- Investigation of Straightforward, Photoinduced Alkylations of Electron-Rich Heterocompounds with Electron-Deficient Alkyl Bromides in the Sole Presence of 2,6-Lutidine
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Alkylations of simple electron-rich heterocompounds deliver valuable target structures in bioorganic and medicinal chemistry. Herein, we present a straightforward and photosensitizer free approach for the photoinduced C–C coupling of electron-rich unsaturated heterocompounds with alkyl bromides using 405 nm and 365 nm irradiation. Comprehensive mechanistic studies indicate the involvement of 2,6-lutidine in the formation of a non-covalently bound intermediate to which the function of a photosensitizer is attributed. UV/Vis spectra reveal the formation of a bathochromic shifted band when the electron-deficient alkyl bromide is mixed with the structural motif of 2,6-substituted pyridine. Upon photochemical excitation of this band, we find the initiation of the C–C bond-forming reaction. Using this approach highly versatile alkylation products, e.g. α-substituted ketones and 2-substituted furan, thiophene, and pyrrole derivatives, are obtained in high selectivity. Furthermore, this synthetic methodology can be applied to access substituted indoles, which cannot be obtained by other transformations.
- Fuks, Elina,Huber, Laura,Schinkel, Thea,Trapp, Oliver
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supporting information
p. 6192 - 6198
(2020/08/19)
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- Ytterbium-Catalyzed Intramolecular [3 + 2] Cycloaddition based on Furan Dearomatization to Construct Fused Triazoles
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The 1,2,3-triazole-containing polycyclic architecture widely exists in a broad spectrum of synthetic bioactive molecules, and the development of expeditious methods to synthesize these skeletons remains a challenging task. In this work, the catalytic cyclization of biomass-derived 2-furylcarbinols with an azide to form fused triazoles is described. This approach takes advantage of a single catalyst Yb(OTf)3 and operates via a furfuryl-cation-induced intramolecular [3 + 2] cycloaddition/furan ring-opening cascade.
- Xu, Xiaoming,Zhong, Ying,Xing, Qingzhao,Gao, Ziwei,Gou, Jing,Yu, Binxun
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supporting information
p. 5176 - 5181
(2020/07/14)
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- A Photochemical Organocatalytic Strategy for the α-Alkylation of Ketones by using Radicals
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Reported herein is a visible-light-mediated radical approach to the α-alkylation of ketones. This method exploits the ability of a nucleophilic organocatalyst to generate radicals upon SN2-based activation of alkyl halides and blue light irradiation. The resulting open-shell intermediates are then intercepted by weakly nucleophilic silyl enol ethers, which would be unable to directly attack the alkyl halides through a traditional two-electron path. The mild reaction conditions allowed functionalization of the α position of ketones with functional groups that are not compatible with classical anionic strategies. In addition, the redox-neutral nature of this process makes it compatible with a cinchona-based primary amine catalyst, which was used to develop a rare example of enantioselective organocatalytic radical α-alkylation of ketones.
- Goti, Giulio,Melchiorre, Paolo,O?eka, Maksim,Schweitzer-Chaput, Bertrand,Spinnato, Davide
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supporting information
p. 9485 - 9490
(2020/04/09)
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- Corresponding amine nitrile and method of manufacturing thereof
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The invention relates to a manufacturing method of nitrile. Compared with the prior art, the manufacturing method has the characteristics of significantly reduced using amount of an ammonia source, low environmental pressure, low energy consumption, low production cost, high purity and yield of a nitrile product and the like, and nitrile with a more complex structure can be obtained. The invention also relates to a method for manufacturing corresponding amine from nitrile.
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Paragraph 0153; 0154; 0155; 0164; 0165
(2018/05/07)
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- Regio- and stereoselective synthesis of chiral nitrilolactones using Baeyer–Villiger monooxygenases
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This work describes the regio- and enantioselective synthesis of nitrile-containing chiral lactones from easily accessible ketone precursors using Baeyer–Villiger monooxygenases. These biocatalysts controlled the distribution of regioisomers much more tightly than commonly used stoichiometric reagents, additionally with good to excellent optical purity of products. A surprising case of strong stereoelectronic control was also observed. We tested a library of 14 catalysts using five-to eight-membered cyclic ketones with two different tether lengths to the nitrile group. In all but the largest series we found suitable wild-type enzymes for preparative scale synthesis of the target compounds. The diverse possibilities to further functionalize lactones and nitriles make this method interesting for the generation of chiral building blocks.
- Fink, Michael J.,Snajdrova, Radka,Winninger, Alexander,Mihovilovic, Marko D.
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p. 7241 - 7248
(2016/10/26)
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- The 2-(2-Azidoethyl)cycloalkanone strategy for bridged amides and medium-sized cyclic amine derivatives in the Aubé-Schmidt reaction
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2-(2-Azidoethyl)cycloalkanones afford bridged lactams in the Aubé-Schmidt reaction, sometimes in excellent yield, and solvolysis yields derivatives of medium-ring amines. Attempts to divert the Schmidt reaction with an arene-mediated fragmentation of the normal Schmidt intermediate have led to an initial example. Georg Thieme Verlag Stuttgart.
- Macleod, Fraser,Lang, Stuart,Murphy, John A.
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supporting information; experimental part
p. 529 - 534
(2010/10/02)
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- Reaction control in synthetic organic photochemistry: Switching between [5+2] and [2+2] Modes of Cycloaddition
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Split personality: Reaction conditions that enable powerful control over the mode of photocycloaddition in maleimides have been developed. Direct irradiation favors the [5+2] mode whereas sensitized irradiation allows a complete switch to the [2+2] mode (see scheme; TBS=tertbutyldimethylsilyl).
- Roscini, Claudio,Cubbage, Kara L.,Berry, Malcolm,Orr-Ewing, Andrew J.,Booker-Milburn, Kevin I.
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supporting information; experimental part
p. 8716 - 8720
(2010/03/01)
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- Triethylborane induced radical reaction of gallium enolates with α-halo esters
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Treatment of silyl enolates with methyllithium followed by an addition of gallium trichloride afforded the corresponding gallium enolates. The reaction of the resulting gallium enolates with α-halo carbonyl compounds in the presence of triethylborane as a radical initiator provided 1,4-dicarbonyl compounds in good yields.
- Usugi, Shin-ichi,Yorimitsu, Hideki,Shinokubo, Hiroshi,Oshima, Koichiro
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p. 2049 - 2052
(2007/10/03)
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- Synthetic utility of stannyl enolates as radical alkylating agents
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(Equation presented) The radical-initiated β-ketoalkylation of haloalkanes with tributylstannyl enolates is described. Stannyl enolates derived from aromatic ketones are reactive toward the homolytic β-ketoalkylation of simple haloalkanes as well as those activated by an electron-withdrawing group. The reactivity of stannyl enolates as radical alkylating agents can be utilized for an efficient three-component coupling reaction among stannyl enolates, haloalkanes, and electron-deficient alkenes.
- Miura, Katsukiyo,Fujisawa, Naoki,Saito, Hiroshi,Wang, Di,Hosomi, Akira
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p. 2591 - 2594
(2007/10/03)
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- Inter- and intramolecular reductive coupling reactions: an approach to the phorbol skeleton.
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[reaction: see text] An expeditious convergent route to the ABC-tricyclic core of the phorbol esters is described. The chemistry capitalizes upon both inter- and intramolecular reductive coupling processes promoted electrochemically and via the use of sam
- Carroll,Little
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p. 2873 - 2876
(2007/10/03)
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- Cyclic amidino agents useful as nitric oxide synthase inhibitors
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The current invention discloses useful amidino derivative useful as nitric oxide synthase inhibitors.
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- Azepine derivatives useful as nitric oxide synthase inhibitors
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The current invention discloses azepine derivatives useful as nitric oxide synthase inhibitors.
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- Biotransformation of αβ-unsaturated carbonyl compounds: sulfides, sulfoxides, sulfones, nitriles and esters by yeast species: carbonyl group and carbon-carbon double bond reduction
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The reduction of αβ-unsaturated ketones with γ-sulfide, sulfoxide, sulfone, nitrile and ester functions has been investigated.Both C=O and C=C reduction was observed.In the sulfur series, C=O bond reduction was always observed, but significant C=C bond reduction was observed only with the sulfide.The unsaturated nitriles gave the corresponding alcohols as the major bioreduction product, with smaller but significant amounts of fully reduced product.A similar result was obtained with the ester substrate.Relative and absolute configurations of bioreduction products were determined.A comparison was made between reductions catalysed by bakers' yeast (Saccharomyces cerevisiae) and by other yeasts (Zygosaccharomyces rouxii, Pichia capsulata, P. farinosa, Candida chalmersi and C. diddensiae).The tendency of Z. rouxii to give products enantiomeric with thouse obtained using S. cerevisiae was noted.The relationship between substrate structure and the stereochemistry of C=C double bond reduction is discussed.
- Koul, Surinder,Crout, David H. G.,Errington, William,Tax, Jiri
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p. 2969 - 2988
(2007/10/03)
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- STEREOSELECTIVE SYNTHESIS OF THE TRICYCLIC CONDENSED DERIVATIVES OF THIAZOLIDINE
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The perhydro derivatives of thiazoloquinoline, thiazolocyclopentapyridine, thiazoloindole, and cyclopentapyrrolothiazole and also their 2-methyl derivatives were synthesized by the addition of thiirane and methylthiirane at the C=N bond in bicyclic imines of the 2,3,4,4a,5,6,7,8-octahydroquinoline type.An alternative method involves reaction of the thiiranes with amino ketones of the 2,2-ethylenedioxycyclohexylpropylamine type, protected at the carbomyl group, followed by acid deblocking and cyclization by treatment with alkali.The last method is the only method for the production of perhydrocyclopentapyrrolothiazoles, since 2,3,3a,4,5,6-hexahydrocyclopentapyrrole is not a stable imine.Some of the compounds were obtained in the form of single diastereomers, the configurations of which for the two subjects were determined by NMR.In other cases mixtures of the stereoisomers are formed with a srtong preponderance of one of them; arguments concerning their configurations are presented.It is shown that both methods of synthesis lead to an identical stereochemical result.
- Sokolov, V. V.,Potekhin, A. A.,Ovchinnikova, I. V.,Gindin, V. A.,Smirnov, S. N.
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p. 582 - 589
(2007/10/02)
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- Preparation of useful intermediates of dextrorphan - Note I
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Dextrorphan is the main metabolite of Dextromethorphan, a drug with high anti-tussive activity. In this preliminary work we report on the synthesis of two essential intermediates for its preparation: 2-(1-cyclohexenyl)ethyl amine and (R;S)-1-(4-methoxy-benzyl)-2-methyl-1,2,3,4,5,6,7,8-octahydroisoquinol ine.
- Passarotti,Valenti,Grianti
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p. 472 - 474
(2007/10/02)
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