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Selective bromination of sp3 C-H bonds by organophotoredox catalysis

หน่วยงาน Nanyang Technological University, Singapore

รายละเอียด

ชื่อเรื่อง : Selective bromination of sp3 C-H bonds by organophotoredox catalysis
นักวิจัย : Kee, Choon Wee , Chan, Ke Min , Wong, Ming Wah , Tan, Choon-Hong
คำค้น : DRNTU::Science::Chemistry::Organic chemistry
หน่วยงาน : Nanyang Technological University, Singapore
ผู้ร่วมงาน : -
ปีพิมพ์ : 2557
อ้างอิง : Kee, C. W., Chan, K. M., Wong, M. W., & Tan, C.-H. (2014). Selective Bromination of sp3 C-H Bonds by Organophotoredox Catalysis . Asian Journal of Organic Chemistry, 3(4), 536-544. , 2193-5807 , http://hdl.handle.net/10220/19712 , http://dx.doi.org/10.1002/ajoc.201300169
ที่มา : -
ความเชี่ยวชาญ : -
ความสัมพันธ์ : Asian journal of organic chemistry
ขอบเขตของเนื้อหา : -
บทคัดย่อ/คำอธิบาย :

We report that bromination of aliphatic and benzylic sp3 C[BOND]H bonds can be achieved with visible light photoredox catalysis by using a low loading of Eosin Y disodium salt, an inexpensive organic dye, as a photoredox catalyst. The light source is a low-power household lamp and the reaction can be performed without the need of an inert atmosphere and anhydrous solvent. Easy-to-handle CBr4 is the source of bromine and morpholine is necessary for the reaction. Preliminary experimental and computational studies on the mechanism strongly suggest that an N-morpholino radical is responsible for the C[BOND]H activation step. This led us to propose that this is a radical relay reaction, in which a longer-lived morpholine radical is generated from a CBr3 radical, which is relatively more transient, by a thermodynamically favorable reaction. Additional evidence for the existence of such an N-radical was obtained from radical trapping experiments. The strong preference of this reaction for electron-rich hydrogen atoms, and the high sensitivity to the steric environment around the C[BOND]H bond enables bromination to occur on the relatively stronger C[BOND]H bond (as quantified by bond dissociation enthalpy) on the same molecule. The potential for utilizing this reaction to achieve mild and regioselective bromination of sp3 C[BOND]H bonds in complex molecules is exemplified by the bromination of (+)-sclareolide and acetate-protected estrone.

บรรณานุกรม :
Kee, Choon Wee , Chan, Ke Min , Wong, Ming Wah , Tan, Choon-Hong . (2557). Selective bromination of sp3 C-H bonds by organophotoredox catalysis.
    กรุงเทพมหานคร : Nanyang Technological University, Singapore.
Kee, Choon Wee , Chan, Ke Min , Wong, Ming Wah , Tan, Choon-Hong . 2557. "Selective bromination of sp3 C-H bonds by organophotoredox catalysis".
    กรุงเทพมหานคร : Nanyang Technological University, Singapore.
Kee, Choon Wee , Chan, Ke Min , Wong, Ming Wah , Tan, Choon-Hong . "Selective bromination of sp3 C-H bonds by organophotoredox catalysis."
    กรุงเทพมหานคร : Nanyang Technological University, Singapore, 2557. Print.
Kee, Choon Wee , Chan, Ke Min , Wong, Ming Wah , Tan, Choon-Hong . Selective bromination of sp3 C-H bonds by organophotoredox catalysis. กรุงเทพมหานคร : Nanyang Technological University, Singapore; 2557.