(±)-2,3-dialkyl-1,2,3,4-tetrahydroquinoline-3-carboxylic esters by a tandem reduction-reductive amination reaction
作者:Richard A. Bunce、James E. Schammerhorn、LeGrande M. Slaughter
DOI:10.1002/jhet.5570440512
日期:2007.9
alkyl cis to the C3 ester. The product ratios were synthetically useful (6-16:1), but less than that observed in cyclizations to prepare (±)-2-alkyl-1,2,3,4-tetrahydroquinoline-4-carboxylic esters. The reduced selectivity in the current reactions has been rationalized in terms of the greater conformational mobility around the ester bearing carbon, which decreases the ability of the ester to sterically influence
一系列2-甲基-2-(2-硝基苄基)取代的β-酮酯衍生物已在氢化条件下进行了还原环化反应,以评估酯基位置对该方法的非对映选择性的重要性。在4个大气压下在5%钯碳上氢化可导致形成(±)-2,3-二烷基-1,2,3,4-四氢喹啉-3-羧酸酯,优选具有C2烷基顺式到C3酯。产物比率可用于合成(6-16:1),但低于在环化中制备(±)-2-烷基-1,2,3,4-四氢喹啉-4-羧酸酯所观察到的比率。根据围绕酯的碳周围更大的构象迁移率,已经合理地解释了当前反应中降低的选择性,这降低了酯在空间上影响氢向最终亚胺中间体的加成的能力。