An Organocatalyst Bearing Stereogenic Carbon and Sulfur Centers as an Efficient Promoter for Enantioselective Hydrosilylation of 1,4-Benzooxazines
摘要:
The efficient and enantioselective hydrosilylation of 3-aryl-1,4-benzooxazines was achieved using an l-phenyl alanine derived new Lewis base catalyst bearing stereogenic carbon and sulfur centers. In the presence of 2 mol % of catalyst, a broad range of 3-aryl-1,4-benzooxazines were hydrosilylated to afford the corresponding chiral 3-aryl-3,4-dihydro-2H-1,4-benzooxazine products with good to high yields (66-98%) and enantioselectivities (70-99% ee). This method provides an alternative approach with great practical application potential to access chiral 3-aryl-3,4-dihydro-2H-1,4-benzooxazines.
First I2–K2CO3-promoted sequential C–N and C–O bond forming approach for one-pot synthesis of 1,4-benzoxazines
作者:Sunil K. Singh、Anil K. Bajpai、Rajesh Saini
DOI:10.1016/j.tetlet.2013.10.092
日期:2013.12
system for the one-potsynthesis of 3-aryl-2H-benz[1,4]oxazine viarapid CN and C–O bond formation. No by-product formation, operational simplicity, ambient temperature, and high yield (85–94%) are the attractive features of the envisaged reaction. The reported one-potsynthesis of 1,4-benzoxazine involves the application of I2–K2CO3 catalyst system for the first time and proceeds via in situ imine
已经发现,I 2 –K 2 CO 3组合是一种通过快速CN和C–O一锅合成3-芳基-2 H-苯并[1,4]恶嗪的有效,可重复使用和廉价的催化剂体系。键的形成。没有副产物的形成,操作简便,环境温度和高产率(85-94%)是预期反应的吸引人的特征。已报道的1,4-苯并恶嗪的一锅法合成首次涉及I 2 -K 2 CO 3催化剂体系的应用,并通过原位亚胺形成,随后进行分子内环转化级联反应进行。
Lewis Base Organocatalyzed Enantioselective Hydrosilylation of 1,4-Benzoxazines
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。
A metal-free hydrogenation of 3-substituted 2H-1,4-benzoxazines
作者:Simin Wei、Xiangqing Feng、Haifeng Du
DOI:10.1039/c6ob01556e
日期:——
A metal-free hydrogenation of 3-substituted 2H-1,4-benzoxazines has been successfully realized with 2.5 mol% of B(C6F5)3 as a catalyst to furnish a variety of 3,4-dihydro-2H-1,4-benzoxazines in 93–99% yields. Up to 42% ee was also achieved for the asymmetric hydrogenation with the use of a chiral diene and HB(C6F5)2.
以2.5摩尔%的B(C 6 F 5)3为催化剂,成功地实现了3取代2 H -1,4-苯并恶嗪的无金属氢化,以提供各种3,4-二氢-2 H -1,4-苯并恶嗪的产率为93-99%。通过使用手性二烯和HB(C 6 F 5)2进行不对称氢化反应,还可以达到高达42%ee 。
Ir-Catalyzed Enantioselective Hydrogenation of 2<i>H</i>-1,4-Benzoxazines with a Chiral 1,2,3,4-Tetrahydro-1-naphthylamine Derived Phosphine-aminophosphine Ligand
作者:Juan Hu、Daoyong Wang、Zhuo Zheng、Xiangping Hu
DOI:10.1002/cjoc.201200944
日期:2012.11
Unsymmetrical hybrid chiral phosphine‐aminophosphine ligandderived from 1,2,3,4‐tetrahydro‐1‐naphthylamine has been found to be highly efficient in the Ir‐catalyzed asymmetric hydrogenation of various 3‐aryl‐2H‐1,4‐benzoxazines, providing good enantioselectivities (up to 95% ee) and high catalytic activity (S/C up to 5000).
已发现衍生自1,2,3,4-四氢-1-萘胺的不对称杂化手性膦-氨基膦配体在各种3-芳基-2 H -1,4-苯并恶嗪的Ir催化不对称氢化中非常有效,提供良好的对映选择性(高达95%ee)和高催化活性(S / C高达5000)。