- Synthesis of 4,5-Benzotropones by Cyclization of 1,3-Bis-Silyl Enol Ethers with 1,2-Dialdehydes
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The cyclization of 1,3-bis-silyl enol ethers or (2,4 -dioxobutylidene)triphenylphosphoranes with phthalic dialdehyde allowed a convenient synthesis of a variety of 4,5-benzotropones. The hydrogenation of benzotropones afforded functionalized benzocycloheptanones which were transformed into tricyclic butenolides.
- Albrecht, Uwe,Van Nguyen, Thi Hong,Langer, Peter
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- Gold-catalyzed tandem cycloisomerization/Petasis-Ferrier rearrangement: A direct route to 3-alkoxyindanones from enynals and alcohols
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A method to prepare 3-alkoxyindanones efficiently by gold-catalyzed tandem cycloisomerization/Petasis-Ferrier rearrangement from ortho-ethynylarylaldehydes with alcohols is described. The reaction was accomplished in moderate to excellent yields under mild reaction conditions and also offers a convenient synthetic route to 3-alkoxycyclopentenones.
- Cao, Ziping,Zhang, Huaqing,Zhang, Xiaoxiang,Zhang, Ludan,Meng, Xin,Chen, Guang,Zhao, Xian-En,Sun, Xuejun,You, Jinmao
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p. 103155 - 103158
(2015)
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- Regio- and Stereoselective Synthesis of (Z)-3-Ylidenephthalides via H3PMo12O40-Catalyzed Cyclization of 2-Acylbenzoic Acids with Benzylic Alcohols
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We report an exclusively tandem C—O and C—C bond forming beyond the esterification and cyclization reaction of 2-acylbenzoic acids with alcohols to regio- and stereoselective synthesis of the (Z)-3-ylidenephthalides. The reaction uses the nontoxic, inexpensive H3PMo12O40 as catalyst and produces water as the sole by-product, making the reaction environmentally benign and sustainable. Moreover, this reaction features an eco-friendly reaction condition, facile scalability, and easy derivatization of the products to drugs and bioactive compounds. The mechanism studies and density functional theory calculations reveal that the appropriate acid catalyst is the key to the selectivity of this transformation.
- Yang, Guoping,Li, Ke,Lin, Xiaoling,Li, Yijin,Cui, Chengxing,Li, Shixiong,Cheng, Yuanyuan,Liu, Yufeng
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supporting information
p. 3017 - 3022
(2021/09/13)
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- Rhodium-catalyzed reductive carbonylation of aryl iodides to arylaldehydes with syngas
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The reductive carbonylation of aryl iodides to aryl aldehydes possesses broad application prospects. We present an efficient and facile Rh-based catalytic system composed of the commercially available Rh salt RhCl3·3H2O, PPh3 as phosphine ligand, and Et3N as the base, for the synthesis of arylaldehydes via the reductive carbonylation of aryl iodides with CO and H2 under relatively mild conditions with a broad substrate range affording the products in good to excellent yields. Systematic investigations were carried out to study the experimental parameters. We explored the optimal ratio of Rh salt and PPh3 ligand, substrate scope, carbonyl source and hydrogen source, and the reaction mechanism. Particularly, a scaled-up experiment indicated that the catalytic method could find valuable applications in industrial productions. The low gas pressure, cheap ligand and low metal dosage could significantly improve the practicability in both chemical researches and industrial applications.
- Chen, Suqing,Liu, Zhenghui,Mu, Tiancheng,Wang, Peng,Yan, Zhenzhong,Yu, Dongkun,Zhao, Xinhui
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p. 645 - 656
(2020/05/14)
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- Enantioselective Synthesis of 6,6-Disubstituted Pentafulvenes Containing a Chiral Pendant Hydroxy Group
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Simple enantioselective synthesis of 6,6-disubstituted pentafulvenes bearing chiral pendant hydroxy groups are attained by cascade reactivity using commercially available proline-based organocatalysts. Condensation of cyclopentadiene with the acetyl function of a 1,2-formylacetophenone, followed by cyclization of a resulting fulvene-stabilized carbanion with the formyl group, generates bicyclic chiral alcohols with initial er values up to 94:6. Exceptional enantio-enrichment of the resultant alcohols results upon crystallization—even near racemic samples spontaneously de-racemize. This enables new families of substituted cyclopentadienes that are both enantiomerically and diastereomerically pure to be rapidly attained.
- Nouch, Ryan,Cini, Melchior,Magre, Marc,Abid, Mohammed,Diéguez, Montserrat,Pàmies, Oscar,Woodward, Simon,Lewis, William
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supporting information
p. 17195 - 17198
(2017/11/27)
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- Enantioselective N-Heterocyclic Carbene Catalyzed Synthesis of Functionalized Indenes
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An enantioselective NHC (N-heterocyclic carbene) catalyzed synthesis of indenes from bifunctional α,β-unsaturated acyl fluorides and TMS enol ethers has been discovered. The reaction has broad generality (31 examples) and proceeds with high levels of enantioselectivity (most >92:8 er). Mechanistically the reaction likely occurs via a Michael/β-lactonization/decarboxylation sequence. Derivatization studies and limitations are discussed.
- Zhang, Changhe,Lupton, David W.
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supporting information
p. 4456 - 4459
(2017/09/11)
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- Synthesis of 3-hydroxyindanones via potassium salt of amino acid catalyzed regioselective intramolecular aldolization of ortho-diacylbenzenes
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First organocatalytic intramolecular aldolization of ortho-diacylbenzenes to construct highly functionalized 3-hydroxyindanones is described. In this transformation a high trans-selectivity is achieved by the use of metal salt of amino acid. This method allows an easy access to the strained spirocyclic 3-hydroxyindanones related to a number of natural product frameworks. Synthesis of a new class of indole skeleton substituted by 3-hydroxyindanones added an extra essence to this new protocol.
- Chanda, Tanmoy,Chowdhury, Sushobhan,Anand, Namrata,Koley, Suvajit,Gupta, Ashutosh,Singh, Maya Shankar
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supporting information
p. 981 - 985
(2015/03/04)
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- Bulky, spherical, and fluorinated anion BArF induces 'on-water' activity of silver salt for the hydration of terminal alkynes
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AgBArF displays remarkable 'on-water' activity for catalytic hydration of terminal alkynes although it is ineffective in common organic solvents. Liquid alkynes do not require additive or co-solvent whereas a small amount of ethyl acetate triggers quantitative conversions for solid alkynes.
- Saha, Sayantani,Sarbajna, Abir,Bera, Jitendra K.
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supporting information
p. 1444 - 1447
(2014/03/21)
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- Phthalides by rhodium-catalyzed ketone hydroacylation
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(Chemical Equation Presented) Phthalides are biologically relevant five-membered lactones found in herbs, fruits, and vegetables. Herein we communicate the first atom-economical approach to phthalides by using enantioselective ketone hydroacylation. In the presence of Rh[(Duanphos)]X (X = NO3, OTf, OMs), various 2-ketobenzaldehydes undergo intramolecular hydroacylation to produce phthalide products in good yields and 92-98% ee's. Our study highlights the key role counterions play in controlling both reactivity and enantioselectivity. A concise asymmetric total synthesis of the celery extract (S)-(-)-3-n-butylphthalide is also presented.
- Phan, Diem H. T.,Kim, Byoungmoo,Dong, Vy M.
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supporting information; experimental part
p. 15608 - 15609
(2010/01/30)
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- Rational design of inhibitors of VirA-VirG two-component signal transduction
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VirA-VirG two-component system regulates the vir (virulence) operon in response to specific host factors (xenognosins) in the plant pathogen Agrobacterium tumefaciens. Using whole cell assays, stable inhibitors inspired by the labile natural benzoxazinone inhibitor HDMBOA are developed. It is found that aromatic aldehydes represent a minimal structural unit for activity. In particular, 3-hydroxy-4,6-dimethoxy-3H-isobenzofuran-1-one (HDI) was found to have the highest activity, making it the most potent developed inhibitor of virulence gene expression in Agrobacterium.
- Maresh, Justin,Zhang, Jin,Tzeng, Yih-Ling,Goodman, Nora A.,Lynn, David G.
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p. 3281 - 3286
(2008/02/08)
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- A new, mild, and rapid transformation of acylals to bisulfites in one-pot synthesis by bismuth (III) nitrate pentahydrate
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Direct conversion of acylals to the corresponding bisulfites can be easily performed in the presence of bismuth (III) nitrate pentahydrate in ethanol at room temperature in good yields. Copyright Taylor & Francis Inc.
- Khodaei, Mohammad Mehdi,Kordestani, Davood
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p. 2403 - 2405
(2007/10/03)
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- Copper-catalyzed oxidative cleavage of carbon-carbon double bond of enol ethers with molecular oxygen
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A novel CC bond cleavage reaction of aromatic enol ethers (1) to give ketones (2) using molecular oxygen as oxidant is described. Among the examined catalysts (Cu(II), Pd(II), Ru(II), and H+), CuCl2 exhibited the highest activity. The reaction proceeded smoothly with several kinds of substrates.
- Tokunaga, Makoto,Shirogane, Yuki,Aoyama, Hiroshi,Obora, Yasushi,Tsuji, Yasushi
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p. 5378 - 5382
(2007/10/03)
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- Deprotection of 1,1-diacetates with [NO+·Crown·H(NO3) 2-]
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An ionic complex has been obtained from N2O4 in the presence of the macrocyclic polyether 18-crown-6. This crystalline compound was used as an effective deprotecting agent for the conversion of 1,1-diacetates to their corresponding aldehydes at room temperature with quantitative yields.
- Zolfigol, Mohammad Ali,Zebarjadian, Mohammad Hassan,Mohammadpoor-Baltork, Iraj,Shamsipur, Mojtaba
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p. 2803 - 2808
(2007/10/03)
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- Sterically hindered lithium dialkylcuprates for the generation of highly functionalized mixed cuprates through a halogen-copper exchange
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Even aldehyde and ketone functions are tolerated in mixed organocuprates prepared by copper-halogen exchange using (Me3CCH2)2CuLi (Neopent2CuLi) or (PhMe2CCH2)2CuLi (Neophyl2CuLi). The steric hindrance of the neopentyl and neophyl groups is essential to ensure the chemoselectivity of the reaction (see scheme), and therefore allows a general preparation of polyfunctionalized organocuprates.
- Piazza, Claudia,Knochel, Paul
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p. 3263 - 3265
(2007/10/03)
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- Preparation of 1,2-diacylbenzenes from o-hydroxyaryl ketone acylhydrazones using cross-linked poly[styrene(iodoso diacetate)]
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The 2 percent cross-linked poly[styrene(iodoso diacetate)] was used to synthesis of 1,2-diacylbenzenes, which gave high yields, and could be recycled.
- Xian, Huang,Qing, Zhu,Jizheng, Zhang
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p. 2413 - 2418
(2007/10/03)
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- Thermolysis and CoII-tetraphenylporphyrin-catalysed decomposition of substituted cycloheptatriene endoperoxides: A new synthetic approach to substituted dihydrooxepines
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Photooxygenation of the carbonyl group-substituted cycloheptatrienes 14-17 affords the corresponding [2+4] cycloaddition products derived from cycloheptatriene and its valence isomer norcaradiene as well as rearranged aromatic compounds. Thermolysis of the cycloheptatriene endoperoxides 19, 22, 23, 26, 27 and 31 at 174°C gives the corresponding bis-epoxides, no rearranged products being observed. However, treatment of 19, 26 and 31 with cobalt tetraphenylporphyrin provides the ring-opened products 47, 49 and 51 which are easily converted into the substituted 4,5-dihydrooxepine derivatives 48, 50 and 52. The outcome of Co-TPP-catalysed rearrangement is discussed in terms of different conformers.
- Senguel, M. Emin,Balci, Metin
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p. 2071 - 2077
(2007/10/03)
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- Synthesis of 1,2-diacylbenzenes from o-hydroxyaryl ketone acylhydrazones using [(diacetoxy)iodo]benzene
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2'-Hydroxyacetophenone and 2'-hydroxypropiophenone acylhydrazones 3 are oxidized to 1,2-diacylbenzenes 4 using [(diacetoxy)iodo]benzene in dichloromethane at room temperature in a synthetically useful and high yield reaction.
- Moriarty,Berglund,Rao
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p. 318 - 321
(2007/10/02)
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