247579-54-0Relevant articles and documents
Synthesis of phthalideisoquinoline and protoberberine alkaloids and indolo[2,1-α]isoquinolines in a divergent route involving palladium(0)- catalyzed carbonylation
Orito, Kazuhiko,Miyazawa, Mamoru,Kanbayashi, Ryo,Tokuda, Masao,Suginome, Hiroshi
, p. 6583 - 6596 (2007/10/03)
6,7,3',4'-Alkoxy-substituted 1-(2'-bromobenzoyl)-3,4-dihydroisoquinoline methiodides 17 were treated with sodium borohydride in methanol or acetic acid to give erythro-1-(2'-bromo-α-hydroxybenzyl)-2-methyl-1,2,3,4- tetrahydroisoquinolines 19. Treatment of 17 with lithium aluminum hydride in tetrahydrofuran gave the threo-isomer 20 in preference to the erythro 19. On the basis of studies on palladium(0)-catalyzed carbonylation of 2-bromo-3,4- dimethoxybenzyl alcohol to 6,7-dimethoxyphthalide, amino alcohol 19 or 20 was treated with a catalytic amount of palladium(II) acetate and triphenylphosphine in an atmosphere of carbon monoxide in the presence of chlorotrimethylsilane and potassium carbonate in boiling toluene to give the corresponding erythro- or threo-types of phthalideisoquinoline alkaloids 1 or 2, respectively. One-pot cyclization of the erythro-amino alcohols 19 was achieved by heating in N,N-dimethylformamide containing potassium carbonate to give 2,3,8,9- or 2,3,9,10-alkoxy-substituted 5,6-dihydroindolo[2,1- α]isoquinolines 3, which have a unique tetracyclic skeleton characteristic of dibenzopyrrocoline alkaloids. Similarly, palladium-(0)-catalyzed carbonylation of 1-(2'-bromobenzyl)tetrahydroisoquinolines 21 in the presence of excess potassium carbonate was found to give 8-oxoberbines 22, which on reduction with lithium aluminum hydride can be converted to protoberberine alkaloids 4.
