- Asymmetric Enzymatic Synthesis of Allylic Amines: A Sigmatropic Rearrangement Strategy
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Sigmatropic rearrangements, while rare in biology, offer opportunities for the efficient and selective synthesis of complex chemical motifs. A "P411" serine-ligated variant of cytochrome P450BM3 has been engineered to initiate a sulfimidation/[2,3]-sigmatropic rearrangement sequence in whole E. coli cells, a non-natural function for any enzyme, providing access to enantioenriched, protected allylic amines. Five mutations in the enzyme substantially enhance its activity toward this new function, demonstrating the evolvability of the catalyst toward challenging nitrene transfer reactions. The evolved catalyst additionally performs the highly enantioselective imidation of non-allylic sulfides.
- Prier, Christopher K.,Hyster, Todd K.,Farwell, Christopher C.,Huang, Audrey,Arnold, Frances H.
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supporting information
p. 4711 - 4715
(2016/04/19)
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- Expanding the horizon of intermolecular trapping of in situ generated α-oxo gold carbenes: Efficient oxidative union of allylic sulfides and terminal alkynes via C-C bond formation
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With a new P,S-bidentate phosphine as the ligand to gold(i), the α-oxo gold carbenes generated in situ via gold-catalyzed intermolecular oxidation of terminal alkynes were effectively trapped by various allylic sulfides, resulting in the formation of α-aryl(alkyl)thio-γ,δ- unsaturated ketones upon facile [2,3]sigmatropic rearrangements. This journal is the Partner Organisations 2014.
- Li, Jiabin,Ji, Kegong,Zheng, Renhua,Nelson, Jonathan,Zhang, Liming
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supporting information
p. 4130 - 4133
(2014/04/03)
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- Catalytic activation of diazo compounds using electron-rich, defined iron complexes for carbene-transfer reactions
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Carbene transfer: The electron-rich iron complex Bu4N[Fe(CO) 3(NO)] efficiently catalyzes different carbene-transfer reactions. Various diazo compounds can be used. The high stability of the employed iron complexes is demonstrated by the generation of the diazo reagent in situ and a sequential iron-catalyzed allylic sulfenylation/Doyle-Kirmse reaction. Copyright
- Holzwarth, Michael S.,Alt, Isabel,Plietker, Bernd
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supporting information; experimental part
p. 5351 - 5354
(2012/07/14)
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- Catalyst-free imidation of allyl sulfides with chloramine-T and subsequent [2,3]-sigmatropic rearrangement
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A facile synthesis of various allyl sulfonamides based on imidation of allyl sulfides with chloramine-T and subsequent [2,3]-sigmatropic rearrangement has been achieved without metal catalysts. The reaction completes smoothly within 10 min, providing excellent yields in environment friendly solvent of alcohol. Functional groups such as bromine, hydroxyl, protected amido and aldehyde are tolerant under this condition.
- Jiang, Yubo,Mo, Fanyang,Qiu, Di,Kuang, Chunxiang,Zhang, Yan,Wang, Jianbo
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p. 2029 - 2035
(2012/11/07)
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- Regio- and enantioselective iridium-catalyzed allylation of thiophenol: Synthesis of enantiopure allyl phenyl sulfides
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A highly regio- and enantioselective allylic alkylation of sodium thiophenoxide has been realized by [Ir(COD)Cl]2/phosphoramidite along with CsF as an additive, producing highly enantioenriched allyl phenyl sulfide compounds with up to 99% ee.
- Zheng, Shengcai,Gao, Ning,Liu, Wei,Liu, Dongge,Zhao, Xiaoming,Cohen, Theodore
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supporting information; experimental part
p. 4454 - 4457
(2010/11/19)
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- Silylene transfer to allylic sulfides: Formation of substituted silacyclobutanes
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Silylene transfer to allylic sulfides results in a formal 1,2-sulfide migration. The rearrangement yields substituted silacyclobutanes, not the expected silacyclopropanes. The silacyclobutanes were elaborated by insertions of carbonyl compounds selectively into one carbon-silicon bond. A mechanism for the 1,2-sulfide migration is proposed involving an episulfonium ion intermediate.
- Ager, Bryan J.,Bourque, Laura E.,Buchner, Kay M.,Woerpel
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supporting information; experimental part
p. 5729 - 5732
(2010/11/04)
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- Fast ruthenium-catalysed allylation of thiols by using allyl alcohols as substrates
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The allylation of aromatic and aliphatic thiols, by using allyl alcohols as substrates, requires only minutes at ambient temperature with either a Ru Iv catalyst, [Ru(Cp*)(n3CH5)(CH 3CN)2](PF6)2 (2; Cp* = pentamethylcyclopentadienyl) or a combination of [Ru(Cp*)(CH 3CN)3](PF6) and camphor sulfonic acid. Quantitative conversion is normal and the catalyst possesses high functional-group tolerance. The use of [Ru(Cp*)(CH3CN) 3](PF6) alone affords poor results. A comparison is made to the results from catalytic runs based on the use of carbonates rather than alcohols, by using 2 as the catalyst, and it is shown that the products from the alcohols are formed faster, so there is no advantage in using a carbonate substrate. The observed branched-to-linear (b/1) ratios when using substituted alcohols decrease with time suggesting that the catalysts isomerise the products. A new methodology from which one can select the desired isomeric product is proposed. DFT calculations and NMR spectroscopic measurements, by using an arene sulfonic acid as co-catalyst, suggest that 6-complexes are not relevant for the catalytic system. Moreover, the DFT results indicate that l)any rf-complexes from the acids RC6H4SO 3H result from deprotonation of the acid, 2) complexation of the thiol, via the deprotonated sulfur atom, is preferred over complexation of the O atom of the sulfonate, RC6H4SO3and 3) a sulfonate O-atom complex will be difficult to detect.
- Zaitsev, Alexey B.,Caldwell, Helen F.,Pregosin, Paul S.,Veiros, Luis F.
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scheme or table
p. 6468 - 6477
(2010/02/28)
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- Mechanical stirring speed in water/hexane biphasic catalyst controls regioselectivity of Pd-catalyzed allylation reaction
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Vigorous mechanical mixing of the water/hexane biphasic Pd-catalyzed allylation of benzenethiol gave sterically congested allyl sulfides, due to high reactivity of the enforced orientation of the η1-allylpalladium intermediate at the solvent in
- Komiya, Sanshiro,Sako, Akari,Kosuge, Hirofumi,Hirano, Masafumi,Komine, Nobuyuki
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p. 640 - 641
(2008/12/21)
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- Selective allylation of arenethiols using water-soluble palladium complex catalyst in recyclable water/hexane biphasic media
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Allylation of arenethiols by allylic alcohol with sterically hindered carbon of the allylic moiety is smoothly catalyzed by Pd(OAc)2/TPPTS in biphasic water/hexane media under ambient conditions. The catalyst water layer can be repeatedly reuse
- Komine, Nobuyuki,Sako, Akari,Hirahara, Shin-Ya,Hirano, Masafumi,Komiya, Sanshiro
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p. 246 - 247
(2007/10/03)
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- Low pressure hydrogenation of unsaturated sulphides with homogeneous and heterogeneous ruthenium catalysts
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Ru2O·nH2O and [Ru3O(AcO)6(H2O)3]+AcO- were examined for catalytic activity in the hydrogenation of a series of unsaturated sulphides under heterogeneous and homogeneous conditions, respectively. By the appropriate combination of these two methodologies, a number of saturated sulphides could be synthesized in satisfactory to good yields, thus minimizing side reactions.
- Cere, Vanda,Massaccesi, Franco,Pollicino, Salvatore,Ricci, Alfredo
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p. 899 - 907
(2007/10/03)
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- Free-Radical Chain Substitution Reactions (SH2') of Alkenyl-, Alkynyl-, and (Alkenyloxy)stannanes
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Free-radical chain substitution reactions of allyltributylstannane were observed with PhSSPh, PhCH2SSCH2Ph, PhSeSePh, PhSO2Cl, n-PrSO2Cl, or CCl3SO2Cl, where the attacking radicals leading to allylic rearrangement with displacement of Bu3Sn(radical) were PhS(radical), PhCH2S(radical), PhSe(radical), PhSO2(radical), n-PrSO2(radical), and CCl3(radical), respectively.Allylic rearrangement was also observed in the SH2' reaction of crotyltributylstannane with PhSSPh, PhCH2SSCH2Ph, PhSO2Cl, or n-PrSO2Cl.Propargyltriphenylstannane underwent SH2' substitution to form the allenic substitution products with PhSO2Cl, n-PrSO2Cl, CCl4, and CHCl3 while 2-butynyltriphenylstannane formed the 1,2-butadiene with PhSO2Cl or n-PrSO2Cl.Reaction of (1-cyclohexenyloxy)tributylstannane with CCl4 or BrCCl3 formed α-(trichloromethyl)cyclohexanone.With HCBr3 the initially formed α-(dibromomethyl)cyclohexanone readily underwent dehydrobromination to form α-(bromomethylene)cyclohexanone. tributylstannane formed α-(trichloromethyl)isobutyraldehyde with CCl4 or BrCCl3.Reaction with HCBr3 gave a mixture of α-(dibromomethyl)isobutyraldehyde and 1-(dibromomethyl)-2,2-dimethyloxirane.
- Russell, Glen A.,Herold, Lourdes Lucas
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p. 1037 - 1040
(2007/10/02)
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- The Formation of Allyl Sulphides by Phenylthio-migration: Control by Silicon
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When γ-silyl-β-phenylthio-alcohols are treated with acid, the strategically placed silyl group encourages the rearrangement of the phenylthio-group, both from a secondary migration origin to a secondary migration terminus, and from a secondary migration origin to a tertiary migration terminus (4)->(6).Geraniol/nerol (12) and linalool (14) have been synthesised from a common intermediate (11) using this type of reaction.Phenylthio-migration from a tertiary migration origin (17)->(3) can be controlled to a limited extent by a suitably placed silyl group, but it is easier to achieve direct β-elimination of the silyl and phenylthio-groups (17)->(18).
- Fleming, Ian,Paterson, Ian,Pearce, Andrew
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p. 256 - 262
(2007/10/02)
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- Thermal and Photochemical Reactions of Organocobaloximes with Diphenyl Disulphide and Diphenyl Diselenide
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Alkyl- and benzyl-bis(dimethylglyoximato)pyridinecobalt(III) complexes react with diphenyl disulphide or diphenyl diselenide, thermally and photochemically, to give good yields of alkyl or benzyl phenyl sulphides or selenides.Chiral alkylcobalt(III) complexes react to give racemic alkyl phenyl sulphides or selenides.Allyl- and propadienyl-bis(dimethylglyoxymato)pyridinecobalt(III) complexes react similarly to give the thermodynamically more stable allyl, propadienyl, or propynyl phenyl sulphides or selenides.These reactions are interpreted in terms of free radical processes in which organic radicals formed as a result of thermal, photochemical, or chemically induced homolysis of the organocobalt complex, attack the diphenyl dichalcogenide to give the product organo phenyl chalcogenide.No evidence could be obtained for the direct attack of phenylthiyl or phenylselenyl radicals on the organic ligand of the organocobalt complexes, though this process cannot be excluded in the case of allylcobalt complexes.
- Deniau, Jean,Duong, Kiem N. V.,Gaudemer, Alain,Bougeard, Peter,Johnson, Michael D.
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p. 393 - 398
(2007/10/02)
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- Regio- and Stereo-selectivity in the Reactions of Anions of Aryl Allyl Sulfides with Benzaldehyde
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Addition reactions of anions of aryl allyl sulfides to benzaldehyde proceed readily and in good yields and afford mixtures of products resulting from α- and γ-attack on the allyl anion. γ-Products predominate, and the ratio of (E):(Z) isomers usually surrounds unity, although in the case of the reaction involving 3-(phenylthio)but-1-ene the ratio is 10:1.The ratio of diastereoisomers formed in products resulting from α-attack ranges from 3:1 to 1.3:1 (starting from 3-(2,4,6-trimethyl-phenylthio)prop-1-ene and 2-methyl-3-(phenylthio)prop-1-ene respectively).
- Ridley, Damon D.,Smal, Mary A.
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p. 1345 - 1355
(2007/10/02)
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