- Using Terpene Synthase Plasticity in Catalysis: On the Enzymatic Conversion of Synthetic Farnesyl Diphosphate Analogues
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Four synthetic farnesyl diphosphate analogues were enzymatically converted with three bacterial sesquiterpene synthases, including β-himachalene synthase (HcS) and (Z)-γ-bisabolene synthase (BbS) from Cryptosporangium arvum, and germacrene A synthase (SmTS6) from Streptomyces mobaraensis. These enzyme reactions not only yielded several previously unknown compounds, showing that this approach opened the door to a new chemical space, but substrates with blocked or altered reactivities also gave interesting insights into the cyclisation mechanisms and the potential to catalyse reactions with different initial cyclisation modes.
- Hou, Anwei,Dickschat, Jeroen S.
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p. 15644 - 15649
(2021/10/04)
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- AuCl3-Catalyzed Ring-Closing Carbonyl–Olefin Metathesis
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Compared with the ripeness of olefin metathesis, exploration of the construction of carbon–carbon double bonds through the catalytic carbonyl–olefin metathesis reaction remains stagnant and has received scant attention. Herein, a highly efficient AuCl3-catalyzed intramolecular ring-closing carbonyl–olefin metathesis reaction is described. This method features easily accessible starting materials, simple operation, good functional-group tolerance and short reaction times, and provides the target cyclopentenes, polycycles, benzocarbocycles, and N-heterocycle derivatives in good to excellent yields.
- Wang, Rui,Chen, Yi,Shu, Mao,Zhao, Wenwen,Tao, Maoling,Du, Chao,Fu, Xiaoya,Li, Ao,Lin, Zhihua
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supporting information
p. 1941 - 1946
(2020/02/11)
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- Hydrogenative metathesis of enynes via piano-stool ruthenium carbene complexes formed by alkyne gem-hydrogenation
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The only recently discovered gem-hydrogenation of internal alkynes is a fundamentally new transformation, in which both H atoms of dihydrogen are transferred to the same C atom of a triple bond while the other position transforms into a discrete metal carbene complex. [Cp?RuCl]4 is presently the catalyst of choice: the resulting piano-stool ruthenium carbenes can engage a tethered alkene into either cyclopropanation or metathesis, and a prototypical example of such a reactive intermediate with an olefin ligated to the ruthenium center has been isolated and characterized by X-ray diffraction. It is the substitution pattern of the olefin that determines whether metathesis or cyclopropanation takes place: a systematic survey using alkenes of largely different character in combination with a computational study of the mechanism at the local coupled cluster level of theory allowed the preparative results to be sorted and an intuitive model with predictive power to be proposed. This model links the course of the reaction to the polarization of the double bond as well as to the stability of the secondary carbene complex formed, if metathesis were to take place. The first application of "hydrogenative metathesis"to the total synthesis of sinularones E and F concurred with this interpretation and allowed the proposed structure of these marine natural products to be confirmed. During this synthesis, it was found that gem-hydrogenation also provides opportunities for C-H functionalization. Moreover, silylated alkynes are shown to participate well in hydrogenative metathesis, which opens a new entry into valuable allylsilane building blocks. Crystallographic evidence suggests that the polarized [Ru-Cl] bond of the catalyst interacts with the neighboring R3Si group. Since attractive interligand Cl/R3Si contacts had already previously been invoked to explain the outcome of various ruthenium-catalyzed reactions, including trans-hydrosilylation, the experimental confirmation provided herein has implications beyond the present case.
- Peil, Sebastian,Bistoni, Giovanni,Goddard, Richard,Fürstner, Alois
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supporting information
p. 18541 - 18553
(2020/11/17)
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- Hydrogenative Cyclopropanation and Hydrogenative Metathesis
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The unusual geminal hydrogenation of a propargyl alcohol derivative with [CpXRuCl] as the catalyst entails formation of pianostool ruthenium carbenes in the first place; these reactive intermediates can be intercepted with tethered alkenes to give either cyclopropanes or cyclic olefins as the result of a formal metathesis event. The course of the reaction is critically dependent on the substitution pattern of the alkene trap.
- Peil, Sebastian,Guthertz, Alexandre,Biberger, Tobias,Fürstner, Alois
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supporting information
p. 8851 - 8856
(2019/05/28)
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- Evolution of a Polyene Cyclization Cascade for the Total Synthesis of (?)-Cyclosmenospongine
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We report a full account on the development of a unique cationic polyene cyclization for the total synthesis of the tetracyclic meroterpenoid (?)-cyclosmenospongine. A highly convergent three-component coupling strategy enabled rapid access to individual cyclization precursors that were tested for their reactivity. The successful transformation generates three rings and sets four consecutive stereocenters in a single operation proceeding in a highly efficient manner to give exclusively the trans-decalin framework. In addition, we found that the enol ether geometry and the relative configuration of C3 and C8 are crucial for the success of the polyene cyclization.
- Speck, Klaus,Magauer, Thomas
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supporting information
p. 1157 - 1165
(2017/02/05)
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- DIHYDROOROTIC ACID DEHYDROGENASE INHIBITOR
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The present invention provides a novel dihydroorotic acid dehydrogenase inhibitor which is applicable to various diseases. When used as an active ingredient, a compound represented by formula (I): (wherein X represents a halogen atom, R1 represents a hydrogen atom, R2 represents an alkyl group containing 1 to 7 carbon atoms, R3 represents -CHO, and R4 represents -CH2-CH=C(CH3)-R0 (wherein R0 represents an alkyl group containing 1 to 12 carbon atoms which may have a substituent on the terminal carbon and/or on a non-terminal carbon, etc.)), an optical isomer thereof or a pharmaceutically acceptable salt thereof has a high inhibitory effect on dihydroorotic acid dehydrogenase and can be used as an immunosuppressive agent, a therapeutic agent for rheumatism, an anticancer agent, a therapeutic agent for graft rejection, an antiviral agent, an anti-H. pylori agent, a therapeutic agent for diabetes or the like.
- -
-
Paragraph 0293; 0296; 0309
(2015/04/15)
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- Photocatalytic One-Pot Synthesis of Homoallyl Ketones via a Norrish Type i Reaction of Cyclopentanones
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A photocatalytic synthesis of homoallyl ketones was achieved via a one-pot procedure starting from a Norrish Type I reaction of cyclopentanones, followed by a decatungstate-catalyzed hydroacylation of electron-deficient olefins by the resulting 4-pentenals. The site-selective formyl H-abstraction in the second step can be explained by radical polar effects in the transition state.
- Okada, Megumi,Yamada, Keiichi,Fukuyama, Takahide,Ravelli, Davide,Fagnoni, Maurizio,Ryu, Ilhyong
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p. 9365 - 9369
(2015/09/28)
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- Synthesis of (±) debenzoyl analogs of norsampsones as potential anticancer agents
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Synthesis of (±) debenzoyl analogs of norsampsones 1 and 2 is reported starting from commercially available 1,3-cyclohexadione in six steps with overall yields of 37% and 36%, respectively. Compounds 1 and 2 were tested for their anticancer activity and showed moderate anticancer activity against HeLa cell lines.
- Jadhav, Amol R.,Thombal, Raju S.,Nigam, Preeti,Jadhav, Vrushali H.
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supporting information
p. 5235 - 5237
(2015/08/19)
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- ISOPRENE OLIGOMER, POLYISOPRENE, PROCESSES FOR PRODUCING THESE MATERIALS, RUBBER COMPOSITION, AND PNEUMATIC TIRE
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The invention relates to an isoprene oligomer that contains a trans structural moiety and a cis structural moiety, which can be represented by the following formula (1), wherein at least 1 atom or group in the trans structural moiety is replaced by another atom or group. The invention also relates to a polyisoprene, which is biosynthesized using the isoprene oligomer and isopentenyl diphosphate. Further, this invention provides a rubber composition comprising the isoprene oligomer and/or the polyisoprene, and a pneumatic tire, including tire components (e.g., treads and sidewalls) formed from the rubber composition. wherein n represents an integer from 1 to 10; m represents an integer from 1 to 30; and Y represents a hydroxy group, a formyl group, a carboxy group, an ester group, a carbonyl group, or a group represented by the following formula (2):
- -
-
Paragraph 266
(2014/06/25)
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- Analysis of enantiofacial selective epoxidation catalyzed by flavin-containing monooxygenase Lsd18 involved in ionophore polyether lasalocid biosynthesis
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Enzymatic epoxidation represents a key biosynthetic transformation in the construction of polyether skeletons. A single flavin-containing monooxygenase, Lsd18, is involved in ionophore polyether lasalocid biosynthesis and participates in the enantioselective epoxidations of the diene precursor. Biotransformation studies utilizing structurally simplified monoolefin analogs with different substitution patterns revealed important structural requirements for the enantiofacial selectivity of Lsd18-catalyzed epoxidations. These results enabled us to propose a substrate binding model of Lsd18, which was applied to the biosynthesis of other polyethers.
- Suzuki, Gaku,Minami, Atsushi,Shimaya, Mayu,Kodama, Takeshi,Morimoto, Yoshiki,Oguri, Hiroki,Oikawa, Hideaki
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supporting information
p. 1779 - 1781
(2015/02/19)
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- Synthesis of cycloalkanone-fused cyclopropanes by Au(I)-catalyzed oxidative ene-yne cyclizations
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Au(I)-catalyzed oxidative cyclizations that successfully convert 1,5-ene-ynes and a 1,6-ene-yne to the corresponding cycloalkanone-fused cyclopropanes are described. This Au(I)-catalyzed oxidative cyclization can be effectively applied to various substrat
- Uetake, Yuta,Niwa, Takashi,Nakada, Masahisa
-
supporting information
p. 6847 - 6850
(2015/01/09)
-
- Stereospecific nickel-catalyzed cross-coupling reactions of alkyl grignard reagents and identification of selective anti-breast-cancer agents
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Alkyl Grignard reagents that contain β-hydrogen atoms were used in a stereospecific nickel-catalyzed cross-coupling reaction to form C(sp 3)-C(sp3) bonds. Aryl Grignard reagents were also utilized to synthesize 1,1-diarylalkanes. Sev
- Yonova, Ivelina M.,Johnson, A. George,Osborne, Charlotte A.,Moore, Curtis E.,Morrissette, Naomi S.,Jarvo, Elizabeth R.
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supporting information
p. 2422 - 2427
(2014/03/21)
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- NOVEL DIHYDROXYBENZENE DERIVATIVES AND ANTIPROTOZOAL AGENT COMPRISING SAME AS ACTIVE INGREDIENT
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Novel compounds below are useful for preventing or treating diseases caused by protozoans. At least one of a compound represented by Formula (I) (wherein, X represents a hydrogen atom or a halogen atom; R1 represents a hydrogen atom; R2 represents a hydrogen atom or a C1-7 alkyl group; R3 represents -CHO, -C(=O)R5, -COOR5 (wherein R5 represents a C1-7 alkyl group), -CH2OH or -COOH; and R4 represents a C1-16 alkyl group having one or more substituents on a terminal carbon atom and/or non-terminal carbon atom(s), a C2-16 alkenyl group having one or more substituents on a terminal carbon atom and/or non-terminal carbon atom(s), or a C2-16 alkynyl group having one or more substituents on a terminal carbon atom and/or non-terminal carbon atom(s)), an optical isomer thereof, and a pharmaceutically acceptable salt is used.
- -
-
Paragraph 0317; 0319
(2013/09/26)
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- Alkoxy radical cyclizations onto silyl enol ethers relative to alkene cyclization, hydrogen atom transfer, and fragmentation reactions
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This study examines the chemoselectivity of alkoxy radical cyclizations onto silyl enol ethers compared to competing cyclizations, 1,5-hydrogen atom transfers (1,5-HATs), and β-fragmentations. Cyclization onto silyl enol ethers in a S-exo mode is greatly preferred over cyclization onto a terminal alkene. The selectivity decreases when any alkyl substitution is present on the competing alkene radical acceptor. Alkoxy radical 5-exo cyclizations displayed excellent chemoselectivity over competing β-fragmentations. Alkoxy radical S-exo cyclizations onto silyl enol ether also outcompeted 1,5-HATs, even for activated benzylic hydrogen atoms. In tetrahydropyran synthesis, where 1,5-HAT has plagued alkoxy radical cyclization methodologies, 6-exo cyclizations were the dominant mode of reactivity. β-Fragmentation still remains a challenge for tetrahydropyran synthesis when an aryl group is present in the β position.
- Rueda-Becerril, Montserrat,Leung, Joe C.T.,Dunbar, Christine R.,Sammis, Glenn M.
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supporting information; experimental part
p. 7720 - 7729
(2011/12/01)
-
- Nucleophilic substitution reaction at an sp2 carbon of vinyl halides with an intramolecular thiol moiety: synthesis of thio-heterocycles
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This article presents a full account of intramolecular vinylic substitution reactions of bromoalkenes having an acetylthio moiety, which give sulfur-containing heterocycles such as dihydrothiophene, tetrahydrothiopyran, and 2-alkylidenethietane derivative
- Lei, Mao-Yi,Xiao, Yong-Jun,Liu, Wei-Min,Fukamizu, Koji,Chiba, Shunsuke,Ando, Kaori,Narasaka, Koichi
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experimental part
p. 6888 - 6902
(2009/12/06)
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- Tandem Pd(II)-catalyzed vinyl ether exchange-claisen rearrangement as a facile approach to γ,δ-unsaturated aldehydes
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(Chemical Equation Presented) A sequential allyl vinyl ether formation-Claisen rearrangement process catalyzed by a palladium(II)- phenanthroline complex is reported. The effects of allylic alcohol structure, type of vinylating agent, and palladium catalysts are discussed. This method provides a convenient approach to γ,δ unsaturated aldehydes under mild conditions that avoid the use of toxic Hg(II) catalysts. The new methodology has been successfully demonstrated on the kilogram scale.
- Wei, Xudong,Lorenz, Jon C.,Kapadia, Suresh,Saha, Anjan,Haddad, Nizar,Busacca, Carl A.,Senanayake, Chris H.
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p. 4250 - 4253
(2008/02/04)
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- Tandem Diels-Alder/ene reactions
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(Chemical Equation Presented) The reactions of unsaturated aldehydes and triene 3 afford adducts via a tandem Diels-Alder/ene reaction.
- Kraus, George A.,Kim, Junwon
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p. 3115 - 3117
(2007/10/03)
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- Synthesis of methoxynor polyisoprenoid alcohols by alkylation of (3-methoxyallyl)lithium reagents
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A series of six methyl enol ether analogs 8-13 of geraniol, (E,E)-farnesol, and (E,E,E)-geranyl-geraniol was synthesized from a group of three allylic methyl ethers and three allylic chlorides. Lithiation of the 1-methyl-, or 1-alkenylvinyl ethers with se
- Jin, Qingwu,Coates, Robert M.
-
-
- Asymmetric hydroformylation of conjugated dienes catalyzed by chiral phosphine-phosphite-Rh(I) complex
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Asymmetric hydroformylation of conjugated dienes has been investigated using (R,S)-BINAPHOS-Rh(I) complex as a catalyst [(R,S)-BINAPHOS = (R)-2-(diphenylphosphino)-1,1'-binaphthalen-2'-yl (S)-1,1'-binaphthalene-2,2'-diyl phosphite]. Optically active β,γ-unsaturated aldehydes were obtained in high regio- (78-94%) and enantioselectivities (80-97% ee) from 1-vinylcyclohexene, 4-methyl-1,3-pentadiene, and (E)-1-phenyl-1,3-butadiene. On the other hand, hydroformylation of 1,3-butadiene gave achiral product, (E)- and (Z)-3-pentenal, in up to 95% selectivity. (R)-(E)-2-Methyl-3-pentenal was formed as the major product from both (E)- and (Z)-1,3-pentadiene, but enantioselectivity of the reaction was low. Mechanistic aspects are also discussed.
- Horiuchi, Toshihide,Ohta, Tetsuo,Shirakawa, Eiji,Nozaki, Kyoko,Takaya, Hidemasa
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p. 7795 - 7804
(2007/10/03)
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- Asymmetric hydroformylation of conjugated dienes catalysed by [(R)-2-diphenylphosphino-1,1′-dinaphthalen-2′-yl] [(S)-1,1′-dinaphthalene-2,2′-diyl]phosphite-rhodium(I)
-
Asymmetric hydroformylation of conjugated dienes such as vinylcyclohexene, (E)-phenyl-buta-1,3-diene and 4-methyl-penta-1,3-diene using BINAPHOS-RhI complexes as catalysts {(R,S)-BINAPHOS = [(R)-2-diphenylphosphino-1,1′-dinaphthalen-2′-yl] [(S)-1,1′-dinaphthalene-2,2′-diyl]-phosphite} gives optically active β,γ-unsaturated aldehydes in high regio- (81-91%) and enantio-selectivities (84-97% ee).
- Horiuchi, Toshihide,Ohta, Tetsuo,Nozaki, Kyoto,Takaya, Hidemasa
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p. 155 - 156
(2007/10/03)
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- Tandem inter [4+2]/intra [3+2] cycloadditions. 8. Cycloadditions with unactivated dipolarophiles
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The tandem intermolecular [4+2]/intramolecular [3+2] cycloaddition of nitroalkenes bearing a pendant olefin is presented. The success of the tandem process is remarkable in view of the potential for intramolecular reaction with the tethered alkene. Cycloadditions of di- and trisubstituted nitroalkenes bearing two- and three-methylene tethers which contain mono-, di- and trisubstituted olefins are described. In all cases the tandem process is high yielding (with n-butyl vinyl ether as the dienophile) and highly stereoselective. Hydrogenolysis of the resulting nitroso acetals leads cleanly to fused pyrrolidines in high yields.
- Denmark, Scott E.,Senanayake
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p. 11579 - 11600
(2007/10/03)
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- Highly stereoselective cationic cyclization assisted by a sulfenyl group, scope, limitation, and mechanism
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When 8-acetoxy-2-naethyl-9-(phenylthio)-2-nonene (la) was treated with an acid, followed by a base, alkylative cyclization proceeded to give a mixture of 1,2-disubstituted cyclohexanes: 2a, 3a, and 4a. The stereochemistry of the reaction was only slightly affected by the leaving group and the reaction conditions, such as the temperature, solvent, and acid. However, the bulkiness of the sulfenyl group had a great effect on the stereochemical course of the reaction. High trans selectivity was attained when 1c (a derivative of 1a with a bulkier sulfenyl group) was used as a substrate. On the other hand, the length and rigidity of the carbon chain of the substrate also had a major effect on the stereochemistry of the reaction; a high cis selectivity was observed when 10a (a one-carbon-fewer analog of Ia) or 15a (a derivative with one more double bond in the carbon chain than in 1a) was used as the substrate. The reaction proceeded via a 6,5- or 5,5-fused-ring intermediate. The sulfenyl-group-assisted reaction could be a useful method for the stereoselective cyclization of acetates of α-sulfenylated secondary alcohols.
- Liu, Changqing,Kudo, Kazuaki,Hashimoto, Yukihiko,Saigo, Kazuhiko
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p. 494 - 502
(2007/10/02)
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- Intramolecular cyclization of Δ4-alkenols with t-butyl hypochlorite in the presence of pyridine
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The reaction of some Δ4-alkenols (1,4) with t-butyl hypochlorite in the presence of pyridine (t-BuOCl/Py) has been investigated.It has been found that these olefinic alcohols afford, as major reaction products, chlorinated and in some cases unsaturated cyclic ethers of the tetrahydrofuran and/or tetrahydropyran type.
- Konstantinovic, S.,Bugarcic, Z.,Milovanovic, J. N.,Mihailovic, M. Lj.
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p. 354 - 356
(2007/10/02)
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- Cohalogenation of alkenes in ethylene oxide: Efficient methodology for the preparation of allyl vinyl ether precursors of γ,δ-unsaturated aldehydes
-
An investigation of the cohalogenation-dehydrohalogenation sequence as a method for the preparation of allyl vinyl ethers from simple olefins has been performed. Alkenes 1a-k react with bromide or chloride in the presence of ethylene oxide at -80°C to for
- Dulcere,Rodriguez
-
p. 399 - 405
(2007/10/02)
-
- Intramolecular cyclization of acetylenic homoallylic ketones mediated by the addition of stannyl radicals; a short facile pathway to α-methylene-β-substituted cyclopentanones
-
α-(Stannyl)methylenecyclopentanones are obtained by tributylstannane addition reactions of acetylenic homoallylic ketones. α-Methylenecyclopentanones are produced upon destannylation.
- Lee,Hur,Park
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p. 7219 - 7220
(2007/10/02)
-
- Process for producing lactones from unsaturated carbonyl compounds
-
A method for producing an alkyl substituted lactone including the steps of alkylating an unsaturated ketone with a C1 -C12 alkyl organometallic reagent such as a Grignard reagent or an alkali metal alkyl, to form an unsaturated alcohol, and oxidatively cleaving the unsaturated alcohol to form the lactone, and recovering the lactone.
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-
-
- Palladium-Catalyzed Reaction of Tributyltin Hydride with Acyl Chlorides. A Mild, Selective, and General Route to Aldehydes
-
Tetrakis(triphenylphosphine)palladium(0), various palladium(II) complexes, and even PdCl2 in the presence of triphenylphosphine catalyze the reaction of acyl chlorides with tri-n-butyltin hydride to specifically give aldehydes under very mild conditions and in very good yields.The reaction is quite general and tolerates the presence of many other reducible groups on the acyl chloride.Tetrakis(triphenylphosphine)palladium(0) also catalyzes the tributyltin hydride reduction of α,β-unsaturated carbonyl compounds to saturated carbonyl compounds; however, α,β-unsaturated acyl chlorides may be reduced to α,β-unsaturated aldehydes with a very good selectivity.The mechanism of the catalytic reductions is discussed.
- Four, P.,Guibe, F.
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p. 4439 - 4445
(2007/10/02)
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