2371-23-5Relevant academic research and scientific papers
Expedient Synthesis of Ketones via N-Heterocyclic Carbene/Nickel-Catalyzed Redox-Economical Coupling of Alcohols and Alkynes?
Li, Yu-Qing,Li, Feng,Shi, Shi-Liang
supporting information, p. 1035 - 1039 (2020/06/30)
An N-heterocyclic carbene/nickel-catalyzed direct coupling of alcohols and internal alkynes to form α-branched ketones has been developed. This methodology provides a new approach to afford branched ketones, which are difficult to access through the hydroacylation of simple internal alkenes with aldehydes. This redox-neutral and redox-economical coupling is free from any oxidative or reductive additives as well as stoichiometric byproducts. These reactions convert both benzylic and aliphatic alcohols and alkynes, two basic feedstock chemicals, into various α-branched ketones in a single chemical step.
Highly Stereoselective Synthesis of Tetrasubstituted Acyclic All-Carbon Olefins via Enol Tosylation and Suzuki-Miyaura Coupling
Li, Beryl X.,Le, Diane N.,Mack, Kyle A.,McClory, Andrew,Lim, Ngiap-Kie,Cravillion, Theresa,Savage, Scott,Han, Chong,Collum, David B.,Zhang, Haiming,Gosselin, Francis
supporting information, p. 10777 - 10783 (2017/08/15)
A highly stereocontrolled synthesis of tetrasubstituted acyclic all-carbon olefins has been developed via a stereoselective enolization and tosylate formation, followed by a palladium-catalyzed Suzuki-Miyaura cross-coupling of the tosylates and pinacol boronic esters in the presence of a Pd(OAc)2/RuPhos catalytic system. Both the enol tosylation and Suzuki-Miyaura coupling reactions tolerate an array of electronically and sterically diverse substituents and generate high yield and stereoselectivity of the olefin products. Judicious choice of substrate and coupling partner provides access to either the E- or Z-olefin with excellent yield and stereochemical fidelity. Olefin isomerization was observed during the Suzuki-Miyaura coupling. However, under the optimized cross-coupling reaction conditions, the isomerization was suppressed to 5% in most cases. Mechanistic probes indicate that the olefin isomerization occurs via an intermediate, possibly a zwitterionic palladium carbenoid species.
Ruthenium-NHC Catalyzed α-Alkylation of Methylene Ketones Provides Branched Products through Borrowing Hydrogen Strategy
Schlepphorst, Christoph,Maji, Biplab,Glorius, Frank
, p. 4184 - 4188 (2016/07/12)
The α-alkylation of a broad range of methylene ketones was achieved using a ruthenium(II)-NHC catalyst under borrowing hydrogen conditions. Primary alcohols served as alkylating agents and could be used in a one-to-one stoichiometry with respect to the ketone. The selectivity of the process for methyl over branched ketones enabled a one-pot double alkylation protocol utilizing two different alcohols with a single catalyst. Moreover, this methodology could be applied directly to the one-step synthesis of donepezil, the best-selling drug for the treatment of Alzheimer's disease.
Photosensitizer-Free Visible-Light-Mediated Gold-Catalyzed 1,2-Difunctionalization of Alkynes
Huang, Long,Rudolph, Matthias,Rominger, Frank,Hashmi, A. Stephen K.
, p. 4808 - 4813 (2016/04/19)
Under visible-light irradiation, the gold-catalyzed intermolecular difunctionalization of alkynes with aryl diazonium salts in methanol affords a variety of α-aryl ketones in moderate to good yields. In contrast to previous reports on gold-catalyzed reactions that involve redox cycles, no external oxidants or photosensitizers are required. The reaction proceeds smoothly under mild reaction conditions and shows broad functional-group tolerance. Further applications of this method demonstrate the general applicability of the arylation of a vinyl gold intermediate instead of the commonly used protodemetalation step. This step provides facile access to functionalized products in one-pot processes. With a P,N-bidentate ligand, a stable aryl gold(III) species was obtained, which constitutes the first direct experimental evidence for the commonly postulated direct oxidative addition of an aryl diazonium salt to a pyridine phosphine gold(I) complex.
Carbolithiation of diphenylacetylene as a stereoselective route to (Z)-tamoxifen and related tetrasubstituted olefins
McKinley, Neola F.,O'Shea, Donal F.
, p. 9552 - 9555 (2007/10/03)
(Chemical Equation Presented) Carbolithiation of diphenylacetylene can be exploited to generate (E)-1-lithio-1,2-diphenylalkyl-1-enes which can be reacted in situ with triisopropylborate to stereoselectively provide (E)-1,2-diphenyl-1-alkylene boronic acids. These tetrasubstituted vinylboronic acids served as versatile intermediates for the generation of tetrasubstituted olefins with retention of stereochemistry. The application of this method for the stereoselective synthesis of (Z)-tamoxifen and related analogues is described.
Acyclic selenoiminium salts: Isolation, first structural characterization, and reactions
Mutoh, Yuichiro,Murai, Toshiaki
, p. 1361 - 1364 (2007/10/03)
(Matrix presented) A variety of selenoiminium salts were obtained by reacting the corresponding selenoamides with methyl triflate at room temperature for 30 s. All of the salts were stable under air. The structures of the selenoiminium salts were determined by X-ray molecular analysis. An aromatic selenoiminium salt reacted with BuLi (3 equiv) to give two types of ketones. In a reaction with LiAlH4/Te, the selenoiminium salts were converted to telluroamides.
Dramatic rate enhancement by ultrasonic irradiation in liquid-liquid phase-transfer catalytic reactions
Ooi,Tayama,Doda,Takeuchi,Maruoka
, p. 1500 - 1502 (2007/10/03)
Significant rate enhancement was observed in the liquid-liquid phase-transfer catalytic epoxidations and alkylations under ultrasonic irradiation. Its advantage was also demonstrated in the asymmetric alkylation of tert-butyl glycinate-benzophenone Schiff base using C2-symmetric chiral phase-transfer catalyst.
Macrocyclic Polyethers as Enolate Activators in Base-Catalyzed Phase-Transfer Reactions
Gobbi, Alessandro,Landini, Dario,Maia, Angelamaria,Petricci, Silvia
, p. 5356 - 5361 (2007/10/03)
A kinetic study of the alkylation reaction of deoxybenzoin (1) with alkylating agents 2-4, catalyzed by PHDB18C6 7 or [2.2.2,C10]cryptand 8, has been performed in chlorobenzene-aqueous (or solid) base (NaOH, KOH) two-phase systems, under liquid
Debenzotriazolylation of α-benzotriazolyl ketones with samarium diiodide
Katritzky, Alan R.,Wang, Junquan,Henderson, Scott A.
, p. 1567 - 1574 (2007/10/03)
Removal of the benzotriazolyl moiety of α-benzotriazolyl ketones by samarium diiodide at room temperature to give the corresponding ketones in good yields is described.
Transformations of N-Substituted Benzotriazoles into the Corresponding Carbanions by C-Benzotriazole Bond Scission
Katritzky, Alan R.,Qi, Ming
, p. 4116 - 4120 (2007/10/03)
Various TV-substituted benzotriazoles are transformed, by scission of the C-benzotriazole bond, into the corresponding carbanions by treatment with lithium. Thus, N-(diphenylmethyl)benzotriazole (1), N-benzylbenzotriazole (6), and N-allylbenzotriazole (10) all gave carbanions that reacted with diverse electrophiles to afford the corresponding products in good yields. This new methodology was successfully utilized to convert N-benzylbenzotriazole (6) and N-allylbenzotriazole (10) into dianion synthons by a sequential lithiation and reductive coupling and bis(benzotriazolyl)toluene (18) by double reductive couplings, demonstrating the synthetic potential of the present methodology.
