- Pd(II)-Catalyzed Intramolecular C(sp2)-H Arylation of Tryptamines Using the Nonsteric NH2as a Directing Group
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The free amine-directed C-H functionalization reactions are challenging and mainly restricted to bulky amines. In this work, we report the nonsteric NH2-directed Pd(II)-catalyzed intramolecular C(sp2)-H arylation of tryptamines, which enables the efficient, gram-scale, and regioselective synthesis of versatile 2-aryltryptamines (35 examples, up to 98% yield). This approach broadens the substrate scope of the free amine-directed C-H functionalization, not limited to bulky amine substrates. Late-stage elaborations of 2-aryltryptamines achieve the divergent construction of the complex core structures that are prevalent in highly valuable natural products such as aurantioclavine, chimonanthine, and phalarine.
- Wang, Sixi,Yu, Bin,Liu, Hong-Min
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supporting information
p. 42 - 48
(2021/01/09)
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- Design, synthesis, and structure–activity relationship studies of the anaephene antibiotics
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The natural products, anaephenes A (1) and B (2), were found to have antimicrobial activity against methicillin-resistant Staphylococcus aureus (MRSA). In this report, we expanded on our previous synthetic efforts by preparing a library of eighteen analogues in order to understand the structure–activity relationships (SAR) of this interesting class of natural products. These analogues were selected to explore the biological impact of structural variations in the alkyl chain and on the phenol moiety. Last, we further assessed the biological activity of anaephene B (2) and two additional analogues against other clinically relevant bacterial strains and the hemolytic activity of each and determined that these compounds act via a bactericidal mechanism. These studies led to the identification of compound 7, which was 4-fold more potent than the natural product (2) against MRSA (2 vs. 8?μg/ml) and a 2-hydroxypyridine analogue (18) which demonstrated equal potency compared with the natural product (2), albeit with a significant reduction in hemolytic activity (1% vs. 80% at 100?μM).
- Kukla, David L.,Canchola, Juan,Rosenthal, Joseph D.,Mills, Jonathan J.
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p. 295 - 304
(2021/06/25)
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- Copper-catalyzed (4+1) and (3+2) cyclizations of iodonium ylides with alkynes
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The copper(ii)-catalyzed (4+1) cyclizations and copper(i)-catalyzed (3+2) cycloadditions of iodonium ylides and alkynes were successfully developed by employing efficient and safe iodonium ylides instead of traditional diazo compounds. Highly functionaliz
- Liang, Hao,He, Xiaobo,Zhang, Yaqi,Chen, Bin,Ouyang, Jia-Sheng,Li, Yongsu,Pan, Bendu,Subba Reddy, Chitreddy V.,Chan, Wesley Ting Kwok,Qiu, Liqin
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supporting information
p. 11429 - 11432
(2020/10/12)
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- Synthesis of indole-fused heteroacenes by cascade cyclisation involving rhodium(ii)-catalysed intramolecular C-H amination
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Heteroacenes are potentially important materials for organic electronics and their syntheses are of topical interest. Herein we report the development of a catalytic, redox-neutral reaction for the synthesis of the 5,10-dihydroindolo[3,2-b]indole class of
- Matsuda, Takanori,Ito, Hirotaka
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supporting information
p. 6703 - 6707
(2018/09/29)
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- Transition-Metal-Free Decarboxylative Iodination: New Routes for Decarboxylative Oxidative Cross-Couplings
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Constructing products of high synthetic value from inexpensive and abundant starting materials is of great importance. Aryl iodides are essential building blocks for the synthesis of functional molecules, and efficient methods for their synthesis from chemical feedstocks are highly sought after. Here we report a low-cost decarboxylative iodination that occurs simply from readily available benzoic acids and I2. The reaction is scalable and the scope and robustness of the reaction is thoroughly examined. Mechanistic studies suggest that this reaction does not proceed via a radical mechanism, which is in contrast to classical Hunsdiecker-type decarboxylative halogenations. In addition, DFT studies allow comparisons to be made between our procedure and current transition-metal-catalyzed decarboxylations. The utility of this procedure is demonstrated in its application to oxidative cross-couplings of aromatics via decarboxylative/C-H or double decarboxylative activations that use I2 as the terminal oxidant. This strategy allows the preparation of biaryls previously inaccessible via decarboxylative methods and holds other advantages over existing decarboxylative oxidative couplings, as stoichiometric transition metals are avoided.
- Perry, Gregory J. P.,Quibell, Jacob M.,Panigrahi, Adyasha,Larrosa, Igor
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p. 11527 - 11536
(2017/08/30)
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- Gold-Catalyzed Domino Synthesis of Functionalized Benzofurans and Tetracyclic Isochromans via Formal Carboalkoxylation
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A domino synthesis of benzofurans with the modification of side chains from α-alkoxyalkyl o-alkynylaryl ethers (n = 0) and electron-rich arenes has been developed. In the present domino reaction, which would proceed via the α-alkoxyalkylation of arenes with an intermediate in the migratory cycloisomerization of o-alkynylaryl ethers followed by the nucleophilic addition of benzofurans to benzyl ethers, a cationic Au(III) catalyst activates the C-C π bond and the C-O σ bond. The present method could be extended to Au(I)-catalyzed domino synthesis of tetracyclic isochromans from α-alkoxyalkyl (o-alkynylaryl)methyl ethers (n = 1) and aryl methoxymethyl ethers.
- Obata, Tomoyuki,Suzuki, Sho,Nakagawa, Asuka,Kajihara, Ryota,Noguchi, Keiichi,Saito, Akio
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supporting information
p. 4136 - 4139
(2016/08/30)
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- Enantioselective intramolecular cyclization of alkynyl esters catalyzed by a chiral Br?nsted base
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An enantioselective intramolecular cyclization reaction of alkynyl esters was developed, which employs a Br?nsted base catalyst generated in situ from a chiral Schiff base and t-BuOK. This reaction is a rare example of the enantioselective intramolecular addition of simple ester enolates to alkynes under Br?nsted base catalysis.
- Kondoh, Azusa,Tran, Hoa Thi Quynh,Kimura, Kyoko,Terada, Masahiro
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supporting information
p. 5726 - 5729
(2016/05/19)
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- Dual Photoredox/Gold Catalysis Arylative Cyclization of o-Alkynylphenols with Aryldiazonium Salts: A Flexible Synthesis of Benzofurans
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A new method for the arylative cyclization of o-alkynylphenols with aryldiazonium salts via dual photoredox/gold catalysis is described. The reaction proceeds smoothly at room temperature in the absence of base and/or additives and offers an efficient app
- Xia, Zhonghua,Khaled, Omar,Mouriès-Mansuy, Virginie,Ollivier, Cyril,Fensterbank, Louis
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p. 7182 - 7190
(2016/08/30)
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- Glucocorticoid receptor modulators informed by crystallography lead to a new rationale for receptor selectivity, function, and implications for structure-based design
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The structural basis of the pharmacology enabling the use of glucocorticoids as reliable treatments for inflammation and autoimmune diseases has been augmented with a new group of glucocorticoid receptor (GR) ligands. Compound 10, the archetype of a new f
- Carson, Matthew W.,Luz, John G.,Suen, Chen,Montrose, Chahrzad,Zink, Richard,Ruan, Xiaoping,Cheng, Christine,Cole, Harlan,Adrian, Mary D.,Kohlman, Dan T.,Mabry, Thomas,Snyder, Nancy,Condon, Brad,Maletic, Milan,Clawson, David,Pustilnik, Anna,Coghlan, Michael J.
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p. 849 - 860
(2014/03/21)
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- Alkoxyboration: Ring-closing addition of B-O σ bonds across alkynes
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For nearly 70 years, the addition of boron-X σ bonds to carbon-carbon multiple bonds has been employed in the preparation of organoboron reagents. However, the significantly higher strength of boron-oxygen bonds has thus far precluded their activation for addition, preventing a direct route to access a potentially valuable class of oxygen-containing organoboron reagents for divergent synthesis. We herein report the realization of an alkoxyboration reaction, the addition of boron-oxygen σ bonds to alkynes. Functionalized O-heterocyclic boronic acid derivatives are produced using this transformation, which is mild and exhibits broad functional group compatibility. Our results demonstrate activation of this boron-O σ bond using a gold catalysis strategy that is fundamentally different from that used previously for other boron addition reactions.
- Hirner, Joshua J.,Faizi, Darius J.,Blum, Suzanne A.
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supporting information
p. 4740 - 4745
(2014/04/17)
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- Highly efficient heterogeneous synthesis of benzofurans under aqueous condition
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Highly efficient organic reactions in water are important for designing environmental-friendly and low cost synthetic processes. Herein, we demonstrate an intermediate-in-water strategy for the heterogeneous synthesis of benzofurans in aqueous media. The cyclization reaction of 2-(phenylethynyl)phenol to 2-phenylbenzofuran cannot proceed in pure water. However, this reaction can be efficiently promoted by the formation of sparingly soluble intermediate in the presence of alkaline. Quantitative conversion of a variety of substrates to benzofuran derivatives has been achieved in the absence of noble metal catalyst. Other remarkable features including easy-isolation and purification of product, along with wide range of functional group tolerance render the methodology promising in the realm of green-synthesis.
- Sun, Shi-Xin,Wang, Jun-Jie,Xu, Zi-Jun,Cao, Lu-Ya,Shi, Zi-Fa,Zhang, Hao-Li
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supporting information
p. 3798 - 3806
(2014/05/20)
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- Exploring the potential of diarylacetylenediols as hydrogen bonding catalysts
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In the course of a search for new classes of hydrogen bonding catalysts, we have examined diarylacetylenediols as potential catalysts for the Diels-Alder reaction. General and efficient methods have been developed for the preparation of these diols. Their structures were systematically modified, and increased activity was observed for those possessing an electron-withdrawing group on the aryl groups. The electron-deficient diarylacetylenediol catalysts, while more active, undergo spontaneous cyclization to the corresponding benzo[b]furans. A mechanism is postulated to explain this facile transformation. Computational studies performed on 2-ethynylphenol help to explain the effect of the alkyne on the conformation and hydrogen bond donating ability of the adjacent OH group. Finally, the crystal structure of one of the diols is reported, and it displays an intricate network of intermolecular hydrogen bonds.
- Tuerkmen, Yunus E.,Rawal, Viresh H.
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p. 8340 - 8353
(2013/09/24)
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- From ynamides to highly substituted benzo[b]furans: Gold(I)-catalyzed 5-endo-dig-cyclization/rearrangement of alkylic oxonium intermediates
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A series of arylynamides with alkyloxy groups at the ortho position of the aryl group was prepared through a short alkylation/cross-coupling/amidation sequence. The gold-catalyzed conversion of these substrates combined both C-O and C-C formation steps, thus providing benzofurans with amine functionalities at the 2-position and alkyl groups at the 3-position. Cross-over experiments showed that the alkyl-migration step was an intermolecular process. X-ray crystal-structure analysis of two of the products supported our structural assignment. In some cases, the corresponding benzofurans without the alkyl group at the 3-position were obtained as side-products, which were formed through a competing protodeauration process. Golden touch: Arylynamides with o-alkyloxy groups were prepared through an alkylation/cross-coupling/amidation sequence. Their Au-catalyzed conversion provided benzofurans with amine groups at the 2-position and alkyl groups at the 3-position. Copyright
- Blanco Jaimes, Maria Camila,Weingand, Vanessa,Rominger, Frank,Hashmi, A. Stephen K.
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supporting information
p. 12504 - 12511
(2013/09/23)
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- Gold-catalyzed cyclizations of (o-alkynyl)phenoxyacrylates with external nucleophiles: Regio-and stereoselective synthesis of functionalized benzo[b]oxepines
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A catalytic approach to benzo[b]oxepines with high stereoselectivity by Au-catalyzed cyclization of (o-alkynyl)phenoxyacrylates with various nucleophiles under mild reaction conditions has been developed. Notably, the use of vinyl ether instead of alcohol could afford the same benzoxepines. The reaction may proceed by Au-catalyzed oligomerization of vinyl ether to release the alcohol, which then reacts with (o-alkynyl)phenoxyacrylates to furnish the benzoxepines.
- Liu, Jun,Liu, Yuanhong
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supporting information
p. 4742 - 4745,4
(2020/09/16)
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- Allenylphosphonates/allenylphosphine oxides as intermediates/precursors for intramolecular cyclization leading to phosphorus-based indenes, indenones, benzofurans, and isochromenes
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Utilizing internally available functional groups, a simple protocol for the efficient synthesis of phosphorus-based indenes, indenones, benzofurans, and isochromenes via intramolecular cyclization of allene intermediates/precursors is generated; the latter intermediates/precursors are conveniently obtained through aldehyde-, alkylidene-, and hydroxyl-functionalized propargyl alcohols and PIII-Cl precursors. The structures of key products have been unequivocally confirmed by X-ray crystallography.
- Sajna,Kumara Swamy
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body text
p. 5345 - 5356
(2012/08/27)
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- Domino rhodium(I)-catalysed reactions for the efficient synthesis of substituted benzofurans and indoles
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Rhodium(I) catalysts promote the transformation of o-alkynyl phenols and anilines to the corresponding benzo[b]furans and indoles. The reaction is postulated to proceed via a transient 3-rhodium heterocycle intermediate, which can be trapped with suitable electrophiles to give poly-substituted heterocycles. In the case of mono-substituted electron-withdrawn electrophiles, excellent yield and selectivity for conjugate addition versus Heck-Mizoroki reaction can be achieved. In the case of 2-alkynyl pyridine electrophiles, novel 2-(benzofuran-3-yl)vinylpyridines are formed.
- Boyer, Alistair,Isono, Naohiro,Lackner, Sebastian,Lautens, Mark
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scheme or table
p. 6468 - 6482
(2010/10/03)
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- On the trapping of vinylgold intermediates
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An internal aryl-substituted ortho-alkynylphenol and a similar aniline with stoichiometric amounts of N,N'-bis(2,6-diisopropylphenyl)imidazol-2-ylidene- gold tosylate [(IPr)AuOTs] and triethylamine gave the aurated heterocycles as stable intermediates of
- Hashmi, A. Stephen K.,Ramamurthi, Tanuja Dondeti,Rominger, Frank
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experimental part
p. 971 - 975
(2010/06/13)
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- Iodocyclization of ethoxyethyl ethers to alkynes: A broadly applicable synthesis of 3-iodobenzo[b]furans
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(Chemical Equation Presented) A wide variety of 3-iodobenzo[b]furans were readily prepared by iodocyclization of 2-alkynyl-1-(1-ethoxyethoxy)benzenes with the I(coll)2PF6-BF3-OEt2 combination. Aryl-, vinyiic-, a
- Okitsu, Takashi,Nakazawa, Daisuke,Taniguchi, Rie,Wada, Akimori
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supporting information; experimental part
p. 4967 - 4970
(2009/05/31)
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- Stereoselective synthesis of the rocaglamide skeleton via a silyl vinylketene formation/[4 + 1] annulation sequence
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(Chemical Equation Presented) The tricyclic core of the cyclopentabenzofurans has been prepared in an efficient and stereoselective manner utilizing an intramolecular silyl vinylketene formation/[4 + 1] annulation sequence. This novel approach affords the
- Giese, Matthew W.,Moser, William H.
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supporting information; experimental part
p. 4215 - 4218
(2009/06/06)
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- Synthesis of aromatic spiroacetals related to γ-rubromycin based on a 3H-spiro[1-benzofuran-2,2′-chromane] skeleton
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The synthesis of a series of aromatic 5,6-benzannelated and naphthyl-benzannelated spiroacetals related to the spiroacetal unit present in the quinonoid antibiotic γ-rubromycin is reported. The key steps include the use of Sonogashira coupling to construct an aryl acetylene that is coupled to an aryl aldehyde forming a propargyl alcohol intermediate. Hydrogenation of the resultant alkynol followed by oxidation produces a masked dihydroxyketone that upon treatment with silica-supported sodium hydrogen sulfate undergoes concomitant deprotection and cyclisation to afford the desired fused aromatic spiroacetal.
- Tsang, Kit Yee,Brimble, Margaret A.
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p. 6015 - 6034
(2008/02/02)
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- Heterocycles by PtCl2-catalyzed intramolecular carboalkoxylation or carboamination of alkynes
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PtCl2 constitutes a convenient catalyst for intramolecular hydroalkoxylation, carboalkoxylation, hydroamination, and carboamination reactions of alkynes, effecting the formation of substituted benzo[b]furan, indole-, and isochromene-1-one derivatives, respectively. This procedure allows for the transfer of (substituted) allyl, methoxymethyl (MOM), benzyloxymethyl (BOM), and (trimethylsilyl)ethoxymethyl (SEM) groups from oxygen to carbon and is compatible with functional groups that are susceptible to oxidative insertion of low valent metal species previously used for similar purposes. Although some of the reactions can even be carried out in air, the rates are significantly increased when conducted under an atmosphere of CO. A mechanistic rationale is proposed, implying activation of the alkyne by the carbophilic Pt(2+) template as the primary step of the catalytic cycle. Copyright
- Fuerstner, Alois,Davies, Paul W.
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p. 15024 - 15025
(2007/10/03)
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- Quinuclidine compounds and drugs containing the same as the active ingredient
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The present invention provides an excellent squalene synthesizing enzyme inhibitor. Specifically, it provides a compound (I) represented by the following formula, a salt thereof or a hydrate of them. In which R1 represents (1) hydrogen atom or (2) hydroxyl group; HAr represents an aromatic heterocycle which may be substituted with 1 to 3 groups; Ar represents an optionally substituted aromatic ring; W represents a chain represented by (1) —CH2—CH2— which may be substituted, (2) —CH=CH— which may be substituted, (3) —C≡C—, (4) —NH—CO—, (5) —CO—NH—, (6) —NH—CH2—, (7) —CH2—NH—, (8) —CH2—CO—, (9) —CO—CH2—, (10) —NH—S(O)l—, (11) —S(O)l—NH—, (12) —CH2—S(O)— or (13) —S(O)l—CH2— (l denotes 0, 1 or 2); and X represents a chain represented by (1) a single bond, (2) an optionally substituted C1-6 alkylene chain, (3) an optionally substituted C2-6 alkenylene chain, (4) an optionally substituted C2-6 alkynylene chain, (5) a formula —Q— (wherein Q represents oxygen atom, sulfur atom, CO or N(R2) (wherein R2 represents a C1-6 alkyl group or a C1-6 alkoxy group)), (6) —NH—CO—, (7) —CO—NH—, (8) —NH—CH2—, (9) —CH2—NH—, (10) —CH2—CO—, (11) —CO—CH2—, (12) —NH—S(O)m—, (13) —S(O)m—NH—, (14) —CH2—S(O)m—, (15) —S(O)m—CH2— (wherein m denotes 0, 1 or 2) or (16) —(CH2)n—O— (wherein n denotes an integer from 1 to 6).
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- Use of a Sonogashira - Acetylide Coupling Strategy for the Synthesis of the Aromatic Spiroketal Skeleton of γ-Rubromycin
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(Equation presented) The synthesis of the fused aromatic spiroketal core of γ-rubromycin is described via addition of an aryl acetylide fragment to an aryl acetaldehyde fragment. In turn, the aryl acetylene precursor was readily prepared with use of a Sonogashira reaction.
- Tsang, Kit Y.,Brimble, Margaret A.,Bremner, John B.
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p. 4425 - 4427
(2007/10/03)
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- Photochromic films prepared by oxidation polymerization of a diarylethene having phenol moieties
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Photochromic films containing diarylethene chromophores were prepared by oxidation polymerization of a diarylethene having phenol moieties. Upon alternate irradiation with UV and visible light, the polymer films exhibited coloration/decoloration cycles. The films were amorphous and kept the state after one year storage at room temperature.
- Uchida, Kingo,Takata, Atsushi,Nakamura, Shinichiro,Irie, Masahiro
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p. 476 - 477
(2007/10/03)
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- Asymmetric palladium(0)-mediated synthesis of 2-vinylchroman
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Optically active 2-vinylchroman was synthesized from the corresponding hydroxy allylic carbonate by palladium-catalyzed cyclization in the presence of various chiral ligands. Enantioselectivity of up to 53% was obtained using NMDPP as the chiral phosphine
- Labrosse, Jean-Robert,Poncet, Cecilia,Lhoste, Paul,Sinou, Denis
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p. 1069 - 1078
(2007/10/03)
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- Rhodium-catalysed cyclic carbonylation of 2-alkynylphenols: Synthesis of benzofuranones and coumarins
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Rhodium-catalysed carbonylation of 2-alkynylphenols 1 under water-gas shift reaction conditions gives benzofuranone derivatives 2 and coumarin derivatives 3 in high yield (up to 96%, 2:3 = 65:35), in which the hydroxy group adjacent to the carbon-carbon triple bond participitates in the cyclic carbonylation.
- Yoneda, Eiji,Sugioka, Takashi,Hirao, Kojiro,Zhahg, Shi-Wei,Takahashi, Shigetoshi
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p. 477 - 483
(2007/10/03)
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- STUDIES OF METHOXYMETHYL-DIRECTED METALATION
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To explore the use of methoxymethyl groups to elaborate simple benzenoid precursors to more complex polyketide-derived natural products, the reaction of phenolmethoxymethyl ether ortho-anion was investigated with a number of electrophiles.
- Townsend, Craig A.,Bloom, Leslie M.
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p. 3923 - 3924
(2007/10/02)
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