- Halogen-Substituted Allenyl Ketones through Ring Opening of Nonstrained Cycloalkanols
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An efficient synthesis of halogen-substituted allenyl ketones via Ag-catalyzed oxidative ring opening of allenyl cyclic alcohols under mild reaction conditions has been achieved. The reaction features a wide substrate scope and excellent regioselectivity. The synthetic potential of the products has been demonstrated by their conversion to stereodefined alkenes and heterocyclic compounds.
- Wu, Penglin,Ma, Shengming
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supporting information
p. 2533 - 2537
(2021/04/13)
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- Enantio- And Diastereodivergent Construction of 1,3-Nonadjacent Stereocenters Bearing Axial and Central Chirality through Synergistic Pd/Cu Catalysis
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In contrast to the widely explored methods for the asymmetric synthesis of molecules bearing a single stereocenter or adjacent stereocenters, the concurrent construction of 1,3-stereogenic centers in an enantio- and diastereoselective manner remains a challenge, especially in acyclic systems. Herein, we report an enantio- and diastereodivergent construction of 1,3-nonadjacent stereocenters bearing allenyl axial and central chirality through synergistic Pd/Cu-catalyzed dynamic kinetic asymmetric allenylation with racemic allenylic esters. The protocol is suitable for a wide range of substrates including the challenging allenylic esters with less sterically bulky substituents and provided chiral allenylic products bearing 1,3-nonadjacent stereocenters with high levels of enantio- and diastereoselectivities (up to >20:1 dr and >99% ee). Furthermore, several representative transformations involving axial-to-central chirality transfer were conducted, affording useful structural motifs containing nonadjacent stereocenters in a diastereodivergent manner.
- Huo, Xiaohong,Ma, Shengming,Xiao, Junzhe,Zhang, Jiacheng,Zhang, Wanbin,Zhao, Ling
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supporting information
p. 12622 - 12632
(2021/08/31)
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- ETHERS AND ESTERS OF 1-SUBSTITUTED CYCLOALKANOLS FOR USE AS AROMA CHEMICALS
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The present invention relates to the use of an ether or an ester of a 1 -substituted cycloalkanol or of mixtures of two or more ethers or esters of 1 -substituted cycloalkanols or of a stereoisomer thereof or of a mixture of two or more stereoisomers thereof as aroma chemicals; to the use thereof for modifying the scent character of a fragranced composition; to an aroma chemical composition containing an ether or an ester of a 1 -substituted cycloalkanol or of mixtures of two or more ethers or esters of 1 -substituted cycloalkanols or of a stereoisomer thereof or of a mixture of two or more stereoisomers thereof; and to a method of preparing a fragranced composition or for modifying the scent character of a fragranced composition. The invention further relates to specific ethers or esters of 1 -substituted cycloalkanols.
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Page/Page column 55
(2020/05/21)
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- Trialkylborane-Mediated Propargylation of Aldehydes Using γ-Stannylated Propargyl Acetates
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A transition-metal-free three-component process that combines aldehydes, 3-(tributylstannyl)propargyl acetates formed in situ from readily available propargyl acetates, and trialkylboranes provides access to a range of 1,2,4-trisubstituted homopropargylic alcohols. The addition of diisopropylamine plays a crucial role in the selective formation of homopropargylic alcohols. Importantly, this methodology can be extended to a single-flask reaction sequence starting from propargyl acetates.
- Horino, Yoshikazu,Murakami, Miki,Ishibashi, Mayo,Lee, Jun Hee,Watanabe, Airi,Matsumoto, Rio,Abe, Hitoshi
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supporting information
p. 9564 - 9568
(2019/12/24)
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- Opioid receptor agonists and application thereof
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The invention discloses compounds and salts thereof that can be used as opioid receptor ligands, a preparation method of the compounds, compositions containing the compounds, and a use of the compounds as [mu] opioid receptor agonists; the compounds are used for treatment of [mu] opioid receptor-mediated related diseases, such as pains and pain-related disorders.
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- Synthesis of Imidazo[1,2-a]pyridines and Imidazo[2,1-b]thiazoles Attached to a Cycloalkyl or Saturated Heterocycle Containing a Tertiary Hydroxy Substitution
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A new method has been developed for the synthesis of imidazo[1,2-a]pyridines, imidazo[2,1-b]thiazoles, and benzo[d]imidazo[2,1-b]thiazoles attached to a cycloalkyl or saturated heterocycle containing a tertiary hydroxy substitution. Readily available substituted 2-aminopyridines, 2-aminothiazoles, and 2-aminobenzothiazoles were treated with bromohydroxycycloalkyl ethanones to afford the desired products in good yields.
- Chenna Reddy,Patil, Vineetkumar B.,Nawaz Khan, Fazlur Rahman,Saravanan, Vadivelu
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p. 1486 - 1497
(2019/04/04)
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- Synthesis of Vinyl-, Allyl-, and 2-Boryl Allylboronates via a Highly Selective Copper-Catalyzed Borylation of Propargylic Alcohols
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An efficient methodology for the synthesis of vinyl-, allyl-, and (E)-2-boryl allylboronates from propargylic alcohols via Cu-catalyzed borylation under mild conditions is reported. In the presence of commercially available Cu(OAc)2 or Cu(acac)2 and Xantphos, the reaction affords the desired products in up to 92% yield with a broad substrate scope (43 examples). Isolation of an allenyl boronate as the reaction intermediate suggests that an insertion-elimination-type reaction, followed by borylcupration, is involved in the borylation of propargylic alcohols.
- Mao, Lujia,Bertermann, Rüdiger,Emmert, Katharina,Szabó, Kálmán J.,Marder, Todd B.
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supporting information
p. 6586 - 6589
(2017/12/26)
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- Fluoride-assisted activation of calcium carbide: A simple method for the ethynylation of aldehydes and ketones
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The fluoride-assisted ethynylation of ketones and aldehydes is described using commercially available calcium carbide with typically 5 mol % of TBAF·3H2O as the catalyst in DMSO. Activation of calcium carbide by fluoride is thought to generate an acetylide "ate"-complex that readily adds to carbonyl groups. Aliphatic aldehydes and ketones generally provide high yields, whereas aromatic carbonyls afford propargylic alcohols with moderate to good yields. The use of calcium carbide as a safe acetylide ion source along with economic amounts of TBAF·3H2O make this procedure a cheap and operationally simple method for the preparation of propargylic alcohols.
- Hosseini, Abolfazl,Seidel, Daniel,Miska, Andreas,Schreiner, Peter R.
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supporting information
p. 2808 - 2811
(2015/06/16)
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- Facile synthesis of halogenated spiroketals via a tandem iodocyclization
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A strategy for the synthesis of spiroketal compounds through a tandem iodocyclization of 1-(2-ethynylphenyl)-4-hydroxybut-2-yn-1-one derivatives is presented. This reaction could proceed under very mild conditions in a short time and avoid the use of expensive and toxic metal catalysts. Moreover, the resulting halides can be further exploited by subsequent palladium-catalyzed coupling reactions, which act as the important intermediates for building other valuable compounds.
- Wang, Jia,Zhu, Hai-Tao,Li, Ying-Xiu,Wang, Li-Jing,Qiu, Yi-Feng,Qiu, Zi-Hang,Zhong, Mei-Jin,Liu, Xue-Yuan,Liang, Yong-Min
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supporting information
p. 2236 - 2239
(2014/05/06)
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- Au-catalyzed formation of functionalized quinolines from 2-alkynyl arylazide derivatives
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A new method for converting 2-alkynyl arylazide derivatives into functionalized polysubstituted quinolines following a gold-catalyzed 1,3-acetoxy shift/cyclization/1,2-group shift sequence has been developed. This transformation proceeds under mild reaction conditions, is efficient, and tolerates a large variety of functional groups.
- Gronnier, Colombe,Boissonnat, Guillaume,Gagosz, Fabien
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p. 4234 - 4237
(2013/09/12)
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- Gold-catalyzed regioselective hydration of propargyl acetates assisted by a neighboring carbonyl group: Access to α-acyloxy methyl ketones and synthesis of (±)-actinopolymorphol B
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A general atom-economical approach for the synthesis of α-acyloxy methyl ketone is demonstrated through regioselective hydration of a wide range of propargyl acetates. Readily available catalyst comprising of 1% Ph 3PAuCl and 1% AgSbF6 in dioxane-H2O efficiently hydrolyzes the terminal alkynes of the propargyl acetate in the absence of acid promoters at ambient temperature within a short time. Effective regioselective hydration is facilitated by the neighboring carbonyl group as demonstrated through 18O-labeling study. Compatibility of functional moieties and tolerance to various acid-labile protecting groups are observed. The catalytic condition is also suitable to perform hydration of TMS-substituted propargyl acetates, even though it requires prolonged reaction time for completion. Stereointegrity of the propargylic acetate is preserved during the hydration. The robustness of the system is successfully demonstrated through gram scale preparation of the product in nearly quantitative yield. The common α-acyloxy methyl ketone is transformed to 1,2-diol and 1,2-amino alcohol derivatives. Synthesis of actinopolymorphol B is achieved for the first time involving hydration of the propargyl acetate as the key step.
- Ghosh, Nayan,Nayak, Sanatan,Sahoo, Akhila K.
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p. 500 - 511
(2011/04/17)
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- Stereoselective One-Pot synthesis of 1-Aminoindanes and 5,6-Fused azacycles using a Gold-Catalyzed Redox-Pinacol-Mannich-Michael cascade
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"Chemical Equation Presented" Just another Mannich Monday: A cascade intramolecular redox-pinacol-Mannich-Michael reaction sequence catalyzed by gold complexes can be used to generate a variety of structures including spirocycles, 1-aminoindanes, and 5,6-fused azabicycles that have a quaternary carbon center. The reaction is characterized by complete atom-economy, high diastereoselectivity, and remarkable efficiency through tandem reactions.
- Yeom, Hyun-Suk,Lee, Youngun,Jeong, Jaewon,So, Eunsoo,Hwang, Soojin,Lee, Ji-Eun,Lee, Shim Sung,Shin, Seunghoon
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supporting information; experimental part
p. 1611 - 1614
(2010/06/15)
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- Efficient synthesis of 3-chloromethyl-2(5H)-furanones and 3-chloromethyl- 5,6-dihydropyran-2-ones via the PdCl2-catalyzed chlorocyclocarbonylation of 2,3- or 3,4-allenols
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(Chemical Equation Presented) A mild and efficient methodology involving PdCl2-catalyzed chlorocyclocarbonylation of 2,3- or 3,4-allenols with CuCl2 for the synthesis of 3-chloromethyl-2(5H)-furanones and 3-chloromethyl-5,6-dihydropyran-2-ones was developed. This reaction proceeded in a highly regioselective manner, i.e., the chlorine atom was introduced to the terminal position of the allene moiety while the lactone linkage was formed between the center carbon atom of the allene moiety and the hydroxyl oxygen, which was established by the X-ray single crystal diffraction study of γ-lactone 3p. The highly optically active 3-chloromethyl-2(5H)-furanones could be easily prepared from the readily available optically active 2,3-allenols. A mechanism for this reaction was proposed.
- Cheng, Xin,Jiang, Xuefeng,Yu, Yihua,Ma, Shengming
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scheme or table
p. 8960 - 8965
(2009/04/11)
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- Synthesis of alkyne derivatives of a novel triazolopyrazine as A 2A adenosine receptor antagonists
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A novel [1,2,4]triazolo[1,5-a]pyrazine core was synthesized and coupled with terminal acetylenes. The structure-activity relationship of the alkynes from this novel template was studied for their in vitro and in vivo adenosine A2A receptor antagonism. Selected compounds from this series were shown to have potent in vitro and in vivo activities against adenosine A 2A receptor. Compound 12, in particular, was found to be orally active at 3 mg/kg in both a mouse catalepsy model and a 6-hydroxydopamine- lesioned rat model.
- Yao, Gang,Haque, Serajul,Sha, Li,Kumaravel, Gnanasambandam,Wang, Joy,Engber, Thomas M.,Whalley, Eric T.,Conlon, Patrick R.,Chang, Hexi,Kiesman, William F.,Petter, Russell C.
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p. 511 - 515
(2007/10/03)
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- New heterocycles: 4-Methyl-2H-pyrano[6,5-f]cycloalka[2,1-b]2H-chromen-2- ones
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A synthesis of the new heterocycles, 4-methyl-2H-pyrano[6,5-f]cycloalka[2, 1-b]2H-chromen-2-ones (3) was described, via the unexpected intermediates 2-chloro-1-chloroethenylidenecycloalkanes (6) from the reaction of 1-ethynylcycloalkanols with thionyl chloride. The mechanism of some steps was discussed.
- Zhang, Qian,Chen, Ying,Xia, Yi,Yang, Zhengyu,Xia, Peng
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p. 1637 - 1643
(2007/10/03)
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- Effects of Structural Factors in Silyl Ethers Derived from Terminal Acetylenic Alcohols on 1,4-O→Csp Migration of the Silyl Group
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Effects of structural factors in silyl ethers derived from terminal acetylenic alcohols on 1,4-O-→Csp migration of the silyl group in the Iotsitch reagent were studied. The effect of steric factor at the carbon atom neighboring to the reaction center was found to be stronger than that at the silicon atom in the migrating group.
- Medvedeva,Novokshonov,Mareev,Borisova
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p. 336 - 339
(2007/10/03)
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- Facile approach to versatile chiral intermediates for fused cyclopentanoid natural products
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A facile approach to cis- and trans-2-(1-hydroxymethyl)vinyl-1-vinylcyclohexan-1-ols and to the corresponding cyclopentane, cycloheptane, and cyclooctane derivatives has been developed, starting from cycloalkanones involving the key steps of Rupe and Claisen orthoester rearrangements. The formation of intervening products could be explained by allylic strain and π-stacking, respectively.
- Zulfiqar, Fazila,Malik, Abdul
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p. 1227 - 1234
(2007/10/03)
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- Phenol catalyzed Claisen ortho ester rearrangment of allylic alcohols with trimethyl-β-(methoxy) ortho propionate
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Phenol catalyzed Claisen ortho ester rearrangment of allylic alcohols with trimethyl-β-(methoxy) ortho propionate can be affected in relatively quick time and lower temperature with only 1.5 equivalents of ortho ester. The rearrangement does not experience undesirable side reactions reported earlier in literature [3].
- Iqbal, Fazila,Ateeq, Humayun S.,Malik, Abdul,Zeeshan,Ali, Zulfiqar
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p. 1244 - 1245
(2007/10/03)
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- Preparation of Triesters by Palladium-Catalyzed Vicinal Carbonylation of Substituted-3-methoxycarbonyl-2-propynyl Methyl Carbonates
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The palladium-catalyzed vicinal carbonylation of the 1-substituted-3-methoxycarbonyl-2-propynyl methyl carbonates 6 proceeds at room temperature under atmospheric pressure of CO to give the triesters 7 in good yields.
- Mandai, Tadakatsu,Tsujiguchi, Yoshikazu,Matsuoka, Shin,Tsuji, Jiro,Saito, Seiki
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p. 5697 - 5700
(2007/10/02)
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- AN EFFICIENT AND QUICK LABORATORY SCALE METHOD FOR THE ETHYNYLATION OF SOME ALIPHATIC AND CYCLOALIPHATIC CARBONYL COMPOUNDS.
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A number of aliphatic and cycloaliphatic carbonyl compounds have been ethynylated in tetrahydrofuran at atmospheric pressure using uncomplexed potassium tert-butoxide as a catalyst.
- Verkruijsse, Hermann D.,Graaf, Wim de,Brandsma, Lambert
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p. 131 - 134
(2007/10/02)
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- SYNTHESIS OF TERTIARY ACETYLENIC ALCOHOLS AND THEIR ETHERS IN THE KOH-DMSO SYSTEM.
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The authors developed a universal single-stage method of synthesis of acetylenic alcohol ethers, including allyl and propargyl. Conducting the synthesis in one preparative stage is due to the fact that etherification of acetylenic alcohol alcoholates by organyl halides takes place in the same apparatus without separation of the intermediate product, i. e. , the synthesis is actually reduced to successive treatment of ketone with acetylene (or vinylacetylene) and organyl halides. The yield of ethers is weakly dependent on the structure of the ketone and organyl halide radicals. In the case of propargyl chloride, the formation of dipropargyl ether is observed (yield of 5%), which indicates the possibility of partial hydrolysis of the halide.
- Trofimov,Sobenina,Korostova,Mikhaleva,Shishov,Fel'dman,Shevchenko,Vasil'ev
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p. 1291 - 1295
(2007/10/02)
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