A chiral Lewisbaseorganocatalyzedenantioselectivehydrosilylation of 1,4-benzoxazines is presented. The reactions afforded various enantioenriched 3-substituted dihydro-2 H -1,4-benzoxazines with high yields (up to 98%) in moderate enantioselectivities (up to 87% ee).
提出了一种手性路易斯碱有机催化的 1,4-苯并恶嗪的对映选择性氢化硅烷化。该反应以中等对映选择性(高达 87% ee)的高产率(高达 98%)提供了各种对映体富集的 3-取代二氢-2 H -1,4-苯并恶嗪。
The highly enantioselective hydrogenation of 3-aryl-2H-1,4-benzoxazines was achieved using the (cyclooctadiene)iridium chloride dimer/(S)-SegPhos/iodine [Ir(COD)Cl]2/(S)-SegPhos/I2} system as catalyst with up to 92% ee. The 3-styryl-2H-1,4-benzoxazine derivatives were also hydrogenated by the iridium catalyst and Pd/C in two consecutive steps whereby 93–95% ee values were obtained.
使用(环辛二烯)铱氯化二聚物/(S)-SegPhos /碘[Ir(COD)Cl] 2 /(S)-SegPhos实现对3-芳基2 H -1,4-苯并恶嗪的高度对映选择性氢化/ I 2 }体系作为催化剂,ee最高可达92%。3-styryl-2 H -1,4-苯并恶嗪衍生物还通过铱催化剂和Pd / C在两个连续的步骤中进行氢化,从而获得93-95%ee值。
Biocatalytic asymmetric Mannich reaction of ketimines using wheat germ lipase
作者:Ling-Ling Wu、Yang Xiang、Da-Cheng Yang、Zhi Guan、Yan-Hong He
DOI:10.1039/c5cy01923k
日期:——
highly enantioselective Mannichreaction between 3-substituted-2H-1,4-benzoxazines and acetone catalyzed by lipase from wheat germ type I (WGL) is described. Enantioselectivity of up to 95% ee was achieved in DMSO at 25 °C. This research provides a new and simple method for the synthesis of β-amino ketone derivatives and promotes the development of enzyme-catalyzed Mannichreactions.
描述了由I型小麦胚芽(WGL)的脂肪酶催化的3-取代-2 H -1,4-苯并恶嗪与丙酮之间的高度对映选择性曼尼希反应。在25°C的DMSO中,对映体选择性高达95%ee。该研究为合成β-氨基酮衍生物提供了一种新的简便方法,并促进了酶催化曼尼希反应的发展。
Synthesis of spiropyrans <i>via</i> the Rh(<scp>iii</scp>)-catalyzed annulation of 3-aryl-2<i>H</i>-benzo[<i>b</i>][1,4]oxazines with diazo ketoesters
Rh(III)-catalyzed 1:2 coupling of 3-aryl-2H-benzo[b][1,4]oxazines with α-diazo-β-ketoesters has been realized for mild synthesis of spiropyrans. The reaction proceeded via twofold C-H activation followed by unusual [3+3] and [4+2] annulation with decent functional group tolerance. Moreover, A pyranoid-skelecton intermediate has been isolated as a key intermediate as a result of mono-alkylation and