- The first addition of silyl enol ethers to internal unactivated alkynes
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The EtAlCl2-mediated intramolecular addition of silyl enol ethers to both terminal and internal unactivated alkynes, bearing alkyl and phenyl susbstituents at the alkyne moiety, proceeded exclusively in the endo- fashion to give mono- and bicyc
- Imamura, Ken-Ichiro,Yoshikawa, Eiji,Gevorgyan, Vladimir,Yamamoto, Yoshinori
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- Lewis Acid Catalyzed Enantioselective Photochemical Rearrangements on the Singlet Potential Energy Surface
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The oxadi-methane rearrangement of 2,4-cyclohexadienones to bicyclic ketones was found to proceed with high enantioselectivity (92-97% ee) in the presence of catalytic amounts of a chiral Lewis acid (15 examples, 52-80% yield). A notable feature of the transformation is the fact that it proceeds on the singlet hypersurface and that no triplet intermediates are involved. Rapid racemic background reactions were therefore avoided, and the catalyst loading could be kept low (10 mol %). Computational studies suggest that the enantioselectivity is determined within a Lewis acid bound singlet intermediate via a conical intersection. The utility of the method was demonstrated by a concise synthesis of the natural product trans-chrysanthemic acid.
- Leverenz, Malte,Merten, Christian,Dreuw, Andreas,Bach, Thorsten
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supporting information
p. 20053 - 20057
(2019/12/30)
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- Ketone Formation from Carboxylic Acids by Ketonic Decarboxylation: The Exceptional Case of the Tertiary Carboxylic Acids
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For the reaction mechanism of the ketonic decarboxylation of two carboxylic acids, a β-keto acid is favored as key intermediate in many experimental and theoretical studies. Hydrogen atoms in the α-position are an indispensable requirement for the substrates to react by following this mechanism. However, isolated observations with tertiary carboxylic acids are not consistent with it and these are revisited and discussed herein. The experimental results obtained with pivalic acid indicate that the ketonic decarboxylation does not occur with this substrate. Instead, it is consumed in alternative reactions such as disintegration into isobutene, carbon monoxide, and water (retro-Koch reaction). In addition, the carboxylic acid is isomerized or loses carbon atoms, which converts the tertiary carboxylic acid into carboxylic acids bearing α-proton atoms. Hence, the latter are suitable to react through the β-keto acid pathway. A second substrate, 2,2,5,5-tetramethyladipic acid, reacted by following the same retro-Koch pathway. The primary product was the monocarboxylic acid 2,2,5-trimethyl-4-hexenoic acid (and its double bond isomer), which might be further transformed into a cyclic enone or a lactone. The ketonic decarboxylation product, 2,2,5,5-tetramethylcyclopentanone was observed in traces (0.2 % yield). Therefore, it can be concluded that the observed experimental results further support the proposed mechanism for the ketonic decarboxylation via the β-keto acid intermediate.
- Oliver-Tomas, Borja,Renz, Michael,Corma, Avelino
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p. 12900 - 12908
(2017/09/25)
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- OPSIN-BINDING LIGANDS, COMPOSITIONS AND METHODS OF USE
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Compounds I are disclosed that are useful for treating ophthalmic conditions caused by or related to production of toxic visual cycle products that accumulate in the eye, such as dry adult macular degeneration, as well as conditions caused by or related t
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Paragraph 0222
(2015/12/04)
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- OPSIN-BINDING LIGANDS, COMPOSITIONS AND METHODS OF USE
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Compounds are disclosed that are useful for treating ophthalmic conditions caused by or related to production of toxic visual cycle products that accumulate in the eye, such as dry adult macular degeneration, as well as conditions caused by or related to the misfolding of mutant opsin proteins and/or the mis-localization of opsin proteins. Compositions of these compounds alone or in combination with other therapeutic agents are also described, along with therapeutic methods of using such compounds and/or compositions. Methods of synthesizing such agents are also disclosed.
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Page/Page column 77-78
(2013/05/09)
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- OPSIN-BINDING LIGANDS, COMPOSITIONS AND METHODS OF USE
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Compounds and compositions are disclosed that are useful for treating ophthalmic conditions caused by or related to production of toxic visual cycle products that accumulate in the eye, such as dry adult macular degeneration, as well as conditions caused by or related to the misfolding of mutant opsin proteins and/or the mis-localization of opsin proteins. Compositions of these compounds alone or in combination with other therapeutic agents are also described, along with therapeutic methods of using such compounds and/or compositions. Methods of synthesizing such agents are also disclosed.
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Page/Page column 122
(2013/06/27)
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- OPSIN-BINDING LIGANDS, COMPOSITIONS AND METHODS OF USE
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Compounds are disclosed that are useful for treating ophthalmic conditions caused by or related to production of toxic visual cycle products that accumulate in the eye, such as dry adult macular degeneration, as well as conditions caused by or related to
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Page/Page column 81
(2013/06/27)
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- Lewis acid-catalyzed oxidative rearrangement of tertiary allylic alcohols mediated by TEMPO
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Two methods for the oxidative rearrangement of tertiary allylic alcohols have been developed. Most of tertiary allylic alcohols studied were oxidized to their corresponding transposed carbonyl derivatives in excellent to fair yields by reaction with TEMPO in combination with PhIO and Bi(OTf)3 or copper (II) chloride in the presence or not of oxygen. Other primary oxidants of TEMPO such as PhI(OAc)2, mCPBA, and Oxone were unsatisfactory giving the enone in modest to low yields.
- Vatèle, Jean-Michel
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experimental part
p. 904 - 912
(2010/03/24)
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- OPSIN-BINDING LIGANDS, COMPOSITIONS AND METHODS OF USE
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Compounds and compositions of said compounds along with methods of use of compounds are disclosed for treating ophthalmic conditions related to mislocalization of opsin proteins, the misfolding of mutant opsin proteins and the production of toxic visual cycle products that accumulate in the eye. Compounds and compositions useful in the these methods, either alone or in combination with other therapeutic agents, are also described.
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Page/Page column 174
(2010/12/31)
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- Copper-catalyzed aerobic oxidative rearrangement of tertiary allylic alcohols mediated by TEMPO
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A mild method for the oxidative rearrangement of tertiary allylic alcohols to β-substituted enones using a TEMPO/CuCl2 system, in the presence of molecular sieves, is described. Depending on the substrate, CuCl2 was used in either a catalytic amount under an oxygen atmosphere or stoichiometrically. Georg Thieme Verlag Stuttgart.
- Vatèle, Jean-Michel
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experimental part
p. 2143 - 2145
(2011/04/15)
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- Lewis acid promoted oxidative rearrangement of tertiary allylic alcohols with the PhIO/TEMPO system
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A mild and environmentally friendly method for Lewis acid catalyzed oxidative rearrangement of tertiary allylic alcohols to β-disubstituted enones by the TEMPO/PhIO system is described. Bismuth triflate was found to be the most efficient catalyst for the majority of the substrates tested except for tertiary vinyl carbinols which could be transformed to enals in fair yields only when Re2O7 was used as catalyst. A plausible mechanism for this oxidative rearrangement is discussed. Georg Thieme Verlag Stuttgart.
- Vatèle, Jean-Michel
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experimental part
p. 1785 - 1788
(2009/04/07)
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- Vinylcyclopropylacyl and polyeneacyl radicals. Intramolecular ketene alkyl radical additions in ring synthesis
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Treatment of a variety of substituted vinylcyclopropyl selenyl esters, e.g. 11, with Bu3SnH-AIBN in refluxing benzene leads to the corresponding acyl radical intermediates, which undergo rearrangement and intramolecular cyclisations via their ketene alkyl radical equivalents producing cyclohexenones in 50-60% yield. By contrast, treatment of conjugated triene selenyl esters, e.g. 32, with Bu3SnH-AIBN produces substituted 2-cyclopentenones via intramolecular cyclisations of their ketene alkyl radical intermediates. Under the same radical-initiating conditions the selenyl esters derived from o-vinylbenzoic acid and o-vinylcinnamic acid undergo intramolecular cyclisations producing 1-indanone and 5,6-dihydrobenzocyclohepten-7-one respectively in 60-70% yields. A tandem radical cyclisation from the α,β,γ, δ-diene selenyl ester 31 provides an expeditious synthesis of the diquinane 35 in 69% yield.
- De Boeck, Benoit,Herbert, Nicola M. A.,Harrington-Frost, Nicole M.,Pattenden, Gerald
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p. 328 - 339
(2007/10/03)
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- Lewis acid-mediated intramolecular addition of silyl enol ethers to internal unactivated alkynes
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The EtAlCl2-mediated intramolecular addition of silyl enol ethers to both terminal and internal unactivated alkynes, bearing alkyl and phenyl susbstituents at the alkyne moiety, gave mono- and bicyclic β,γ-unsaturated ketones in good to excelle
- Imamura, Ken-Ichiro,Yoshikawa, Eiji,Gevorgyan, Vladimir,Sudo, Tomoko,Asao, Naoki,Yamamoto, Yoshinori
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p. 1624 - 1631
(2007/10/03)
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- Vinylcyclopropylacyl Radicals. Intramolecular Ketene Additions leading to Concise Syntheses of Cyclohexenones
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Treatment of a range of vinylcyclopropyl selenyl esters with Bu3SnH-AIBN produces cyclohexenone products (50-60%) via 6-exo-dig radical cyclisations involving ketene intermediates.
- Herbert, Nicola,Pattenden, Gerald
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- A General Preparative Method for Carbonyl-Protected γ-Lithioketones via Reductive Lithiation. Synthetic Uses of the Bishomoenolate Equivalents
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The mixed cuprates, generated by reductive lithiation of bis(phenylthio)acetals using lithium 4,4'-di-tert-butylbiphenylide (LDBB), followed by addition of cuprous bromide-dimethyl sulfide complex, undergo conjugate addition to enones in the presence of t
- Cohen, Theodore,Zhang, Birong,Cherkauskas, John P.
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p. 11569 - 11584
(2007/10/02)
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- A ONE-POT AND SELECTIVE PREPARATION OF ALKYLATED 3-CYCLOHEXEN-1-ONE
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Tretment of lithiated nitrile with conjugated 1,3-dienes, such as isoprene, myrcene, and butadiene, followed by hydrolysis with 3N-HCl gave selectively alkylated 3-cyclohexen-1-ones.
- Takabe, Kunihiko,Ohkawa, Suguru,Katagiri, Takao
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p. 489 - 490
(2007/10/02)
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- Synthesis of three new compounds structurally related to damascone and ionone
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1-(3,6,6-Trimethyl-1,3-cyclohexadien-1-yl)-2-buten-1-one (1), a β-damascenone isomer, was synthesized from 3,6,6-trimethyl-2-cyclohexenone (14).This starting ketone 14 was obtained in good yield from 3-methyl-2-butanone (11) and 3-buten-2-one (12).Ethynyl
- Witteveen, Jan G.,Weerdt, Anton J. A. van der
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p. 383 - 386
(2007/10/02)
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- Alkyl Substituent Effects on the Photorearrangement of Cyclohex-2-en-1-ones to Lumiketones
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The effect of alkyl substitution on the photorearrangement of cyclohex-2-en-1-ones to bicyclohexan-2-ones (lumiketones) was investigated.Contrary to earlier reports, both 2,4,4- and 3,4,4-trimethylcyclohex-2-en-1-one undergo this rearrangement upon
- Schuster, David I.,Rao, Jampani Madhusudana
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p. 1515 - 1521
(2007/10/02)
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