Asymmetric synthesis of drug-like spiro[chroman-3,3′-indolin]-2′-ones through aminal-catalysis
作者:Dhevalapally B. Ramachary、M. Shiva Prasad、S. Vijaya Laxmi、R. Madhavachary
DOI:10.1039/c3ob42100g
日期:——
Asymmetric synthesis of drug-like functionalized spiro[chroman-3,3â²-indolin]-2â²-ones 5 containing three contiguous stereocenters with high diastereo- and enantioselectivities was achieved using the reflexive-Michael (r-M) reaction of unmodified hydroxyenals 1 with various (E)-3-alkylideneindolin-2-ones 2 in the presence of (R)-DPPOTMS/AcOH (R)-3/4b as a catalyst at room temperature. Chiral spiro[chroman-3,3â²-indolin]-2â²-ones 5 were transformed into the functionalized spiranes 7, 9, and 10 in good yields with high selectivity through Wittig, TCRA, acetal protection and reduction reactions, respectively. Supporting evidence for the reaction pathway through the formation of the important catalytic species of âaminalsâ was observed through NMR and ESI-HRMS analysis of an ongoing reaction between 1 and (R)-3 in CDCl3 and also shown by the structural requirement in hydroxyenals 1 to generate the âaminalsâ with (R)-3 through controlled experiments.
成功实现了药物类似物功能化的Spiro[chroman-3,3′-indolin]-2′-酮5的非对称合成,该化合物含有三个相邻的立体中心,并具有高的二面体和对映选择性。通过在室温下,使用未修饰的羟基醛1与各种(E)-3-烯基吲哚-2-酮2的反射迈克尔(r-M)反应,在催化剂(R)-DPPOTMS/醋酸(R)-3/4b的存在下进行的合成。手性Spiro[chroman-3,3′-indolin]-2′-酮5经过维蒂希反应、TCRA反应、保护反应和还原反应相继转化为功能化的旋转体7、9和10,且均具有良好的产率和高选择性。通过NMR和ESI-HRMS分析观察到在CDCl3中1与(R)-3的进行反应中形成重要催化物种“亚胺”的反应途径的支持证据,并且通过对羟基醛1进行控制实验显示了生成“亚胺”与(R)-3之间的结构需求。