An efficient gold-catalyzed anti-Markovnikov cycloisomerization-initiated tandem reaction of Bocprotected indole tethered homopropargyl amides has been achieved.This method delivers a wide range of valuable bridged az...An efficient gold-catalyzed anti-Markovnikov cycloisomerization-initiated tandem reaction of Bocprotected indole tethered homopropargyl amides has been achieved.This method delivers a wide range of valuable bridged aza-[n.2.1]skeletons(n=3-7)at room temperature with high diastereoselectivity and enantioselectivity by a chirality-transfer strategy.Moreover,the gold-catalyzed tandem reaction of homopropargyl alcohol is also achieved to produce the bridged oxa-[3.2.1]skeleton.展开更多
Classical Julia-Kocienski fluoroolefination represents an indispensable platform for the construction of monofluoroalkenes.Nevertheless,its complex multistep mechanistic manifold along with the unrevealed intrinsic“f...Classical Julia-Kocienski fluoroolefination represents an indispensable platform for the construction of monofluoroalkenes.Nevertheless,its complex multistep mechanistic manifold along with the unrevealed intrinsic“fluorine effect”in nucleophilic reactions might be responsible for the difficult control of the original stereoselectivity and is thus often ambiguous to predict.Herein,a novel strategy involving the defined fluorine effect and new reaction mechanism was developed for tunable C-C and C-S bond cleavage,providing a versatile avenue for highly stereoselective and easily scalable construction of diverse monofluoroalkenes.Density functional theory(DFT)investigations indicate the fluorine substituents can activate the C-C and C-S bond leading toα-elimination by antiphase orbital interaction.The rate-limiting step were calculated via fourmembered transition states with ring strain.Both the sterically eclipsed repulsion and secondary orbital interaction affect the stereoselectivity.展开更多
基金financial support from the National Natural Science Foundation of China(Nos.21622204,21572186,21772161,21572163 and 21372178)the Natural Science Foundation of Fujian Province of China(No.2019J02001)+3 种基金the President Research Funds from Xiamen University(No.20720180036)NFFTBS(No.J1310024)PCSIRTScience&Technology Cooperation Program of Xiamen(No.3502Z20183015)。
文摘An efficient gold-catalyzed anti-Markovnikov cycloisomerization-initiated tandem reaction of Bocprotected indole tethered homopropargyl amides has been achieved.This method delivers a wide range of valuable bridged aza-[n.2.1]skeletons(n=3-7)at room temperature with high diastereoselectivity and enantioselectivity by a chirality-transfer strategy.Moreover,the gold-catalyzed tandem reaction of homopropargyl alcohol is also achieved to produce the bridged oxa-[3.2.1]skeleton.
基金The authors gratefully acknowledge the National Natural Science Foundation of China(nos.21602231,21890722,21702109,and 11811530637)Chinese Academy of Sciences“Light of West China”Program,and the Natural Science Foundation of Jiangsu Province(nos.BK20160396 and BK20191197)+2 种基金the Natural Science Foundation of Tianjin Municipality(nos.18JCYBJC21400 and 19JCJQJC62300)Tianjin Research Innovation Project for Postgraduate Students(no.2019YJSB081)the Fundamental Research Funds for Central Universities[Nankai University(nos.63191515 and 63196021)]for generous financial support.
文摘Classical Julia-Kocienski fluoroolefination represents an indispensable platform for the construction of monofluoroalkenes.Nevertheless,its complex multistep mechanistic manifold along with the unrevealed intrinsic“fluorine effect”in nucleophilic reactions might be responsible for the difficult control of the original stereoselectivity and is thus often ambiguous to predict.Herein,a novel strategy involving the defined fluorine effect and new reaction mechanism was developed for tunable C-C and C-S bond cleavage,providing a versatile avenue for highly stereoselective and easily scalable construction of diverse monofluoroalkenes.Density functional theory(DFT)investigations indicate the fluorine substituents can activate the C-C and C-S bond leading toα-elimination by antiphase orbital interaction.The rate-limiting step were calculated via fourmembered transition states with ring strain.Both the sterically eclipsed repulsion and secondary orbital interaction affect the stereoselectivity.
