- Sustainable Passerini-tetrazole three component reaction (PT-3CR): selective synthesis of oxaborol-tetrazoles
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A sustainable catalyst- and solvent-free Passerini-tetrazole three component reaction (PT-3CR) has been developed for the selective synthesis of benzoxaborol-tetrazoles for the first time. The synthetic potential of oxaboroles was demonstrated towards various functionalized tetrazoles, which are otherwise difficult to achieve through conventional PT-3CR from aromatic aldehydes/ketones. The reaction features high practicality, broad substrate scope and excellent yields (80-98%). Preliminary results of the asymmetric PT-3CR are also shown for the synthesis of chiral benzoxaboroles.
- Singh, Akansha,Kumar, Ravindra
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supporting information
p. 9708 - 9711
(2021/09/30)
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- Catalytic Synthesis of 1 H-2-Benzoxocins: Cobalt(III)-Carbene Radical Approach to 8-Membered Heterocyclic Enol Ethers
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The metallo-radical activation of ortho-allylcarbonyl-aryl N-arylsulfonylhydrazones with the paramagnetic cobalt(II) porphyrin catalyst [CoII(TPP)] (TPP = tetraphenylporphyrin) provides an efficient and powerful method for the synthesis of novel 8-membered heterocyclic enol ethers. The synthetic protocol is versatile and practical and enables the synthesis of a wide range of unique 1H-2-benzoxocins in high yields. The catalytic cyclization reactions proceed with excellent chemoselectivities, have a high functional group tolerance, and provide several opportunities for the synthesis of new bioactive compounds. The reactions are shown to proceed via cobalt(III)-carbene radical intermediates, which are involved in intramolecular hydrogen transfer (HAT) from the allylic position to the carbene radical, followed by a near-barrierless radical rebound step in the coordination sphere of cobalt. The proposed mechanism is supported by experimental observations, density functional theory (DFT) calculations, and spin trapping experiments.
- De Bruin, Bas,De Zwart, Felix J.,Li, Zirui,Mathew, Simon,Wolzak, Lukas A.,Zhou, Minghui
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supporting information
p. 20501 - 20512
(2021/12/03)
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- Palladium-Catalyzed Intramolecular Mizoroki-Heck-Type Reaction of Diarylmethyl Carbonates
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A palladium-catalyzed intramolecular Mizoroki-Heck-type reaction of diarylmethyl tert-butyl carbonates has been developed. The reaction proceeds under external base-free, neutral conditions to form the corresponding methyleneindanes in good yields only with liberation of CO2 and tBuOH. The resulting exo-methylene moiety is reactive and thus a good synthetic handle for further manipulations. Additionally, the asymmetric synthesis is also possible through a Pd/chiral Mandyphos ligand-mediated kinetic resolution. To the best of our knowledge, this is the first successful example of catalytic enantioselective Mizoroki-Heck-type reaction of secondary benzyl electrophiles. (Figure presented.).
- Matsude, Akihiro,Hirano, Koji,Miura, Masahiro
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supporting information
p. 518 - 522
(2019/12/24)
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- Catalytic synthesis of isoquinolines via intramolecular migration of n-aryl sulfonyl groups on 1,5-yne-imines
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Isoquinolines are ubiquitous structural motifs in a variety of bioactive compounds, including medicinal agents and natural products. The development of novel strategies for the preparation of isoquinolines using non-toxic organocatalysts is thus worthwhile. Herein, we report a simple amine-catalyzed protocol for the synthesis of isoquinolines from 1,5-yne-imines via the intramoleular migration of an N-aryl sulfonyl group to the carbon atom of the alkyne moiety.
- Hoshimoto, Yoichi,Kumar, Ravindra,Nishimura, Chika,Ogoshi, Sensuke,Sasaoka, Yukari
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supporting information
p. 182 - 186
(2020/04/27)
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- HETEROCYCLIC SPIRO-COMPOUNDS AS AM2 RECEPTOR INHIBITORS
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Disclosed are compounds of the formula (I) and pharmaceutically acceptable salts thereof: wherein R1, R2, R4, R5, R6, R7, R8, R9, R10,Z, X1, X2, X3, L2, HET, n and q are as defined herein. The compounds are inhibitors of adrenomedullin receptor subtype 2 (AM2). Also disclosed are the compounds for use in the treatment of diseases modulated AM2, including proliferative diseases such as cancer; pharmaceutical compositions comprising the compounds; methods for preparing the compounds; and intermediates useful in the preparation of the compounds.
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Page/Page column 148; 155
(2020/06/05)
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- AuCl3-Catalyzed Ring-Closing Carbonyl–Olefin Metathesis
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Compared with the ripeness of olefin metathesis, exploration of the construction of carbon–carbon double bonds through the catalytic carbonyl–olefin metathesis reaction remains stagnant and has received scant attention. Herein, a highly efficient AuCl3-catalyzed intramolecular ring-closing carbonyl–olefin metathesis reaction is described. This method features easily accessible starting materials, simple operation, good functional-group tolerance and short reaction times, and provides the target cyclopentenes, polycycles, benzocarbocycles, and N-heterocycle derivatives in good to excellent yields.
- Wang, Rui,Chen, Yi,Shu, Mao,Zhao, Wenwen,Tao, Maoling,Du, Chao,Fu, Xiaoya,Li, Ao,Lin, Zhihua
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supporting information
p. 1941 - 1946
(2020/02/11)
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- Synthesis and Structure-Affinity Relationships of Spirocyclic Benzopyrans with Exocyclic Amino Moiety
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σ1 and/or σ2 receptors play a crucial role in pathological conditions such as pain, neurodegenerative disorders, and cancer. A set of spirocyclic cyclohexanes with diverse O-heterocycles and amino moieties (general structure III) was prepared and pharmacologically evaluated. In structure-activity relationships studies, the σ1 receptor affinity and σ1:σ2 selectivity were correlated with the stereochemistry, the kind and substitution pattern of the O-heterocycle, and the substituents at the exocyclic amino moiety. cis-configured 2-benzopyran cis-11b bearing a methoxy group and a tertiary cyclohexylmethylamino moiety showed the highest σ1 affinity (Ki = 1.9 nM) of this series of compounds. In a Ca2+ influx assay, cis-11b behaved as a σ1 antagonist. cis-11b reveals high selectivity over σ2 and opioid receptors. The interactions of the novel σ1 ligands were analyzed on the molecular level using the recently reported X-ray crystal structure of the σ1 receptor protein. The protonated amino moiety forms a persistent salt bridge with E172. The spiro[benzopyran-1,1′-cyclohexane] scaffold and the cyclohexylmethyl moiety occupy two hydrophobic pockets. Exchange of the N-cyclohexylmethyl moiety by a benzyl group led unexpectedly to potent and selective μ-opioid receptor ligands.
- Kronenberg, Elisabeth,Weber, Frauke,Brune, Stefanie,Schepmann, Dirk,Almansa, Carmen,Friedland, Kristina,Laurini, Erik,Pricl, Sabrina,Wünsch, Bernhard
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p. 4204 - 4217
(2019/05/06)
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- Silver-Catalyzed Radical Cascade Cyclization toward 1,5-/1,3-Dicarbonyl Heterocycles: An Atom-/Step-Economical Strategy Leading to Chromenopyridines and Isoxazole-/Pyrazole-Containing Chroman-4-Ones
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A novel and convenient silver-catalyzed radical cascade cyclization toward a large variety of 1,5-/1,3-dicarbonyl heterocycles containing a chroman-4-one, indanone, or 2,3-dihydroquinolin-4(1H)-one moiety was developed, by reacting various 2-functionalized benzaldehydes, including 2-allyloxy benzaldehydes, 2-allyl benzaldehyde, and 2-N(Ts)CH2-CH CH2 substituted benzaldehyde, with 1,3-dicarbonyl compounds in the presence of AgNO3/K2S2O8 in one pot under mild reaction conditions. The newly obtained 1,5-/1,3-dicarbonyl-containing heterocycles were further used directly to synthesize more structurally diverse polyheterocycles, mainly including chromenopyridines as well as isoxazole- or pyrazole-containing chroman-4-ones.
- Hu, Hao,Chen, Xiaolan,Sun, Kai,Wang, Junchao,Liu, Yan,Liu, Hui,Fan, Lulu,Yu, Bing,Sun, Yuanqiang,Qu, Lingbo,Zhao, Yufen
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supporting information
p. 6157 - 6160
(2018/10/05)
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- COMPOUNDS
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Disclosed are compounds of the formula (I) and pharmaceutically acceptable salts thereof: (I) wherein R1, R2, R3, R4, R5, R6, R8, R9, X, X1, X2, X3, L1 and n are as defined herein. The compounds are inhibitors of adrenomedullin receptor subtype 2 (AM2). Also disclosed are the compounds for use in the treatment of diseases modulated AM2, including proliferative diseases such as cancer; pharmaceutical compositions comprising the compounds; methods for preparing the compounds;and intermediates useful in the preparation of the compounds.
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Page/Page column 125; 126
(2018/12/13)
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- House bulb light-induced photochemical acetalization of carbonyl compounds catalyzed by Eosin Y
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We have systematically studied the reactions of acetalization and found that high reaction efficiency can be achieved using cheap and readily available organic Eosin Y as catalyst. The reaction proceeds smoothly under house bulbs and shows excellent functional group tolerance. The substrates of the reaction system are compatible with aromatic aldehydes, aliphatic aldehydes, aromatic ketones, and cyclic ketones with high yields.
- Zhou, Quan,Jia, Tao,Li, Xiao-Xuan,Zhou, Lin,Li, Chang-Jiang,Feng, Yi-Si
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supporting information
p. 1068 - 1075
(2018/05/23)
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- Synthesis of Trifluoromethylated Naphthoquinones via Copper-Catalyzed Cascade Trifluoromethylation/Cyclization of 2-(3-Arylpropioloyl)benzaldehydes
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A novel copper-catalyzed cascade trifluoromethylation/cyclization of 2-(3-arylpropioloyl)benzaldehydes is described, allowing a direct access to structurally diverse trifluoromethylated naphthoquinones under mild reaction conditions. It represents the first trans-acyltrifluoromethylation of internal alkynes.
- Zhang, Yan,Guo, Dongmei,Ye, Shangyi,Liu, Zhicheng,Zhu, Gangguo
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supporting information
p. 1302 - 1305
(2017/03/23)
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- Copper-Catalyzed Radical Cascade Difluoromethylation/Cyclization of 2-(3-Arylpropioloyl)benzaldehydes: A Route to Difluoromethylated Naphthoquinones
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A novel copper-catalyzed cascade difluoromethylation/cyclization of 2-(3-arylpropioloyl)benzaldehydes has been developed. This method affords an efficient and straightforward access to structurally diverse difluoromethylated naphthoquinones in one pot, starting from readily available starting materials. The reaction represents the first trans-acyldifluoromethylation of internal alkynes, which features aldehydes as acceptors for the addition of alkenyl radicals. Furthermore, this protocol can also access to monofluoromethylated naphthoquinone and difluoromethylated indanones in the same reaction condition.
- Zhang, Yan,Ye, Shangyi,Ji, Mingming,Li, Lisha,Guo, Dongmei,Zhu, Gangguo
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p. 6811 - 6818
(2017/07/17)
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- Visible-light-induced acetalization of aldehydes with alcohols
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In this work, we have achieved a simple and general method for acetalization of aldehydes by means of a photochemical reaction under low-energy visible light irradiation. A broad range of aromatic, heteroaromatic, and aliphatic aldehydes have been protected under neutral conditions in good to excellent yields using a catalytic amount of Eosin Y as the photocatalyst. Our visible light mediated acetalization strategies are successful for more challenging acid-sensitive aldehydes and sterically hindered aldehydes. Notably, this protocol is chemoselective to aldehydes, while ketones remain intact.
- Yi, Hong,Niu, Linbin,Wang, Shengchun,Liu, Tianyi,Singh, Atul K.,Lei, Aiwen
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supporting information
p. 122 - 125
(2017/11/27)
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- Fused Catechol Ethers from Gold(I)-Catalyzed Intramolecular Reaction of Propargyl Ethers with Acetals
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Selective gold(I)-catalyzed rearrangement of aromatic methoxypropynyl acetals leads to fused catechol ethers (1,2-dialkoxynapthalenes) in excellent yields. Furthermore, this process extends to the analogous heterocyclic and aliphatic substrates. Alkyne activation triggers nucleophilic addition of the acetal oxygen that leads to an equilibrating mixture of oxonium ions of similar stability. This mixture is "kinetically self-sorted" via a highly exothermic cyclization. Selective formation of 1,2-dialkoxy naphthalenes originates from chemoselective aromatization of the cyclic intermediate via 1,4-elimination of methanol.
- Pati, Kamalkishore,Dos Passos Gomes, Gabriel,Harris, Trevor,Alabugin, Igor V.
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supporting information
p. 928 - 931
(2016/03/15)
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- Combining Traceless Directing Groups with Hybridization Control of Radical Reactivity: From Skipped Enynes to Defect-Free Hexagonal Frameworks
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This work discloses the first general solution for converting oligoalkynes into polyaromatic polycyclic systems free of pentagonal defects. The efficiency and selectivity of this cascade originate from the combination of the Bu3Sn-mediated TDG
- Pati, Kamalkishore,dos Passos Gomes, Gabriel,Alabugin, Igor V.
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supporting information
p. 11633 - 11637
(2016/11/17)
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- Regiodivergent cyclobutanone cleavage: Switching selectivity with different Lewis acids
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The exploitation of strain release in small rings as driving force to enable complex transformations is a powerful synthetic tool. Among them, cyclobutanones are particularly versatile substrates that can be elaborated in a wide variety of structurally diverse building blocks. Herein, Lewis acid catalyzed rearrangement reactions are presented that provide selective access to two structurally distinct polycyclic scaffolds, that is, indenylacetic acid derivatives and benzoxabicyclo[3.2.1]octan-3-ones. The choice of the Lewis acid fully controls the reaction pathway and the regioselectivity of the cyclobutanone C-C bond cleavage site.
- Souillart, Laetitia,Cramer, Nicolai
-
supporting information
p. 1863 - 1867
(2015/01/30)
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- Enantioselective intramolecular propargylic amination using chiral copper-pybox complexes as catalysts
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Intramolecular propargylic amination of propargylic acetates bearing an amino group at the suitable position in the presence of chiral copper-pybox complexes proceeds enantioselectively to give optically active 1-ethynyl-isoindolines (up to 98% ee). The method described in this communication provides a useful synthetic approach to the enantioselective preparation of nitrogen containing heterocyclic compounds with an ethynyl group at the α-position. This journal is the Partner Organisations 2014.
- Shibata, Masashi,Nakajima, Kazunari,Nishibayashi, Yoshiaki
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supporting information
p. 7874 - 7877
(2014/07/08)
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- The asymmetric Cu(ii)-indolinylmethanol complex catalyzed Diels-Alder reaction of 2-vinylindoles with β,γ-unsaturated α-ketoesters: An efficient route to functionalized tetrahydrocarbazoles
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An efficient asymmetric Diels-Alder reaction of 2-vinylindoles with β,γ-unsaturated α-ketoesters has been developed for the construction of functionalized tetrahydrocarbazoles. The products were obtained in high yields (up to 96%) with good stereoselectiv
- Ouyang, Banlai,Yu, Tingting,Luo, Renshi,Lu, Gui
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supporting information
p. 4172 - 4176
(2014/06/10)
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- Highly enantioselective rhodium(I)-catalyzed carbonyl carboacylations initiated by C-C bond activation
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The lactone motif is ubiquitous in natural products and pharmaceuticals. The Tishchenko disproportionation of two aldehydes, a carbonyl hydroacylation, is an efficient and atom-economic access to lactones. However, these reaction types are limited to the transfer of a hydride to the accepting carbonyl group. The transfer of alkyl groups enabling the formation of C-C bonds during the ester formation would be of significant interest. Reported herein is such asymmetric carbonyl carboacylation of aldehydes and ketones, thus affording complex bicyclic lactones in excellent enantioselectivities. The rhodium(I)-catalyzed transformation is induced by an enantiotopic C-C bond activation of a cyclobutanone and the formed rhodacyclic intermediate reacts with aldehyde or ketone groups to give highly functionalized lactones. Delivering the goods: Asymmetric carbonyl carboacylations of aldehydes and ketones provide access to functionalized bicyclic lactones. The rhodium(I)-catalyzed transformation is induced by an enantiotopic C-C bond activation of a cyclobutanone and the transient rhodacyclic adds across an appended carbonyl group to deliver the lactones in excellent enantioselectivities.
- Souillart, Laetitia,Cramer, Nicolai
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supporting information
p. 9640 - 9644
(2014/11/27)
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- Zeolite nanofiber assemblies as acid catalysts with high activity for the acetalization of carbonyl compounds with alcohols
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Zeolite nanofiber assemblies (HNB-MOR) as efficient heterogeneous catalysts for the formation of a range of acetals in good yields. The mesoporosity of HNB-MOR benefits mass transfer, and the strong acidic sites on HNB-MOR facilitate acetalization activity. The catalyst can be reused 10 times without loss of activity.
- Liu, Taotao,Fu, Wenqian,Zheng, Xiang,Jiang, Jun,Hu, Maolin,Tang, Tiandi
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p. 18217 - 18221
(2014/05/20)
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- Environmentally benign synthesis of indeno[1,2-b]quinolines via an intramolecular povarov reaction
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A new synthetic route to indeno[1,2-b]quinolines via reactions of o-propargylbenzaldehydes with N-aryl amines based on an intramolecular aza-Diels-Alder (Povarov) reaction has been developed. This method offers several advantages such as no requirement fo
- Chen, Ming,Sun, Ning,Liu, Yuanhong
-
supporting information
p. 5574 - 5577
(2013/11/19)
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- Efficient enantioselective synthesis of dihydropyrans using a chiral N, N ′-dioxide as organocatalyst
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The bifunctional organocatalyst C3 N,N′-dioxide has been successfully applied to the asymmetric cascade Michael/hemiacetalization reaction of α-substituted cyano ketones and β,γ-unsaturated α-ketoesters for the synthesis of multifunctionalized chiral dihydropyrans. The corresponding products were obtained in excellent yields (up to 99%) with high to excellent enantioselectivities (up to 99% ee).
- Feng, Juhua,Fu, Xuan,Chen, Zhenling,Lin, Lili,Liu, Xiaohua,Feng, Xiaoming
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supporting information
p. 2640 - 2643
(2013/07/19)
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- Gold(I)-catalyzed enantioselective carboalkoxylation of alkynes
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A highly enantioselective carboalkoxylation of alkynes catalyzed by cationic (DTBM-MeO-Biphep)gold(I) complexes is reported. Various optically active β-alkoxyindanone derivatives were obtained in good yields with high enantioselectivities. Furthermore, this methodology was extended to the enantioselective synthesis of 3-methoxycyclopentenones. The reaction is proposed to proceed through an enantioselective cyclization of intermediates containing vinylgold(I) and prochiral oxocarbenium moieties.
- Zi, Weiwei,Toste, F. Dean
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supporting information
p. 12600 - 12603
(2013/09/23)
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- Enantioselective copper-catalyzed conjugate addition of trimethylaluminium to β,γ-unsaturated α-ketoesters
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Not a cop out: The copper-catalyzed asymmetric conjugate addition of organometallic reagents to Michael acceptors is an important methodology for forming a C-C bond in an enantioselective manner. Such an addition of Me 3Al to β,γ-unsaturated α-
- Gremaud, Ludovic,Alexakis, Alexandre
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supporting information; experimental part
p. 794 - 797
(2012/03/09)
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- Lewis acid catalyzed intramolecular condensation of ynol ether-acetals. synthesis of alkoxycycloalkene carboxylates
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Treatment of ynol ether-tethered dialkyl acetals with catalytic quantities of scandium triflate in CH3CN gives rise to five-, six-, and seven-membered alkoxycycloalkene carboxylates in good to excellent yields. Tri- and tetrasubstituted carbocyclic and heterocyclic alkenes may be formed by this method, and the products obtained may serve as useful intermediates for natural product synthesis.
- Tran, Vincent,Minehan, Thomas G.
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supporting information
p. 6100 - 6103
(2013/02/26)
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- Chemoselectivities in the platinum-catalyzed hydrative carbocyclizations of oxo-alkyne-nitrile functionalities
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Two new hydrative carbocyclizations of oxa-alkyne-nitrile functionalities are reported to produce distinct nitrogen-containing heterocycles. Protracted heating of oxoalkynyl nitrile substrates with PtCl2/CO/H2O in hot 1,4-dioxane gave 2,3-dihydro-1H-pyrido[1.2-b]-isoquinolin-4(6H)-ones. In this hydration reaction, dicarbonyl nitrile intermediates were isolated efficiently after a brief period, and they were subjected to an NHC-based crossed benzoin coupling to give spiro alcohols that further reacted with TfOH to give spiro[indene-2,2′-piperidine]-1,6′(3H)-diones.
- Mukherjee, Anupam,Liu, Rai-Shung
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supporting information; experimental part
p. 660 - 663
(2011/05/03)
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- Mesoporous aluminosilicate-catalyzed allylation of carbonyl compounds and acetals
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A mesoporous aluminosilicate (Al-MCM-41) was found to be an effective heterogeneous catalyst for the reaction of both carbonyl compounds and acetals with allylsilanes to afford the corresponding homoallyl silyl ethers and homoallyl alkyl ethers, respectively. Both the mesoporous structure and the presence of aluminum moiety were indispensable for the high catalytic activity of Al-MCM-41. Moreover, Al-MCM-41 could catalyze the reaction of acetals chemoselectively in the presence of the corresponding carbonyl compounds. The solid acid catalyst Al-MCM-41 could be recovered easily by filtration and could be reused three times without a significant loss of catalytic activity.
- Ito, Suguru,Hayashi, Akira,Komai, Hirotomo,Yamaguchi, Hitoshi,Kubota, Yoshihiro,Asami, Masatoshi
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supporting information; experimental part
p. 2081 - 2089
(2011/04/19)
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- Catalytic synthesis of γ-alkoxy-α-keto esters
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Copper(II) triflate effectively catalyzes the reaction of (trimethylsilyloxy)acrylic esters and acetals to form -alkoxy - keto esters. The reaction proceeds under mild conditions providing products in good to excellent yields. The substrate scope was investigated, and it was demonstrated that the products could be converted into related compounds such as γ-hydroxy -α- keto esters and α-oximes. Georg Thieme Verlag Stuttgart - New York.
- Krebs, Anke,Bolm, Carsten
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supporting information; experimental part
p. 671 - 673
(2011/05/16)
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- Gold-catalyzed dealkoxylative carbocyclization/[3+3] annulation cascade of acetal-allene or ketal-allene substrates
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(Chemical Equatation Reprentation) Rapid construction: We report the first successful implementation of a catalytic tandem carbocyclization/annulation cascade reaction (e.g., see scheme) using acetal-allene or ketal-aliene substrates through a dealkoxylat
- Teng, Tse-Min,Lin, Ming-Shiun,Vasu, Dhananjayan,Bhunia, Sabyasachi,Liu, Ting-An,Liu, Rai-Shung
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supporting information; experimental part
p. 4744 - 4748
(2010/07/05)
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- Tetrafluoroboric acid adsorbed on silica gel as a reusable heterogeneous dual-purpose catalyst for conversion of aldehydes/ketones into acetals/ketals and back again
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Aldehydes and ketones can be protected as acetals and ketals by treatment with trimethyl orthoformate (TMOF) or triethyl orthoformate (TEOF) under the catalytic influence of tetrafluoroboric acid adsorbed on silica gel (HBF 4-SiO2). In the case of aldehydes or ketones with highly electrophilic carbonyl group, the reactions are carried out under solvent-free conditions. Aryl alkyl ketones, aryl styryl ketones, aldehydes with weakly electrophilic carbonyl groups, and aldehydes with substituents that can coordinate with the catalyst require the presence of the corresponding alcohol as solvent. For substrates that can be converted into acetals under neat conditions, the acetal formation takes place at a faster rate when the alcohol is used as the solvent. The catalyst can be recovered and reused/recycled four times (after reactivation after each use) without any significant decrease in its catalytic efficiency. The parent aldehydes/ketones are regenerated from the corresponding acetals/ketals in high yields by the treatment with water-alcohol in the presence of HBF4-SiO2 at room temperature for short times. Excellent selectivity was observed during inter- and intramolecular competition studies involving carbonyl substrates with varying electronic and steric environments. Selective acetal formation of benzaldehyde takes place in the presence of 4-(dimethylamino)benzaldehyde, thiophene-2-carboxaldehyde, 1-naphthaldehyde, 9-anthraldehyde, or acetophenone, but 3-nitrobenzaldehyde undergoes selective acetal formation in preference to benzaldehyde. In the case of 4-acetylbenzaldehyde, exclusive acetal formation of the aldehyde carbonyl group occurs. Georg Thieme Verlag Stuttgart.
- Kumar, Dinesh,Kumar, Raj,Chakraborti, Asit K.
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p. 1249 - 1256
(2008/12/22)
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- Gold-catalyzed 1,3-addition of a sp3-hybridized C-H bond to alkenylcarbenoid intermediate
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We report stereoselective synthesis of bicyclo[3.2.1]oct-6-en-2-ones through Au(I)-catalyzed cycloisomerization of an allenene-acetal functionality. This cyclization is mechanistically significant because it involves an unprecedented 1,3-addition of a sp
- Bhunia, Sabyasachi,Liu, Rai-Shung
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supporting information; scheme or table
p. 16488 - 16489
(2009/04/12)
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- Perchloric acid adsorbed on silica gel (HClO4-SiO2) as an inexpensive, extremely efficient, and reusable dual catalyst system for acetal/ketal formation and their deprotection to aldehydes/ketones
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Perchloric acid adsorbed on silica gel (HClO4-SiO2) is reported as extremely efficient, inexpensive, and reusable catalyst for dual role for protection of aldehydes/ketones (with trialkyl orthoformates) as acetals/ketals and deprotection (with water-alcohol) to regenerate the carbonyl compounds in high yields at room temperature and in short times. Acetalization/ketalization of electrophilic aldehydes/ketones was carried out under solvent-free conditions. Weakly electrophilic aldehydes/ketones and aldehydes having a substituent that can coordinate with the catalyst, required the corresponding alcohol as solvent. Georg Thieme Verlag Stuttgart.
- Kumar, Raj,Kumar, Dinesh,Chakraborti, Asit K.
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p. 299 - 303
(2007/10/03)
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- Reductive coupling of aromatic dialkyl acetals using the combination of zinc and chlorotrimethylsilane in the presence of potassium carbonate
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The treatment of aromatic acetals with zinc and chlorosilane in the presence of potassium carbonate in toluene brought about facile and effective reductive coupling to give the corresponding coupling products. Copyright
- Hatano, Bunpei,Nagahashi, Keita,Habaue, Shigeki
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p. 1418 - 1419
(2008/03/14)
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- Copper(II) tetrafluoroborate as a novel and highly efficient catalyst for acetal formation
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Commercially available copper(II) tetrafluoroborate hydrate has been found to be a highly efficient catalyst for dimethyl/diethyl acetal formation in high yields from aldehydes and ketones by reaction with trimethyl/triethyl orthoformate at room temperature and in short period. Acetalisation was carried out under solvent-free conditions with electrophilic aldehydes/ketones. For weakly electrophilic aldehydes/ketones (e.g., benzaldehyde, cinnamaldehyde and acetophenone) and for aldehydes having a substituent that can coordinate with the catalyst, the corresponding alcohol was used as solvent.
- Kumar, Raj,Chakraborti, Asit K.
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p. 8319 - 8323
(2007/10/03)
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- A remarkable bismuth nitrate-catalyzed protection of carbonyl compounds
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Bismuth nitrate has been found to be an outstanding catalyst for the protection of carbonyl compounds as acetal, ketal, mixed ketal and thioketal with an excellent yield.
- Srivastava, Neeta,Dasgupta, Swapan K.,Banik, Bimal K.
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p. 1191 - 1193
(2007/10/03)
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- Synthesis of spiro- and fused heterocycles by palladium catalysed carbo- and heteroannulation cascades of allenes
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Two novel palladium catalysed cascade processes involving the generation of a (π-allyl)palladium intermediate from allenes in an intra- or intermolecular fashion, followed by regioselective intramolecular nucleophilic addition of amines, alcohols or malon
- Grigg,Koeppen,Rasparini,Sridharan
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p. 964 - 965
(2007/10/03)
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- Synthesis of oxa-bridged analogues of farnesyltransferase inhibitor RPR 115135
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Two synthetic routes to new oxygen-bridged analogues of farnesyltransferase inhibitors are described that follow either a [3 + 2]/[4 + 2] or a [4 + 2]/[3 + 2] sequence of reactions. The first approach has been achieved by reacting the in situ generated phenylisobenzofuran (PIBF) 4 with pyrroline 5a and has led stereoselectively to racemic 18, which was transformed in a few steps into the target molecule 2. The second pathway relies on a key intermediate 6, obtained either by condensation of PIBF with methyl acrylate, followed by a deprotonation/selenation and an oxidation/elimination sequence, or by cycloaddition between PIBF and α-phenylselenoacrylate 11, followed by the same oxidation/elimination sequence. The reaction of 6 with amino dipole 7 gives diastereoselective access to pyrrolidine 25, a precursor of the second target 3, an epimer of 2.
- Martin,Mailliet,Maddaluno
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p. 3797 - 3805
(2007/10/03)
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- Catalyst ligands, catalytic metal complexes and processes using and methods of making the same
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A new ligands that include a benzene ring in the backbone can be combined with a metal or metal precursor compound or formed into a metal-ligand complex catalyze a number of different chemical transformations, including olefin polymerization reactions. Th
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- Efficient enantioselective synthesis of sertraline, a potent antidepressant, via a novel intramolecular nucleophilic addition to imine
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(equation presented) An efficient enantioselective synthesis of sertraline, an antidepressant, utilizing anionic imine ring closure is described.
- Chen, Cheng-Yi,Reamer, Robert A.
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p. 293 - 294
(2008/02/12)
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- Naphthalene derivatives, process for the preparation thereof, and intermediates therefor
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Naphthalene derivatives of the formula [I]: STR1 wherein R1 and R2 are the same or different and are each H, protected or unprotected OH, one of R3 and R4 is protected or unprotected hydroxymethyl, and the other is H, lower alkyl, or protected or unprotected hydroxymethyl, R5 and R6 are the same or different and are each H, substituted or unsubstituted lower alkyl, substituted or unsubstituted phenyl or protected or unprotected NH2, or both combine together with the adjacent N to form substituted or unsubstituted heterocyclic group, and pharmaceutically acceptable salts thereof, these compounds showing excellent bronchoconstriction inhibitory activity, and hence, being useful in the prophylaxis or treatment of asthma.
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- Hemirubin: An Intramolecularly Hydrogen-Bonded Analogue for One-Half Bilirubin
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A model for one-half bilirubin, the neurotoxic yellow-orange pigment of jaundice, 9-[2-(2-carboxyethyl)benzyl]-2,3,7,8-tetramethyl-l,10-dihydrodipyrrin (1, hemirubin) was synthesized following SnCl4-catalyzed Friedel-Crafts acylation at C(9) of
- Chen, Qingqi,Lightner, David A.
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p. 2665 - 2675
(2007/10/03)
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- Synthesis of a 5-deaza-10-selenaflavin derivative, a new type of 5-deazaflavin redox coenzyme model
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A new class of 5-deazaflavin derivatives, 3-methyl-5-deaza-10-selenaflavin (1), in which the nitrogen at the N(10) position of the 5-deazaflavin is replaced by a selenium atom, was synthesized via two different routes. Spectroscopic properties of the 5-de
- Ikeuchi,Tanaka,Chen,Yoneda
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p. 282 - 284
(2007/10/02)
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- Biaryl aldehyde
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This invention relates to a method of synthesis of certain substituted carboxylic acids useful in lowering serum triglyceride and total cholesterol levels in mammals (including man) represented by the general formula I: wherein Ar1 is selected from STR1 Ar2 is selected from STR2 and R is selected from C1-5 alkyl, halogen, perhalo-C1-4 alkyl, C1-4 alkoxy, phenyl, C1-4 acyl, C1-6 alkoxycarbonyl, amino or hydroxy.
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