- Synthesis of 5-[(Pentafluorosulfanyl)methyl]-γ-butyrolactones via a Silver-Promoted Intramolecular Cyclization Reaction
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The synthesis of 5-[(pentafluorosulfanyl)methyl]-γ-butyrolactones bearing different substituents at position 3 or 4 is reported. A silver-promoted intramolecular cyclization of substituted 4-chloro-5-(pentafluorosulfanyl)pentanoic acids allows the preparation of the substituted SF5-containing γ-butyrolactones in up to 96 % yield.
- Roudias, Majdouline,Gilbert, Audrey,Paquin, Jean-Fran?ois
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p. 6655 - 6665
(2019/11/03)
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- Synthesis of key intermediate for (+)-tofacitinib through CoIII(salen)-catalyzed two stereocentered hydrolytic kinetic resolution of (±)-methyl-3-(oxiran-2-yl)butanoate
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An enantiopure piperidine, a key intermediate for the synthesis of (+)-tofacitinib, has been achieved in high optical purity (98% ee) from readily available crotyl alcohol. The key steps involved is a CoIII(salen)-OAc-catalyzed two stereocentered hydrolytic kinetic resolution of (±)-methyl-3-(oxiran-2-yl)butanoate.
- Kamble, Rohit B.,Suryavanshi, Gurunath
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p. 1045 - 1051
(2018/03/23)
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- Pd(II)-catalyzed allylic C-H amination for the preparation of 1,2- and 1,3-cyclic ureas
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A general synthesis of 1,2- and 1,3-cyclic ureas is accomplished by intramolecular allylic C-H amination employing Pd(TFA)2/bis-sulfoxide as a catalyst. By careful modification of substrates and catalyst, a variety of 1,2-cyclic ureas are accessible from not previously employed terminal olefins substituted in allylic or vinylic positions. Furthermore, MS4A is found to be an effective additive for the synthesis of 1,3-cyclic ureas in good yields and excellent diastereoselectivities.
- Nishikawa, Yasuhiro,Kimura, Seikou,Kato, Yuri,Yamazaki, Natsuka,Hara, Osamu
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supporting information
p. 888 - 891
(2015/03/18)
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- Optically pure γ-butyrolactones and epoxy esters via two stereocentered HKR of 3-substituted epoxy esters: A formal synthesis of (-)-paroxetine, Ro 67-8867 and (+)-eldanolide
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The HKR of racemic anti- or syn-3-substituted epoxy esters catalyzed by a Co(iii)salen complex provides ready access to the corresponding enantioenriched 3,4-disubstituted γ-butyrolactones and 3-substituted epoxy esters. This strategy has been successfully employed in the formal synthesis of biologically active 3,4-disubstituted piperidine derivatives, (-)-paroxetine and Ro 67-8867 and a natural product, (+)-eldanolide.
- Devalankar, Dattatray A.,Karabal, Pratibha U.,Sudalai, Arumugam
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supporting information
p. 1280 - 1285
(2013/05/08)
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- Acyloxylactonisations mediated by lead tetracarboxylates
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The reaction of lead(IV) tetracarboxylates with carboxylic acids containing unsaturated side chains has been found to give acyloxy lactone products in a diastereoselective process; the reaction can be extended to lead(IV) tetrazolates to give the analogous outcome. Mechanistic implications of these results are discussed.
- Cottrell, Ian F.,Cowley, Andrew R.,Croft, Laura J.,Hymns, Lauren,Moloney, Mark G.,Nettleton, Ewan J.,Kirsty Smithies,Thompson, Amber L.
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supporting information; experimental part
p. 2537 - 2550
(2009/08/07)
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- Copper(I) catalysts for the stereoselective addition of N-chloroamines to double bonds: A diastereoselective radical cyclisation
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Copper(I) catalysts for the diastereoselective radical cyclisation of N-chloro-N-pentenylamines have been developed. The stereoselectivity of the cyclisation depends upon the ligands employed, proving that the radical is bound to the catalyst during the formation of the new stereocentre and making a catalyst-influenced stereoselective radical reaction possible. The influence of the catalyst on the Beckwith-Houk transition states is discussed. Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002).
- Heuger, Gerold,Kalsow, Stefanie,Gottlich, Richard
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p. 1848 - 1854
(2007/10/03)
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- Chiral sulfur-containing 1,2-disubstituted ferrocenes
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Enantiopure 1-t-butylsulfinyl-2-subsituted ferrocenes were synthesized in reactions of(SR, 18,2R)-1-t-butylsulfinyl-2-lithioferrocene (11) with various electrophiles in good yields. (SR,1S,2R)-l-t-Butylsufinyl-2- formylferrocene (19), prepared this way, underwent complete stereoselective addition reactions with Grignard reagents under chelation controlled conditions with titanium tetraisopropoxide. 1,4-Addition reactions of selected α,β-unsaturated esters with cuprate reagents gave mixtures of two diastereomers. The lack of stereoselectivity in these 1,4-addition reactions is due presumably to the remote reactive site (C-3') and the flexibility of the side chain of the cater. A stereoselective cationic displacement reaction of (1S,2R,1'S)-1-(t-butylsulfonyl)-2-[α-(2-propenoyl)oxybenzyl]ferrocene (44) with 1-acetoxy-1,3-butadiene was found to produce (18,2R,1's)-l-(t- butylsulfonyl)-2-(5'-oxo-1'-phenyl-3'-pentenyl) ferrocene (45).
- Lagneau, Nadege M.,Chen, Yi,Robben, Paul M.,Sin, Hong-Sig,Takasu, Kiyosei,Chen, Jin-Shan,Robinson, Paul D.,Hua, Duy H.
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p. 7301 - 7334
(2007/10/03)
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- Conformationally Restricted Peptide Mimetics: The Incorporation of 6,5-Bicyclic Lactam Ring Skeleton into Peptides
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This manuscript describes a convenient procedure for the synthesis of peptide fragments containing 6,5-bicyclic lactam-based conformational constraints.The syntheses capitalize on an electrochemical oxidation to functionalize a substituted proline derivative, an N-acyliminium ion-initiated cyclization in order to form a transient seven-membered-ring lactam, and a rearragement reaction to form the desired six-membered-ring lactam.The bicyclic lactam products were converted into peptide building blocks and the stereochemistry of the building blocks assigned using two-dimensional NMR techniques.Once synthesized, the building blocks were readily incorporated into peptide fragments with the use of standard peptide synthesis techniques.The synthetic route employed was shown to be compatible with both aryl and branched amino acid side chains.
- Li, Wenhao,Hanau, Cathleen E.,d'Avignon, Andre,Moeller, Kevin D.
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p. 8155 - 8170
(2007/10/02)
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- Aza-Claisen rearrangements initiated by acid-catalyzed Michael addition
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The reaction of allylic amines with dimethyl acetylenedicarboxylate is subject to protic acid catalysis and affords 15, the product of Michael addition and aza-Claisen rearrangement. The sequence involves Michael addition of 4c or 19-21 to generate an int
- Vedejs, Edwin,Gingras, Marc
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p. 579 - 588
(2007/10/02)
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- General Synthesis of Methyl- and Dimethyl-cyclobutanes from Simple 1,3-Diols by Phase Transfer Catalysis
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A general method is described for the preparation of methyl- and dimethyl-cyclobutanes from simple 1,3-diols.The key steps of the procedure are a phase transfer catalysed ring closure and the transformation of a carboxyl group to a methyl group.Phase transfer catalysis provides good yields in the synthesis of the cyclobutane skeleton.
- Toeroek, Bela,Molnar, Arpad
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p. 801 - 804
(2007/10/02)
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- Regio- and Stereoselective Ring Opening of ω-Alkenyllactones Using Organocopper Reagents
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New synthetic methods are described for the preparation of (E)-3, (E)-4, and (E)-5-alkenoic acids by the regio- and stereoselective ring opening of β, γ, and δ-lactones with unsaturated substituents at the ω-position using organocopper reagents such as halomagnesium diorganocuprates or Grignard reagents in the presence of copper(I) iodide.Both the organocopper reagents with primary, secondary, tertiary alkyl, and phenyl groups gave the corresponding carbon homologated alkenoic acids in good yields.Alkadienoic acids were also obtained in good yields by the reactions of ω-alkenyllactones with divinyl- and diallylcuprates.Utilizing the ring opening of β-isopropenyl-β-propiolactone, homoterpenoid carboxylic acids were easly obtained in good yields.The ring opening of β-(1-chlorovinyl)-β-propiolactone afforded 4-chloro-3-alkenoic acids which were easly transformed to 4-oxoalkanoic acids and 4-oxo-2-alkenoic acids.
- Kawashima, Masatoshi,Sato, Toshio,Fujisawa, Tamotsu
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p. 3255 - 3264
(2007/10/02)
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- Synthesis of 4-Penten-4-olides (γ-Methylene-γ-butyrolactones) via 4-Pentenoic Acids
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4-Penten-4-olides (γ-Methylene-γ-butyrolactones) 7 are easily accessible starting from allylic alcohols 1, which on ortho ester Claisen rearrangement and hydrolytic work-up furnish 4-pentenoic acids 5.The latter on iodolactonization and hydrogen iodide elimination by means of 1,8-diazabicycloundec-7-ene (DBU) furnish 7, in good over-all yield and with variable substitution patterns. - Iodolactonization under kinetic control shows moderate 1,2- or 1,3-asymmetric induction (3:1 and ca. 2:1, respectively).The composition of the iodolactone mixtures 6 as well as the individual relative configurations are deduced from 1H and 13C NMR data. - Similary, the spirobipentenolide 13 is obtained starting from diethyl diallylmalonate (9) via 11 resulting from ester iodocyclization.
- Guenther, Hans Juergen,Guntrum, Eberhard,Jaeger, Volker
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- SYNTHESE DE MONODIOXOLANNES DE DICETONES-1,4 ET DE DICETONES-1,4 AU MOYEN DES ANHYDRIDES MIXTES CARBOXYLIQUES ET CARBONIQUES: APPLICATION A LA PREPARATION DE LA DIHYDROJASMONE, DE LA Z-JASMONE ET DE LA DEHYDROJASMONE
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Levulinic acid 1 is easily converted by two steps into mixed carboxylic and carbonic anhydride 3 which reacts with the organolithium reagent issued from trimethylsilyl esters.Monoethylene acetal of 1,4-diketones 4 can be prepared; it is also possible to obtain 1,4-diketones 5 in one step by hot acid hydrolysis.The preparation of the dihydrojasmone 6d, Z-jasmone 6e and dehydrojasmone 6f shows the efficiency of the process.
- Moreau, J.-L.,Couffignal, R.,Arous-Chtara, R.
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p. 307 - 310
(2007/10/02)
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- A CONVENIENT METHOD FOR THE SYNTHESIS OF (E)-3-ALKENOIC ACIDS BY A REGIO- AND STEREOSELECTIVE REACTION OF β-VINYL-β-PROPIOLACTONE WITH ORGANOCOPPER REAGENTS
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β-Vinyl-β-propiolactone reacts regio- and stereoselectively with Grignard reagents in the presence of copper(I) catalyst or with diorganocuprates to afford (E)-3-alkenoic acids in high yields.
- Sato, Toshio,Takeuchi, Masashi,Itoh, Toshiyuki,Kawashima, Masatoshi,Fujisawa, Tamotsu
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p. 1817 - 1820
(2007/10/02)
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