63795-90-4Relevant academic research and scientific papers
Enantioselective β-Protonation by a Cooperative Catalysis Strategy
Wang, Michael H.,Cohen, Daniel T.,Schwamb, C. Benjamin,Mishra, Rama K.,Scheidt, Karl A.
, p. 5891 - 5894 (2015/05/27)
An enantioselective N-heterocyclic carbene (NHC)-catalyzed β-protonation through the orchestration of three distinct organocatalysts has been developed. This cooperative catalyst system enhances both yield and selectivity, compared to only the NHC-catalyz
Novel one-pot vicinal double C-acylation of styrenes and methacrylates by electroreduction
Yamamoto, Yoshimasa,Maekawa, Hirofumi,Goda, Satoshi,Nishiguchi, Ikuzo
, p. 2755 - 2758 (2007/10/03)
Electroreduction of styrenes or alkyl methacrylates in the presence of aliphatic acid anhydrides or N-acylimidazoles with an undivided cell equipped with zinc electrodes as the anode and the cathode brought about novel one-pot vicinal double C-acylation to afford the corresponding 1,4-diketones in satisfactory yields.
Preparation of β-substituted γ-keto esters by the grignard reaction on N-acylpyrazoles
Kashima, Choji,Shirahata, Yoshie,Tsukamoto, Yoshihiro
, p. 309 - 317 (2007/10/03)
Various γ-keto esters were prepared by either the alcoholysis of N-(4-oxoalkanoyl)pyrazoles or the Grignard replacement of pyrazole moiety of 4-(N-pyrazolyl)-4-oxoalkanoic esters. By using 3-phenyl-ι-menthopyrazole as a chiral auxiliary, β-substituted γ-keto esters were enantioselectively obtained.
Mg-promoted regio- and stereoselective C-acylation of aromatic α,/β-unsaturated carbonyl compounds
Ohno, Toshinobu,Sakai, Masahiro,Ishino, Yoshio,Shibata, Toshihide,Maekawa, Hirofumi,Nishiguchi, Ikuzo
, p. 3439 - 3442 (2007/10/03)
(matrix presented) Treatment of aromatic α/β-unsaturated carbonyl compounds with Mg turnings in the presence of acid anhydrides/TMSCI or acyl chlorides in DMF brought about a facile and efficient cross-coupling to give C-acylation products, which are usef
Electroreductive acylation of activated olefins using a reactive metal anode
Ohno, Toshinobu,Aramaki, Hideo,Nakahiro, Hideki,Nishiguchi, Ikuzo
, p. 1943 - 1952 (2007/10/03)
Electroreductive acylation of 3-aryl substituted α,β-unsaturated esters and nitriles in the presence of aliphatic carboxylic anhydrides using reactive metal anode (Mg, Al, Zn) in an undivided cell afforded the corresponding β-acyl compounds in moderate to good yields. It was found that anionic species formed by electron transfer from a cathode may be stabilized by metal ions freshly formed from an anode and undergo electrophilic attack of carboxylic anhydrides to give the β-acyl products in high yields as compared with the previously reported method using a divided cell.
Chemoselectivity of rhodium carbenoids. A comparison of the selectivity for O-H insertion reactions or carbonyl ylide formation versus aliphatic and aromatic C-H insertion and cyclopropanation
Cox,Moody,Austin,Padwa
, p. 5109 - 5126 (2007/10/02)
A range of diazocarbonyl compounds 1-9 containing two different functional groups has been prepared, and their rhodium(II) catalysed decomposition studied as a means of probing the chemoselectivity of carbenoid intermediates. The results indicate that wereas O-H insertion reactions predominate over cyclopropanation and aromatic insertion reactions, carbonyl ylide formation vs other competing processes is more finely balanced, and is catalyst dependent.
Ligand effects on dirhodium(II) carbene reactivities. Highly effective switching between competitive carbenoid transformations
Padwa, Albert,Austin, David J.,Price, Alan T.,Semones, Mark A.,Doyle, Michael P.,Protopopova, Marina N.,Winchester, William R.,Tran, Andrea
, p. 8669 - 8680 (2007/10/02)
Carboxylate and carboxamide ligands of dirhodium(II) catalysts control chemoselectivity in competitive metal carbene transformations of diazo compounds. For competitive intramolecular cyclopropanation versus intramolecular aromatic substitution with 1-diazo-3-aryl-5-hexen-2-ones, use of Rh2(OAc)4 results in the products from both transformations in nearly equal amounts, but dirhodium(II) perfluorobutyrate (Rh2(pfb)4) provides only the aromatic substitution product while dirhodium(II) caprolactamate (Rh2(cap)4) gives only the cyclopropanation product. Similar results are obtained from dirhodium(II) catalysts in competitive intramolecular cyclopropanation versus tertiary C-H insertion, aromatic cycloaddition versus C-H insertion, cyclopropanation versus aromatic cycloaddition, and C-H insertion versus aromatic substitution. The order of reactivity for metal carbenes generated from Rh2(pfb)4 is aromatic substitution > tertiary C-H insertion > cyclopropanation ～ aromatic cycloaddition > secondary C-H insertion, and the rate differences between them are as much as 100-fold. For Rh2(cap)4 the order of reactivity is cyclopropanation > tertiary C-H insertion > secondary C-H insertion > aromatic cycloaddition with aromatic substitution not observed as a competing process for the diazo compounds examined. Control of chemoselectivity through charge and/or frontier molecular orbital properties of the intermediate metal carbene has been evaluated. Competitive product formation from dirhodium(II) caprolactamate catalyzed reactions of N-tert-butyl-N-benzyldiazoacetoacetamide is temperature dependent over a narrow 15-deg range. The effect of carbene substituents other than the ligated dirhodium(II) on chemoselectivity is described and discussed.
Alternatives to α-Diazo Ketones for Tandem Cyclization-Cycloaddition and Carbenoid-Alkyne Metathesis Strategies. Novel Cyclic Enol-Ether Formation via Carbonyl Ylide Rearrangement Reactions
Fairfax, David J.,Austin, David J.,Xu, Simon L.,Padwa, Albert
, p. 2837 - 2844 (2007/10/02)
Attempts to form carbonyl ylides from free carbenes derived from diazirines or diazo compounds lacking electron-withdrawing substituents resulted in azine formation or Wolff rearrangement, respectively.Iodonium ylides proved to be a possible alternative to α-diazo compounds for metallocarbenoid generation, similar reactivity being observed for both systems.Studies into the rearrangement chemistry of carbonyl ylides provided a novel cyclic enol-ether synthesis via a 1,4-hydrogen shift process.
Electrogenerated Superoxide-Initiated Autoxidation. A Convenient Electrochemical Method for the Conversion of Secondary Nitroalkanes to Ketones and the Use of Primary Nitroalkanes as Acyl Anion Equivalents in Michael Reactions
Monte, William T.,Baizer, Manuel M.,Little, R. Daniel
, p. 803 - 806 (2007/10/02)
Electrochemically generated superoxide ion was used as a base to deprotonate secondary nitroalkanes whose anions were then oxidized with molecular oxygen, thereby providing a means of converting the secondary nitro group to a ketone.In addition, the radical anion of azobenzene was used as an electrogenerated base to catalyze the Michael condensation of primary nitroalkanes with a variety of acceptors; subsequent exposure of the Michael adduct to the electrogenerated superoxide-initiated autoxidation provides a one-pot sequence for the β-addition of an acyl anion equivalent.
