474352-83-5Relevant academic research and scientific papers
Mechanistic investigation of the Ru-catalyzed hydroamidation of terminal alkynes
Arndt, Matthias,Salih, Kifah S. M.,Fromm, Andreas,Goossen, Lukas J.,Menges, Fabian,Niedner-Schatteburg, Gereon
supporting information; experimental part, p. 7428 - 7449 (2011/06/26)
The ruthenium-catalyzed hydroamidation of terminal alkynes has evolved to become a broadly applicable tool for the synthesis of enamides and enimides. Depending on the catalyst system employed, the reaction leads chemo-, regio-, and stereoselectively to a single diastereoisomer. Herein, we present a comprehensive mechanistic study of the ruthenium-catalyzed hydroamidation of terminal alkynes, which includes deuterium-labeling, in situ IR, in situ NMR, and in situ ESI-MS experiments complemented by computational studies. The results support the involvement of ruthenium-hydride and ruthenium-vinylidene species as the key intermediates. They are best explained by a reaction pathway that consists of an oxidative addition of the amide, followed by insertion of a π-coordinated alkyne into a ruthenium-hydride bond, rearrangement to a vinylidene species, nucleophilic attack of the amide, and finally reductive elimination of the product.
Copper-catalyzed cross-coupling of amides and potassium alkenyltrifluoroborate salts: A general approach to the synthesis of enamides
Boishan, Yuri,Batey, Robert A.
experimental part, p. 5283 - 5294 (2010/08/07)
Potassium alkenyltrifluoroborate salts undergo coupling with amides to give enamides using a catalytic amount of Cu(OAc)2 under mild oxidative conditions. The air and water stable alkenyltrifluoroborate salts offer a practical alternative to the use of alkenyl halides and alkenylboronic acids as cross-coupling partners. A range of amides participate in the cross-coupling, including heterocyclic amides, imides, carbamates, benzamides, and acetamides. Optimization studies established two sets of conditions, best suited to either high PKa or low PKa amide substrates. Lower PK amide substrates worked best using a dichloromethane solvent system in the presence of 4 ? molecular sieves, 10 mol % Cu(OAc)2, and 20 mol % N-methylimidazole. Higher PKa amide substrates worked best using a ligandless protocol using a 1:1 dichloromethane/DMSO solvent system in the presence of 4 ? molecular sieves and 10 mol % Cu(OAc)2. The cross-coupling reactions occur stereospecifically with retention of alkene configuration from the alkenyltrifluoroborate salt. The mild reaction conditions employed are tolerant of various functionalities, including nitro, acetals, alkyl and aryl halides, and α,β-unsaturated carbonyls. Finally, the importance of copper sources and the presence of minor impurities were investigated.
Ruthenium-catalyzed addition of primary amides to alkynes: A stereoselective synthesis of secondary enamides
Goossen, Lukas J.,Blanchot, Mathieu,Salih, Kifah S. M.,Goossen, Kaethe
experimental part, p. 2283 - 2288 (2009/12/27)
The anti-Markovnikov addition of primary amides to terminal alkynes under the formation of Z-configured secondary enamides is efficiently promoted by a catalyst system generated in situ from bis(2-methallyl)(cycloocta-1,5-diene) ruthenium(II), 1,4-bis(dic
Synthesis of secondary enamides by ruthenium-catalyzed selective addition of amides to terminal alkynes
Goossen, Lukas J.,Salih, Kifah S. M.,Blanchot, Mathieu
supporting information; experimental part, p. 8492 - 8495 (2009/05/11)
(Chemical Equation Presented) Enamides made easy: A catalyst system generated in situ using bis(2-methallyl)-(cycloocta-1,5-diene)ruthenium(II), 1,4-bis(dicyclohexylphosphino)butane, and ytterbium triflate efficiently catalyzes the addition of primary amides to terminal alkynes, selectively forming the Z-anti-Markovnikov enamides. The E isomers are also accessible by combining the hydroamidation with an in situ double-bond isomerization reaction.
Enamide synthesis by copper-catalyzed cross-coupling of amides and potassium alkenyltrifluoroborate salts
Bolshan, Yuri,Batey, Robert A.
, p. 2109 - 2112 (2008/12/23)
(Chemical Equation Presented) A new partner: Potassium alkenyltrifluoroborate salts undergo coupling with amides to give enamides in the presence of a Cu(OAc)2 catalyst and under mild oxidative conditions (see scheme). The air- and water-stable alkenyltrifluoroborate salts offer a convenient alternative to alkenyl halides as cross-coupling partners. A range of amides undergo coupling including cyclic amides, imides, and carbamates as well as benzamides.
