- Straightforward Synthesis of 5-Bromopenta-2,4-diynenitrile and Its Reactivity Towards Terminal Alkynes: A Direct Access to Diene and Benzofulvene Scaffolds
-
The high-yielding synthesis of 5-bromopenta-2,4-diynenitrile (BrC5N) was achieved for the first time. Its reactivity with triisopropylsilylacetylene and triisopropylsilylbutadiyne in the presence of copper and palladium as co-catalysts and diisopropylamine was evaluated. It revealed an unprecedented cascade reaction leading to a diene in one case and to a benzofulvene in the other case, with a unique structure. Both of them were characterized by X-ray crystallography, among other techniques. The mechanism of the reaction leading to the diene was investigated experimentally. Theoretical calculations at the DFT level suggest that the mechanism leading to the benzofulvene relies on a hexa-dehydro Diels-Alder (HDDA)-type of mechanism. This work constitutes an example of an unanticipated reactivity leading to an important increase of chemical complexity.
- Kerisit, Nicolas,Toupet, Lo?c,Larini, Paolo,Perrin, Lionel,Guillemin, Jean-Claude,Trolez, Yann
-
-
Read Online
- Total Synthesis of the Spliceosome Modulator Pladienolide B via Asymmetric Alcohol-Mediated syn- and anti-Diastereoselective Carbonyl Crotylation
-
The potent spliceosome modulator pladienolide B, which bears 10 stereogenic centers, is prepared in 10 steps (LLS). Asymmetric alcohol-mediated carbonyl crotylations catalyzed by ruthenium and iridium that occur with syn- and anti-diastereoselectivity, re
- Yoo, Minjin,Krische, Michael J.
-
-
Read Online
- Synthesis of Polyynes Using Dicobalt Masking Groups
-
Extended triisopropylsilyl end-capped polyynes have been prepared from the corresponding tetracobalt complexes by removing the complexed dicobalt tetracarbonyldiphenylphosphinomethane (Co2(CO)4dppm) moieties. Unmasking of this "masked alkyne equivalent" was achieved under mild conditions with elemental iodine at room temperature, making it possible to obtain fragile polyynes with up to 20 contiguous sp-hybridized carbon atoms. The Co2(CO)4dppm moiety has a strong geometric and steric effect on the polyyne but does not have a marked electronic effect on the terminal alkyne, as indicated by NMR and IR spectroscopy, density functional theory calculations, and X-ray crystallography. An unusual "alkyne hopping" migration of the dicobalt group was noticed as a minor side reaction during copper-catalyzed Eglinton coupling.
- Kohn, Daniel R.,Gawel, Przemyslaw,Xiong, Yaoyao,Christensen, Kirsten E.,Anderson, Harry L.
-
-
Read Online
- Covalent Cobalt Porphyrin Framework on Multiwalled Carbon Nanotubes for Efficient Water Oxidation at Low Overpotential
-
A noble-metal-free, efficient, and robust catalyst made of Earth-abundant elements for water oxidation is vital to achieve practical water splitting for future clean energy production. Herein, we report the synthesis of multilayer covalent cobalt porphyrin framework on multiwalled carbon nanotubes ((CoP)n-MWCNTs) to produce a highly active electrocatalyst for water oxidation. A linear sweep voltammetry curve showed that a catalytic current density of 1.0 mA/cm2 can be achieved under a potential of only 1.52 V (vs RHE, corresponding to an overpotential of only 0.29 V) in alkaline solution at pH 13.6. Such an onset potential is much lower than that of cobalt porphyrin monomer (CoP-TIPS) and pure MWCNTs. In addition, the chronopotentiometry data confirmed its excellent catalytic activity and suggested that the (CoP)n-MWCNTs catalyst has good durability for water oxidation catalysis. A Tafel slope of 60.8 mV per decade was obtained by bulk electrolysis measurement, and the Faradaic efficiency of oxygen production was >86%. (Chemical Equation Presented).
- Jia, Hongxing,Sun, Zijun,Jiang, Daochuan,Du, Pingwu
-
-
Read Online
- Novel one-pot synthesis of 5-alkenyl-15-alkynylporphyrins and their derivatisation to a butadiyne-linked benzoporphyrin dimer
-
5-Alkenyl-15-alkynylporphyrins have been obtained unexpectedly by [2 + 2] acid-catalyzed condensation of dipyrrylmethane and TMS propynal in addition to 5,15-dialkynylporphyrin, and the unsymmetrical porphyrin can be converted to a butadiyne-linked dimer
- Yamada, Hiroko,Kushibe, Kayo,Okujima, Tetsuo,Uno, Hidemitsu,Ono, Noboru
-
-
Read Online
- The first α-fluoroallenylphosphonate, the synthesis of conjugated fluoroenynes, and the stereoselective synthesis of vinylfluorophosphonates using a new multifunctional fluorine-containing building block
-
Limitations on current methodologies for the introduction of CF2 and CFH in complex α-fluorophosphonates led to the synthesis of a fluorine- containing building block TIPS-C?CCFXP(O)(OEt)2, where X = H or F. This multifunctional fluorine synthon reacts with carbonyl compounds under WHE conditions to give high yields of fluorinated conjugated enynes and enediyne. When X = F, trapping of the desilylated anion with an electrophile after TIPS removal provided exclusive access to γ-substituted derivatives of α- fluorophosphonates. When X = H, TBAF deprotection of the silyl group yields H2C=C=CFP(O)(OEt)2 through an allenyl-propargyl resonance stabilized anion. The allene moiety has been used as template in the stereoselective synthesis of α-fluoro-β,γ-diiodopropenyl phosphonate, via electrophilic iodination, and α-fluoro-γ-amino-α,β-unsaturated phosphonates, including unsaturated phosphononucleosides, by nucleophilic displacement of an allylic iodide. Hydroamination of H2C=C=CFP(O)(OEt)2 using secondary amines produced (Z)- α-fluoroenaminophosphonates, whereas Diels-Alder cycloaddition with cyclopentadiene provides the corresponding exocyclic vinylfluorophosphonate.
- Zapata, Antonio J.,Gu, Yonghong,Hammond, Gerald B.
-
-
Read Online
- carbo-Naphthalene: A Polycyclic carbo-Benzenoid Fragment of α-Graphyne
-
A ring carbo-mer of naphthalene, C32Ar8(Ar=p-n-pentylphenyl), has been obtained as a stable blue chromophore, after a 19-step synthetic route involving methods inspired from those used in the synthesis of carbo-benzenes, or specifically devised for the present target, like a double Sonogashira-type coupling reaction. The last step is a SnCl2/HCl-mediated reduction of a decaoxy-carbo-decalin, which is prepared through successive [8+10] macrocyclization steps. Two carbo-benzene references are also described, C18Ar6and o-C18Ar4(C≡C-SiiPr3)2. The carbo-naphthalene bicycle is locally aromatic according to structural and magnetic criteria, as revealed by strong diatropic ring current effects on the deshielding of1H nuclei of the Ar groups and on the negative value of the DFT-calculated NICS at the center of the C18rings (?12.8 ppm). The stability and aromaticity of this smallest fused molecular fragment of α-graphyne allows prediction of the same properties for the carbon allotrope itself.
- Cocq, Kévin,Saffon-Merceron, Nathalie,Coppel, Yannick,Poidevin, Corentin,Maraval, Valérie,Chauvin, Remi
-
-
Read Online
- Metallated porphyrins containing lead(II), copper(II) or zinc(II)
-
A series of ethynyl and aryl substituted porphyrins and the corresponding metallated derivatives have been synthesised and characterised.
- John Plater,Aiken, Stuart,Bourhill, Grant
-
-
Read Online
- Substituted Tetraethynylethylene–Tetravinylethylene Hybrids
-
A general synthetic approach to molecular structures that are hybrids of tetraethynylethylene (TEE) and tetravinylethylene (TVE) is reported. The synthesis permits the controlled preparation of many previously inaccessible structures, including examples w
- Connor, Kieran P. E.,Horvath, Kelsey L.,Magann, Nicholas L.,Sherburn, Michael S.,Sowden, Madison J.,Westley, Erin
-
supporting information
p. 977 - 986
(2022/02/03)
-
- Total Synthesis of Leiodermatolide A via Transfer Hydrogenative Allylation, Crotylation, and Propargylation: Polyketide Construction beyond Discrete Allyl- or Allenylmetal Reagents
-
The total synthesis of leiodermatolide A was accomplished in 13 steps (LLS). Transfer hydrogenative variants of three carbonyl additions that traditionally rely on premetalated reagents (allylation, crotylation, and propargylation) are deployed together i
- Krische, Michael J.,Roane, James,Siu, Yuk-Ming
-
supporting information
p. 10590 - 10595
(2021/07/28)
-
- A Practical, Component-Based Synthetic Route to Methylthiolincosamine Permitting Facile Northern-Half Diversification of Lincosamide Antibiotics
-
The development of a flexible, component-based synthetic route to the amino sugar fragment of the lincosamide antibiotics is described. This route hinges on the application and extension of nitroaldol chemistry to forge strategic bonds within complex amino sugar targets and employs a glycal epoxide as a versatile glycosyl donor for the installation of anomeric groups. Through building-block exchange and late-stage functionalization, this route affords access to a host of rationally designed lincosamides otherwise inaccessible by semisynthesis and underpins a platform for the discovery of new lincosamide antibiotics.
- Mitcheltree, Matthew J.,Stevenson, Jack W.,Pisipati, Amarnath,Myers, Andrew G.
-
supporting information
p. 6829 - 6835
(2021/05/29)
-
- Enantioselective Synthesis of 7(S)-Hydroxydocosahexaenoic Acid, a Possible Endogenous Ligand for PPARα
-
We report the first total synthesis of the polyunsaturated fatty acid 7-hydroxydocosahexaenoic acid (7-HDHA) in racemic form and the enantioselective synthesis of 7-(S)-HDHA. Both syntheses follow a convergent approach that unites the C1-C9 and C10-C22 fragments using Sonogashira coupling and Boland reduction as key steps. These syntheses enabled the unambiguous characterization of this natural product for the first time and helped establish 7(S)-HDHA as a possible endogenous ligand for peroxisome proliferator-activated receptor alpha.
- Zhang, Minhao,Sayyad, Ashik A.,Dhesi, Anmol,Orellana, Arturo
-
p. 13621 - 13629
(2020/12/15)
-
- NOVEL PORPHYRIN DERIVATIVE, MANUFACTURING METHOD OF PORPHYRIN DERIVATIVE, DONOR MATERIAL, PHOTOELECTRIC CONVERSION DEVICE, AND MANUFACTURING METHOD OF PHOTOELECTRIC CONVERSION DEVICE
-
PROBLEM TO BE SOLVED: To provide a porphyrin derivative and a photoelectric conversion device. SOLUTION: In a photoelectric conversion device having a first electrode EL1, an active layer (charge transport layer) AL, and a second electrode EL2, the active
- -
-
Paragraph 0141
(2020/03/06)
-
- Copper-Catalyzed Asymmetric Radical 1,2-Carboalkynylation of Alkenes with Alkyl Halides and Terminal Alkynes
-
A copper-catalyzed intermolecular three-component asymmetric radical 1,2-carboalkynylation of alkenes has been developed, providing straightforward access to diverse chiral alkynes from readily available alkyl halides and terminal alkynes. The utilization of a cinchona alkaloid-derived multidentate N,N,P-ligand is crucial for the efficient radical generation from mildly oxidative precursors by copper and the effective inhibition of the undesired Glaser coupling side reaction. The substrate scope is broad, covering (hetero)aryl-, alkynyl-, and aminocarbonyl-substituted alkenes, (hetero)aryl and alkyl as well as silyl alkynes, and tertiary to primary alkyl radical precursors with excellent functional group compatibility. Facile transformations of the obtained chiral alkynes have also been demonstrated, highlighting the excellent complementarity of this protocol to direct 1,2-dicarbofunctionalization reactions with C(sp2/sp3)-based reagents.
- Dong, Xiao-Yang,Cheng, Jiang-Tao,Zhang, Yu-Feng,Li, Zhong-Liang,Zhan, Tian-Ya,Chen, Ji-Jun,Wang, Fu-Li,Yang, Ning-Yuan,Ye, Liu,Gu, Qiang-Shuai,Liu, Xin-Yuan
-
supporting information
p. 9501 - 9509
(2020/05/18)
-
- Toward Chromanes by de Novo Construction of the Benzene Ring
-
The work describes three principal Diels-Alder cycloaddition approaches toward chromanes that are designed for the de novo construction of the benzene ring. This study specifically focuses on the potential exploitation in the total synthesis of chromane-bearing natural products such as cebulactam A.
- Geist, Egor,Berneaud-K?tz, Helge,Baikstis, Tomas,Dr?ger, Gerald,Kirschning, Andreas
-
supporting information
p. 8930 - 8933
(2019/11/14)
-
- Total Synthesis and Structural Validation of Phosdiecin A via Asymmetric Alcohol-Mediated Carbonyl Reductive Coupling
-
The first total synthesis and structural validation of phosdiecin A was accomplished in 13 steps through asymmetric iridium-catalyzed alcohol-mediated carbonyl reductive coupling. The present route is the shortest among >30 total and formal syntheses of fostriecin family members.
- Della-Felice, Franco,Sarotti, Ariel M.,Krische, Michael J.,Pilli, Ronaldo A.
-
supporting information
p. 13778 - 13782
(2019/09/10)
-
- LINCONSAMIDE ANTIBIOTICS AND USES THEREOF
-
Provided are lincosamide compounds for the treatment of infectious diseases. The lincosamides described herein are modified at the amino acid (southern) region. The lincosamides may have further modification at the C-1 and C-7 positions of the aminooctose (northern) region, thus distinguishing them from lincomycin and clindamycin. Also provided are methods for preparing the lincosamide compounds, pharmaceutical compositions comprising the lincosamide compounds, and methods of treating infectious diseases using the disclosed lincosamide compounds.
- -
-
Paragraph 00405
(2019/02/25)
-
- NOVEL PORPHYRIN DERIVATIVE, METHOD FOR PRODUCING SAME, DONOR MATERIAL, PHOTO/ELECTRIC CONVERSION DEVICE, AND METHOD FOR PRODUCING SAME
-
PROBLEM TO BE SOLVED: To provide a porphyrin derivative as a donor material for a photo/electric conversion device that can improve charge transport efficiency and characteristics such as long excitation lifetime, and to provide a method for manufacturing
- -
-
Paragraph 0132; 0138; 0139; 0140
(2019/03/30)
-
- Palladium-Catalyzed Hydride Addition/C-H Bond Activation Cascade: Cycloisomerization of 1,6-Diynes
-
The use of ammonium halide salts as metal hydride precursors in a new Pd-catalyzed cycloisomerization of 1,6-diynes, which affords unexplored silylated 2-azafluorenes, is reported. This cascade process includes the addition of a Pd-hydride species to a π-system, intramolecular carbopalladation, and C(sp2)-H bond activation. A variety of functional groups are tolerated, and the synthetic utility of the resulting products has been demonstrated by a series of derivatizations.
- Rodríguez, José F.,Burton, Katherine I.,Franzoni, Ivan,Petrone, David A.,Scheipers, Ina,Lautens, Mark
-
supporting information
p. 6915 - 6919
(2018/11/21)
-
- Catalytic Enantioselective Allylations of Acetylenic Aldehydes via 2-Propanol-Mediated Reductive Coupling
-
Cyclometalated π-allyliridium C,O-benzoates modified by (S)-SEGPHOS or (S)-Cl,OMe-BIPHEP catalyze enantioselective 2-propanol-mediated reductive couplings of diverse nonmetallic allyl pronucleophiles with the acetylenic aldehyde TIPSC≡CCHO. Absolute stere
- Brito, Gilmar A.,Della-Felice, Franco,Luo, Guoshun,Burns, Alexander S.,Pilli, Ronaldo A.,Rychnovsky, Scott D.,Krische, Michael J.
-
supporting information
p. 4144 - 4147
(2018/07/15)
-
- NOVEL IMIDAZOLE DERIVATIVES
-
Provided are novel compounds represented by the following general formula [1] or pharmaceutically acceptable salts thereof, that inhibit LpxC, as well as pharmaceutical drugs comprising those compounds or pharmaceutically acceptable salts thereof, that exhibit antimicrobial activity against gram-negative bacteria including multi-drug resistant strains and that are useful in the treatment of bacterial infections.
- -
-
Page/Page column 216
(2018/12/13)
-
- Catalytic Enantioselective Synthesis of Amino Skipped Diynes
-
The Cu-catalyzed synthesis of nonracemic 3-amino skipped diynes via an enantiodetermining C-C bond formation is described using StackPhos as ligand. Despite challenging issues of reactivity and stereoselectivity inherent to these chiral skipped diynes, the reaction tolerates an extremely broad substrate scope with respect to all components and provides the title compounds in excellent enantiomeric excess. The alkyne moieties are demonstrated here to be useful synthetic handles, and 3-amino skipped diynes are convenient building blocks for enantioselective synthesis.
- Paioti, Paulo H. S.,Abboud, Khalil A.,Aponick, Aaron
-
supporting information
p. 2150 - 2153
(2016/03/05)
-
- Synthesis and Isolation of Organogold Complexes through a Controlled 1,2-Silyl Migration
-
During our efforts toward the synthesis of naturally occurring polyprenylated polycyclic acylphloroglucinol using a AuI-catalyzed 6-endo dig carbocyclization, we isolated stable vinyllic gold intermediates. Optimization lead to isolated yields of up to 98 %, using 2-(di-tert-butylphosphino)biphenyl as the ligand. This transformation is derived from a silyl rearrangement that can be fully controlled according to the nature of the substituent on the ynone. This selective transformation does not require basic conditions to prevent protodeauration. These vinylgold complexes are the first isolated intermediates during a silyl migration with gold(I). More than 16 new organogold complexes were synthesized and characterized by single-crystal X-ray diffraction. Reactivity of these complexes is also presented.
- McGee, Philippe,Bellavance, Gabriel,Korobkov, Ilia,Tarasewicz, Anika,Barriault, Louis
-
supporting information
p. 9662 - 9665
(2015/06/30)
-
- Catalytic Asymmetric Synthesis of Alkynyl Aziridines: Both Enantiomers of cis-Aziridines from One Enantiomer of the Catalyst
-
Alkynyl aziridines can be obtained from the catalytic asymmetric aziridination (AZ reaction) of alkynyl imines with diazo compounds in high yields and high asymmetric inductions mediated by a chiral boroxinate or BOROX catalyst. In contrast to the AZ reaction with aryl- and alkyl-substituted imines, alkynyl imines react to give cis-substituted aziridines with both diazo esters and diazo acetamides. Remarkably, however, the two diazo compounds give different enantiomers of the cis-aziridine from the same enantiomer of the catalyst. Theoretical considerations of the possible transition states for the enantiogenic step reveal that the switch in enantiomers results from a switch from Si-face to Re-face addition to the imine, which in turn is related to a switch from reaction with an E-imine in the former and a Z-isomer of the imine in the latter. The imine did it: The aziridination of alkynyl imines with diazo esters and diazo acetamides gives cis-aziridines with very high enantioselectivities. The absolute configuration of the cis-aziridine is reversed for the two diazo compounds even though the same enantiomer of the catalyst is used. The alkynyl imines can isomerize under the reaction conditions and the enantiomeric switch is proposed to result from the preferential reaction of E-imine with diazo esters and Z-imines with diazo acetamides.
- Guan, Yong,L?pez-Alberca, Maria P.,Lu, Zhenjie,Zhang, Yu,Desai, Aman A.,Patwardhan, Aniruddha P.,Dai, Yijing,Vetticatt, Mathew J.,Wulff, William D.
-
supporting information
p. 13894 - 13900
(2016/02/18)
-
- DIHYDROOXAZINE OR OXAZEPINE DERIVATIVES HAVING BACE1 INHIBITORY ACTIVITY
-
The present invention provides a compound which has an effect of inhibiting amyloid beta production, especially an effect of inhibiting BACE1, and which is useful as a therapeutic or prophylactic agent for diseases induced by production, secretion and/or
- -
-
Paragraph 0183
(2014/05/24)
-
- Catalytic Enantioselective Quick Route to Aldol-Tethered 1,6- and 1,7-Enynes from ω-Unsaturated Aldehydes
-
An effective asymmetric route to functionalized 1,6- and 1,7-enynes has been developed based on a direct cross-aldol reaction between ω-unsaturated aldehydes and propargylic aldehydes (α,β-ynals) promoted by combined α,α-dialkylprolinol ether/Br?nsted acid catalysis. This synergistic activation strategy is key to accessing the corresponding aldol adducts with high stereoselectivity, both enantio- and diastereoselectivity. The aldol reaction also proceeds well with propargylic ketones (α,β-ynones) thus enabling a stereocontrolled access to the corresponding tertiary alcohols. The utility of these adducts, which are difficult to prepare through standard methodology, is demonstrated by their transformation into trisubstituted bicyclic enones using standard Pauson-Khand conditions.
- García, Jesús M.,Odriozola, José M.,Razkin, Jesús,Lapuerta, Irati,Odriozola, Amaiur,Urruzuno, I?aki,Vera, Silvia,Oiarbide, Mikel,Palomo, Claudio
-
supporting information
p. 15543 - 15554
(2016/02/18)
-
- Copper-Catalyzed Propargylic Substitution of Dichloro Substrates: Enantioselective Synthesis of Trisubstituted Allenes and Formation of Propargylic Quaternary Stereogenic Centers
-
An easy and versatile Cu-catalyzed propargylic substitution process is presented. Using easily prepared prochiral dichloro substrates, readily available Grignard reagents together with catalytic amount of copper salt and chiral ligand, we accessed a range of synthetically interesting trisubstituted chloroallenes. Substrate scope and nucleophile scope are broad, providing generally high enantioselectivity for the desired 1,3-substitution products. The enantioenriched chloroallenes could be further transformed into the corresponding trisubstituted allenes or terminal alkynes bearing all-carbon quaternary stereogenic centers, through the copper-catalyzed enantiospecific 1,1/1,3-substitutions. The two successive copper-catalyzed reactions could be eventually combined into a one-pot procedure and different desired allenes or alkynes were obtained respectively with high enantiomeric excesses.
- Li, Hailing,Grassi, David,Guénée, Laure,Bürgi, Thomas,Alexakis, Alexandre
-
supporting information
p. 16694 - 16706
(2016/02/12)
-
- Total synthesis of enantiopure pyrrhoxanthin: Alternative methods for the stereoselective preparation of 4-alkylidenebutenolides
-
A new stereocontrolled total synthesis of the configurationally labile C37-norcarotenoid pyrrhoxanthin in enantiopure form has been completed. A highly stereoselective Horner-Wadsworth-Emmons (HWE) condensation of a C17-allylphosphonate and a C20-aldehyde was used as the last conjunctive step. Both a Sonogashira reaction to form the C 17-phosphonate and the final HWE condensation proved to be compatible with the sensitive C7-C10 enyne E configuration. Regioselective (5-exo-dig) silver-promoted lactonization reactions of three alternative pent-2-en-4-ynoic acid precursors with increased complexity, including a fully functionalized C20-fragment, were explored for the preparation of the γ-alkylidenebutenolide fragment. This survey extends the existing methodologies for the preparation of oxygen-containing carotenoids (xanthophylls) and streamlines the synthesis of additional members of the C 37-norcarotenoid butenolide family of natural products. Silver catalysis: A stereocontrolled total synthesis of enantiopure pyrrhoxanthin has been described (see scheme), using a Horner-Wadsworth-Emmons (HWE) condensation as the last step, providing the desired xanthophyll as a single diastereomer. Along this strategy, alkylidenebutyrolactones have been obtained regio- and stereoselectively by silver-promoted lactonization of pentenynoic acids of increasing complexity. Copyright
- Vaz, Belén,Otero, Leticia,álvarez, Rosana,Delera, ángel R.
-
p. 13065 - 13074
(2013/10/01)
-
- Total regio- and diastereocontrol in the aldol reactions of dienolborinates
-
It is reported that appropriate dienolborinates can provide access to both diastereomers of 2-(hydroxymethyl)but-3-enoates through exclusive α-regiocontrol in a non-vinylogous pathway. Contrary to previous reports in which dialkylchloroboranes failed to enolize propanoates, acidity-enhanced but-3-enoates readily undergo enolization, offering unprecedented control over the formation of these valuable synthons. The first example of an aldol reaction in the presence of a phosphine-borane adduct is also reported.
- Ramachandran, P. Veeraraghavan,Nicponski, Daniel,Kim, Bomi
-
p. 1398 - 1401
(2013/05/09)
-
- Gold(I)-catalyzed rearrangement of N-aryl 2-alkynylazetidines to pyrrolo[1,2-a]indoles
-
Various N-aryl-2-alkynylazetidines were very efficiently converted to pyrrolo[1,2-a]indoles with gold catalysts, especially the 2-biphenyl- dicyclohexylphosphino-gold(I) hexafluoroantimonate, in dichloromethane at room temperature. Additionally, two forma
- Kern, Nicolas,Hoffmann, Marie,Blanc, Aurelien,Weibel, Jean-Marc,Pale, Patrick
-
supporting information
p. 836 - 839
(2013/03/29)
-
- Palladium-catalyzed carbene migratory insertion using conjugated ene-yne-ketones as carbene precursors
-
Palladium-catalyzed cross-coupling reactions between benzyl, aryl, or allyl bromides and conjugated ene-yne-ketones lead to the formation of 2-alkenyl-substituted furans. This novel coupling reaction involves oxidative addition, alkyne activation-cyclization, palladium carbene migratory insertion, β-hydride elimination, and catalyst regeneration. Palladium (2-furyl)carbene is proposed as the key intermediate, which is supported by DFT calculations. The palladium carbene character of the key intermediate is validated by three aspects, including bond lengths, Wiberg bond order indices, and molecular orbitals, by comparison to those reported for stable palladium carbene species. Computational studies also revealed that the rate-limiting step is ene-yne-ketone cyclization, which leads to the formation of the palladium (2-furyl)carbene, while the subsequent carbene migratory insertion is a facile process with a low energy barrier (5 kcal/mol).
- Xia, Ying,Qu, Shuanglin,Xiao, Qing,Wang, Zhi-Xiang,Qu, Peiyuan,Chen, Li,Liu, Zhen,Tian, Leiming,Huang, Zhongxing,Zhang, Yan,Wang, Jianbo
-
supporting information
p. 13502 - 13511
(2013/09/24)
-
- A new metal carboxylate framework based on porphyrin with extended π-conjugation
-
We have designed a new tetracarboxylporphyrin building block, ZnTCPEP-H4, and used it in the construction of a novel porphyrin-based metal carboxylate framework, [Zn4(μ3- OH)2(H2O)2(ZnTCPEP
- Matsunaga, Satoshi,Endo, Nanako,Mori, Wasuke
-
scheme or table
p. 4550 - 4557
(2011/12/15)
-
- An expedient procedure for the oxidative cleavage of olefinic bonds with PhI(OAc)2, NMO, and Catalytic OsO4
-
(Figure Presented) PhI(OAc)2 In the presence of OsO4 (cat.) and 2,6-lutidine cleaves oleflnlc bonds to yield the corresponding carbonyl compounds, albeit, In some cases, with a-hydroxy ketones as byproduct. A more practical and clean protocol to effect oxidative cleavage of olefinic bonds involves NMO, OsO4 (cat.), 2,6-lutidine, and PhI(OAc) 2.
- Nicolaou,Adsool, Vikrant A.,Hale, Christopher R. H.
-
supporting information; experimental part
p. 1552 - 1555
(2010/06/16)
-
- Improved method for the synthesis of β-carbonyl silyl-1,3-dithianes by the double conjugate addition of 1,3-dithiol to propargylic carbonyl compounds
-
(Chemical Equation Presented) Base-mediated double conjugate addition of 1,3-propane dithiol to various silylated propargylic aldehydes and ketones allows for an efficient and scalable synthesis of β-carbonyl silyl-1,3-dithianes.
- Mukherjee, Sumit,Kontokosta, Dimitra,Patil, Aditi,Rallapalli, Sivakumar,Lee, Daesung
-
supporting information; experimental part
p. 9206 - 9209
(2010/03/02)
-
- Modular synthesis of the C9-C27 degradation product of aflastatin a via alkyne-epoxide cross-couplings
-
A modular approach to the synthesis of complex polyketide natural products is demonstrated for the synthesis of the C9-C27 degradation product from aflastatin A. The product of the cross-coupling of C23-C27 terminal alkyne with C17-C22 epoxide underwent f
- Robles, Omar,McDonald, Frank E.
-
supporting information; experimental part
p. 1811 - 1814
(2009/04/10)
-
- Total synthesis of (-)-spirotryprostatin B: Synthesis and related studies
-
The total synthesis of spirotryprostatin B, a cytostatic spiro[pyrrolidine-3,3′-oxindole] alkaloid, is described. The key step of the synthetic approach consists of the application of the Mgl 2-mediated ring-expansion reaction of a spiro[cyclopropane-1, 3′-oxindole] with an aldimine, leading to rapid assembly of the spirotryprostatin core. The route documents the installation of the prenyl side chain by Julia-Kocienski olefination of a key aldehyde precursor, a transformation that ultimately allows for facile synthesis of analogues and facilitates structure-activity relationships studies.
- Marti, Christiane,Carreira, Erick M.
-
p. 11505 - 11515
(2007/10/03)
-
- Peralkynylated buta-1,2,3-trienes: Exceptionally low-rotational barriers of camulenic C=C bonds in the range of those of peptide C-N bonds
-
A variety of 1,1,4,4-tetraal kynylbutatrienes and 1,4-dialkynylbutatrienes was synthezized by dimerization of the corresponding gem-dibromoolefins. Both 1H and 13C NMR spectroscopy indicated that the di- and tetraalkynylated butatrie
- Auffrant, Audrey,Jaun, Bernhard,Jarowski, Peter D.,Houk, Kendall N.,Diederich, Francois
-
p. 2906 - 2911
(2007/10/03)
-
- Synthesis of new cyclic homoconjugated oligodiacetylenes
-
Cyclic homoconjugated oligodiacetylenes, consisting of butadiyne subunits interconnected with two different sp3-linkers in alternation, were synthesized by coupling of different 1,4-pentadiyne synthons. The "exploded" [4]pericyclyne 7 was obtained in a "one-pot" random cyclodehydro-oligomerization reaction, by cross-coupling of two different 1,4-pentadiyne units. Larger ring structures such as the C30 macrocyclic [6]pericyclyne 22 and the unsymmetrically diynetetrayne expanded C24-[4]pericyclyne 27 afforded a stepwise approach. Heterocoupling of two different 1,4-pentadiynes in a molecular ratio of 1:2 and 2:1 afforded the symmetrical pentadecahexaynes 12 and 20, respectively. Cyclodehydrodimerization gave the symmetrically patterned cyclotriacontadodecayne 22. A collective heterocoupling of two different 1,4-pentadiynes with TIPS-acetylene resulted in the formation of acyclic dodecapentayne 26. Final cyclodimerization yielded the cyclotetracosadecayne 27.
- Leibrock, Bernd,Vostrowsky, Otto,Hirsch, Andreas
-
p. 4401 - 4409
(2007/10/03)
-
- Synthesis and third order nonlinear optics of a new soluble conjugated porphyrin polymer
-
The synthesis of a new soluble conjugated porphyrin polymer 4 is reported. The MALDI TOF mass spectrum shows the presence of oligomers with up to 13 repeat units and GPC gives a Mn of 53 kDa. The electronic absorption spectra of this polymer exhibit an intense Q band at 800 nm in solution and 853 nm in the solid state, demonstrating a high degree of conjugation. Electroabsorption spectroscopy shows that thin films of 4 have lower resonant third order NLO susceptibility than our previous conjugated porphyrin polymer 2, whereas closed z-scan measurements indicate that the off-resonance real susceptibility, at 1064 nm, is exceptionally large for both polymers (χ(3)R =-2 × 10-16 m2 V-2). Open z-scan measurements were also made at 1064 nm, demonstrating that the two polymers exhibit similar nonlinear absorption at this wavelength (β= 1 cm GW-1 at 0.2 mM concentration).
- Screen,Lawton,Wilson,Dolney,Ispasoiu,Goodson III,Martin,Bradley,Anderson
-
p. 312 - 320
(2007/10/03)
-
- A stereoselective synthesis of the C13-C19 fragment of sanglifehrin A
-
A short, stereoselective route to the C13-C19 fragment of the immunosuppressant sanglifehrin A 1, is presented. The key step involves a highly diastereoselective boron aldol reaction between β-ketoimide 11 and triisopropylsilyl propargyl aldehyde 21c.
- Hall, Philip,Brun, Jvan,Denni, Donatienne,Metternich, Rainer
-
p. 315 - 318
(2007/10/03)
-
- Utility of the Tandem Pauson-Khand Reaction in the Construction of Tetracycles
-
The scope of the tandem Pauson-Khand reaction has been explored for the regiospecific construction of [5.5.5.5]- and [5.6.6.5]tetracyclic systems via the photolytic method of Livinghouse. The rapid regiospecific entry into the two dicyclopentapentanoid systems 17 and 29 was accomplished from the key diene-diynes 11 and 19b. A photochemically mediated catalytic tandem Pauson-Khand cyclization was employed to prepare the parent ring systems of dicyclopenta[a,e]pentalene (from 19b) and dicyclopenta[a,f]pentalene (from 11) in regiospecific fashion in a one-pot process. Under these conditions, conversion of acyclic diene-diyne 16 into tetracyclic system 17 was achieved in 74% yield, while a similar process was employed to convert 28 into tetracycle 29 in 90% yield. This is much improved over the previous conditions that employed NMO. Six carbon-carbon bonds were generated in this process constituting up to 98% yield for each carbon-carbon bond so formed. Furthermore, tetracyclic [5.6.6.5] systems such as dicyclopenta[b,g]decalins 37, 38, and 40 were prepared from similar diene-diyne precursors via the tandem Pauson-Khand cyclization. Importantly, acetal 36 provided the desired cis-fused [5.6.6.5] system 38a (via 40a/b) in stereospecific fashion. This reaction is unique in that it provides a cis-decalin ring system; moreover, the yield of each of the six carbon-carbon bonds formed in this process was at least 89%. The structure of cis diol 38a was confirmed by X-ray crystallography.
- Van Ornum, Scott G.,Bruendl, Michelle M.,Cao, Hui,Reddy, Mundala,Grubisha, Desiree S.,Bennett, Dennis W.,Cook, James M.
-
p. 1957 - 1971
(2007/10/03)
-
- A direct and stereocontrolled route to conjugated enediynes
-
A unified synthetic route to 3-hex-en-1,5-diynes, a key building block found in many of the enediyne antitumor agents and designed materials, was developed. The method, which relies on a carbenoid coupling-elimination strategy is tolerant of a wide range of functionalities, and was applied to the synthesis of a variety of linear and cyclic enediynes. Reaction parameters can be adjusted to control stereoselectivity of the process, producing linear enediynes from 1:12 to >100:1 E:Z ratio, and in the case of cyclic enediynes, giving the exclusively Z C-9, C-10, or C-11 products. Key features of the process are the ready availability of precursors and the mildness and efficiency of the reaction. Application of the process in the design of materials precursors and preparation of enediyne antitumor agents are presented.
- Jones, Graham B.,Wright, Justin M.,Plourde, Gary W.,Hynd, George,Huber, Robert S.,Mathews, Jude E.
-
p. 1937 - 1944
(2007/10/03)
-
- Towards the synthesis of tetraethynylallene
-
Synthetic routes towards tetraethynylallene (4), a perethynylated modular entity for the construction of three-dimensional all-carbon networks and all-carbon backbone polymers with a stepladder or helical structure, are presented. They comprise propargylic rearrangements, cyclopropanations with carbenes, Peterson and Wittig-type olefinations, and alkylations of ketones with α-bromovinyl anions.
- Lange, Tim,Van Loon, Jan-Dirk,Tykwinski, Rik R.,Schreiber, Martin,Diederich, Francois
-
p. 537 - 550
(2007/10/03)
-