- A Direct Method for the Efficient Synthesis of Benzylidene Acetal at Room Temperature
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For the first time, a metal-free direct method has been developed for the efficient synthesis of benzylidene acetal at room temperature using Dowex 50WX8 as a solid acid catalyst and Cl3CCN as a novel water scavenger. At room temperature, a wide variety of aryl and α,β-unsaturated aldehydes react readily with functionalized 1,2- and 1,3-diols to furnish the corresponding acetals in very good yields. Labile functional groups, like N-Boc, N-Cbz, -OTBDMS, -OBn, -N3 and acetonide are found to be stable under the reaction conditions. The versatility of this method is further demonstrated with carbohydrate substrates and optically active diols.
- Reddy, Narra Rajashekar,Kumar, Rashmi,Baskaran, Sundarababu
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supporting information
p. 1548 - 1552
(2019/01/09)
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- Mass spectrometric characterization of organosulfates related to secondary organic aerosol from isoprene
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Rationale: A considerable fraction of atmospheric particulate fine matter consists of organosulfates, with some of the most polar ones originating from the oxidation of isoprene. Their structural characterization provides insights into the nature of gas-phase precursors as well as into formation pathways. Methods: The structures of unknown polar organosulfates present in ambient particulate fine matter were characterized using liquid chromatography/(-) electrospray ionization mass spectrometry (LC/(-)ESI-MS), including ion trap MSn and accurate mass measurements, derivatization of the carbonyl group into 2,4-dinitrophenylhydrazones, detailed interpretation of the MS data, and in a selected case comparison of their LC and MS behavior with that of synthesized reference compounds. Results: Polar organosulfates with molecular weights (MWs) of 156, 170, 184 and 200 were attributed to/or confirmed as derivatives of glycolic acid (156), lactic acid (170), 1,2-dihydroxy-3-butanone (184), glycolic acid glycolate (200), 2-methylglyceric acid (200), and 2,3-dihydroxybutanoic acid (200). In the case of the MW 184 compound an unambiguous assignment was obtained through synthesis of reference compounds. Conclusions: A more complete structural characterization of polar organosulfates that originate from isoprene secondary organic aerosol was achieved. An important atmospheric finding is the presence of an organosulfate that is related to methyl vinyl ketone, a major gas-phase oxidation product of isoprene. In addition, minor polar organosulfates related to crotonaldehyde were identified. Copyright
- Safi Shalamzari, Mohammad,Ryabtsova, Oxana,Kahnt, Ariane,Vermeylen, Reinhilde,Hérent, Marie-France,Quetin-Leclercq, Jo?lle,Van Der Veken, Pieter,Maenhaut, Willy,Claeys, Magda
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p. 784 - 794
(2013/05/21)
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- Acetalization of carbonyl compounds catalyzed by bismuth triflate under solvent-free conditions
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Carbonyl compounds were converted to the corresponding 1,3-dioxolanes and 1,3-dioxanes with ethylene glycol and 1,3-propandiol in the presence of bismuth triflate under solvent-free conditions. In addition, high chemoselective protection of aldehydes in the presence of ketones has been achieved.
- Aliyan, Hamid,Fazaeli, Razieh,Massah, Ahmad Reza,Momeni, Ahmad Reza,Naghash, Hamid Javaherian,Moeinifard, Behzad
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experimental part
p. 873 - 876
(2012/04/05)
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- 2,4,4,6-Tetrabromo-2,5-cyclohexadienone (TABCO) as a versatile, efficient, and chemoselective catalyst for the acetalization and transacetalization of carbonyl compounds, the preparation of acetonides from epoxides and acylals (1,1-diacetates) from aldehydes
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The efficient and chemoselective preparation of acetals and ketals from carbonyl compounds, transacetalization reactions, the conversion of epoxides to acetonides, and the preparation of acylals from aldehydes in the presence of catalytic amounts of 2,4,4,6-tetrabromo-2,5-cyclohexadienone (TABCO) are described.
- Firouzabadi, Habib,Iranpoor, Nasser,Shaterian, Hamid Reza
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p. 2195 - 2205
(2007/10/03)
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- Cadmium iodide catalyzed and efficient synthesis of acetals under microwave irradiations
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A new selective method of acetalization of aldehydes and ketones with 1,2-diols, 1,3-diols or alcohols mediated by cadmium iodide under microwave irradiation is achieved in excellent yields.
- Laskar, Dhrubojyoti Dey,Prajapati, Dipak,Sandhu, Jagir S.
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p. 1283 - 1284
(2007/10/03)
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- Selective Catalytic Transesterification, Transthiolesterification, and Protection of Carbonyl Compounds over Natural Kaolinitic Clay
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Transesterification and transthiolesterification of β-keto esters with variety of alcohols and thiols and selective protection of carbonyl functions with various protecting groups catalyzed by natural kaolinitic clay are described. The clay has been found to be an efficient catalyst in transesterifying long chain alcohols, unsaturated alcohols, and phenols to give their corresponding β-keto esters in high yields. For the first time, transthiolesterification of β-keto esters with a variety of thiols has been achieved under catalytic conditions. Clay also catalyzes selective transesterification of β-keto esters by primary alcohols in the presence of secondary and tertiary alcohols giving corresponding β-keto esters. A systematic study involving the reactivity of different nucleophiles (alcohols, amines, and thiols) toward β-keto esters is also described. Sterically hindered carbonyl groups as well as α,β-unsaturated carbonyl groups underwent protection without the deconjugation of the double bond. Chemoselective protection of aldehydes in the presence of ketones has also been achieved over natural kaolinitic clay.
- Ponde, Datta E.,Deshpande, Vishnu H.,Bulbule, Vivek J.,Sudalai, Ammugam,Gajare, Anil S.
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p. 1058 - 1063
(2007/10/03)
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