51004-14-9Relevant academic research and scientific papers
A Photochemical Organocatalytic Strategy for the α-Alkylation of Ketones by using Radicals
Goti, Giulio,Melchiorre, Paolo,O?eka, Maksim,Schweitzer-Chaput, Bertrand,Spinnato, Davide
supporting information, p. 9485 - 9490 (2020/04/09)
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.
Investigation of Straightforward, Photoinduced Alkylations of Electron-Rich Heterocompounds with Electron-Deficient Alkyl Bromides in the Sole Presence of 2,6-Lutidine
Fuks, Elina,Huber, Laura,Schinkel, Thea,Trapp, Oliver
supporting information, p. 6192 - 6198 (2020/08/19)
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.
Regio- and stereoselective synthesis of chiral nitrilolactones using Baeyer–Villiger monooxygenases
Fink, Michael J.,Snajdrova, Radka,Winninger, Alexander,Mihovilovic, Marko D.
, p. 7241 - 7248 (2016/10/26)
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.
The 2-(2-Azidoethyl)cycloalkanone strategy for bridged amides and medium-sized cyclic amine derivatives in the Aubé-Schmidt reaction
Macleod, Fraser,Lang, Stuart,Murphy, John A.
supporting information; experimental part, p. 529 - 534 (2010/10/02)
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.
Reaction control in synthetic organic photochemistry: Switching between [5+2] and [2+2] Modes of Cycloaddition
Roscini, Claudio,Cubbage, Kara L.,Berry, Malcolm,Orr-Ewing, Andrew J.,Booker-Milburn, Kevin I.
supporting information; experimental part, p. 8716 - 8720 (2010/03/01)
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).
Ruthenium-catalyzed hydrative cyclization of 1,5-enynes
Chen, Yiyun,Ho, Douglas M.,Lee, Chulbom
, p. 12184 - 12185 (2007/10/03)
A ruthenium-catalyzed hydrative cyclization of enynes has been developed. The reaction converts a range of 1,5-enynes bearing terminal alkyne and Michael acceptor moieties into cyclopentanone derivatives. From extensive catalyst screening experiments, a t
RADICAL β-FRAGMENTATION OF BICYCLOCARBINOLAMIDES: SYNTHESIS OF FIVE- AND EIGHT-MEMBERED CYCLIC IMIDES
Hernandez, Rosendo,Melian, Daniel,Prange, Thierry,Suarez, Ernesto
, p. 439 - 454 (2007/10/02)
The influence of 4-alkyl or 4-aryl substituents in the regioselectivity of the β-fragmentation of carbinolamidyl radicals generated from the corresponding carbinolamides (7-13) by irradiation with visible light in the presence of (diacetoxyiodo)benzene an
STEREOSELECTIVE SYNTHESIS OF THE TRICYCLIC CONDENSED DERIVATIVES OF THIAZOLIDINE
Sokolov, V. V.,Potekhin, A. A.,Ovchinnikova, I. V.,Gindin, V. A.,Smirnov, S. N.
, p. 582 - 589 (2007/10/02)
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.
