- Chiral quaternary ammonium aryloxide/N,O-bis(trimethyl-silyl)acetamide combination as efficient organocatalytic system for the direct vinylogous aldol reaction of (5H)-furan-2-one derivatives
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A chiral quaternary ammonium amide was generated in situ from N,O-bis(trimethylsilyl)acetamide (BSA) as non-nucleophilic Bronsted base precursor and the combination of chiral quaternary ammonium halide/sodium aryloxide as chiral Lewis base. This system was applied to an anti-selective organocatalytic direct vinylogous aldol (ODVA) reaction of (5H)-furan-2-one derivatives with aldehydes. Several 5-(1′-hydroxy)-γ-butenolides were obtained in good diastereomeric ratios (up to 95/5) and excellent enantioselectivities (up to 94%) with both aliphatic or (hetero)aromatic aldehydes, so providing a rare example of general and efficient conditions for the ODVA reaction. Copyright
- Claraz, Aurelie,Oudeyer, Sylvain,Levacher, Vincent
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supporting information
p. 841 - 846
(2013/05/09)
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- Integration of heterogeneous catalysts into complex synthetic routes: Sequential vs. one-pot reactions in a (Knoevenagel + Mukaiyama-Michael + hydrogenation + transesterification) sequence
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Heterogeneous catalysts of different nature can be combined in one-pot tandem reactions, but the compatibility issues of catalysts with reagents, products, and by-products make more convenient the application of a sequential procedure, in which the catalyst is filtered after each reaction and the crude is used in the following reaction without purification. In this way the recovery and reuse of each catalyst can be optimized to obtain the maximum productivity. The nature of the reactions, and the catalysts involved in them, conditions the maximum number of successive steps in the sequence. In the case of the (Knoevenagel + Mukaiyama-Michael + hydrogenation + transesterification) process tested in this work, the optimal results are obtained when the sequential method is applied to only three reactions, whereas the four reactions sequence shows limitations in the yield of the last transesterification step. The Royal Society of Chemistry 2013.
- Fraile, Jose M.,Garcia, Nuria,Herrerias, Clara I.,Mayoral, Jose A.
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p. 436 - 443
(2013/03/28)
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- Synthesis of (+)-L-733,060, (+)-CP-99,994 and (2S,3R)-3-hydroxypipecolic acid: Application of an organocatalytic direct vinylogous aldol reaction
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The γ-butenolide obtained from an organocatalyzed, direct vinylogous aldol reaction of γ-crotonolactone and benzaldehyde serves as the key starting material in the expedient synthesis of a 3-hydroxy-2-phenyl piperidine intermediate which is converted to the target 2,3-disubstituted piperidines.
- Pansare, Sunil V.,Paul, Eldho K.
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experimental part
p. 2119 - 2125
(2012/04/17)
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- General switch in regioselectivity in the Mukaiyama aldol reaction of silyloxyfuran with aldehydes in aqueous solvents
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An unexpected yet disciplined course of catalytic Mukaiyama-aldol reaction instead of the expected vinylogous Mukaiyama-aldol reaction has been observed for the reaction of silyloxyfuran with various aldehydes under Lewis acid catalytic control in water-containing solvents.
- Woyciechowska, Marta,Forcher, Gwenael,Buda, Szymon,Mlynarski, Jacek
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p. 11029 - 11031
(2013/01/15)
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- Organocatalytic asymmetric direct vinylogous aldol reactions of γ-crotonolactone with aromatic aldehydes
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The direct aldol reaction of γ-crotonolactone and various aromatic aldehydes is catalyzed by bifunctional aminothiourea and aminosquaramide organocatalysts to provide diastereomerically and enantiomerically enriched 5-substituted 2(5H) furanones (γ-buteno
- Pansare, Sunil V.,Paul, Eldho K.
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supporting information; experimental part
p. 1027 - 1029
(2011/02/25)
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- Asymmetric vinylogous aldol reaction of silyloxy furans with a chiral organic salt
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Despite their synthetic significance there is a general lack of asymmetric vinylogous aldol reactions that tolerate variations of both the silyloxy furans and aldehydes. We have developed a new chiral organic catalyst based on a carboxylate-ammonium salt prepared from a thiourea-amine and a carboxylic acid. This new catalyst enabled us to develop an efficient asymmetric vinylogous aldol reaction of unprecedented scope with respect to both 2-trimethylsilyloxy furans and aldehydes.
- Singh, Ravi P.,Foxman, Bruce M.,Deng, Li
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supporting information; experimental part
p. 9558 - 9560
(2010/08/20)
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- Organocatalyzed highly enantioselective and anti-selective construction of γ-butenolides through vinylogous Mukaiyama aldol reaction
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The formation of chiral γ-butenolides has been achieved with good yields (up to 90%), high enantioselectivity (up to 91%) and diastereoselectivity (up to 9/1, anti-selective) through an organocatalyzed vinylogous Mukaiyama aldol reaction of 2-(trimethylsilyloxy)furan and aldehydes. A wide range of chiral γ-butenolides was obtained under mild conditions by this methodology.
- Zhu, Ning,Ma, Bao-Chun,Zhang, Yong,Wang, Wei
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supporting information; experimental part
p. 1291 - 1295
(2010/07/03)
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- The first organocatalytic addition of 2-trimethylsilyloxyfuran to carbonyl compounds: hydrogen-bond catalysis in γ-butenolides synthesis
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This letter describes the first example of diastereoselective 'organocatalyzed' synthesis of the butenolide products substituted at the γ-position by a chain bearing hydroxyl groups. The urea-derivative 4 has proved to be an efficient catalyst for the addition of the commercial TMSOF to carbonyl compounds under solvent-free conditions. The reaction conditions and generality of the procedure have been examined.
- De Rosa, Margherita,Citro, Lucia,Soriente, Annunziata
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p. 8507 - 8510
(2007/10/03)
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- Silicon tetrachloride in organic synthesis: New applications for the vinylogous aldol reaction
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This paper describes a novel and efficient methodology for vinylogous aldol reactions based on SiCl4 catalysis. According to the nucleophilicity Mayr's scale, vinylogous aldol reaction of Chan's diene proved to be effective by using catalytic amount of SiCl4, without any other promoter. On the contrary, the SiCl4/Lewis base system has been conveniently exploited for the efficient and selective vinylogous reaction of less nucleophilic Danishefsky's diene and 2-trimethylsilyloxyfuran (TMSOF). Indeed, a number of Lewis bases, such as sulfoxides, formamides and phosphoramides have been successfully used as SiCl4 promoters. TMSOF and silyloxydienes, resulting from 2,2,6-trimethyl-[1,3]-dioxin-4-one derivatives, required stoichiometric amount of SiCl4, while vinylogous aldol reaction of Chan's and Danishefsky's dienes took satisfactorily place in the presence of catalytic or sub-stoichiometric amount of catalyst.
- Acocella, Maria R.,De Rosa, Margherita,Massa, Antonio,Palombi, Laura,Villano, Rosaria,Scettri, Arrigo
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p. 4091 - 4097
(2007/10/03)
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- Mixed crossed aldol condensation between conjugated esters and aldehydes using aluminum tris(2,6-diphenylphenoxide)
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The combined use of aluminum tris(2,6-diphenylphenoxide) (ATPH) and lithium 2,2,6,6-tetramethylpiperidide (LTMP) has proven to be effective for the mixed crossed aldol condensation between conjugated esters and various aldehydes. An example is shown in Eq
- Saito, Susumu,Shiozawa, Masahito,Yamamoto, Hisashi
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p. 1769 - 1771
(2007/10/03)
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- Clay montmorillonite K10 catalyzed aldol-type reaction of aldehydes with silyl enol ethers in water
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An environmentally friendly method for the cross aldol reaction of silyl enol ethers and ketene silyl acetal with various aldehydes using montmorillonite K10 is described. Cheap and commercially available montmorillonite K10 can be used without the need of an ion exchange process under solvent-free conditions or in water. Hydrate of aldehydes such as glyoxylic acid can be used directly. Thermal treatment of K10 increased the catalytic activity. The catalytic activity was supposed due to the properties of the structure of K10 and its inherent Bronsted acidity.
- Loh, Teck-Peng,Li, Xu-Ran
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p. 10789 - 10802
(2007/10/03)
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- γ-Regioselectivity of lithiated 2-buten-4-olide towards aromatic aldehydes: A simple synthesis of γ-arylidenebutenolides
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Lithiated 2-buten-4-olide was found to react with aromatic aldehydes regioselectively at γ-position to provide 4-(1-aryl-1-hydroxymethyl)-2- buten-4-olides which could be readily converted into the corresponding (Z)- γ-arylidenebutenolides.
- Pohmakotr, Manat,Tuchinda, Patoomratana,Premkaisorn, Pornchai,Reutrakul, Vichai
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p. 11297 - 11304
(2007/10/03)
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- REGIOSELECTIVE FUNCTIONALIZATION OF THE Δαβ-BUTENOLIDE RING VIA GROUP IV-B ORGANOMETALLICS
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The Δα,β-butenolide ring reacts with amino- and thiosilanes to give 4-substituted γ-butyrolactone and siloxyfuran.The latter undergoes regiospecific functionalization at the 5 position with benzaldehyde under F- catalysis.
- Fiorenza, Mariella,Ricci, Alfredo,Romanelli, M. Novella,Taddei, Maurizio,Dembech, Pasquale,Seconi, Giancarlo
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p. 2327 - 2329
(2007/10/02)
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- SYNTHESIS OF 4-YLIDENEBUTENOLIDES FROM 2-TRIMETHYLSILOXYFURAN
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Dehydration or dealkoxylation of the reaction products of various aldehydes, ketones, and acetals with 2-trimethylsiloxyfuran gave corresponding 4-ylidenebutenolides in good to high overall yields.
- Asaoka, Morio,Yanagida, Noboru,Ishibashi, Keiji,Takei, Hisashi
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p. 4269 - 4270
(2007/10/02)
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