Studies on 1,2,3,4-tetrahydroisoquinolines. V. A convenient synthesis of (.+-.)-5,7-dihydroxy-1-(3,4,5-trimethoxybenzyl)-1,2,3,4-tetrahydroisoquinoline (racemic TA-073).
作者:KOICHIRO YAMADA、MIKIO TAKEDA、NOBUO ITOH、HISAO OHTSUKA、AKIRA TSUNASHIMA、TAKEO IWAKUMA
DOI:10.1248/cpb.30.3197
日期:——
A convenient synthetic route to (±)-5, 7-dihydroxy-1-(3, 4, 5-trimethoxybenzyl)-1, 2, 3, 4-tetrahydroisoquinoline (racemic TA-073), an orally active bronchodilator, through the cyclization of the amine 4 or its N-acyl derivative (10b, c) is presented. Catalytic reduction of 4 over 10% Pd-C in EtOH-H2O in the presence of oxalic acid (6 eq) afforded racemic TA-073 in 65% yield. The acid-catalyzed reaction of 10b, c was also investigated. Cyclization of 10b, c with 1 N HCl (1 eq) in THF gave the corresponding N-acyl enamine 12b, c in quantitative yield. Further treatment of 12b with conc. HCl in THF afforded the pavine derivative 14 in 80% yield. Cyclization of 10b with neat HCOOH, however, resulted in the formation of the isopavine derivative 11b in 80% yield. This result parallels the reported observation by McDonald et al.
本文介绍了通过胺 4 或其 N-酰基衍生物 (10b, c) 的环化反应制备 (±)-5,7-二羟基-1-(3,4,5-三甲氧基苄基)-1,2,3,4-四氢异喹啉(外消旋 TA-073)的简便合成路线,TA-073 是一种口服活性支气管扩张剂。在草酸(6 eq)存在下,在 EtOH-H2O 中用 10% Pd-C 催化还原 4,得到外消旋 TA-073,收率为 65%。还研究了 10b、c 的酸催化反应。在 THF 中用 1 N HCl(1 eq)使 10b, c 环化,得到相应的 N-酰基烯胺 12b,c,产率为定量。用 THF 中的浓盐酸进一步处理 12b,可得到帕维宁衍生物 14,收率为 80%。然而,用纯净的 HCOOH 对 10b 进行环化处理后,生成了异巴维因衍生物 11b,收率为 80%。这一结果与 McDonald 等人报告的观察结果相似。