- Catalytic Highly Regioselective C-H Oxygenation Using Water as the Oxygen Source: Preparation of 17O/18O-Isotope-Labeled Compounds
-
We found that the oxygen atom of water is activated to iodosylbenzene derivatives via reversible hydrolysis of PhI(OOCR)2 and can be used to the oxygen source for ruthenium(bpga)-catalyzed site-selective C-H oxygenation. Ru(bpga)/PhI(OOCR)2/H2O system, sterically less bulky methinic and methylenic C-H bonds in various compounds can be converted to desired oxygen functional groups in a site-selective manner. Using this method, oxygen-isotope labeled compounds such as d-[3-17O/18O]-mannose can be prepared in a multigram scale.
- Doiuchi, Daiki,Uchida, Tatsuya
-
supporting information
p. 7301 - 7305
(2021/10/01)
-
- Palladium-Catalyzed Low Pressure Carbonylation of Allylic Alcohols by Catalytic Anhydride Activation
-
A direct carbonylation of allylic alcohols has been realized for the first time with high catalyst activity at low pressure of CO (10 bar). The procedure is described in detail for the carbonylation of E-nerolidol, an important step in a new BASF-route to (?)-ambrox. Key to high activities in the allylic alcohol carbonylation is the finding that catalytic amounts of carboxylic anhydride activate the substrate and are constantly regenerated with carbon monoxide under the reaction conditions. The identified reaction conditions are transferrable to other substrates as well.
- Schelwies, Mathias,Paciello, Rocco,Pelzer, Ralf,Siegel, Wolfgang,Breuer, Michael
-
p. 9263 - 9266
(2021/05/27)
-
- Flavin Nitroalkane Oxidase Mimics Compatibility with NOx/TEMPO Catalysis: Aerobic Oxidization of Alcohols, Diols, and Ethers
-
Biomimetic flavin organocatalysts oxidize nitromethane to formaldehyde and NOx - providing a relatively nontoxic, noncaustic, and inexpensive source for catalytic NO2 for aerobic TEMPO oxidations of alcohols, diols, and ethers. Alcohols were oxidized to aldehydes or ketones, cyclic ethers to esters, and terminal diols to lactones. In situ trapping of NOx and formaldehyde suggest an oxidative Nef process reminiscent of flavoprotein nitroalkane oxidase reactivity, which is achieved by relatively stable 1,10-bridged flavins. The metal-free flavin/NOx/TEMPO catalytic cycles are uniquely compatible, especially compared to other Nef and NOx-generating processes, and reveal selectivity over flavin-catalyzed sulfoxide formation. Aliphatic ethers were oxidized by this method, as demonstrated by the conversion of (-)-ambroxide to (+)-sclareolide.
- Thapa, Pawan,Hazoor, Shan,Chouhan, Bikash,Vuong, Thanh Thuy,Foss, Frank W.
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p. 9096 - 9105
(2020/08/14)
-
- Direct Decarboxylative Functionalization of Carboxylic Acids via O-H Hydrogen Atom Transfer
-
Decarboxylative functionalization via hydrogen atom transfer offers an attractive alternative to standard redox approaches to this important class of transformations. Herein, we report a direct decarboxylative functionalization of aliphatic carboxylic acids using N-xanthylamides. The unique reactivity of amidyl radicals in hydrogen atom transfer enables decarboxylative xanthylation under redox-neutral conditions. This platform provides expedient access to a range of derivatives through subsequent elaboration of the xanthate group.
- Na, Christina G.,Ravelli, Davide,Alexanian, Erik J.
-
supporting information
p. 44 - 49
(2020/01/22)
-
- Chiral complementary alkyl heterocyclic compounds and their use as fungicides
-
The invention relates to a chiral drimane heterocyclic compound and a purpose of the chiral drimane heterocyclic compound as a sterilizing agent. A chemical structural general formula of the compoundis shown as a formula (I), in the formula (I), 8-bit stereo configuration is R or S, and represents the heterocyclic compound, comprising iso-oxazoline, isoxazole, pyrazoline, pyrimidine, benzimidazole and pyrimidine, or diazepine.
- -
-
Paragraph 0060-0064
(2020/10/20)
-
- METHOD FOR PRODUCING SCLAREOLIDE
-
A method for producing slcareolide comprising the following steps: (a) providing sclareol as starter material; (b) contacting the starter material sclareol with ozone in air or oxygen as the sole oxidant in an acidic medium.
- -
-
Paragraph 0027; 0028
(2020/12/30)
-
- Selective C(sp3)?H Aerobic Oxidation Enabled by Decatungstate Photocatalysis in Flow
-
A mild and selective C(sp3)?H aerobic oxidation enabled by decatungstate photocatalysis has been developed. The reaction can be significantly improved in a microflow reactor enabling the safe use of oxygen and enhanced irradiation of the reaction mixture. Our method allows for the oxidation of both activated and unactivated C?H bonds (30 examples). The ability to selectively oxidize natural scaffolds, such as (?)-ambroxide, pregnenolone acetate, (+)-sclareolide, and artemisinin, exemplifies the utility of this new method.
- Laudadio, Gabriele,Govaerts, Sebastian,Wang, Ying,Ravelli, Davide,Koolman, Hannes F.,Fagnoni, Maurizio,Djuric, Stevan W.,No?l, Timothy
-
supporting information
p. 4078 - 4082
(2018/03/21)
-
- Synthesis and bio-inspired optimization of drimenal: Discovery of chiral drimane fused oxazinones as promising antifungal and antibacterial candidates
-
The synthesis of antifungal natural product drimenal was accomplished. Bio-inspired optimization protruded chiral 8-(R)-drimane fused oxazinone D as a lead, considering favorable physicochemical profiles for novel pesticides. The improved scalable synthesis of scaffold D was implemented by Hofmann rearrangment under mild conditions. Detailed structural optimization was discussed for both antifungal and antibacterial exploration. Substituted groups (SGs) with C3～C5 hydrocarbon chain are recommended for exploration of antifungal agents, while substituents with C4～C6 carbon length are preferred for antibacterial ingredients. The chiral drimane fused oxazinone D8 was selected as a promising antifungal candidate against Botrytis cirerea, with an EC50 value of 1.18 mg/L, with the enhancement of up to >25 folds and >80 folds than the mother compound D, and acyclic counterpart AB5, respectively. The in vivo bioassay confirmed much better preservative effect of D8 than that of Carbendazim. The chiral oxazinone variant D10 possessed prominent antibacterial activity, with MIC values of 8 mg/L against both Bacillus subtilis and Ralstonia solanacearum, showing advantages over the positive control streptomycin sulfate.
- Li, Dangdang,Zhang, Shasha,Song, Zehua,Li, Wei,Zhu, Feng,Zhang, Jiwen,Li, Shengkun
-
supporting information
p. 558 - 567
(2017/12/07)
-
- Chiral drimane oxazinone compounds and use thereof as bactericide
-
The invention relates to chiral drimane oxazinone compounds and a use thereof as a bactericide. The chemical formula of the compounds is represented by a formula (I) as shown in the description, wherein the stereoscopic configuration of a site 8 is R or S.
- -
-
Paragraph 0043-0047
(2018/04/03)
-
- Synthesis and antifungal activities of drimane-amide derivatives from sclareol
-
Aim and Objective: Plant diseases are caused by fungal pathogens lead to severe economic losses in many agriculture crops. And the increasing resistance of many fungi to commonly used antifungal agents necessitates the discovery and development of new fungicides. So this study was focused on synthesizing novel skeleton compounds to effectively control plant diseases. Materials and Methods: A series of drimane-amide derivatives were designed, synthesized by aminolysis reaction of amine with intermediate sclareolide which was prepared from sclareol. The structures of all the synthesized compounds were confirmed using1H NMR,13C NMR, and HR-MS (ESI) spectroscopic data. Their in vitro antifungal activity were preliminarily evaluated by using the mycelium growth rate method against five phytopathogenic fungi: Botrytis cinerea, Glomerella cingulata, Alternaria alternate, Alternaria brassicae, and Fusarium graminearum. Results: 23 target compounds were successfully obtained in yields of 52-95%. Compounds358 A2 and A3 displayed favorable inhibitory potency against B. cinerea, G. cingulata and A. brassicae with IC50 values ranging from 3.18 to 10.48 μg/mL. These two compounds displayed higher fungicidal activity than sclareol against all the tested phytopathogenic fungi, and were more effective than the positive control thiabendazole against A. alternate and A. brassicae. The structure-activity relationship studies of compounds A1-10 indicated that both the position and type of substituent on the phenyl ring had significant effects on antifungal activity. Conclusion: The drimane-amide derivatives A2 and A3 were the most promising derivatives and should be selected as new templates for the potential antifungal agents.
- Ma, Miaofeng,Feng, Jili,Wang, Dezhi,Chen, Shu-Wei,Xu, Hui
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p. 501 - 509
(2018/12/13)
-
- Method for preparing acid through oxidating alcohols or aldehydes by oxygen
-
The invention provides a method for preparing acid through oxidating alcohols or aldehydes by using oxygen or oxygen in air as an oxidant. The method comprises the steps: oxidating the alcohols or aldehydes to produce the acid at room temperature in an organic solvent in a manner of taking ferric nitrate (Fe(NO3)3.9H2O), 2,2,6,6-tetramethylpiperidyl nitrogen oxide (TEMPO) and an inorganic halide as catalysts and taking the oxygen or air as an oxidant, and oxidating diols to produce lactone; or, carrying out a reaction on the aldehydes, which serve as a raw material, under neutral conditions by taking ferric nitrate as a catalyst, and oxidating the aldehydes to produce the acid and peroxy acid. The method has the advantages that the method is environmentally friendly, the cost is low, the yield is high, the atomic economical efficiency is high, the compatibility of substrate functional groups is good, the reaction conditions are mild, a reaction scale can be enlarged, and the like, so that the method is suitable for being applied to industrial production.
- -
-
Paragraph 0051; 0052; 0053; 0054; 0100; 0101; 0102
(2017/09/29)
-
- Iron Complex Catalyzed Selective C-H Bond Oxidation with Broad Substrate Scope
-
The use of a peroxidase-mimicking Fe complex has been reported on the basis of the biuret-modified TAML macrocyclic ligand framework (Fe-bTAML) as a catalyst to perform selective oxidation of unactivated 3° C-H bonds and activated 2° C-H bonds with low catalyst loading (1 mol %) and high product yield (excellent mass balance) under near-neutral conditions and broad substrate scope (18 substrates which includes arenes, heteroaromatics, and polar functional groups). Aliphatic C-H oxidation of 3° and 2° sites of complex substrates was achieved with predictable selectivity using steric, electronic, and stereoelectronic rules that govern site selectivity, which included oxidation of (+)-artemisinin to (+)-10β-hydroxyartemisinin. Mechanistic studies indicate FeV(O) to be the active oxidant during these reactions.
- Jana, Sandipan,Ghosh, Munmun,Ambule, Mayur,Sen Gupta, Sayam
-
supporting information
p. 746 - 749
(2017/03/01)
-
- Based on drop ambergris lactone latent flavor compound and its preparation method and application
-
The invention discloses an ambergris lactone based precursor-aroma compound as well as a preparation method and an application thereof. The preparation method comprises the following steps: ambergris lactone is dissolved in sufficient quantity of a solvent, alkali is added at the temperature ranging from subzero 78 DEG C to 50 DEG C, the mixture is stirred and reacts for more than 10 min, then acyl pyridine is added, the mixture is stirred at the temperature ranging from subzero 78 DEG C to 50 DEG C and reacts for more than 30 min, a quenching reaction is performed, and finally, the target precursor-aroma compound is obtained through postprocessing, separation and purification and added in the ratio of 0.00001%-10% by weight to a product which can release aroma during burning or heating. A very good model is provided for application of small fragrance molecules with high volatility and lower threshold value, meanwhile, the variety of the ambergris fragrance can be increased and enriched, the application ranges of the ambergris raw materials and acyl pyridine are broadened, and the defects of the ambergris lactone and acyl pyridine can be overcome.
- -
-
Paragraph 0019
(2018/01/05)
-
- Chiral 8-hydroxyhomodrimane sesquiterpene amide compound and application of same as agricultural bactericide
-
The invention relates to a chiral 8-hydroxyhomodrimane sesquiterpene amide compound and application of the same in inhibition of a plurality of pathogenic bacteria attacking crops. The compound has a chemical structural formula as shown in a formula (I) which is defined in the specification. In the formula (I), spatial configuration at position 8 is R or S.
- -
-
Paragraph 0034; 0035; 0036; 0043; 0044; 0045; 0046
(2017/08/27)
-
- Bioactivity-guided mixed synthesis accelerate the serendipity in lead optimization: Discovery of fungicidal homodrimanyl amides
-
The bioactivity-guided mixed synthesis was conceived, in which the designed mix-reactions were run in parallel for simultaneous construction of different kinds of analogs. The valuable ones were protruded by biological screening. This tactic will facilitate more rapid incorporation of bioactive candidates into pesticide chemists' repertoire, exemplified by the optimization of less explored homodrimanes as antifungal ingredients. The discovery of D9 as a potent fungicidal agent can be completed in 50 of 3.33?mg/L and 2.45?mg/L against S.?sclerotiorum and B.?cinerea, respectively. To confirm the practicability, time-efficiency, and reliability, specific homodrimanes (82 derivatives) were synthesized and elucidated separately and determined for EC50 values. The SAR correlated well with the intentionally mixed synthesis and the potential was further confirmed by the in vivo bioassay. This methodology will foster more efficient exploration of biologically relevant chemical space of natural products in pesticide discovery, and can also be tailored readily for the lead optimization in medicinal chemistry.
- Li, Dangdang,Zhang, Shasha,Song, Zehua,Wang, Guotong,Li, Shengkun
-
supporting information
p. 114 - 121
(2017/05/10)
-
- From DNA to catalysis: A thymine-acetate ligated non-heme iron(III) catalyst for oxidative activation of aliphatic C-H bonds
-
A non-heme, iron(iii)/THA(thymine-1-acetate) catalyst together with H2O2 as an oxidant is efficient in oxidative C-H activation of alkanes. Although having a higher preference for tertiary C-H bonds, the catalyst also oxidizes aliphatic secondary C-H bonds into carbonyl compounds with good to excellent conversions. Based on the site selectivity of the catalyst and our mechanistic studies the reaction proceeds via an Fe-oxo species without long lived carbon centered radicals.
- Al-Hunaiti, Afnan,R?is?nen, Minn?,Repo, Timo
-
p. 2043 - 2046
(2016/02/05)
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- METHOD FOR THE CONVERSION OF ABIENOL TO SCLAREDIOL
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A method of selective conversion of Abienol, represented by formula 1, to Sclareodial, represented by formula 2 by ozonolysis and subsequent reduction. The ozonolysis is carried out at temperatures above -60 °C, preferably in nonhalogenated solvents. R is selected from H, acetals, aminals, optionally substituted alkyl groups, such as benzyl group, carboxylates such as acetates or formates, carbonates such as methyl or ethyl carbonates, carbamates, and any protecting group which can be attached to 1 and cleaved from 2, R' is selected from CH=CH2, an alkyl moiety with C2-C20, e.g. CH2-CH3, or a cycloalkyl or polycycloalkyl moiety with C3-C20, e.g. cyclopropyl, optionally alkylated, respectively, and the wavy bond is depicting an unspecified configuration of the adjacent double bond between C2 and C3.
- -
-
Page/Page column 8-9
(2016/10/04)
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- Iron Catalysis for Room-Temperature Aerobic Oxidation of Alcohols to Carboxylic Acids
-
Oxidation from alcohols to carboxylic acids, a class of essential chemicals in daily life, academic laboratories, and industry, is a fundamental reaction, usually using at least a stoichiometric amount of an expensive and toxic oxidant. Here, an efficient and practical sustainable oxidation technology of alcohols to carboxylic acids using pure O2 or even O2 in air as the oxidant has been developed: utilizing a catalytic amount each of Fe(NO3)3·9H2O/TEMPO/MCl, a series of carboxylic acids were obtained from alcohols (also aldehydes) in high yields at room temperature. A 55 g-scale reaction was demonstrated using air. As a synthetic application, the first total synthesis of a naturally occurring allene, i.e., phlomic acid, was accomplished.
- Jiang, Xingguo,Zhang, Jiasheng,Ma, Shengming
-
supporting information
p. 8344 - 8347
(2016/07/26)
-
- Method for synthesizing sclareolide under catalysis of immobilized epoxidase
-
The invention belongs to the technical field of biochemical engineering and particularly discloses a method for synthesizing sclareolide under catalysis of immobilized epoxidase. According to the method, sclareol is taken as a starting material. The method is characterized in that sclareol, immobilized epoxidase, a hydrogen peroxide solution and dichloroethane are added to a beaker and react under the conditions that the pH value is 2 and the temperature is 50 DEG C, epoxidized sclareol is obtained, oxidative degradation is continuously performed under the action of hydrogen peroxide, hydroxy acid is obtained, methylbenzene is added, the mixture is heated for reflux, and sclareolide is obtained. The method has the advantages that the production technological conditions are mild, the steps are simple, the method is environment-friendly, the economic benefits are high and the like, the reaction time is greatly shortened, the reaction temperature is reduced, and the production cost is saved.
- -
-
Paragraph 0016
(2016/12/01)
-
- Efficient oxidation of ethers with pyridine N-oxide catalyzed by ruthenium porphyrins
-
We found that oxidation of cyclic ethers with the Ru porphyrin-heteroaromatic N-oxide system gave lactones or/and ring-opened oxidized products with regioselectivity. A relatively high kinetic isotope effect was observed in the ether oxidation, suggesting that the rate-determining step is the first hydrogen abstraction.
- Kato, Nobuki,Hamaguchi, Yu,Umezawa, Naoki,Higuchi, Tsunehiko
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p. 411 - 416
(2015/05/13)
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- Mechanism of Selective C-H Hydroxylation Mediated by Manganese Aminopyridine Enzyme Models
-
The mechanism of selective oxidation of aliphatic C-H groups with H2O2 in the presence of aminopyridine Mn complexes, modeling the reactivities of natural oxygenases of the cytochrome P450 superfamily, has been examined. The oxygenation of C-H groups proceeds via hydrogen atom abstraction by the electrophilic metal site; the logarithm of C-H oxidation rates correlates linearly with bond dissociation energies for homolytic C-H bond cleavage. Hammett correlations and stereospecificity studies reflect the formation of a short-lived electron-deficient radical intermediate. Isotopic labeling studies confirm the incorporation of 18O from added H218O, thus providing so far lacking evidence for the oxomanganese(V)-mediated oxidation mechanism. (Figure Presented).
- Ottenbacher, Roman V.,Talsi, Evgenii P.,Bryliakov, Konstantin P.
-
-
- STRIGOLACTONE FORMULATIONS AND USES THEREOF
-
Disclosed herein plant propagation materials, methods of manufacturing, formulations and uses thereof. The plant propagation materials disclosed herein may comprise a strigolactone obtained by a biosynthetic process. The plant propagation material may comprise a chemical mimic of a strigolactone. The strigolactone may be 5-deoxystrigol. Methods of manufacturing the plant propagation materials may comprise a chemical process. Alternatively, methods of manufacturing the plant propagation material may comprise a biosynthetic process. The methods may comprise use of one or more polynucleotides. The polynucleotides may encode a metabolite. The polynucleotides may comprise one or more genes encoding one or more components of a strigolactone pathway.
- -
-
Paragraph 0293
(2015/05/06)
-
- Synthesis and antifungal activity of ethers, alcohols, and iodohydrin derivatives of sclareol against phytopathogenic fungi in vitro
-
This study synthesized 20 sclareol derivatives. The antifungal activities of these derivatives were evaluated in vitro against five phytopathogenic fungi using the mycelium growth rate method. Among all the tested compounds, compound 16 with one iodine atom and three hydroxyl groups displayed higher fungicidal activities against all the tested phytopathogenic fungi than precursor sclareol. Compound 16 also showed more pronounced antifungal activities against Curvularia lunata (IC50 = 12.09 μg/mL) and Alternaria brassicae (IC50 = 14.47 μg/mL) than the positive control, a commercial agricultural fungicide thiabendazole.
- Ma, Miaofeng,Feng, Jili,Li, Ruoxin,Chen, Shu-Wei,Xu, Hui
-
supporting information
p. 2773 - 2777
(2015/06/08)
-
- The iron(II) complex [Fe(CF3SO3)2(mcp)] as a convenient, readily available catalyst for the selective oxidation of methylenic sites in alkanes
-
The efficient and selective oxidation of secondary C-H sites of alkanes is achieved by using low catalyst loadings of a non-expensive, readily available iron catalyst [Fe(II)(CF3SO3)2(mcp)], {Fe-mcp, [mcp=N,N'-dimethyl-N,N'-bis(2-pyridylmethyl)cyclohexane-trans-1,2-diamine]}, and hydrogen peroxide (H2O2) as oxidant, via a simple reaction protocol. Natural products are selectively oxidized and isolated in synthetically amenable yields. The easy access to large quantities of the catalyst and the simplicity of the C-H oxidation procedure make this system a particularly convenient tool to carry out alkane C-H oxidation reactions on the preparative scale, and in short reaction times.
- Canta, Merce,Font, David,Gomez, Laura,Ribas, Xavi,Costas, Miquel
-
supporting information
p. 818 - 830
(2014/04/03)
-
- Making Fe(BPBP)-catalyzed C-H and CC oxidations more affordable
-
The limited availability of catalytic reaction components may represent a major hurdle for the practical application of many catalytic procedures in organic synthesis. In this work, we demonstrate that the mixture of isomeric iron complexes [Fe(OTf)2(mix-BPBP)] (mix-1), composed of Λ-α-[Fe(OTf)2(S,S-BPBP)] (S,S-1), Δ-α- [Fe(OTf)2(R,R-BPBP)] (R,R-1) and Δ/Λ-β-[Fe(OTf) 2(R,S-BPBP)] (R,S-1), is a practical catalyst for the preparative oxidation of various aliphatic compounds including model hydrocarbons and optically pure natural products using hydrogen peroxide as an oxidant. Among the species present in mix-1, S,S-1 and R,R-1 are catalytically active, act independently and represent ca. 75% of mix-1. The remaining 25% of mix-1 is represented by mesomeric R,S-1 which nominally plays a spectator role in both C-H and C=C bond oxidation reactions. Overall, this mixture of iron complexes displays the same catalytic profile as its enantiopure components that have been previously used separately in sp3 C-H oxidations. In contrast to them, mix-1 is readily available on a multi-gram scale via two high yielding steps from crude dl/meso-2,2′-bipyrrolidine. Next to its use in C-H oxidation, mix-1 is active in chemospecific epoxidation reactions, which has allowed us to develop a practical catalytic protocol for the synthesis of epoxides.
- Yazerski, Vital A.,Spannring, Peter,Gatineau, David,Woerde, Charlotte H.M.,Wieclawska, Sara M.,Lutz, Martin,Kleijn, Henk,Klein Gebbink, Robertus J.M.
-
supporting information
p. 2062 - 2070
(2014/03/21)
-
- Enantioselective access to (-)-Ambrox starting from β-farnesene
-
Starting from inexpensive (E)-β-farnesene (1), an eight-step enantioselective synthesis of the olfactively precious Ambrox ((-)-2a) has been performed. The crucial step is the catalytic asymmetric isomerization of (2E,6E)-N,N-diethylfarnesylamine (3) to t
- Chapuis, Christian
-
p. 197 - 214
(2014/03/21)
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- An iron catalyst for oxidation of alkyl C-H bonds showing enhanced selectivity for methylenic sites
-
Many are called but few are chosen: A nonheme iron complex catalyzes the oxidation of alkyl C-H bonds by using H2O2 as the oxidant, showing an enhanced selectivity for secondary over tertiary C-H bonds (see scheme). Copyright
- Prat, Irene,Gomez, Laura,Canta, Merce,Ribas, Xavi,Costas, Miquel
-
p. 1908 - 1913
(2013/03/14)
-
- Cp* iridium precatalysts for selective C-h oxidation with sodium periodate as the terminal oxidant
-
Sodium periodate (NaIO4) is shown to be a milder and more efficient terminal oxidant for C-H oxidation with CpIr (Cp* = C 5Me5) precatalysts than ceric(IV) ammonium nitrate. Synthetically useful yields, regioselectivities, and functional group tolerance were found for methylene oxidation of substrates bearing a phenyl, ketone, ester, or sulfonate group. Oxidation of the natural products (-)-ambroxide and sclareolide proceeded selectively, and retention of configuration was seen in cis-decalin hydroxylation. At 60 C, even primary C-H bonds can be activated: whereas methane was overoxidized to CO2 in 39% yield without giving partially oxidized products, ethane was transformed into acetic acid in 25% yield based on total NaIO4. 18O labeling was demonstrated in cis-decalin hydroxylation with 18OH2 and NaIO 4. A kinetic isotope effect of 3.0 ± 0.1 was found in cyclohexane oxidation at 23 C, suggesting C-H bond cleavage as the rate-limiting step. Competition experiments between C-H and water oxidation show that C-H oxidation of sodium 4-ethylbenzene sulfonate is favored by 4 orders of magnitude. In operando time-resolved dynamic light scattering and kinetic analysis exclude the involvement of metal oxide nanoparticles and support our previously suggested homogeneous pathway.
- Zhou, Meng,Hintermair, Ulrich,Hashiguchi, Brian G.,Parent, Alexander R.,Hashmi, Sara M.,Elimelech, Menachem,Periana, Roy A.,Brudvig, Gary W.,Crabtree, Robert H.
-
supporting information
p. 957 - 965
(2013/04/23)
-
- Regioselective oxidation of nonactivated alkyl C-H groups using highly structured non-heme iron catalysts
-
Selective oxidation of alkyl C-H groups constitutes one of the highest challenges in organic synthesis. In this work, we show that mononuclear iron coordination complexes Λ-[Fe(CF3SO3) 2((S,S,R)-MCPP)] (Λ-1P), Δ-[Fe(CF3SO 3)2((R,R,R)-MCPP)] (Δ-1P), Λ-[Fe(CF 3SO3)2((S,S,R)-BPBPP)] (Λ-2P), and Δ-[Fe(CF3SO3)2((R,R,R)-BPBPP)] (Δ-2P) catalyze the fast, efficient, and selective oxidation of nonactivated alkyl C-H groups employing H2O2 as terminal oxidant. These complexes are based on tetradentate N-based ligands and contain iron centers embedded in highly structured coordination sites defined by two bulky 4,5-pinenopyridine donor ligands, a chiral diamine ligand backbone, and chirality at the metal (Λ or Δ). X-ray diffraction analysis shows that in Λ-1P and Λ-2P the pinene rings create cavity-like structures that isolate the iron site. The efficiency and regioselectivity in catalytic C-H oxidation reactions of these structurally rich complexes has been compared with those of Λ-[Fe(CF3SO3) 2((S,S)-MCP)] (Λ-1), Λ-[Fe(CF3SO 3)2((S,S)-BPBP)] (Λ-2), Δ-[Fe(CF 3SO3)2((R,R)-BPBP)] (Δ-2), Λ-[Fe(CH3CN)2((S,S)-BPBP)](SbF6) 2 (Λ-2SbF6), and Δ-[Fe(CH3CN) 2((R,R)-BPBP)](SbF6)2 (Δ-2SbF 6), which lack the steric bulk introduced by the pinene rings. Cavity-containing complexes Λ-1P and Λ-2P exhibit enhanced activity in comparison with Δ-1P, Δ-2P, Λ-1, Λ-2, and Λ-2SbF6. The regioselectivity exhibited by catalysts Λ-1P, Λ-2P, Δ-1P, and Δ-2P in the C-H oxidation of simple organic molecules can be predicted on the basis of the innate properties of the distinct C-H groups of the substrate. However, in specific complex organic molecules where oxidation of multiple C-H sites is competitive, the highly elaborate structure of the catalysts allows modulation of C-H regioselectivity between the oxidation of tertiary and secondary C-H groups and also among multiple methylene sites, providing oxidation products in synthetically valuable yields. These selectivities complement those accomplished with structurally simpler oxidants, including non-heme iron catalysts Λ-2 and Λ-2SbF6.
- Gómez, Laura,Canta, Merceì,Font, David,Prat, Irene,Ribas, Xavi,Costas, Miquel
-
p. 1421 - 1433
(2013/03/29)
-
- Synthesis of (+)-sclareolide based on a cyclic enol ether ring contraction induced by peroxy acids
-
(+)-Sclareolide has been synthesised from (+)-sclareol oxide in one step in high yield, by treatment with peroxy acids under very mild conditions. The reaction pathway does not follow the usual oxidative cleavage of the double bond of (+)-sclareol oxide, but the key intermediate is a five-membered ring hemiketal. The direct conversion of a six-membered cyclic enol ether into a γ-lactone is described for the first time.
- Castro, Juan M.,Salido, Sofía,Sánchez, Adolfo,Altarejos, Joaquín
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scheme or table
p. 2747 - 2750
(2010/12/29)
-
- Combined effects on selectivity in Fe-catalyzed methylene oxidation
-
Methylene C-H bonds are among the most difficult chemical bonds to selectively functionalize because of their abundance in organic structures and inertness to most chemical reagents. Their selective oxidations in biosynthetic pathways underscore the power of such reactions for streamlining the synthesis of molecules with complex oxygenation patterns. We report that an iron catalyst can achieve methylene C-H bond oxidations in diverse natural-product settings with predictable and high chemo-, site-, and even diastereoselectivities. Electronic, steric, and stereoelectronic factors, which individually promote selectivity with this catalyst, are demonstrated to be powerful control elements when operating in combination in complex molecules. This small-molecule catalyst displays site selectivities complementary to those attained through enzymatic catalysis.
- Chen, Mark S.,White, M. Christina
-
scheme or table
p. 533 - 571
(2010/10/05)
-
- Synthesis of n-containing drimane sesquiterpenoids from 11-dihomodriman-8α-ol-12-one
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Beckmann reaction products of 11-dihomodriman-8α-ol-12-one oxime with Ac2O in pyridine, 86% H3PO4, p-TsCl in pyridine, and PCl5 in ether were investigated. It has been found that the major product from treatment of the oxime with Ac2O is the oxime acetate. Reaction of the oxime with 86% H3PO4 gave (1S,2S,4aS,8aS)-2,5,5,8a-tetramethyldecahydro-1H-naphtho[1,2][5,6]-3-methyl-4, 5-dihydro[1,2,6]oxazine; with p-TsCl, (1S,2S,4aS,8aS)-2,5,5,8a- tetramethyldecahydro-1H-naphtho[1,2][5,6]-2-methyl-4,5- dihydro[1,3,6]oxazine; with PCl5, a mixture of products containing 11-acetylamino- and 11-methylaminooxodrimenes that were isomeric at the double bond, norambreinolide, and a 1,3,6-oxazine.
- Kuchkova,Aryku,Vlad,Deleanu,Nikolescu
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experimental part
p. 539 - 544
(2010/12/25)
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- Efficient enantioselective synthesis of (+)-sclareolide and (+)-tetrahydroactinidiolide: chiral LBA-induced biomimetic cyclization
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An efficient enantioselective synthesis of the lactones (+)-sclareolide and (+)-tetrahydroactinidiolide has been achieved through Lewis acid-assisted chiral Bronsted acid-induced enantioselective cyclization of terpenic carboxylic acids. The reaction sequ
- Upar, Kiran B.,Mishra, Sanjay J.,Nalawade, Shrikant P.,Singh, Soni A.,Khandare, Reena P.,Bhat, Sujata V.
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experimental part
p. 1637 - 1640
(2009/12/06)
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- Degradation of the side chain of (-)-sclareol: A very short synthesis of nor-ambreinolide and ambrox
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The synthesis of nor-Ambreinolide (8) from (-)-sclareol (1) was carried out by treatment with KMnO4-Ac2O and further alkaline hydrolysis. 8 was directly transformed into (-)-ambrox (11) by reduction with metal borohydride in the presence of Lewis acids.
- Barrero,Alvarez-Manzaneda,Chahboun,Arteaga
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p. 3631 - 3643
(2007/10/03)
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- About a practical synthesis of Ambrox from sclareol: A new preparation of a ketone key intermediate and a close look at its Baeyer-Villiger oxidation
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The latest route to Ambrox (1) starting from sclareol (2) proceeds through an oxy ketone 4 (Scheme 1). A new practical synthesis of the key intermediate 4 is described; it is equivalent to a partial oxidative degradation of sclareol (2) with peracetic and periodic acids (Scheme 2). The final product of the Baeyer - Villiger oxidation of the oxy ketone 4 with commercial peracetic acid is decisively dependent on the reaction conditions because the expected acetate 9 reacts with any nucleophile, especially the peracid (Scheme 3). Furthermore, this acetate 9 is very prone to eliminative coupling (Scheme 4).
- Moulines, Jean,Bats, Jean-Paul,Lamidey, Anne-Marie,Da Silva, Nicole
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p. 2695 - 2705
(2007/10/03)
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- Microbial transformation of sesquiterpenes, (-)-Ambrox and (+)-sclareolide
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The microbial transformation of (-)-Ambrox (1), a perfumery sesquiterpene, by a number of fungi, by means of standard two-stage-fermentation technique, afforded ambrox-1α-ol (2), ambrox-1α,11α-diol (3), ambrox-1α,6α-diol (4), ambrox-1α,6α,11α-triol (5), ambrox-3-one (6), ambrox-3β-ol (7), ambrox-3β,6β-diol (8), 13,14,15,16-tetranorlabdane-3,8,12-triol (9), and sclareolide (10) (Schemes 1 and 2). Further incubation of compound 10 with Cunninghamella elegans afforded 3-oxosclareolide (11), 3β-hydroxysclareolide (12), 2α- hydroxysclareolide (13), 2α,3β-dihydroxysclareolide (14), 1α,3β-dihydroxysclareolide (15), and 3β-hydroxy-8-episclareolide (16) (Scheme 3). Metabolites 2-5, 12, 13, and 16 were found to be new compounds. The major transformations include a reaction path involving hydroxylation, ether-bond cleavage and inversion of configuration. Metabolites 11-16 of sclareolide showed significant phytotoxicity (Table I). The structures of the metabolites were characterized on the basis of spectroscopic techniques.
- Choudhary, M. Iqbal,Musharraf, Syed Ghulam,Sami, Amtul,Atta-Ur-Rahman
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p. 2685 - 2694
(2007/10/03)
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- The x-ray crystal structures of ambraketal and 8-epi-ambraketal
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The crystal structures of ambraketal and 8-epi-ambraketal, synthesised in five steps from (-)-sclareol, are reported.
- Gray, Christopher A.,Davies-Coleman, Michael T.,Caira, Mino R.,Nathanson, Carole A.,Wisch, Gregory A.
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p. 405 - 407
(2007/10/03)
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- A practical synthesis of ambrox from sclareol using no metallic oxidant
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The commercial synthesis of Ambrox is modified so that the key intermediate, the sclareolide, results from an indirect Oxidative degradation of sclareol. This method allows to greatly alleviate the waste disposal problem and to raise the overall yield of Ambrox to 75%.
- Moulines,Lamidey,Desvergnes-Breuil
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p. 749 - 758
(2007/10/03)
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- Resolution of sclareolide as a key intermediate for the synthesis of Ambrox
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Sclareolide was efficiently resolved by a diastereomeric salt formation method using homochiral erythro-2-amino-1,2-diphenylethanol (ADPE) as a resolving agent.
- Koga, Tsukasa,Aoki, Yoshio,Hirose, Takuji,Nohira, Hiroyuki
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p. 3819 - 3823
(2007/10/03)
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- Synthesis of (+)-coronarin E
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The labdane-type diterpenoid (+)-coronatin E (5) has been synthesized in 7 steps from (-)-sclareol (1) for the first time.
- Mueller, Martin,Schroeder, Joerg,Magg, Christine,Seifert, Karlheinz
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p. 4655 - 4656
(2007/10/03)
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- Oxidative degradation of the sclareol side chain: hemisyntheses of ambergris derivatives using in the key steps palladium complexes or ruthenium tetroxide generated in situ
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We report the hemisyntheses of various ambergris-type derivatives: ambraoxide 4, Ambrox 8, 13-methylambraoxide 13, ambraketal 14, norambraketal 15, non-norambraketal 16 and dioxepane 53.Sclareol 12 is used as starting material because it is currently available from Salvia sclarea.The key steps involve an oxidative degradation of the sclareol 12 side chain, using either palladium complexes or ruthenium tetroxide generated in situ. - Keywords: sclareol; Ambrox; ambraoxide; 13-methylambraoxide; ambraketal; norambraketal; nor-norambraketal; farnesylic aldehyde; palladium complex; ruthenium tetroxide generated in situ; oxidative degradation
- Zahra, Jean-Pierre,Chauvet, Frederic,Coste-Maniere, Ivan,Martres, Paul,Perfetti, Patricia,Waegell, Bernard
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p. 1001 - 1024
(2007/10/03)
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- Process for the production of sclareolide
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A process for the production of sclareolide comprising the steps of: (1) providing an aqueous composition comprised of: (a) water; (b) sclareol, abienol, or a mixture of sclareol and abienol, (c) an effective amount of a ruthenium catalyst; and, (d) an emulsifying agent; (2) forming an aqueous alkaline composition by adding an alkali metal hydroxide to said aqueous composition; (3) reacting said aqueous alkaline composition with an oxidizing agent to form a crude product; and either: (4) further reacting said crude product with base to form the salt of 8α-hydroxy-11-carboxyl-12, 13, 14, 15, 16-pentanorlabdane and; (5) reacting said salt with acid to form sclareolide; or: (4) heating said crude product to form sclareolide.
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- Oxidation of ethers to esters by photo-irradiation with benzil and oxygen
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A novel method for the conversion of ethers to esters by photo-oxidation using benzil and molecular oxygen, and its plausible reaction mechanism participated by benzoylperoxy radical are described.
- Seto, Hideharu,Yoshida, Keigo,Yoshida, Shigeo,Shimizu, Takeshi,Seki, Hiroshi,Hoshino, Mikio
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p. 4179 - 4182
(2007/10/03)
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- Synthesis of nor-ambreinolide from (+)-cis-abienol
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The synthesis of nor-ambreinolide (2) from cis-abienol (1) was carried out by direct treatment with OsO4-NaIO4 or RuO4-NaIO4. The oxymercuriation-demercuriation of 1 led to a mixture of 8,12-epoxylabdanes (5-17) which was also converted into nor-ambreinolide by treatment with RuO4-NaIO4. The formation pathways of such epoxy derivatives are discussed.
- Barrero, Alejandro F.,Sanchez, Juan F.,Alvarez-Manzaneda, Enrique J.,Altarejos, Joaquin,Munoz, Manuel,Haidour, Ali
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p. 6653 - 6662
(2007/10/02)
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- The Biosynthesis of Labdanoids. The Optical Purity of Naturally Occurring Manool and Abienol
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The co-occurrence in nature of normal- and ent-labdanes is surveyed, and the possibility is explored that the enzyme responsible for the cyclization of geranyl geraniol pyrophosphate to the labdane skeleton allows enantiomeric leakage to yield optically impure products.Naturally occuring manool and abienol have been isolated without enantiomeric fractionation and examined to evaluate in vivo optical purity.
- Carman, Raymond M.,Duffield, Alan R.
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p. 1105 - 1114
(2007/10/02)
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- A Short and Efficient Synthesis of (-)-Ambrox from (-)-Sclareol using a Ruthenium Oxide Catalyzed Key Step
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(-)-Ambrox 5 has been synthesized in 3 steps from natural (-)-sclareol 1.Depending on the reoxidizing agents and the reaction conditions used in the ruthenium oxide catalyzed key step, overall yields of 79percent (NaIO4/RuO4) or 48percent (Ca(OCl)2/RuO4) were observed.Key Words: Ambrox, sclareol, ruthenium tetroxide.
- Martres, Paul,Perfetti, Patricia,Zahra, Jean-Pierre,Waegell, B.,Giraudi, Edouard,Petrzilka, Martin
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p. 629 - 632
(2007/10/02)
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- Synthesis of norambracetal: A new ambergris derivative
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We describe the synthesis of norambracetal 14 from sclareol 1 using γ-homobicyclofarnesilic aldehyde10 as a key intermediate.
- Martres, Paul,Perfetti, Patricia,Zahra, Jean Pierre,Waegell, Bernard
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p. 3127 - 3128
(2007/10/02)
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- Ambergris compounds from labdanolic acid
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Labdanolic acid (Cistus ladaniferus) is transformed into derivatives with amber odor. The strategy used allowed a process in which the oxidative decarboxylation reaction was carried out with the hydroxyl group protected.
- Urones,Basabe,Marcos,Gonzalez,Jimenez,Sexmero,Lithgow
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p. 9991 - 9998
(2007/10/02)
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- Chemistry of labdanediol from Cistus ladaniferus, L. synthesis of 12-Nor-ambreinolide and α and β-levantenolides
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Labdanediol, 2, the major component of the neutral part of Cistus ladaniferus L, was transformed into 12-nor-ambreinolide, precursor of ambrox, in three steps with an overall yield of 70%. Molecular modelling techniques have been used to determine the stereochemistry of the byproducts of these reactions. The selenylation and elimination reactions of α and βlevantanolides, obtained from labdanediol, 2, were used to synthetise α and β-levantenolides.
- Urones,Basabe,Marcos,Diez Martin,Sexmero,Peral,Broughton
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p. 10389 - 10398
(2007/10/02)
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