- Preparation of mono-substituted malonic acid half oxyesters (SMAHOs)
-
The use of mono-substituted malonic acid half oxyesters (SMAHOs) has been hampered by the sporadic references describing their preparation. An evaluation of different approaches has been achieved, allowing to define the best strategies to introduce diversity on both the malonic position and the ester function. A classical alkylation step of a malonate by an alkyl halide followed by a monosaponification gave access to reagents bearing different substituents at the malonic position, including functionalized derivatives. On the other hand, the development of a monoesterification step of a substituted malonic acid derivative proved to be the best entry for diversity at the ester function, rather than the use of an intermediate Meldrum acid. Both these transformations are characterized by their simplicity and efficiency, allowing a straightforward access to SMAHOs from cheap starting materials.
- Condon, Sylvie,Le Gall, Erwan,Pichon, Christophe,Presset, Marc,Xavier, Tania
-
supporting information
p. 2085 - 2094
(2021/09/02)
-
- Reduction of Activated Alkenes by PIII/PV Redox Cycling Catalysis
-
The carbon–carbon double bond of unsaturated carbonyl compounds was readily reduced by using a phosphetane oxide catalyst in the presence of a simple organosilane as the terminal reductant and water as the hydrogen source. Quantitative hydrogenation was observed when 1.0 mol % of a methyl-substituted phosphetane oxide was employed as the catalyst. The procedure is highly selective towards activated double bonds, tolerating a variety of functional groups that are usually prone to reduction. In total, 25 alkenes and two alkynes were hydrogenated to the corresponding alkanes in excellent yields of up to 99 %. Notably, less active poly(methylhydrosiloxane) could also be utilized as the terminal reductant. Mechanistic investigations revealed the phosphane as the catalyst resting state and a protonation/deprotonation sequence as the crucial step in the catalytic cycle.
- Longwitz, Lars,Werner, Thomas
-
supporting information
p. 2760 - 2763
(2020/02/05)
-
- Enantioselective α-Amination of Acyclic 1,3-Dicarbonyls Catalyzed by N-Heterocyclic Carbene
-
Herein, we describe a method for the catalytic enantioselective α-amination of α-substituted acyclic 1,3-ketoamides and 1,3-amidoesters that affords the products possessing N-substituted quaternary stereocenters with a chiral N-heterocyclic carbene (NHC). The reaction is based on the utilization of an intrinsic Br?nsted base characteristic of NHC that enables the catalytic formation of a chiral ion pair comprising the enolate and the azolium ion. A series of challenging open-chain α-substituted 1,3-dicarbonyls are aminated via this method with ee's of ≤99%.
- Santra, Surojit,Maji, Ujjwal,Guin, Joyram
-
supporting information
p. 468 - 473
(2020/02/04)
-
- Synthesis of Enantiomerically Enriched 2-Hydroxymethylalkanoic Acids by Oxidative Desymmetrisation of Achiral 1,3-Diols Mediated by Acetobacter aceti
-
The stereoselective desymmetrisation of achiral 2-alkyl-1,3-diols is performed by oxidation of one of the two enantiotopic primary alcohol moieties by means of Acetobacter aceti MIM 2000/28 to afford the corresponding chiral 2-hydroxymethyl alkanoic acids (up to 94 % ee). The procedure, carried out in aqueous medium under mild conditions of pH, temperature and pressure, contributes to enlarge the portfolio of enzymatic oxidations available to organic chemists for the development of sustainable manufacturing processes.
- Brenna, Elisabetta,Cannavale, Flavia,Crotti, Michele,De Vitis, Valerio,Gatti, Francesco G.,Migliazza, Gaia,Molinari, Francesco,Parmeggiani, Fabio,Romano, Diego,Santangelo, Sara
-
p. 3796 - 3803
(2016/12/24)
-
- Substrate-directable electron transfer reactions. Dramatic rate enhancement in the chemoselective reduction of cyclic esters using SmI2-H 2O: Mechanism, scope, and synthetic utility
-
Substrate-directable reactions play a pivotal role in organic synthesis, but are uncommon in reactions proceeding via radical mechanisms. Herein, we provide experimental evidence showing dramatic rate acceleration in the Sm(II)-mediated reduction of cyclic esters that is enabled by transient chelation between a directing group and the lanthanide center. This process allows unprecedented chemoselectivity in the reduction of cyclic esters using SmI2-H2O and for the first time proceeds with a broad substrate scope. Initial studies on the origin of selectivity and synthetic application to form carbon-carbon bonds are also disclosed.
- Szostak, Michal,Spain, Malcolm,Choquette, Kimberly A.,Flowers, Robert A.,Procter, David J.
-
supporting information
p. 15702 - 15705
(2013/11/06)
-
- Copper(II) triflate catalyzed amination and aziridination of 2-Alkyl substituted 1,3-dicarbonyl compounds
-
A method to prepare α-acyl-β-amino acid and 2,2-diacyl aziridine derivatives efficiently from Cu(OTf)2 + 1,10-phenanthroline (1,10-phen)-catalyzed amination and aziridination of 2-alkyl substituted 1,3-dicarbonyl compounds with PhI=NTs is described. By taking advantage of the orthogonal modes of reactivity of the substrate through slight modification of the reaction conditions, a divergence in product selectivity was observed. In the presence of 1.2 equiv of the iminoiodane, amination of the allylic C-H bond of the enolic form of the substrate, formed in situ through coordination to the Lewis acidic metal catalyst, was found to selectively occur and give the β-aminated adduct. On the other hand, increasing the amount of the nitrogen source from 1.2 to 2-3 equiv was discovered to result in preferential formal aziridination of the C-C bond of the 2-alkyl substituent of the starting material and formation of the aziridine product.
- Ton, Thi My Uyen,Tejo, Ciputra,Tiong, Diane Ling Ying,Chan, Philip Wai Hong
-
experimental part
p. 7344 - 7350
(2012/06/16)
-
- Electrochemically induced oxidative rearrangement of alkylidenemalonates
-
Alkylidenemalonates capable of double bond migration being electrolyzed in methanol or ethanol in the presence of alkali metal halides in an undivided cell equipped with Fe cathode are transformed into 2-alkyl-3,3- dimethoxyalkane-1,2-dicarboxylates in 70-90% yield via electrochemically induced oxidative rearrangement. Acidification of the reaction mixture after the electrolysis leads to the formation of 2-alkyl-3-oxoalkane-1,1- dicarboxylates. In the case of isobutylidenemalonate, the electrolysis intermediate dimethyl 3,3-dimethyl-2-methoxy-cyclopropane-1,1-dicarboxylate was isolated in 70% yield.
- Elinson, Michail N.,Feducovich, Sergey K.,Nikishin, Gennady I.
-
p. 14529 - 14540
(2007/10/03)
-
- Electrochemical Cyclodimerization of Alkylidenemalonates
-
Electrolysis of dimethyl alkylidenemalonates RCH=C(COOMe)2 (R=n-Alk, Ph) in an undivided cell in MeOH in the presence of alkali metal halide as mediator, leads to the formation of cyclic dimers, i.e., 3,4-disubstituted 1,1,2,2-cyclobutanetetracarboxylates.The reaction proceeds via the reductive coupling of two substrate molecules at cathode and the cyclization of a hydrodimer dianion by its interaction with an active form of a mediator, an anode-generated halogen.
- Elinson, Michail N.,Feducovich, Sergey K.,Zakharenkov, Alexandre A.,Ugrak, Bogdan I.,Nikishin, Gennady I.,et al.
-
p. 5035 - 5046
(2007/10/02)
-
- Samarium(II) iodide promoted reductive ring opening reaction of cyclopropane-1,1-dicarboxylic esters. Synthesis of substituted 5-Pentanolides from carbonyl compounds and dimethyl cyclopropane-1,1-dicarboxylate
-
Dimethyl cyclopropane-1,1-dicarboxylate is readily subjected to reductive ring opening reaction with samarium(II) iodide in the presence of tris(dibenzoyl-methiodo)iron(III). The generated organosamarium intermediate is trapped by aliphatic ketones to aff
- Imamoto, Tsuneo,Hatajima, Toshihiko,Yoshizawa, Takeshi
-
p. 7805 - 7808
(2007/10/02)
-
- Electrochemical cyclodimerization of alkylidenemalonates into 3,4-disubstituted cyclobutane-1,1,2,2-tetracarboxylates
-
Alkylidenemalonates being electrolyzed in methanol in undivided cell with glassy carbon, carbon or lead cathode in the presence of sodium iodide or sodium bromide are transformed into 3,4-disubstituted cyclobutane-1,1,2,2-tetracarboxylates.
- Nikishin, Gennady I.,Elinson, Michail N.,Feducovich, Sergey K.,Ugrak, Bogdan I.,Struchkov, Yuri T.,Lindeman, Sergey V.
-
p. 3223 - 3226
(2007/10/02)
-
- 30. On the Regioselectivity Control in the Palladium-Catalyzed Hydro-alkoxycarbonylation of α,β-Unsaturated Esters
-
The regioselectivity of the hydro-alkoxycarbonylation of methyl acrylate, methacrylate, and crotonate catalyzed by complexes (L = phosphine ligands) can be largely controlled by variation of the ligands.PPh3 promotes preferential carbonylation a
- Consiglio, Giambattista,Nefkens, Sylvia C. A.,Pisano, Carmelina,Wenzinger, Fritz
-
p. 323 - 325
(2007/10/02)
-
- HYDROFORMYLATION OF OLEFINS WITH PARAFORMALDEHYDE CATALYZED BY RHODIUM COMPLEXES
-
The addition of formaldehyde to olefins is efficiently catalyzed by RhH2(O2COH)2 and gives the corresponding aldehydes in neutral solution.
- Okano, Tamon,Kobayashi, Teruyuki,Konishi, Hisatoshi,Kiji, Jitsuo
-
p. 4967 - 4968
(2007/10/02)
-
- Hydrogenolysis of Small Cycloalkanes, VII. Selective Hydrogenation of 1,1-Disubstituted Cyclopropane Derivatives
-
On hydrogenation of 1,1-disubstituted cyclopropane derivatives 1 hydrogenolysis of the C-2-C-3 bond to yield 2 is promoted by electron releasing groups (R =alkyl, CH2OH, OR).On the other hand the presence of electron attracting substituents (R = CO2R, COR, CN) causes opening of the C-1-C-2 bond and formation of products 3. 1,1-Bis(trifluoromethyl)cyclopropane could not be hydrogenated.
- Groeger, Claus,Musso, Hans,Rossnagel, Ingrid
-
p. 3621 - 3628
(2007/10/02)
-