Abstract:The first enantioselective copper-catalyzed cyanation of propargylic C−H bonds via radical relay was established using novel Box OTMS ligands, providing an efficient and straightforward tool for the construction of structurally diverse chiral allenyl nitriles in good yields with excellent enantioselectivities. This reaction features high functional group tolerance and mild conditions. In addition, the chiral allene products can be readily converted to other chiral compounds via axis-to-center chirality transfe… Show more
“…Very recently, interesting enantioselective propargylic (aryl) C–H cyanations were reported to deliver various enantiomerically enriched allenylnitriles efficiently, but there was no observation of chiral propoarylic nitriles. 91 Although an unactivated C(sp 3 )–H bond could be converted into carbon radicals via HAT, there is still no general method to intercept unstabilized carbon radicals asymmetrically via copper catalysis. In addition, due to the bulky chiral ligands which are required for enantioselective control, asymmetric tertiary C(sp 3 )–H bond functionalization via a copper catalyst is less developed.…”
In this review, we summarize the recent advances in the field of copper-catalyzed C–H functionalization via a radical relay process, with a critical focus on the asymmetrical versions.
“…Very recently, interesting enantioselective propargylic (aryl) C–H cyanations were reported to deliver various enantiomerically enriched allenylnitriles efficiently, but there was no observation of chiral propoarylic nitriles. 91 Although an unactivated C(sp 3 )–H bond could be converted into carbon radicals via HAT, there is still no general method to intercept unstabilized carbon radicals asymmetrically via copper catalysis. In addition, due to the bulky chiral ligands which are required for enantioselective control, asymmetric tertiary C(sp 3 )–H bond functionalization via a copper catalyst is less developed.…”
In this review, we summarize the recent advances in the field of copper-catalyzed C–H functionalization via a radical relay process, with a critical focus on the asymmetrical versions.
“… 14 In 2021, G. Liu, Lin, and coworkers discovered, for the first time, an approach for the synthesis of chiral allenes 32 directly from enantioselective copper-catalyzed cyanation of propargylic C–H bonds. 52 A new type of box OTMS ligands L6 was designed and the structurally diverse chiral allenyl nitriles can be obtained in good yields and with excellent enantioselectivities. The chiral allenes can be smoothly converted into other enantioenriched organic compounds via axis-to-center chirality transfer.…”
Section: Radical Asymmetric Synthesis Of Chiral Allenesmentioning
Allenes are valuable organic molecules that feature unique physical and chemical properties. They are not only often found in natural products, but also act as versatile building blocks for the...
“…Enantioselective cyanation of benzyl alkynes via a copper-catalyzed radical relay was disclosed by Liu and co-workers in 2021, leading to chiral allenyl nitriles 205 in good yields with high enantioselectivity under mild conditions. 48 On the basis of DFT calculations and experimental results, a possible reaction pathway was proposed, as depicted in Scheme 32. Initially, Cu-NCR species 206 was formed through CuOAc, L28 and TMSCN, which went through hydrogen-atom-transfer to deliver allenyl radical 208 along with copper species 209 .…”
Section: Synthesis Of Chiral Allenes From Alkynesmentioning
Chiral allenes, which are widely existed in natural products, bioactive pharmaceuticals and advanced functional materials, , have received considerable attention in chemistry. They are also identified as versatile building blocks...
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