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 。
Iridium-Catalyzed Asymmetric Hydrogenation of 3-Substituted 2H-1,4-Benzoxazines
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。