminereceptors as