An efficient and recyclable homogeneous catalyst is developed using commercially cheap l-proline and melamine for the synthesis of chromenes and spirochromenes (spirooxindoles) via multicomponent reactions at room temperature. Systematic studies were conducted in order to achieve desired reactivity and recyclability of the catalyst using various α-amino acids and aromatic amines as donor-acceptor pairs. Among the screened combinations, l-proline and melamine (3:1 ratio; 3 mol% on total weight) was found to be best catalyst to give the desired products with excellent yields (up to 99%) in very short times (1–15 min) at room temperature in DMSO as solvent. The catalyst was recovered by adding EtOAc and reused up to 5 cycles without losing the catalytic activity.

使用便宜的1-脯氨酸和三聚氰胺开发了一种有效且可循环使用的均相催化剂，用于在室温下通过多组分反应合成色烯和螺环色酮（螺并辛多烯）。为了使用各种α-氨基酸和芳族胺作为供体-受体对，进行系统研究以实现所需的反应性和催化剂的可回收性。在筛选的组合中，l脯氨酸和三聚氰胺（3：1的比例；占总重量的3 mol％）被认为是最佳的催化剂，可以在室温下非常短的时间内（1-15分钟）以优异的产率（高达99％）提供所需的产品在DMSO中作为溶剂。通过添加EtOAc来回收催化剂，并且在不损失催化活性的情况下重复使用多达5个循环。