23033-65-0Relevant academic research and scientific papers
Tandem intramolecular carbolithiation-transmetallation: From lithium to copper or boron chemistry
Ortiz, Rosa,Yus, Miguel
, p. 1699 - 1707 (2005)
Lithium/copper transmetallation from the organolithium intermediate 3 (obtained via intramolecular carbolithiation of the acyclic organolithium 2, generated by a chlorine-lithium exchange) gives the corresponding organocopper intermediate 5. This intermediate reacts with eletrophiles, such as allylic or propargylic halides, acyl chlorides or α,β-unsaturated carbonyl compounds giving the expected compounds 6-10, which are not possible to be obtained directly from the organolithium 3. On the other hand, lithium/boron transmetallation affords the corresponding alkylboronic acid 11 which, after palladium-catalysed Suzuki-Miyaura cross-coupling reaction with different aryl bromides gives the expected products 12 with modest yields, the corresponding Ullman biarylic homocoupling products being the major by-products.
Formation of organomagnesium compounds via EtMgBr-mediated radical cyclization of allyl β-iodoacetals
Inoue, Atsushi,Shinokubo, Hiroshi,Oshima, Koichiro
, p. 651 - 653 (2000)
(Graph presented) Treatment of allyl β-iodoacetals with ethylmagnesium bromide in THF provided tetrahydrofuran derivatives in good yields. On the other hand, the reaction in DME provided tetrahydrofuranylmethylmagnesium compounds in good yields.
Using the Thiyl Radical for Aliphatic Hydrogen-Atom Transfer: Thiolation of Unactivated C?H Bonds
Panferova, Liubov I.,Zubkov, Mikhail O.,Kokorekin, Vladimir A.,Levin, Vitalij V.,Dilman, Alexander D.
supporting information, p. 2849 - 2854 (2020/12/17)
A metal- and catalyst-free thiyl-radical-mediated activation of alkanes is described. Tetrafluoropyridinyl disulfide is used to perform thiolation of the C?H bonds under irradiation with 400 nm light-emitting diodes. The key C?H activation step is believed to proceed via hydrogen-atom abstraction effected by the fluorinated thiyl radical. Secondary, tertiary, and heteroatom-substituted C?H bonds can be involved in the thiolation reaction. The resulting sulfides have wide potential as photoredox-active radical precursors in reactions with alkenes and heteroarenes.
Palladium-Catalyzed Dual Ligand-Enabled Alkylation of Silyl Enol Ether and Enamide under Irradiation: Scope, Mechanism, and Theoretical Elucidation of Hybrid Alkyl Pd(I)-Radical Species
Zhao, Bin,Shang, Rui,Wang, Guang-Zu,Wang, Shaohong,Chen, Hui,Fu, Yao
, p. 1334 - 1343 (2020/02/04)
We report herein that a palladium catalyst in combination with a dual phosphine ligand system catalyzes alkylation of silyl enol ether and enamide with a broad scope of tertiary, secondary, and primary alkyl bromides under mild irradiation conditions by blue light-emitting diodes. The reactions effectively deliver α-alkylated ketones and α-alkylated N-acyl ketimines, and it is difficult to prepare the latter by other methods in a stereoselective manner. The α-alkylated N-acyl ketimine products can be further subjected to chiral phosphoric acid-catalyzed asymmetric reduction with Hantzsch ester to deliver chiral N-acyl-protected α-arylated aliphatic amines in high enantioselectivity up to 99% ee, thus providing a method for facile synthesis of chiral α-arylated aliphatic amines, which are of importance in medicinal chemistry research. The N-acetyl ketimine product also reacted smoothly with various types of Grignard reagents to afford sterically bulky N-acetyl α-tertiary amines in high yields. Theoretical studies in combination with experimental investigation provide understanding of the reaction mechanism with respect to the dual ligand effect and the irradiation effect in the catalytic cycle. The reaction is suggested to proceed via a hybrid alkyl Pd(I)-radical species generated by inner-sphere electron transfer of phosphine-coordinated Pd(0) species with alkyl bromide. This intriguing hybrid alkyl Pd(I)-radical species is elucidated by theoretical calculation to be a triplet species coordinated by three phosphine atoms with a distorted tetrahedral geometry, and spin prohibition rather than metal-to-ligand charge transfer contributes to the kinetic stability of the hybrid alkyl Pd(I)-radical species to impede alkyl recombination to generate Pd(II) alkyl intermediate.
Photoredox Reaction of 2-Mercaptothiazolinium Salts with Silyl Enol Ethers
Zemtsov, Artem A.,Ashirbaev, Salavat S.,Levin, Vitalij V.,Kokorekin, Vladimir A.,Korlyukov, Alexander A.,Dilman, Alexander D.
, (2019/11/29)
A method for the generation of free radicals from thiazolinium salts upon photocatalytic reduction is described. The thiazolinium salts are generated by treatment with methyl triflate of 2-mercaptothiazolines, which can be readily obtained from alkyl bromides and tosylates via a nucleophilic substitution reaction or by hydrothiolation of alkenes. Silyl enol ethers were used to trap the radicals, furnishing ketones after successive single-electron oxidation and elimination of the silyl cation.
Fe-Catalyzed decarbonylative alkylation-peroxidation of alkenes with aliphatic aldehydes and hydroperoxide under mild conditions
Wu, Chuan-Shuo,Li, Rong,Wang, Qi-Qiang,Yang, Luo
, p. 269 - 274 (2019/01/28)
A convenient Fe-catalyzed decarbonylative alkylation-peroxidation of alkenes with aliphatic aldehydes and TBHP to provide chain elongated peroxides is developed, which is further applied to the one-pot synthesis of alkylated ketones. Aliphatic aldehydes were decarbonylated into 1°, 2° and 3° alkyl radicals at low temperature which subsequently allows the cascade construction of C(sp3)-C(sp3) and C(sp3)-O bonds via radical insertion and radical-radical coupling. Various alkenes including mono-substituted, terminally disubstituted or internally disubstituted styrenes bearing synthetically useful functional groups and electron-poor acrylates were tolerated.
Cu/Mn bimetallic catalysis enables carbonylative Suzuki-Miyaura coupling with unactivated alkyl electrophiles
Pye, Dominic R.,Cheng, Li-Jie,Mankad, Neal P.
, p. 4750 - 4755 (2017/07/10)
A bimetallic system consisting of Cu-carbene and Mn-carbonyl co-catalysts was employed for carbonylative C-C coupling of arylboronic esters with alkyl halides, allowing for the convergent synthesis of ketones. The system operates under mild conditions and exhibits complementary reactivity to Pd catalysis. The method is compatible with a wide range of arylboronic ester nucleophiles and proceeds smoothly for both primary and secondary alkyl iodide electrophiles. Preliminary mechanistic experiments corroborate a hypothetical catalytic mechanism consisting of co-dependent cycles wherein the Cu-carbene co-catalyst engages in transmetallation to generate an organocopper nucleophile, while the Mn-carbonyl co-catalyst activates the alkyl halide electrophile by single-electron transfer and then undergoes reversible carbonylation to generate an acylmanganese electrophile. The two cycles then intersect with a heterobimetallic, product-releasing C-C coupling step.
Peroxide promoted tunable decarboxylative alkylation of cinnamic acids to form alkenes or ketones under metal-free conditions
Ji, Jing,Liu, Ping,Sun, Peipei
supporting information, p. 7546 - 7549 (2015/05/04)
A tunable decarboxylative alkylation of cinnamic acids with alkanes was developed to form alkenes or ketones under transition metal-free conditions. In the presence of DTBP or DTBP/TBHP, the reaction gave alkenes and ketones respectively via a radical mechanism in moderate to good yields. This journal is
Radical alkylations of alkyl halides and unactivated C-H bonds using vinyl triflates
Lee, Jin Young,Lim, Kyoung-Chan,Meng, Xiangjian,Kim, Sunggak
experimental part, p. 1647 - 1650 (2010/09/04)
Radical alkylations of activated alkyl iodides and bromides were achieved using vinyl triflates in the presence of hexadimethyltin, whereas those of unactivated C-H bonds using vinyl triflates proceeded cleanly under tin-free conditions. Georg Thieme Verl
Catalytic cross-coupling of alkylzinc halides with α-chloroketones
Malosh, Chrysa F.,Ready, Joseph M.
, p. 10240 - 10241 (2007/10/03)
The cross-coupling of alkylzinc halides with α-chloroketones catalyzed by Cu(acac)2 is described. Using this method, primary and secondary alkyl groups are introduced adjacent to a ketone carbonyl under mild reaction conditions and in good yield. Cyclic, acyclic, aromatic, and aliphatic α-chloroketones are suitable substrates. Optically active α-chloroketones are converted to optically active products. The reaction was found to proceed stereospecifically with inversion of stereochemistry. The reaction is proposed to occur by direct substitution of the chloride with the alkyl group of an organocopper, -magnesium, or -zinc species. Copyright
