incorporated into the side chains of 2- and 4-alkylpyridines participate in intramolecular aldol-like condensations with pyridine benzylic carbons in the presence of Brønsted acid catalysts. Pyridines featuring β-ketoamide side chains undergo cyclization in the presence of 10 mol% TfOH to afford pyridyl-substituted hydroxy lactams in good yield. These products were found to be resistant to further dehydration
在布朗斯台德酸催化剂的存在下,结合到2-和4-烷基
吡啶的侧链中的醛和酮亲电子试剂与
吡啶苄基碳一起参与分子内的醛醇状缩合。以β-酮酰胺侧链为特征的
吡啶在10摩尔%TfOH的存在下进行环化,以高收率得到
吡啶基取代的羟基内酰胺。已发现这些产物在各种条件下均能抵抗进一步的脱
水,但是用亚
硫酰氯处理引发了异常的脱
水/氧化反应顺序。相反,与胺键合的脂族醛与
吡啶的酸催化环化生成
吡啶基取代的脱氢
哌啶产物。相似地,