2884-02-8Relevant articles and documents
Regioselective Vinylation of Remote Unactivated C(sp3)?H Bonds: Access to Complex Fluoroalkylated Alkenes
Wu, Shuo,Wu, Xinxin,Wang, Dongping,Zhu, Chen
supporting information, p. 1499 - 1503 (2019/01/04)
Regioselective incorporation of a particular functional group into aliphatic sites by direct activation of unreactive C?H bonds is of great synthetic value. Despite advances in radical-mediated functionalization of C(sp3)?H bonds by a hydrogen-atom transfer process, the site-selective vinylation of remote C(sp3)?H bonds still remains underexplored. Reported herein is a new protocol for the regioselective vinylation of unactivated C(sp3)?H bonds. The remote C(sp3)?H activation is promoted by a C-centered radical instead of the commonly used N and O radicals. The reaction possesses high product diversity and synthetic efficiency, furnishing a plethora of synthetically valuable E alkenes bearing tri-/di-/mono-fluoromethyl and perfluoroalkyl groups.
Regioselective Sulfonylvinylation of the Unactivated C(sp3)-H Bond via a C-Centered Radical-Mediated Hydrogen Atom Transfer (HAT) Process
Yang, Shan,Wu, Xinxin,Wu, Shuo,Zhu, Chen
supporting information, p. 4837 - 4841 (2019/06/24)
Given the similarity of multiple sp3 C-H bonds in electronic properties and bond dissociation energy (BDE), regioselective sp3 C-H bond functionalization remains a paramount challenge. Here, we report a C-centered radical-mediated approach for site-specific sulfonylvinylation of the C(sp3)-H bond via the hydrogen atom transfer (HAT) process. The reaction features mild conditions, broad substrate scope, and high regioselectivity and stereoselectivity, manifesting the nontrivial synthetic potential.
An umpolung sulfoxide reagent for use as a functionalized benzyl carbanion equivalent
Pinna, Giovanni,Bellucci, Maria Cristina,Malpezzi, Luciana,Pisani, Laura,Superchi, Stefano,Volonterio, Alessandro,Zanda, Matteo
, p. 5268 - 5281 (2011/08/06)
N-Methyl ortho-carbamoylaryl benzyl sulfoxides can be used as synthetic equivalents for α-hydroxy, α-chloro, and α-acetammido benzyl carbanions by means of a two-step sequence involving highly diastereoselective α-C-alkylation with alkyl halides followed by displacement of the sulfinyl residue (which can be recovered and recycled) by a hydroxyl, a chlorine or an acetamido, respectively, under non-oxidative Pummerer conditions. The scope and limits of the method, including a stereoselective version of the reaction, as well as the mechanism of the process are discussed in detail.
Alcohol cross-coupling reactions catalyzed by Ru and Ir terpyridine complexes
Gnanamgari, Dinakar,Leung, Chin Hin,Schley, Nathan D.,Hilton, Sheena T.,Crabtree, Robert H.
experimental part, p. 4442 - 4445 (2009/02/07)
Primary alcohols can be coupled with secondary benzylic alcohols by an air-stable catalytic system involving terpyridine ruthenium or iridium complexes.
Easy α-alkylation of ketones with alcohols through a hydrogen autotransfer process catalyzed by RuCl2(DMSO)4
Martínez, Ricardo,Ramón, Diego J.,Yus, Miguel
, p. 8988 - 9001 (2007/10/03)
The electrophilic α-alkylation of ketones with alcohols is accomplished by a hydrogen autotransfer process catalyzed by RuCl2(DMSO)4. The reaction can produce either simple alkylated ketones or α,β-unsaturated ketones just by choosing the appropriate starting ketones (methyl ketones or bicyclic methylenic ketones, respectively), as well as quinolines (by using 2-aminobenzyl alcohol derivatives) or the corresponding alcohol derivatives by the addition of an extra equivalent of the initial alcohol. In the last case, after the above alkylation process reduction of the carbonyl compound takes place. A mechanistic study seems to indicate that the process goes through the oxidation of the alcohols with ruthenium (after a previous deprotonation) to yield the corresponding aldehyde and a ruthenium hydride intermediate. In turn, the aldehyde suffers a classical aldol reaction with the starting ketone to form the corresponding α,β-unsaturated ketone, which finally is reduced through a Michael-type addition by the aforementioned ruthenium hydride intermediate.
RuCl2(DMSO)4 catalyzes the β-alkylation of secondary alcohols with primary alcohols through a hydrogen autotransfer process
Martínez, Ricardo,Ramón, Diego J.,Yus, Miguel
, p. 8982 - 8987 (2007/10/03)
The electrophilic β-alkylation of secondary alcohols with primary alcohols is accomplished by a hydrogen autotransfer process catalyzed by RuCl2(DMSO)4. The reaction can produce either simple alkylated secondary alcohols or α,β-unsaturated ketones with good to excellent results just by choosing the appropriate starting secondary alcohol (methyl or longer chain secondary alcohol, respectively), as well as quinolines (by using 2-aminobenzyl alcohol).
[Ru(DMSO)4] Cl2 catalyzes the α-alkylation of ketones by alcohols
Martínez, Ricardo,Brand, Gabriel J.,Ramón, Diego J.,Yus, Miguel
, p. 3683 - 3686 (2007/10/03)
The electrophilic α-alkylation of ketones with alcohols was accomplished by a [Ru(DMSO)4]Cl2 catalyzed process, water being the only wasted material. The reaction can be successfully governed to produce either the expected ketones or their related alcohols only by changing the reaction conditions. When 2-aminobenzyl alcohol was used, a cyclization process took place to yield 2,3-disubstituted quinolines.
Direct β-alkylation of secondary alcohols with primary alcohols catalyzed by a Cp*Ir complex
Fujita, Ken-Ichi,Asai, Chiho,Yamaguchi, Tetsuhiro,Hanasaka, Fumihiro,Yamaguchi, Ryohei
, p. 4017 - 4019 (2007/10/03)
(Chemical Equation Presented) A new catalytic system for β-alkylation of secondary alcohols has been developed. In the presence of [Cp*IrCl 2]2 (Cp* = pentamethylcyclopentadienyl) catalyst and base, the reactions of various secondary alcohols with primary alcohols give β-alkylated higher alcohols in good to excellent yields without any hydrogen acceptor or hydrogen donor. This reaction proceeds via successive hydrogen-transfer reactions and aldol condensation.
An umpolung sulfoxide reagent as α-hydroxy and α-chloro benzyl carbanion equivalents
Volonterio, Alessandro,Bravo, Pierfrancesco,Zanda, Matteo
, p. 6537 - 6540 (2007/10/03)
ortho-[(N-Methyl)carbamoyl]phenyl benzyl sulfoxide is used as a synthetic equivalent of α-hydroxy and α-chloro benzyl carbanions by means of a two-step sequence involving (1) highly stereoselective α-C-alkylation with alkyl bromides, and (2) displacement of the sulfinyl group by an OH or a Cl under Pummerer or chloro-Pummerer conditions, respectively. The sulfinyl auxiliary can be effectively regenerated and recycled.
