When treated with an alkoxide base like t-BuOK in aprotic solvent,N-di phenyl methyl imino oxindoles,made conveniently through condensation of corresponding isatins with N-di phenyl methyl amine,are deprotonated to fo...When treated with an alkoxide base like t-BuOK in aprotic solvent,N-di phenyl methyl imino oxindoles,made conveniently through condensation of corresponding isatins with N-di phenyl methyl amine,are deprotonated to form azaallyl anions.Allylation and alkylation of this type of intermediates proceed smoothly with diverse C-electrophiles.Acidic work up finishes 3-amino-3-allyl/alkyl oxindoles.The overall transformation equals to an umpolung process at the C3 of isatins.展开更多
Rh(Ⅲ)-catalyzed, chelation-assisted oxidative C-H imidation of arenes with N-H imide have been realized using PhI(OAc)2 as an oxidant. This transformation exhibits a broad substrate scope and tolerates various functi...Rh(Ⅲ)-catalyzed, chelation-assisted oxidative C-H imidation of arenes with N-H imide have been realized using PhI(OAc)2 as an oxidant. This transformation exhibits a broad substrate scope and tolerates various functional groups. The reaction proceeded via in situ generation of an iodine(Ⅲ) imido. DFT calculations suggest that this oxidative imidaton system proceeds via a Rh(Ⅲ)-Rh(Ⅴ)-Rh(Ⅲ) pathway.展开更多
3,3-Disubstituted oxindoles,forming the core of extensive bioactive natural products and drugs,attract tremendous efforts to develop efficient methods for their preparation.Here,a photocatalyst-free approach for the s...3,3-Disubstituted oxindoles,forming the core of extensive bioactive natural products and drugs,attract tremendous efforts to develop efficient methods for their preparation.Here,a photocatalyst-free approach for the synthesis of 3,3-disubstituted oxindoles via a substrate-photosensitive strategy under visible light was successfully developed.Preliminary mechanistic studies illustrated that isatin-derived imines can be directly excited by visible light to generate strong oxidant states,facilitating subsequent single-electron transfer(SET)processes with Hantzsch esters to afford the correspondingα-amino radical intermediates.Thus,theseα-amino radicals promote the subsequent Giese radical addition or radical/radical cross-coupling reactions to furnish diverse functionalized 3-substituted 3-aminooxindoles in high yields.展开更多
Vicinal all-carbon quaternary stereocenters are widely present in natural products and bioactive molecules.However,the construction of such motif in one step from readily available starting materials remains a signifi...Vicinal all-carbon quaternary stereocenters are widely present in natural products and bioactive molecules.However,the construction of such motif in one step from readily available starting materials remains a significant challenge.Herein,we report a phosphine-catalyzed divergent γ,γ-and ε,γ-umpolung domino addition of bisoxindoles with allenoates.This method serves as a practical tool for the concise synthesis of a series of bisoxindole derivatives bearing sterically hindered vicinal all-carbon quaternary stereocenters under mild reaction conditions.The applicability of this novel method was demonstrated with the gram-scale synthesis of three known advanced intermediates for the total syntheses of calycanthine,chimonanthine and folicanthine.展开更多
An enantioselective umpolung γ-addition reaction of 3’-indolyl-3-oxindoles to allenoates catalyzed by amino acid-derived bifunctional phosphine catalysts has been developed. A wide range of chiral mixed 3,3’-bisind...An enantioselective umpolung γ-addition reaction of 3’-indolyl-3-oxindoles to allenoates catalyzed by amino acid-derived bifunctional phosphine catalysts has been developed. A wide range of chiral mixed 3,3’-bisindole scaffolds containing an all-carbon quaternary stereogenic center were obtained in high yields and with excellent enantioselectivities. 3,3’-Bisindoles are valuable synthetic intermediates, the employment of which led to formal total syntheses of(+)-Chimonanthine,(+)-Folicanthine and(-)-Calycanthine, as well as facile creation of useful pyrrolidinoindoline core structure.展开更多
The electrochemical utilization of electron-deficient methylarenes for radical-radical cross-couplings remains very rare.Enabled by an umpolung strategy,the unprecedented electrochemical cross-coupling of electron-def...The electrochemical utilization of electron-deficient methylarenes for radical-radical cross-couplings remains very rare.Enabled by an umpolung strategy,the unprecedented electrochemical cross-coupling of electron-deficient methylarenes with aldehydes was developed.The paired electrolysis simultaneously generated electron-deficient benzylic radicals and ketyl radicals at both electrodes,which then underwent radical recombination,governed by polarity matching and persistent-radical effect(PRE)to afford functionalized alcohols that are not easily accessible by other methods.This protocol features catalystand external redox agent-free conditions and a formal 100%atom economy.Mechanistic studies support the radical-radical cross-coupling pathway.展开更多
Palladium-catalyzed allylic alkylation enabled by ketone umpolung via Pudovik addition/[1,2]-phospha-Brook rearrangement with phosphites has been developed.The protocol offers a straightforward method for the synthesi...Palladium-catalyzed allylic alkylation enabled by ketone umpolung via Pudovik addition/[1,2]-phospha-Brook rearrangement with phosphites has been developed.The protocol offers a straightforward method for the synthesis of potentially bioactive homoallylic alcohol phosphonates in an efficient and economical way.This cascade reaction proceeds under mild conditions with excellent functional group compatibility.Furthermore,the catalytic asymmetric version has also been explored.展开更多
Zinc-promoted umpolung thiolation of alkyl electrophiles with masked sulfur transfer reagents in the absence of nickel or copper catalysis is described. This protocol proceeds via a SET process of Zn to electrophilic ...Zinc-promoted umpolung thiolation of alkyl electrophiles with masked sulfur transfer reagents in the absence of nickel or copper catalysis is described. This protocol proceeds via a SET process of Zn to electrophilic sulfur reagent followed by insertion of Zn into disulfide and nucleophilic thiolation, providing straightforward access to a wide range of alkyl sulfides with broad substrate scope. A neutral TMEDA-ligated four-coordinated zinc thiolate with tetrahedra geometry was synthesized, isolated and fully characterized by NMR, IR and X-ray analysis. More importantly, the chemical reactivity of this active intermediate has been investigated, enabling the construction of C-Se, C-Te, Sb-S and Bi-S bonds to prepare valuable sulfur-containing molecules and beyond.展开更多
Umpolung is a fundamental concept in organic chemistry, which provides an alternative strategy for the synthesis of target compounds which were not easily accessible by conventional methods. Herein, a mild and efficie...Umpolung is a fundamental concept in organic chemistry, which provides an alternative strategy for the synthesis of target compounds which were not easily accessible by conventional methods. Herein, a mild and efficient PhI(OAc)_2-promoted umpolung acetoxylation reactions of enamides was developed for the synthesis of α-acetoxy ketones. The reaction tolerates a wide range of functional groups and affords α-acetoxy ketones in good to excellent yields. PhI(OAc)_2 serves as a source of acetoxy in the reaction.展开更多
基金the National Natural Science Foundation of China(No.21672027)for financial supportsupported by High-Level Entrepreneurial Talent Team of Jiangsu Province(No.2017-37)。
文摘When treated with an alkoxide base like t-BuOK in aprotic solvent,N-di phenyl methyl imino oxindoles,made conveniently through condensation of corresponding isatins with N-di phenyl methyl amine,are deprotonated to form azaallyl anions.Allylation and alkylation of this type of intermediates proceed smoothly with diverse C-electrophiles.Acidic work up finishes 3-amino-3-allyl/alkyl oxindoles.The overall transformation equals to an umpolung process at the C3 of isatins.
文摘Rh(Ⅲ)-catalyzed, chelation-assisted oxidative C-H imidation of arenes with N-H imide have been realized using PhI(OAc)2 as an oxidant. This transformation exhibits a broad substrate scope and tolerates various functional groups. The reaction proceeded via in situ generation of an iodine(Ⅲ) imido. DFT calculations suggest that this oxidative imidaton system proceeds via a Rh(Ⅲ)-Rh(Ⅴ)-Rh(Ⅲ) pathway.
基金support from the National Natural Science Foundation of China(22377113,21927811,22134004)the Taishan Scholar Program of Shandong Province(tsqn202306103)the Fundamental Research Funds for the Central Universities(Ocean University of China)is greatly appreciated.
文摘3,3-Disubstituted oxindoles,forming the core of extensive bioactive natural products and drugs,attract tremendous efforts to develop efficient methods for their preparation.Here,a photocatalyst-free approach for the synthesis of 3,3-disubstituted oxindoles via a substrate-photosensitive strategy under visible light was successfully developed.Preliminary mechanistic studies illustrated that isatin-derived imines can be directly excited by visible light to generate strong oxidant states,facilitating subsequent single-electron transfer(SET)processes with Hantzsch esters to afford the correspondingα-amino radical intermediates.Thus,theseα-amino radicals promote the subsequent Giese radical addition or radical/radical cross-coupling reactions to furnish diverse functionalized 3-substituted 3-aminooxindoles in high yields.
基金the financial support provided by the National Natural Science Foundation of China(22207063),111 Project(D20015)the Natural Science Research Project of Yichang City(A23-2-002)the Opening Funding of Hubei Key Laboratory of Natural Products Research and Development,China Three Gorges University(2024NPRD03,2024NPRD04,2024NPRD05).
文摘Vicinal all-carbon quaternary stereocenters are widely present in natural products and bioactive molecules.However,the construction of such motif in one step from readily available starting materials remains a significant challenge.Herein,we report a phosphine-catalyzed divergent γ,γ-and ε,γ-umpolung domino addition of bisoxindoles with allenoates.This method serves as a practical tool for the concise synthesis of a series of bisoxindole derivatives bearing sterically hindered vicinal all-carbon quaternary stereocenters under mild reaction conditions.The applicability of this novel method was demonstrated with the gram-scale synthesis of three known advanced intermediates for the total syntheses of calycanthine,chimonanthine and folicanthine.
基金Yixin Lu thanks the Singapore National Research Foundation,Prime Minister’s Office for the NRF Investigatorship Award(R-143-000-A15-281)Financial supports from the National University of Singapore(R-143-000-695-114 and C-141-000-092-001)the National Natural Science Foundation of China(21672158)are also gratefully acknowledged.
文摘An enantioselective umpolung γ-addition reaction of 3’-indolyl-3-oxindoles to allenoates catalyzed by amino acid-derived bifunctional phosphine catalysts has been developed. A wide range of chiral mixed 3,3’-bisindole scaffolds containing an all-carbon quaternary stereogenic center were obtained in high yields and with excellent enantioselectivities. 3,3’-Bisindoles are valuable synthetic intermediates, the employment of which led to formal total syntheses of(+)-Chimonanthine,(+)-Folicanthine and(-)-Calycanthine, as well as facile creation of useful pyrrolidinoindoline core structure.
基金the National Natural Science Foundation of China(grant nos.22271009 and 22171015)Beijing Natural Science Foundation(grant no.2222003)Beijing Municipal Education Committee Project(grant nos.KZ202110005003 and KM202110005006).
文摘The electrochemical utilization of electron-deficient methylarenes for radical-radical cross-couplings remains very rare.Enabled by an umpolung strategy,the unprecedented electrochemical cross-coupling of electron-deficient methylarenes with aldehydes was developed.The paired electrolysis simultaneously generated electron-deficient benzylic radicals and ketyl radicals at both electrodes,which then underwent radical recombination,governed by polarity matching and persistent-radical effect(PRE)to afford functionalized alcohols that are not easily accessible by other methods.This protocol features catalystand external redox agent-free conditions and a formal 100%atom economy.Mechanistic studies support the radical-radical cross-coupling pathway.
基金supported by the National Key Research and Development Program of China(2021YFA0804900)the Leading Innovative and Entrepreneur Team Introduction Program of Zhejiang(2022R01007)Shanghai Frontiers Science Center of Optogenetic Techniques for Cell Metabolism。
文摘Palladium-catalyzed allylic alkylation enabled by ketone umpolung via Pudovik addition/[1,2]-phospha-Brook rearrangement with phosphites has been developed.The protocol offers a straightforward method for the synthesis of potentially bioactive homoallylic alcohol phosphonates in an efficient and economical way.This cascade reaction proceeds under mild conditions with excellent functional group compatibility.Furthermore,the catalytic asymmetric version has also been explored.
基金the National Science Foundation of China(22001051)Zhejiang Provincial Natural Science Foundation of China(LY23B020002)for financial supportfunding from the STU Scientific Research Foundation for Talents(NTF20022)。
文摘Zinc-promoted umpolung thiolation of alkyl electrophiles with masked sulfur transfer reagents in the absence of nickel or copper catalysis is described. This protocol proceeds via a SET process of Zn to electrophilic sulfur reagent followed by insertion of Zn into disulfide and nucleophilic thiolation, providing straightforward access to a wide range of alkyl sulfides with broad substrate scope. A neutral TMEDA-ligated four-coordinated zinc thiolate with tetrahedra geometry was synthesized, isolated and fully characterized by NMR, IR and X-ray analysis. More importantly, the chemical reactivity of this active intermediate has been investigated, enabling the construction of C-Se, C-Te, Sb-S and Bi-S bonds to prepare valuable sulfur-containing molecules and beyond.
基金supported by the National Natural Science Foundation of China (21622203, 21472147, 21272183)the Fund of Northwest University (334100036)
文摘Umpolung is a fundamental concept in organic chemistry, which provides an alternative strategy for the synthesis of target compounds which were not easily accessible by conventional methods. Herein, a mild and efficient PhI(OAc)_2-promoted umpolung acetoxylation reactions of enamides was developed for the synthesis of α-acetoxy ketones. The reaction tolerates a wide range of functional groups and affords α-acetoxy ketones in good to excellent yields. PhI(OAc)_2 serves as a source of acetoxy in the reaction.
