A Novel Synthesis of Berbines- Condensation of 2-(3,4-Dimethoxyphenyl) Ethyl Bromide with 1,4-Dihydro-6,7-Dimethoxy-3 (2H) Isoquinolone-Synthesis of (+)-Xylopinine

Abstract

Recently we reported an efficient synthesis of the berbine alkaloids^3,4 by the use of the bromo esters⁵ prepared from 3-isochromanones. Now a new general synthetic route to the berbine alkaloids beginning with the condensation of the phenethylbromide 3 and 3-(2H) isoquinolone 2 is being described. The method gains added advantage of placing desired substitution on both rings A and D of the berbine, emerging from the easy availability of the starting compounds. In conclusion, the present results have not only added one more efficient example to more than a dozen successful procedures of the berbine synthesis⁶ but also offer a potential route to the structurally parallel indoloquinolizidine alkaloids.