依靠商业上可买到的催化剂构件的组装,已经实现了具有无与伦比的底物多样性的高度立体控制的季碳(所有碳取代的)形成。例如,三组分催化剂体系的原位组装允许将α-支链醛加成到硝基烯烃或马来酰亚胺亲电试剂中(Michael产品),而将α-支链醛加成可以得到曼尼希反应产物。观察到非常高的收率,在18个实例中,有15个实例的96-99%ee被观察到。使用外消旋的α-支链醛,可以通过高效的原位动态动力学拆分在高非对映异构体和对映体过量(八个实例)中形成两个连续的(四级-三级)立体中心,尤其是解决了已知的马来酰亚胺亲电试剂的缺点。该方法具有实用价值,仅需要1.2当量的醛,每种催化剂组分的负载量为5.0 mol%,例如O- t Bu- L-苏氨酸(O- t Bu- L- Thr),磺酰胺,DMAP或O-吨BU-大号-Thr,KOH,和室温下的反应。作为亮点,乙基异戊醛(7公开了添加),提供迄今已知的最拥挤的含
4-Aminothiourea Prolinol<i>tert</i>-Butyldiphenylsilyl Ether: A Chiral Secondary Amine-Thiourea as Organocatalyst for Enantioselective<i>anti</i>-Mannich Reactions
anti-Selective Mannich reactions of N-p-methoxyphenyl (PMP)-protected α-iminoglyoxylate with unmodified aldehydes or ketones were effectively catalyzed by 4-aminothiourea prolinol tert-butyldiphenylsilyl ether. The reactions led to chiral β-amino carbonyl compounds in high yields (up to 94%), excellent diastereo- and enantioselectivities (up to 98% de and >99% ee). The study demonstrated for the first
抗的-选择性曼尼希反应ñ - p -甲氧基苯基(PMP)与未改性的醛或酮-保护的α-iminoglyoxylate得到有效利用4-氨基硫脲脯氨醇催化叔-butyldiphenylsilyl醚。反应导致高收率(高达94%),出色的非对映异构和对映选择性(高达98%de和> 99%ee)的手性β-氨基羰基化合物。该研究首次证明,仲胺-硫脲手性有机催化剂可促进未修饰醛或酮与α-亚氨基乙醛酸酯的直接曼尼希型反应。
3-Trifluoromethanesulfonamido-pyrrolidine: A General Organocatalyst for <i>anti</i>-Selective Mannich Reactions
Mannich-type reactions of a glyoxylate imine with carbonyl compounds catalyzed by 3-trifluoromethanesulfonamidopyrrolidine proceed with high yields and anti-stereoselectivity. The catalyst is easily prepared and the transformation appears to be quite general accommodating aldehydes or ketones.