24785-76-0Relevant academic research and scientific papers
A facile generation of enolates from silyl enol ethers by potassium ethoxide
Yu, Wensheng,Jin, Zhendong
, p. 369 - 372 (2001)
Cyclic silyl enol ethers were successfully cleaved by EtOK to generate the corresponding enolates. Reactions with EtOK were faster and the corresponding enolates could be trapped by electrophiles and oxidants to give the kinetic products exclusively.
NNN pincer Ru(II)-complex-catalyzed α-alkylation of ketones with alcohols
Cao, Xiao-Niu,Wan, Xiao-Min,Yang, Fa-Liu,Li, Ke,Hao, Xin-Qi,Shao, Tian,Zhu, Xinju,Song, Mao-Ping
, p. 3657 - 3668 (2018/04/14)
A series of novel ruthenium(II) complexes supported by a symmetrical NNN ligand were prepared and fully characterized. These complexes exhibited good performance in transfer hydrogenation to form new C-C bonds using alcohols as the alkylating agents, generating water as the only byproduct. A broad range of substrates, including (hetero)aryl- or alkyl-ketones and alcohols, were well tolerated under the optimized conditions. Notably, α-substituted methylene ketones were also investigated, which afforded α-branched steric hindrance products. A potential application of α-alkylation of methylene acetone to synthesize donepezil was demonstrated, which provided the desired product in 83% yield. Finally, this catalytic system could be applied to a one-pot double alkylation procedure with sequential addition of two different alcohols. The current protocol is featured with several characteristics, including a broad substrate scope, low catalyst (0.50 mol %) loadings, and environmental benignity.
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.
Deaminative and decarboxylative catalytic alkylation of amino acids with ketones
Kalutharage, Nishantha,Yi, Chae S.
supporting information, p. 13651 - 13655 (2014/01/06)
It cuts two ways: The cationic [Ru-H] complex catalyzes selective coupling of α- and β-amino acids with ketones to form α-alkylated ketone products. The reaction involves C-C and C-N bond cleavage which result in regio- and stereoselective alkylation using amino acids. A broad substrate scope and high functional-group tolerance is demonstrated. Copyright
5-exo-trig Versus 6-endo-trig cyclization of Alk-5-enoyl radicals: The role of one-carbon ring expansion
Chatgilialoglu, Chryssostomos,Ferreri, Carla,Lucarini, Marco,Venturini, Alessandro,Zavitsas, Andreas A.
, p. 376 - 387 (2007/10/03)
Alk-5-enoyl radicals were made to cyclize in exo and endo modes to give the corresponding cycloketone radicals, which are related through one-carbon ring expansion. Relative kinetic data were determined for the ring closure of the 2-methylhept-5-enoyl radical generated by the reaction of the corresponding phenyl-seleno ester with Bu3SnH over the temperature range 233-323 K. The conversion to absolute rates provided Arrhenius expressions for the 5-exo-trig and 6-endo-trig cyclizations. Ab initio and semiempirical (AM1) calculations were performed on the hex-5-enoyl and hept-5-enoyl radicals, respectively, and the outcomes aided in the rationalization of the preexponential factors and activation energies. Both 1,5- and 1,6-ring closure occur via in a lower energy 'chairlike' transition state. The observed high regioselectivity is due to favorable entropic and enthalpic factors associated with the formation of the smaller ring. The stereoselectivity was higher in the 1,6-ring closure (70:30) than in the 1,5-ring closure (55:45), the trans isomer being predominant in both. For the one-carbon ring expansion studies, the radicals of interest were obtained by deoxygenation of suitable alcohols via the O-phenyl thiocarbonates with (TMS)3-SiH. The one-carbon ring expansion in the cyclopentanone series for the secondary alkyl radicals was studied over the temperature range 343-413 K by means of free-radical clock methodology and yielded the Arrhenius expression. The rate constant was 4.2 x 103 s-1 at room temperature and the reverse reaction (ring contraction) was found to be at least 10 times slower. Since the intermediacy of acyl radicals can be excluded, the reaction must occur via 3-membered cyclic intermediate radicals (or transition states).
Highly Regioselective Monoalkylation of Ketones via Manganese Enolates. Prepared from Lithium Enolates
Cahiez, Gerard,Chau, Khi,Clery, Patrick
, p. 3069 - 3072 (2007/10/02)
Li-enolates are readily converted to Mn-enolates by treatment with manganese halides.In THF, the reaction is easily and economically performed with manganese chloride at room temperature.Mn-enolates can then be regioselectively monoalkylated in good yields.The formation of di and polyalkylated products is never observed (1percent).
