A Facile Route to Indolo
Treatment of 1-(2'-bromobenzyl)-3,4-dihydroisoquinolines 2 in the presence of K(2)CO(3) in boiling DMF efficiently provided a variety of alkoxy-substituted indolo[2,1-a]isoquinolines 3. Application of this cyclization to 7-benzyloxyisoquinoline derivatives, followed by further elaboration of the resultant 2-benzyloxy-5,6-dihydroindolo[2,1-a]isoquinolines 16a,b, led to the formal synthesis of dibenzopyrrocoline alkaloids, (+/-)-cryptaustoline (1a) and (+/-)-cryptowoline (1b).
Orito
K
Laboratory of Organic Synthesis, Division of Molecular Chemistry, Graduate School of Engineering, Hokkaido University, Sapporo 060-8628, Japan.
Harada
R
Uchiito
S
Tokuda
M