- Stereospecific synthesis of a new N-tosyl bromo-aminocyclitol
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Abstract: Aminocyclitols are cyclic polyhydroxylated amines formally derived from cyclitols, and they constitute an important class of biologically active compounds. In the current research, the synthesis and characterization of a new N-tosyl bromo-aminoc
- Kurbano?lu, Namudar ?zzet
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- Collective Synthesis of Schilancidilactones A, B and Schilancitrilactones A, B, C, 20-epi-Schilancitrilactone A
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Schisandraceae triterpenoids are novel natural products that contain highly fused ring systems bearing multiple chiral centers surrounding. Some of them exhibit promising bioactivities, such as antitumor, anti-HIV, etc. In this article, we describe our ef
- Wang, Hengtao,Wang, Liang,Li, Yihang,Zhang, Xiunan,Tang, Pingping
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- Synthesis of branched carbasugars via photooxygenation and manganese(III) acetate free radical cyclization
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Transformation of cyclohexa-1,3- and 1,4-dienes to carbasugars is described. Photooxygenation of dienes gave bicyclic endoperoxides, which were reduced with thiourea to the corresponding 1,4-diols with cis-configuration. Lactonization of the remaining dou
- Altun, Yasemin,Dogan, Sengul Dilem,Balci, Metin
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- Reductive Difunctionalization of Aryl Alkenes with Sodium Metal and Reduction-Resistant Alkoxy-Substituted Electrophiles
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A general method for alkali-metal-promoted reductive difunctionalization of alkenes has been developed by means of reduction-resistant alkoxy-substituted electrophiles. A series of 1,2-diboration and 1,2-dicarbofunctionalization products can be synthesize
- Fukazawa, Mizuki,Nogi, Keisuke,Sasamori, Takahiro,Takahashi, Fumiya,Yorimitsu, Hideki
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supporting information
(2020/03/13)
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- Unusual Oxidative Dealkylation Strategy toward Functionalized Phenalenones as Singlet Oxygen Photosensitizers and Photophysical Studies
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A series of functionalized 6-alkoxy phenalenones was prepared through an unprecedented oxidative dealkylation of readily available phenalene precursors. The starting phenalenes were efficiently synthesized via an aminocatalyzed annulation/O-alkylation str
- De Bonfils, Paul,Verron, Elise,Sandoval-Altamirano, Catalina,Jaque, Pablo,Moreau, Xavier,Gunther, German,Nun, Pierrick,Coeffard, Vincent
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p. 10603 - 10616
(2020/09/23)
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- A Pd-catalyzed asymmetric allylic substitution cascade: Via an asymmetric desymmetrization for the synthesis of bicyclic dihydrofurans
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A Pd-catalyzed asymmetric allylic substitution cascade of allylic meso-dicarbonates with 3-oxo-nitriles has been developed for the synthesis of chiral bicyclic dihydrofurans bearing two vicinal carbon stereocenters. The reaction proceeds via an asymmetric desymmetrization process with the desired products being obtained in high yields and with up to 97% ee. The reaction was performed on a gram-scale and the corresponding bicyclic dihydrofurans could undergo several transformations. The methodology provides an efficient synthetic route to biologically active chiral bicyclic dihydrofurans derivatives.
- Xu, Kai,Liu, Hao,Hou, Yilin,Shen, Jiefeng,Liu, Delong,Zhang, Wanbin
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supporting information
p. 13295 - 13298
(2019/11/13)
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- Amine Catalysis for the Organocatalytic Diboration of Challenging Alkenes
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The generation of in situ sp2–sp3diboron adducts has revolutionised the synthesis of organoboranes. Organocatalytic diboration reactions have represented a milestone in terms of unpredictable reactivity of these adducts. However, current methodologies have limitations in terms of substrate scope, selectivity and functional group tolerance. Here a new methodology based on the use of simple amines as catalyst is reported. This methodology provides a completely selective transformation overcoming current substrate scope and functional/protecting group limitations. Mechanistic studies have been included in this report.
- Farre, Albert,Soares, Kaline,Briggs, Rachel A.,Balanta, Angelica,Benoit, David M.,Bonet, Amadeu
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supporting information
p. 17552 - 17556
(2016/11/28)
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- Total synthesis of schilancitrilactones B and C
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The first total syntheses of schilancitrilactones B and C have been accomplished in 17 steps (longest linear sequence) from commercially available materials. Key steps include an intramolecular radical cyclization to provide the seven-membered ring, late-stage iodination, and an intermolecular radical addition reaction to complete the total synthesis. In step: The first total syntheses of schilancitrilactones B and C have been accomplished by using an intramolecular radical cyclization to provide the seven-membered ring, late-stage iodination, and an intermolecular radical addition reaction as key steps. The approach provides a sequence for the syntheses of compounds related to the schilancitrilactones, as well as their derivatives and analogues.
- Wang, Liang,Wang, Hengtao,Li, Yihang,Tang, Pingping
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supporting information
p. 5732 - 5735
(2015/09/21)
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- Composition
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PROBLEM TO BE SOLVED: To provide a hair dye composition which has excellent hair-bleaching power and little damages hair. SOLUTION: This hair dye composition comprises (a) a first agent containing a nitrogen-containing compound represented by the general formula (1) [R1, R3to R5are each H, OH, a ≤12C alkyl which may have one or more substituents, or the like; R2is OH, -R or -OR (R is the same meaning as R3to R5); two or more of R1to R5may together form a 3 to 8-membered ring which may have one or more substituents] or its salt and (b) a second agent containing an oxidizing agent, and has pH 7.5 to 12, when used. COPYRIGHT: (C)2007,JPOandINPIT
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- Expanding the scope of biomass-derived chemicals through tandem reactions based on oxorhenium-catalyzed deoxydehydration
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New modes of DODH: Oxorhenium compounds act as deoxydehydration(DODH)/acid dual-purpose catalysts to transform biomass-derived diol substrates into a variety of commodity chemical precursors. The power of this approach is highlighted by a tandem [1,3]-OH shift/DODH of 2-ene-1,4-diols and 2,4-diene-1,6-diols, and by a DODH/esterification sequence of sugar acids to unsaturated esters for the production of polymers and plasticizers. Copyright
- Shiramizu, Mika,Toste, F. Dean
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supporting information
p. 12905 - 12909
(2014/01/06)
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- Ni(0)-catalyzed 1,4-selective diboration of conjugated dienes
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Figure Presented. A catalytic stereoselective 1,4-diboration of conjugated dienes with B2(pin)2 was accomplished with Ni(cod) 2 and PCy3 as the catalyst. This reaction broadens the substrate scope of current methods for catalytic diene diboration by including internal and sterically hindered dienes, and it proceeds efficiently at low catalyst loadings. The intermediate allylboronate was oxidized to the stereodefined allylic 1,4-diol.
- Ely, Robert J.,Morken, James P.
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supporting information; experimental part
p. 4348 - 4351
(2010/11/19)
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- A novel and stereospecific synthesis of aminocyclitol:N- tosyldihydroconduramine E2
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A stereospecifi c synthesis of N-tosyldihydroconduramine E2, a new aminocyclitol, has been synthesised starting from cyclohexa-1,3-diene. The photooxygenation of cyclohexa-1,3-diene afforded the bicyclic endoperoxide. Reduction of the endoperoxide with th
- Kelebekli, Latif,Celik, Murat,Kara, Yunus
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scheme or table
p. 54 - 56
(2010/05/19)
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- Stereospecific synthesis of N-tosyl derivatives of dihydroconduramine E-2 and ent-F-2
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Conduramines, dihydroconduramines and structurally related compounds belong to an important class of glycosidase inhibitors which are essential elements of many biologically active compounds. The synthesis and characterization of N-tosyl dihydroconduramin
- Kurbanoglu, Izzet N.,Besoluka, Senol,Zengin, Mustafa
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scheme or table
p. 77 - 85
(2011/01/12)
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- Silica- and polymer-supported platinum(II) polypyridyl complexes: Synthesis and application in photosensitized oxidation of alkenes
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Square-planar polypyridine platinum(II) complexes have been introduced into a silica/polymer matrix by covalent ligand modification. The photophysical properties of the supported matrices are well retained as their model complexes, and the quantum yields for singlet oxygen (1O2) generation are comparable with that of TPP (tetraphenylporphyrin) under similar conditions. A preliminary application in photosensitized oxidation indicates the silica/polymer-supported matrices are promising, which can be reused without loss of reactivity by a simple filtration. Moreover, the polymer-supported matrix exhibits excellent compatibility in various solvents. The Royal Society of Chemistry 2009.
- Feng, Ke,Peng, Ming-Li,Wang, Deng-Hui,Zhang, Li-Ping,Tung, Chen-Ho,Wu, Li-Zhu
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scheme or table
p. 9794 - 9799
(2010/03/04)
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- Triphenylphosphine reduction of saturated endoperoxides
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(Figure Presented) Triphenylphosphine reduction of saturated endoperoxides derived from 6,6-dimethylfulvene and spiro[2.4]hepta-4,6-diene in the presence of nucleophiles results in the formation of products that mainly stem from deoxygenation followed by carbocation formation. Nucleophilic attack by solvent proceeds by an SN1 like mechanism; allyl shifts and cyclopropylcarbinyl-cyclobutyl rearrangements also occur. With the systems lacking carbocation-stabilizing groups, the deoxygenation step is preceded by attack of H2O at the phosphorus.
- Erden, Ihsan,Gaertner, Christian,Saeed Azimi
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scheme or table
p. 3986 - 3989
(2009/12/05)
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- IRA-200 resin-supported platinum(II) complex for photooxidation of olefins
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Cyclometalated platinum(II) 4,6-diphenyl-2,2′-bipyridine complex is supported on a commercially available cationic ion-exchange resin (amberlite IRA-200). Photophysical and ESR determinations indicate that the combined photosensitized system is able to generate singlet oxygen with high quantum yield upon irradiation of light in the visible region. The platinum(II) complex loaded on IRA-200 resin is stable and the photooxidation occurs in an environmentally friendly way. Only a simple filtration is needed to recycle the expensive metal catalyst.
- Feng, Ke,Wu, Li-Zhu,Zhang, Li-Ping,Tung, Chen-Ho
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p. 4907 - 4911
(2008/02/01)
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- Concise synthesis of the neo-clerodane skeleton of teucrolivin A using a pericyclic reaction cascade
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Herein, we describe the synthesis of advanced intermediate 39 on the path towards the total synthesis of teucrolivin A (3) in 16 steps from commercially available 1,3-cyclohexadiene. We have constructed the trans-decalin core of the natural product 3 as a
- Arns, Steve,Barriault, Louis
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p. 1809 - 1816
(2007/10/03)
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- Photooxidation of olefins under oxygen in platinum(II) complex-loaded mesoporous molecular sieves
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Cyclometalated platinum(II) complex has been successfully incorporated into the (3-aminopropyl) triethoxysilane-modified channels of ordered mesoporous silica SBA-15 that has large pore hexagonal channels. Studies on the 1O2 generation conclusively demonstrates that the olefins in the nano-channels of SBA-15 can be enriched 8 times higher than those in the homogeneous solution as the diffusion quantum yield of singlet oxygen ( 1O2) is assumed to be unit. The platinum(II) complex loaded in the channel of SBA-15 is stable, and the photosensitized oxidation occurs efficiently. No obvious degradation and leaching of photosensitizers is observed even after 10 runs. Only a simple filtration is needed for the recycled use of the expensive noble metal catalysts. This versatile system is a good example of photochemical reactions occurring in the mesoporous silica molecular sieve. SBA-15 not only provides a support for the photosensitizer, but also acts as a nano-reactor to facilitate the photooxidation.
- Feng, Ke,Zhang, Ren-Yuan,Wu, Li-Zhu,Tu, Bo,Peng, Ming-Li,Zhang, Li-Ping,Zhao, Dongyuan,Tung, Chen-Ho
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p. 14685 - 14690
(2008/02/03)
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- Polystyrene-supported N-methylthiourea: A convenient new reagent for the hydrogenolysis of bicyclic endoperoxides
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The single-step preparation of a polystyrene-bound N-methylthiourea 4 and its use for the hydrogenolysis of bicyclic endoperoxides is described. The Royal Society of Chemistry 2005.
- Spivey, Alan C.,Manas, Carles Giro,Mann, Inderjit
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p. 4426 - 4428
(2007/10/03)
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- Pyrrolizidine alkaloids by intramolecular palladium-catalysed allylic alkylation: Synthesis of (±)-isoretronecanol
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An efficient and stereoconvergent approach to 3-substituted hexahydroindol-2-one derivatives by palladium-catalysed intramolecular allylic alkylation has been developed. Subsequently, the straightforward conversion of the hexahydroindol-2-one 7d into the alkaloid (±)-isoretronecanol has been performed. The synthesis entails 11 steps starting from 1,3-cyclohexadiene, affording the final target in a 29% overall yield. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.
- Lemaire, Sebastien,Giambastiani, Giuliano,Prestat, Guillaume,Poli, Giovanni
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p. 2840 - 2847
(2007/10/03)
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- A concise synthesis of fumagillol
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A concise synthesis of fumagillol was accomplished in twelve steps starting from cyclohexadiene, proceeding by way of ring-opening of a symmetrical protected epoxydiol with a cuprate reagent and subsequent protecting group manipulation to give a key keton
- Hutchings, Martin,Moffat, David,Simpkins, Nigel S.
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p. 661 - 663
(2007/10/03)
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- Tandem ring opening-ring closing metathesis of cyclic olefins
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Ruthenium alkylidene 1 has been utilized in the tandem ring opening-ring closing metathesis of cyclic olefins. This reaction produces a bicyclic molecule from a cyclic olefin. Reactivity is dependent upon strain, and thus ring size, in the substrate molecules. Competing oligomerization is observed in substrates having low ring strain; this process is inhibited by increasing dilution of the reaction or by adding alkyl substitution to the acyclic olefins.
- Zuercher, William J.,Hashimoto, Masakazu,Grubbs, Robert H.
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p. 6634 - 6640
(2007/10/03)
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- Facile stereoselective syntheses of four of the six 1, 2, 3, 4-cyclohexanetetrols: Increasing the accessibility of cyclitols for probing the molecular recognition of saccharides
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New and stereoselective syntheses of (1,2,3/4)-, (1,2/3,4)-, (1,4/2,3)-, and (1,2,4/3)-cyclohexanetetrols (1,2,3 and 4 respectively) are described. The known syn and anti 1,4-cyclohex-2-enediols 9 and 10 were used as starting materials. Diols 9 and 10 wer
- Huang,Cabell,Anslyn
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p. 2757 - 2764
(2007/10/02)
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- Synthesis of 2,9,10-Trioxatricyclo3,8>decane Analogues of Resiniferatoxin
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Structurally simplified analogues of the daphnane diterpene resiniferatoxin (RTX) 1, possessing the unusual 2,9,10-trioxatricyclo3,8>decane system have been synthesised stereoselectively from cyclohexa-1,3-diene: functionalisation of th
- Bloomfield, Graham C.,Ritchie, Timothy J.,Wrigglesworth, Roger
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p. 1229 - 1236
(2007/10/02)
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- ENZYMATIC PREPARATION OF (3S,6R) AND (3R,6S)-3-HYDROXY-6-ACETOXYCYCLOHEX-1-ENE
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Pseudomonas cepacia lipase-catalyzed enantioselective hydrolysis of 2 in water afforded (3S,6R)-3.The antipode (3R,6S)-3 was prepared by enantioselective acylation of 4 using the same enzyme.
- Harris, Keith J.,Gu, Qu-Ming,Shih, Yun-Er,Girdaukas, Gary,Sih, Charles J.
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p. 3941 - 3944
(2007/10/02)
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- PALLADIUM(0) CATALYZED REACTIONS OF 1,4-EPIPEROXIDES
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The Pd(PPh3)4 catalyzed reaction of 2,3-saturated and 2,3-unsaturated 1,4-epiperoxides proceeds by courses markedly different from those of the previously reported transition metal catalyses.The Pd(0)-promoted reaction of 2,3-saturated epiperoxides gives the corresponding 4-hydroxy ketones and 1,4-diols as the major products.From 2,3-dedihydroepiperoxides are formed the corresponding 4-hydroxy enones, syn-1,2;3,4-diepoxides, and 1,4-diols.The results are interpreted in terms of competing Pd(0)/Pd(II) exchange mechanisms.Exposure of prostaglandin (PG) H2 methyl esterto Pd(PPh3)4 produces a mixture of methyl esters of PGD2, PGE2, PGF2α, and (5Z,8E,10E,12S)-12-hydroxy-5,8,10-heptadecatrienoic acid.
- Suzuki, Masaaki,Oda, Yoshihisa,Hamanaka, Nobuyuki,Noyori, Ryoji
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p. 517 - 535
(2007/10/02)
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- Stereo-and Regioselective Palladium-Catalyzed 1,4-Diacetoxylation of 1,3-Dienes
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Palladium-catalyzed oxidation of 1,3-dienes in acetic acid using an oxidation system of MnO2 and catalytic amounts of p-benzoquinone selectively gives 1,4-diacetoxy-2-alkenes.The reaction proceeds with high stereo-and regioselectivity, and by ligand control the reaction can be made to take place with either cis or trans 1,4-diacetoxylation across the diene in cyclic systems.Also in an acyclic system the 1,4-relative stereochemistry can be controlled as shown by the stereoselective oxidation of (E,E)- and (E,Z)-2,4-hexadiene to their corresponding dl (>88percent dl) and meso (>95percent meso) diacetates 15 and 18, respectively.Evidence is provided that supports a mechanism involving a trans acetoxypalladation of the conjugated diene to give an intermediate (?-allyl)palladium complex, followed by either a cis or trans attack by acetate on the allyl group.The cis attack is best explained by a cis migration from a (?-allyl)palladium intermediate.The diacetoxylation reaction was applied to the preparation of a key intermediate for the synthesis of dl-shikimic acid.
- Baeckvall, Jan-E.,Bystroem, Styrbjoern E.,Nordberg, Ruth E.
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p. 4619 - 4631
(2007/10/02)
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- Vinyl Epoxide Hydrolysis Reactions
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The rates of hydrolysis of cyclopentadiene oxide (3), cyclohexadiene oxide (4), cycloheptadiene oxide (5), cyclooctadiene oxide (6), butadiene oxide (7), and styrene oxide (8) have been determined as a function of pH.Each epoxide exhibited acid-catalyzed hydrolysis at low pH, and 3-5 showed significant rates for "spontaneous" reaction with solvent at intermediate pH values.The hydrolyses of several of the vinyl epoxides (4 and 5) showed kinetic terms in HO- at pH > ca. 13.Specific chloride effects attributed to nucleophilic addition of Cl- to neutral epoxide were observed for those compounds (3, 4, and 8) hydrolyzed in KCl solutions.From kinetic and product studies, mechanisms for hydrolyses of the vinyl epoxides are postulated.Acid-catalyzed hydrolyses of 3, 4, 5, and 6 were found to be A-1 in nature, proceeding via intermediate allyl cations.Product distributions depended on the structure of the cation.Mechanisms and product distributions for the spontaneous hydrolyses of vinyl epoxides were found to be variable, and dependent on the structure of the epoxide.
- Ross, Angela M.,Pohl, Terese M.,Piazza, Kathryn,Thomas, Michael,Fox, Bonnie,Whalen, Dale L.
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p. 1658 - 1665
(2007/10/02)
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- PALLADIUM(O) CATALYZED REACTION OF 1,3-DIENE 1,4-EPIPEROXIDES
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Reaction of 1,3-diene 1,4-epiperoxides with Pd(PPh3)4 catalyst forms the corresponding 4-hydroxy enones, syn diepoxides, and 1,4-diols as the major products.The results are interpreted as being due to competing Pd(O)/ Pd(II) and Pd(O)/ Pd(I) exchange mechanisms.
- Suzuki, M.,Oda, Y.,Noyori, R.
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p. 4413 - 4416
(2007/10/02)
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- STEREOCHEMICAL STUDIES - LVII. SYNTHESIS OF OPTICALLY ACTIVE COMPOUNDS BY THE NOVEL USE OF MESO-COMPOUNDS -1. EFFICIENT SYNTHESIS OF TWO STRUCTURAL TYPES OF OPTICALLY PURE PROSTAGLANDIN INTERMEDIATES.
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With an aim to overcome several inefficient aspects of ordinary methods of preparing optically active compounds, we have developed a new method which recommends utilization of symmetrically functionalized meso-compounds in place of racemic compounds.As shown in Scheme 1, when the meso-compound (I) is monofunctionalized by an optically active functional group (A) and each of the formed diastereomers (II and III) is subjected to further chemical elaborations including protective group transposition, it is theoretically possible to convert the total amount of the starting material (I) into the requisite optically pure product (VI or VII) by selecting synthetic schemes.By employing this novel concept, two structural types of the prostaglandin intermediates ((-)- and (+)-2a,b) have been prepared from the meso-diols (1a,b) by way of the two diastereomeric monoesters (13a,b and 14a,b) which are produced by the reactions 1a,b with N-mesyl- and N-phthaloyl-(S)-phenylalanyl chloride (3a,b).
- Nara, M,Terashima, S.,Yamada, S.
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p. 3161 - 3170
(2007/10/02)
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