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
An investigation toward the synthesis of the lindenane-type sesquiterpenoid monomer of Chlorahololide A using a Yamamoto rearrangement, intramolecular cyclopropanation reaction, 1,3-dipolar cyclization, and an intra- ...An investigation toward the synthesis of the lindenane-type sesquiterpenoid monomer of Chlorahololide A using a Yamamoto rearrangement, intramolecular cyclopropanation reaction, 1,3-dipolar cyclization, and an intra- molecular Heck reaction gave the pivotal intermediate 20. This gives a practical synthetic route that could generate further natural products of the Chloranthaceae family.展开更多
An efficient route to the natural products bupleurynol and its analog（RB-2）,isolated from Bupleuri Radix,was established based on versatile intermediate（15）.In this synthetic route,Sonogashira and CadiotChodkiewic...An efficient route to the natural products bupleurynol and its analog（RB-2）,isolated from Bupleuri Radix,was established based on versatile intermediate（15）.In this synthetic route,Sonogashira and CadiotChodkiewicz coupling as well as Julia-Kocienski olefination are utilized as key steps.The highly efficient synthetic route provides opportunities to explore the biological behavior of bupleurynol and RB-2.展开更多
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.
基金Acknowledgement This work was supported by The National Natural Science Foundation of China （Nos. 30725049, 81021062, 81072652）.
文摘An investigation toward the synthesis of the lindenane-type sesquiterpenoid monomer of Chlorahololide A using a Yamamoto rearrangement, intramolecular cyclopropanation reaction, 1,3-dipolar cyclization, and an intra- molecular Heck reaction gave the pivotal intermediate 20. This gives a practical synthetic route that could generate further natural products of the Chloranthaceae family.
基金financially supported by National Natural Science Foundation of China(Nos.21402111,81473415)Basic research program of Shanxi Province(No.2015021039)+1 种基金Shanxi Scholarship Council of China(No.2015-020)science and technology innovation project of Shanxi Province(No.2016115)
文摘An efficient route to the natural products bupleurynol and its analog（RB-2）,isolated from Bupleuri Radix,was established based on versatile intermediate（15）.In this synthetic route,Sonogashira and CadiotChodkiewicz coupling as well as Julia-Kocienski olefination are utilized as key steps.The highly efficient synthetic route provides opportunities to explore the biological behavior of bupleurynol and RB-2.
