- Are bis(pyridine)iodine(i) complexes applicable for asymmetric halogenation?
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Enantiopure halogenated molecules are of tremendous importance as synthetic intermediates in the construction of pharmaceuticals, fragrances, flavours, natural products, pesticides, and functional materials. Enantioselective halofunctionalizations remain
- Andreasson, M?ns,Erdelyi, Mate,Németh, Flóra Boróka,Pápai, Imre,Sethio, Daniel,von der Heiden, Daniel
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supporting information
p. 8307 - 8323
(2021/10/12)
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- Quaternary Charge-Transfer Complex Enables Photoenzymatic Intermolecular Hydroalkylation of Olefins
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Intermolecular C-C bond-forming reactions are underdeveloped transformations in the field of biocatalysis. Here we report a photoenzymatic intermolecular hydroalkylation of olefins catalyzed by flavin-dependent 'ene'-reductases. Radical initiation occurs via photoexcitation of a rare high-order enzyme-templated charge-transfer complex that forms between an alkene, α-chloroamide, and flavin hydroquinone. This unique mechanism ensures that radical formation only occurs when both substrates are present within the protein active site. This active site can control the radical terminating hydrogen atom transfer, enabling the synthesis of enantioenriched γ-stereogenic amides. This work highlights the potential for photoenzymatic catalysis to enable new biocatalytic transformations via previously unknown electron transfer mechanisms.
- Page, Claire G.,Cooper, Simon J.,Dehovitz, Jacob S.,Oblinsky, Daniel G.,Biegasiewicz, Kyle F.,Antropow, Alyssa H.,Armbrust, Kurt W.,Ellis, J. Michael,Hamann, Lawrence G.,Horn, Evan J.,Oberg, Kevin M.,Scholes, Gregory D.,Hyster, Todd K.
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supporting information
p. 97 - 102
(2021/01/12)
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- Development of Nitrolactonization Mediated by Iron(III) Nitrate Nonahydrate
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The nitrolactonization of alkenyl carboxylic acids mediated by Fe(NO3)3·9H2O has been developed. Nitrolactones were obtained in up to 93% yield by treatment of alkenyl carboxylic acids with Fe(NO3)3·9H2O. Mechanistic studies disclosed that the reaction proceeded through a radical intermediate generated from addition of NO2 to alkenyl carboxylic acids.
- Yoshimura, Tomoyuki,Umeda, Yuki,Takahashi, Risako,Matsuo, Jun-Ichi
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p. 1220 - 1225
(2020/12/17)
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- Double Functionalization of Styrenes by Cu-Mediated Assisted Tandem Catalysis
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The double functionalization of styrenes through Cu-mediated assisted tandem catalysis was developed. The reaction was initiated by Cu-catalyzed aziridination and the subsequent nucleophilic ring-opening, which was triggered by the addition of (NH4)2S2O8 as an oxidant of Cu-catalyst to form a variety of C–C and C–X bonds. The expansion to three contiguous catalytic cycles led to the synthesis of functionalized indolines by one-pot operation.
- Kawauchi, Daichi,Ueda, Hirofumi,Tokuyama, Hidetoshi
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supporting information
p. 2056 - 2060
(2019/03/13)
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- Copper-Catalyzed Modular Amino Oxygenation of Alkenes: Access to Diverse 1,2-Amino Oxygen-Containing Skeletons
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Copper-catalyzed alkene amino oxygenation reactions using O-acylhydroxylamines have been achieved for a rapid and modular access to diverse 1,2-amino oxygen-containing molecules. This transformation is applicable to the use of alcohols, carbonyls, oximes, and thio-carboxylic acids as nucleophiles on both terminal and internal alkenes. Mild reaction conditions tolerate a wide range of functional groups, including ether, ester, amide, carbamate, and halide. The reaction protocol allows for starting with free amines as the precursor of O-benzoylhydroxylamines to eliminate their isolation and purification, contributing to broader synthetic utilities. Mechanistic investigations reveal the amino oxygenation reactions may involve distinct pathways, depending on different oxygen nucleophiles.
- Hemric, Brett N.,Chen, Andy W.,Wang, Qiu
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supporting information
p. 1468 - 1488
(2019/01/25)
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- Metal-Free Arylation-Lactonization Sequence of γ-Alkenoic Acids Using Anilines as Aryl Radical Precursors
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The presence of salicylic acid (10 mol-%) and H2O (10 equiv.) significantly improves the arylation-lactonization sequence of γ-alkenoic acids with in situ formed diazonium salts (from bench stable anilines). The reaction is finished in less than 5 h without thermal or photochemical activation, giving access to a variety of γ,γ-disubstituted butyrolactones. The protocol is user-friendly and can be used at gram-scale or adapted to transform alkenols into phthalanes. Control experiments revealed that aryl radicals participate in the reaction and a plausible mechanism is proposed to include this and other mechanistic investigations, for the catalyzed and the background reaction.
- Felipe-Blanco, Diego,Gonzalez-Gomez, Jose C.
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p. 7735 - 7744
(2019/12/24)
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- Synthesis of Novel C 2-Symmetric Sulfur-Based Catalysts: Asymmetric Formation of Halo- and Seleno-Functionalized Normal- and Medium-Sized Rings
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The synthesis of novel, highly functionalized, C 2 -symmetric sulfur-based catalysts is developed and their catalytic applications are explored in asymmetric bromo-, iodo- and seleno-functionalizations of alkenoic acids. This protocol provides
- Jana, Sadhan,Kumar, Sangit,Rathore, Vandana,Verma, Ajay
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p. 1667 - 1672
(2019/08/28)
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- Cyclic Hypervalent Iodine Reagents for Azidation: Safer Reagents and Photoredox-Catalyzed Ring Expansion
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Azides are building blocks of increasing importance in synthetic chemistry, chemical biology, and materials science. Azidobenziodoxolone (ABX, Zhdankin reagent) is a valuable azide source, but its safety profile has not been thoroughly established. Herein, we report a safety study of ABX, which shows its hazardous nature. We introduce two derivatives, tBu-ABX and ABZ (azidobenziodazolone), with a better safety profile, and use them in established photoredox- and metal-mediated azidations, and in a new ring-expansion of silylated cyclobutanols to give azidated cyclopentanones.
- Alazet, Sebastien,Preindl, Johannes,Simonet-Davin, Raphael,Nicolai, Stefano,Nanchen, Annik,Meyer, Thierry,Waser, Jerome
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supporting information
p. 12334 - 12356
(2018/09/27)
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- Enantioselective Halo-oxy- and Halo-azacyclizations Induced by Chiral Amidophosphate Catalysts and Halo-Lewis Acids
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Catalytic enantioselective halocyclization of 2-alkenylphenols and enamides have been achieved through the use of chiral amidophosphate catalysts and halo-Lewis acids. Density functional theory calculations suggested that the Lewis basicity of the catalyst played an important role in the reactivity and enantioselectivity. The resulting chiral halogenated chromans can be transformed to α-Tocopherol, α-Tocotrienol, Daedalin A and Englitazone in short steps. Furthermore, a halogenated product with an unsaturated side chain may provide polycyclic adducts under radical cyclization conditions.
- Lu, Yanhui,Nakatsuji, Hidefumi,Okumura, Yukimasa,Yao, Lu,Ishihara, Kazuaki
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supporting information
p. 6039 - 6043
(2018/05/14)
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- Gold(I)-Catalyzed Enantioselective Annulations between Allenes and Alkene-Tethered Oxime Ethers: A Straight Entry to Highly Substituted Piperidines and aza-Bridged Medium-Sized Carbocycles
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Piperidine scaffolds are present in a wide range of bioactive natural products and are therefore considered as highly valuable, privileged synthetic targets. In this manuscript, we describe a gold-catalyzed annulation strategy that allows a straightforward assembly of piperidines and piperidine-containing aza-bridged products from readily available alkene-tethered oxime ethers (or esters) and N-allenamides. Importantly, we demonstrate the advantages of using oxime derivatives over imines, something pertinent to the whole area of gold catalysis, and provide relevant mechanistic experiments that shed light into the factors affecting the annulation processes. Moreover, we also describe preliminary experiments demonstrating the viability of enantioselective versions of the above reactions.
- Marcote, David C.,Varela, Iván,Fernández-Casado, Jaime,Mascarenas, José L.,López, Fernando
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supporting information
p. 16821 - 16833
(2018/12/11)
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- Synthesis of Chiral Sulfonyl Lactones via Copper-Catalyzed Asymmetric Radical Reaction of DABCO?(SO2)
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In the present work, an asymmetric copper-catalyzed radical multi-component cascade reaction of an unsaturated carboxylic acid, aryldiazonium tetrafluoroborate, and DABCO?(SO2)2 (DABSO) has been developed for the enantioselective synthesis of sulfonyl lactones. In this reaction, this SO2 surrogate, DABSO was applied for the first time in the construction of chiral compounds. This multiple-step asymmetric radical reaction was carried out under mild conditions and tolerated a wide range of substrates, resulting in the corresponding sulfonyl lactones with up to 95% chemical yields and 88% ee. The current reaction enriches the research contents of DABSO, and provides a new and efficient strategy to chiral functionalized lactones bearing quarternary stereogenic center. (Figure presented.).
- Wang, Yang,Deng, Lingling,Zhou, Jie,Wang, Xiaochen,Mei, Haibo,Han, Jianlin,Pan, Yi
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supporting information
p. 1060 - 1065
(2018/01/22)
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- Visible-Light-Catalyzed Phosphonation-Annulation: an Efficient Strategy to Synthesize β-Phosphonopyrrolidines and β-Phosphonolactones
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A new type of phosphine radical precursor for C—P bond formation has been developed and successfully used in visible-light-catalyzed phosphonation-annulation of unsaturated sulfonamides and carboxylic acids. The catalytic process is simple and green acces
- Li, Chong,Qi, Zhi-Chao,Yang, Qiang,Qiang, Xiao-Yue,Yang, Shang-Dong
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supporting information
p. 1052 - 1058
(2018/09/25)
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- Divergent Access to (1,1) and (1,2)-Azidolactones from Alkenes using Hypervalent Iodine Reagents
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A versatile synthesis of azidolactones through azidation and cyclization of carboxylic acids onto alkenes has been developed. Based on either photoredox or palladium catalysis, (1,1) and (1,2) azido lactones can be selectively synthesized. The choice of catalyst and benziodoxol(on)e reagent serving as azide source was essential to initiate either a radical or Lewis acid mediated process with divergent outcome. These transformations were carried out under mild conditions using a low catalyst loading and gave access to a large scope of azido lactones.
- Alazet, Sébastien,Le Vaillant, Franck,Nicolai, Stefano,Courant, Thibaut,Waser, Jerome
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supporting information
p. 9501 - 9504
(2017/07/22)
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- Photoredox-Catalyzed Cascade Difluoroalkylation and Intramolecular Cyclization for Construction of Fluorinated γ-Butyrolactones
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A cascade visible-light photocatalytic difluoroalkylation and intramolecular cyclization reaction has been developed for the synthesis of difluoroalkylated oxygen heterocycles. The reaction was carried out under very mild conditions, affording fluorinated
- Sha, Wanxing,Zhang, Wenzhong,Ni, Shengyang,Mei, Haibo,Han, Jianlin,Pan, Yi
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p. 9824 - 9831
(2017/09/23)
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- Cobalt-catalyzed oxidative cyclization of gem-disubstituted conjugated alkenols
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Aryl gem-disubstituted conjugated alkenols underwent oxidative cyclization affording 2,5,5-trisubstituted tetrahydrofurans in reasonable yields and good diastereoselectivities using the reductive termination variation of the Mukaiyama aerobic oxidative reaction. Under oxidative termination, the same alkenols produced diols and ketonic by-products via the double hydration and beta-scission competing pathways. Furthermore, the differences in alkenol reactivity under the reductive and oxidative termination conditions were investigated.
- Alves, Tania M.F.,Costa, Mateus O.,Bispo, Beatriz A.D.,Pedrosa, Fabiana L.,Ferreira, Marco A.B.
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p. 3334 - 3338
(2016/07/11)
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- Copper-Catalyzed Amino Lactonization and Amino Oxygenation of Alkenes Using O-Benzoylhydroxylamines
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A copper-catalyzed amino lactonization of unsaturated carboxylic acids has been achieved as well as the analogous intermolecular three-component amino oxygenation of olefins. The transformation features mild conditions and a remarkably broad substrate sco
- Hemric, Brett N.,Shen, Kun,Wang, Qiu
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supporting information
p. 5813 - 5816
(2016/06/09)
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- Direct oxidative lactonization of alkenoic acids mediated solely by NaIO4: Beyond a simple oxidant
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Triflic acid-catalyzed direct oxidative lactonization of alkenoic acids mediated solely by NaIO4 without halogen salts is described. Sodium periodate works not only as an oxidant, but also as an active reagent and directly mediates the lactonization. A new cheap, green, and practical oxidative lactonization approach has been developed using NaIO4 as the sole reagent.
- Kang, Yan-Biao,Chen, Xian-Min,Yao, Chuan-Zhi,Ning, Xiao-Shan
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supporting information
p. 6193 - 6196
(2016/05/19)
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- A Dual-Catalytic Strategy to Direct Asymmetric Radical Aminotrifluoromethylation of Alkenes
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A novel asymmetric radical aminotrifluoromethylation of alkenes has been developed for the first time, providing straightforward access to densely functionalized CF3-containing azaheterocycles bearing an α-tertiary stereocenter with excellent enantioselectivity. The key to success is not only the introduction of a Cu(I)/chiral phosphoric acid dual-catalytic system but also the use of urea with two acidic N-H as both the nucleophile and directing group. The utility of this method is illustrated by facile transformations of the products into other important compounds useful in organic synthesis and medicinal chemistry.
- Lin, Jin-Shun,Dong, Xiao-Yang,Li, Tao-Tao,Jiang, Na-Chuan,Tan, Bin,Liu, Xin-Yuan
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supporting information
p. 9357 - 9360
(2016/08/12)
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- CuX2-mediated oxybromination/aminochlorination of unsaturated amides: Synthesis of iminolactones and lactams
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We report herein a CuX2-mediated halocyclization of γ,δ-unsaturated amides for the synthesis of functionalized iminolactones and lactams respectively under mild reaction conditions. Mechanism studies indicated that N-attack cyclization was via a radical route while oxycyclization was via a nucleophilic attack on the activated CC bond.
- Zhang, Zhi-Qiang,Liu, Feng
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p. 6690 - 6693
(2015/06/25)
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- Intramolecular Hydroalkoxylation of Unactivated Alkenes Using Silane-Iodine Catalytic System
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A novel catalytic system using I2 and PhSiH3 for the intramolecular hydroalkoxylation of unactivated alkenes is described. NMR study indicated that in situ generated PhSiH2I is a possible active catalytic species. This catalytic system allows an efficient intramolecular hydroalkoxylation of phenyl-, trialkyl-, and 1,1-dialkyl-substituted alkenes as well as a variety of unactivated monoalkyl- and 1,2-dialkyl-substituted alkenes at room temperature. Mechanistic consideration based on significant experimental observations is also discussed.
- Fujita, Shoji,Abe, Masanori,Shibuya, Masatoshi,Yamamoto, Yoshihiko
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supporting information
p. 3822 - 3825
(2015/08/18)
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- Copper-Catalyzed Phosphonation-Annulation Approaches to the Synthesis of β-Phosphonotetrahydrofurans Involving C-P and C-O Bonds Formation
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Substituted tetrahydrofuran derivatives play important roles as biological activities. A versatile method for the synthesis of β-phosphonotetrahydrofurans has been developed based on Cu-catalyzed difunctionalization of alkenes. This transformation would provide a new pathway for the formation of Csp3-P and Csp3-O bonds in one step. Furthermore, this copper catalyst system can be used in the synthesis of β-phosphonotetrahydropyrans and phosphono-β-butyrolactones. These reactions were also performed well by using 3 equiv of Mn(OAc)3·2H2O as the oxidant without copper catalyst.
- Gao, Yuzhen,Li, Xueqin,Chen, Weizhu,Tang, Guo,Zhao, Yufen
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p. 11398 - 11406
(2015/12/01)
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- Intramolecular fluorocyclizations of unsaturated carboxylic acids with a stable hypervalent fluoroiodane reagent
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A new class of fluorinated lactones was prepared by the intramolecular fluorocyclizations of unsaturated carboxylic acids by using the stable fluoroiodane reagent in combination with AgBF4. This unique reaction incorporates a cyclization, an aryl migration, and a fluorination all in one step. The fluoroiodane reagent, prepared easily from fluoride, can also be used without a metal catalyst to give moderate yields within just 1 hour, thus demonstrating that it is a suitable reagent for developing new 18F-labelled radiotracers for PET imaging. All in one: A new class of lactones containing a tertiary alkyl fluoride was prepared in high yields by using a stable fluoroiodane reagent. This unique reaction incorporates a cyclization, an aryl migration, and a fluorination all in one step.
- Geary, Gemma C.,Hope, Eric G.,Stuart, Alison M.
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supporting information
p. 14911 - 14914
(2016/02/05)
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- Cooperative activation with chiral nucleophilic catalysts and n-haloimides: Enantioselective iodolactonization of 4-arylmethyl-4-pentenoic acids
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Chiral triaryl phosphates promote the enantioselective iodolactonization of 4-substituted 4-pentenoic acids to give the corresponding iodolactones in high yields with high enantioselectivity. N-Chlorophthalimide (NCP) is employed as a Lewis acidic activat
- Nakatsuji, Hidefumi,Sawamura, Yasuhiro,Sakakura, Akira,Ishihara, Kazuaki
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supporting information
p. 6974 - 6977
(2014/07/08)
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- Dissecting the stereocontrol elements of a catalytic asymmetric chlorolactonization: Syn addition obviates bridging chloronium
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We report absolute and relative stereochemistry of addition in enantioselective chlorolactonizations of 4-phenyl-4-pentenoic acid and its related t-butyl ester, catalyzed by (DHQD)2PHAL. Predominant syn addition of the chlorenium and the nucleophile across the olefin is observed. As shown by isotopic labeling, NMR spectroscopy, and derivative studies, the two new stereocenters formed by addition across the double bond are set independently and influenced by different factors. These findings suggest a stepwise process via an intermediate capable of lactone closure with either stereochemistry, in contradistinction to the more familiar scenario in which anti addition is dictated by a bridging chloronium ion intermediate.
- Yousefi, Roozbeh,Ashtekar, Kumar Dilip,Whitehead, Daniel C.,Jackson, James E.,Borhan, Babak
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supporting information
p. 14524 - 14527
(2013/10/22)
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- Asymmetric iodolactonization utilizing chiral squaramides
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Asymmetric iodolactonization of γ- and δ-unsaturated carboxylic acids has been explored in the presence of six different chiral organocatalysts 5-8. The catalyst 6b was found to facilitate the cyclization of 5-arylhex-5-enoic acids 1 to the corresponding
- Tungen, Jorn E.,Nolsoe, Jens M. J.,Hansen, Trond V.
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p. 5884 - 5887
(2013/02/23)
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- Copper-catalyzed iminoiodane-mediated aminolactonization of Olefins: Application to the synthesis of 5,5-disubstituted butyrolactones
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A copper(I)-catalyzed reaction of a variety of 4-aryl-pent-4-enoates with nosyliminoiodane generated in situ provides the corresponding 5-aryl-5-nosylamidomethylbutyrolactones. The reaction presumably proceeds via an aziridine intermediate, which could be
- Karila, Delphine,Leman, Loic,Dodd, Robert H.
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supporting information; experimental part
p. 5830 - 5833
(2012/01/06)
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- A peptide bromoiodinane approach for asymmetric bromolactonization
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A series of 37 peptides containing an iodo-aryl amide active site were generated by means of both solid phase and conventional synthesis. These peptides were screened for asymmetric induction in the bromolactonization of 4-phenyl-4-pentenoic acid based on the generation of chiral bromoiodinane bromenium sources. The study culminated in the discovery of a tri-peptide iodo-aryl amide that effected the desired bromolactonization in quantitative conversion with 24% ee. The experiments disclosed herein provided valuable insight that ultimately facilitated the development of more synthetically useful enantioselective halocyclization methodology.
- Whitehead, Daniel C.,Fhaner, Matthew,Borhan, Babak
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p. 2288 - 2291
(2011/05/16)
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- Asymmetric bromolactonization using amino-thiocarbamate catalyst
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A novel amino-thiocarbamate-catalyzed bromolactonization of unsaturated carboxylic acids has been developed. The scope of the reaction is evidenced by 22 examples of γ-lactones with up to 99% yield and 93% ee. The protocol was applied in the enantioselective synthesis of the key intermediates of VLA-4 antagonists.
- Zhou, Ling,Tan, Chong Kiat,Jiang, Xiaojian,Chen, Feng,Yeung, Ying-Yeung
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supporting information; experimental part
p. 15474 - 15476
(2011/02/21)
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- Ortho-substituted iodobenzenes as novel organocatalysts for bromination of alkenes
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Suitably ortho-substituted iodobenzenes act as organocatalysts for the transfer of electrophilic bromine from N-bromosuccinimide to alkenes via the intermediacy of bromoiodinanes. The Royal Society of Chemistry 2006.
- Braddock, D. Christopher,Cansell, Gemma,Hermitage, Stephen A.
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p. 2483 - 2485
(2008/03/28)
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- Rhodium-catalyzed intramolecular, anti-Markovnikov hydroamination. Synthesis of 3-arylpiperidines
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The intramolecular anti-Markovnikov hydroamination of 1-(3-aminopropyl)vinylarenes in the presence of a readily available rhodium catalyst to form 3-arylpiperidines is reported. In contrast to intermolecular hydroamination of vinylarenes, which occurred in high yields in the presence of rhodium catalysts containing DPEphos, the intramolecular reaction occurred in high yield in the presence of [Rh(COD)(DPPB)]BF4 as catalyst. Reactants with substituents β to the nitrogen occurred in high yield, and these reactions formed 3,5-disubstituted piperidines with high diastereomeric excess. The regiochemistry of these cyclizations contrasts with the regiochemistry of intramolecular hydroaminations catalyzed by lanthanide complexes, group III metal complexes, and platinum complexes, all of which have been reported to form cyclization products from Markovnikov addition. Copyright
- Takemiya, Akihiro,Hartwig, John F.
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p. 6042 - 6043
(2007/10/03)
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- CYSTEINE PROTEASE INHIBITORS
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The present invention is directed to compounds that are inhibitors of cysteine protease, in particular, cathepsins B, K, L, F, and S and are therefore useful in treating diseases mediated by these proteases. The present invention is directed to pharmaceut
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Page/Page column 49
(2010/02/07)
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- Manganese(III)-Mediated γ-Lactone Annulation
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The annulation of a γ-lactone ring onto an alkene by manganese(III) acetate oxidation of acetic acid was investigated.The regioselectivity of addition to unsymmetrically substituted alkenes is reported along with the stereoselectivity of addition to various acyclic and cyclic alkenes.Alkenes with ionization potentials above 8.2 eV were found to react in good yield.The role of acetic anhydride in these reactions was studied, and it was shown to be oxidized faster than acetic acid and also led to different products.The fate of oxidized acetic acid or anhydridein the absence of suitable acceptor molecule has also been quantitatively identified.The relationship of enolizability, or C-H acidity, of the carboxylic acid being oxidized was established quantitatively.
- Fristad, William E.,Peterson, John R.
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-