Substituent effects in the ring-chain tautomerism of 4-aryl-1,3,4,6,7,11b-hexahydro-2H-pyrimido[6,1-a]isoquinolines
作者:Zita Zalán、Anasztázia Hetényi、László Lázár、Ferenc Fülöp
DOI:10.1016/j.tet.2005.03.067
日期:2005.5
substituted benzaldehydes, 1,6-unsubstituted and diastereomers of 1-methyl- or 6-methyl-substituted 4-aryl-9,10-dimethoxy-1,3,4,6,7,11b-hexahydro-2H-pyrimido[6,1-a]isoquinolines were prepared. The ring-chain tautomeric equilibria of most of these compounds in CDCl3 at 300 K were found to be shifted nearly totally towards either the cyclic or the open tautomeric forms, while the (6R*,11bR*)-6-methyl substituted
通过将1-(2'-氨基乙基)-1,2,3,4-四氢异喹啉衍生物与取代的苯甲醛,1,6-未取代的和1-甲基或6-甲基取代的4-芳基-9的非对映异构体缩合,制备10-二甲氧基-1,3,4,6,7,11b-六氢-2 H-嘧啶基[6,1- a ]异喹啉。发现大多数化合物在300 K时在CDCl 3中的环链互变异构平衡几乎完全向环状或开放式互变异构形式转移,而(6 R *,11b R*)-6-甲基取代的化合物被证明是三组分互变异构混合物,其平衡可以通过Hammett型方程表征。证明环状形式的构象平衡受1-和6-甲基取代基以及取代的碳原子(C-1或C-6和C-4)相对于C-11b的构型的强烈影响。