3558-61-0Relevant articles and documents
Three-component reaction of aryl diazoacetates, alcohols, and aldehydes (or imines): Evidence of alcoholic oxonium ylide intermediates
Lu, Chong-Dao,Liu, Hui,Chen, Zhi-Yong,Hu, Wen-Hao,Mi, Ai-Qiao
, p. 83 - 86 (2005)
(Chemical Equation Presented) The Rh(II)-catalyzed three-component reaction of aryl diazoacetates, alcohols and aldehydes was explored, which provided evidence of alcoholic oxonium ylide formation for O-H insertion. A new C-C bond formation reaction where alcoholic oxonium ylides were trapped by electron-deficient aryl aldehydes (or imines) was realized.
Synthesis of Overloaded Cyclopentadienyl Rhodium(III) Complexes via Cyclotetramerization of tert-Butylacetylene
Kolos, Andrey V.,Nelyubina, Yulia V.,Perekalin, Dmitry S.,Sundararaju, Basker
supporting information, p. 3712 - 3719 (2021/09/18)
Herein we describe the synthesis and reactivity of rhodium catalysts with the very bulky cyclopentadienyl ligand C8H3tBu4 (designated as tBu4Cp). The reaction of [Rh(cod)Cl]2 with tert-butylacetylene in the presence of Et3N gives the complex (tBu4Cp)Rh(cod) (60-65% yield), in which the cyclopentadienyl ligand tBu4Cp is assembled from four alkyne molecules. The oxidation of (tBu4Cp)Rh(cod) with chlorine or bromine gives the corresponding halide complexes (tBu4Cp)RhX2 (X = Cl (85%), Br (95%)), which have unusual 16-electron monomeric structures due to the steric shielding provided by tBu groups. A similar reaction with iodine gives the ionic dinuclear complex [(tBu4Cp)RhI3Rh(tBu4Cp)]I (99%) with halide bridges. The bromide complex (tBu4Cp)RhBr2 reacts with phosphorus ligands such as P(OMe)3, P(OPh)3, PMe2Ph, and PMePh2 to give the 18-electron adducts (tBu4Cp)RhBr2(PR3), but no reaction occurs with larger phosphines such as PPh3. The racemic chloride (tBu4Cp)RhCl2 can be separated into enantiomers by preparative TLC of its diastereomeric adducts with (R)-phenylglycinol. The complex (tBu4Cp)RhBr2 catalyzes C-H activation and annulation of O-pivaloyl-hydroxamate as well as insertion of phenyldiazoacetate into E-H bonds, although the reaction rates and the substrate scope are limited by the bulky tBu4Cp ligand.
N-SUBSTITUTED ALPHA-AMINO AND ALPHA-HYDROXY CARBOXAMIDE DERIVATIVES
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Paragraph 130-131, (2021/10/30)
Disclosed are N-substituted α-amino and α-hydroxy carboxamides, pharmaceutical compositions comprising them, and methods of using them.
Photocatalytic Alkylation of Pyrroles and Indoles with α-Diazo Esters
Ciszewski, Lukasz W.,Durka, Jakub,Gryko, Dorota
supporting information, p. 7028 - 7032 (2019/09/12)
This article describes the photoalkylation of electron-rich aromatic compounds with diazo esters. C-2-alkylated indoles and pyrroles are obtained with good yields even though the photocatalyst loading is as low as 0.075 mol %. For EWG-substituted substrates, the addition of a catalytic amount of N,N-dimethyl-4-methoxyaniline is required. Both EWG-EWG- and EWG-EDG-substituted diazo esters are suitable as alkylating agents. The reaction selectivity and mechanistic experiments suggest that carbenes/carbenoid intermediates are not involved in the reaction pathway.
Bis(imino)pyridine iron complexes for catalytic carbene transfer reactions
Wang, Ban,Howard, Isaac G.,Pope, Jackson W.,Conte, Eric D.,Deng, Yongming
, p. 7958 - 7963 (2019/09/06)
The bis(imino)pyridine iron complex, for the first time, is developed as an effective metal carbene catalyst for carbene transfer reactions of donor-acceptor diazo compounds. Its broad catalytic capability is demonstrated by a range of metal carbene reactions, from cyclopropanation, cyclopropenation, epoxidation, and Doyle-Kirmse reaction to O-H insertion, N-H insertion, and C-H insertion reactions. The asymmetric cyclopropanation of styrene and methyl phenyldiazoacetate was successfully achieved by the new chiral bis(imino)pyridine iron catalyst, which delivers a new gateway for the development of chiral iron catalysis for metal carbene reactions.
FeII-catalysed insertion reaction of α-diazocarbonyls into X-H bonds (X = Si, S, N, and O) in dimethyl carbonate as a suitable solvent alternative
Tanbouza, Nour,Keipour, Hoda,Ollevier, Thierry
, p. 31241 - 31246 (2019/10/19)
The insertion reaction of a broad range of diazo compounds into Si-H bonds was found to be efficiently catalysed by Fe(OTf)2 in an emerging green solvent i.e. dimethyl carbonate (DMC). The α-silylated products were obtained in good to excellent yields (up to 95%). Kinetic studies showed that the extrusion of N2 to form an iron carbene intermediate is rate-limiting. The iron-catalysed insertion reaction of methyl α-phenyl-α-diazoacetate into polar X-H bonds (S-H, N-H, and O-H) was also established in DMC.
Asymmetric Counter-Anion-Directed Aminomethylation: Synthesis of Chiral β-Amino Acids via Trapping of an Enol Intermediate
Kang, Zhenghui,Wang, Yongheng,Zhang, Dan,Wu, Ruibo,Xu, Xinfang,Hu, Wenhao
supporting information, p. 1473 - 1478 (2019/01/26)
A novel enantioselective aminomethylation reaction of diazo compound, alcohol and α-aminomethyl ether enabled by asymmetric counteranion-directed catalysis is disclosed that offers an efficient and convenient access to furnish optically active α-hydroxyl-β-amino acids in high yield with high to excellent enantioselectivities. Control experiments and DFT calculations indicate that the transformation proceeds through trapping the in situ generated enol intermediate with methylene iminium ion, and the asymmetric induction was enabled by chiral pentacarboxycyclopentadiene anion via H-bonding and electrostatic interaction.
Silylium-Catalyzed Carbon–Carbon Coupling of Alkynylsilanes with (2-Bromo-1-methoxyethyl)arenes: Alternative Approaches
Rubial, Belén,Ballesteros, Alfredo,González, José M.
, p. 6194 - 6198 (2018/07/31)
The catalytic activation of alkynylsilanes towards 2-halo-1-alkoxyalkyl arenes gives β-halo-substituted alkynes. It involves the chemoselective substitution of an alkoxide by an alkyne in the presence of a neighboring C(sp3)–Br bond in a cationic C–C bond-forming event. Two complementary protocols to accomplish this new transformation are reported. The outcome of a direct approach based on mixing the precursors with a freshly prepared solution of the active catalytic species (TMSNTf2) is compared with an alternative based on smooth release of the required silylium ions upon selective activation of the alkyne by gold(I) (JohnPhosAuNTf2). The two approaches gave satisfactory results to access this otherwise elusive alkynylation process, which furnishes 4-bromo-substituted alkynes and tolerates various functional groups.
Insertion of carbenoids into X-H bonds catalyzed by the cyclobutadiene rhodium complexes
Loskutova, Natalia L.,Shvydkiy, Nikita V.,Nelyubina, Yulia V.,Perekalin, Dmitry S.
, p. 86 - 91 (2017/09/08)
The cyclobutadiene rhodium complex [(C4Et4)RhCl]2 (generated from [(C4Et4)Rh(p-xylene)]PF6 and BnNEt3Cl) catalyzes the reaction of methyl α-diazophenylacetate with RnX
Silica-supported HClO4 promotes catalytic solvent- and metal-free O-H insertion reactions with diazo compounds
Gallo, Rafael Douglas C.,Burtoloso, Antonio C. B.
, p. 4547 - 4556 (2018/10/17)
Solvent-free O-H insertion reactions in the presence of diazo carbonyl compounds were carried-out in very mild conditions. Unlike the traditional metal-catalysed version, employing rhodium acetate dimer, this method uses eco-friendly silica-supported HClO4 as the catalyst. Only 0.3 mol% of this Br?nsted acid catalyst, that can also be recycled several times, is necessary to guarantee very good yields (up to 97%) in the O-H insertion reactions. Reaction set-up is simple and permitted the preparation of forty-three α-hydroxy and α-alkoxy esters/ketones in just 1 h and at room temperature.
