Aryl radical cyclizations: one-Pot syntheses of protoberberine and pavine alkaloids.
Treatment of 2-(2'-bromo-beta-phenethyl)isocarbostyrils 7 with AIBN-Bu(3)SnH in boiling benzene gave 8-oxoberbines 3 in good yields. A similar treatment of 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 radical cyclization of 1-(2'-bromobenzyl)isoquinoline methiodide 18a gave a pavine alkaloid, (+/-)-algemonine (19a).
Orito
K
K
Laboratory of Organic Synthesis, Division of Molecular Chemistry, Graduate School of Engineering, Hokkaido University, Sapporo 060-8628, Japan. orito@org-mc.eng.hokudai.ac.jp
Satoh
Y
Y
Nishizawa
H
H
Harada
R
R
Tokuda
M
M
D000470:Alkaloids / Q000138:chemical synthesis* / Q000737:chemistry; D001600:Berberine Alkaloids / Q000138:chemical synthesis* / Q000737:chemistry; D007202:Indicators and Reagents; D008958:Models, Molecular; D008968:Molecular Conformation; D013329:Structure-Activity Relationship
D000470:Alkaloids; D001600:Berberine Alkaloids; D007202:Indicators and Reagents; C009090:protoberberine