61971-91-3Relevant academic research and scientific papers
DABCO-promoted photocatalytic C-H functionalization of aldehydes
Cardozo, Thiago Messias,Da Silva Santos, Bruno Maia,Finelli, Fernanda Gadini,de Souza, Cauê Paula,dos Santos Dupim, Mariana
supporting information, p. 2959 - 2967 (2022/01/12)
Herein we present a direct application of DABCO, an inexpensive and broadly accessible organic base, as a hydrogen atom transfer (HAT) abstractor in a photocatalytic strategy for aldehyde C-H activation. The acyl radicals generated in this step were arylated with aryl bromides through a well stablished nickel cross-coupling methodology, leading to a variety of interesting aryl ketones in good yields. We also performed computational calculations to shine light in the HAT step energetics and determined an optimized geometry for the transition state, showing that the hydrogen atom transfer between aldehydes and DABCO is a mildly endergonic, yet sufficiently fast step. The same calculations were performed with quinuclidine, for comparison of both catalysts and the differences are discussed.
Self-Assembled 2,3-Dicyanopyrazino Phenanthrene Aggregates as a Visible-Light Photocatalyst
He, Min,Yu, Xiaoqiang,Wang, Yi,Li, Fei,Bao, Ming
, p. 5016 - 5025 (2021/04/12)
In this study, 2,3-dicyanopyrazino phenanthrene (DCPP), a commodity chemical that can be prepared at an industrial scale, was used as a photocatalyst in lieu of Ru or Ir complexes in C-X (X = C, N, and O) bond-forming reactions under visible-light irradiation. In these reactions, [DCPP]n aggregates were formed in situ through physical π-πstacking of DCPP monomers in organic solvents. These aggregates exhibited excellent photo- and electrochemical properties, including a visible light response (430 nm), long excited-state lifetime (19.3 μs), high excited-state reduction potential (Ered([DCPP]n*/[DCPP]n·-) = +2.10 V vs SCE), and good reduction stability. The applications of [DCPP]n aggregates as a versatile visible-light photocatalyst were demonstrated in decarboxylative C-C cross-coupling, amidation, and esterification reactions.
Palladium-Catalyzed Carbonylative Coupling of Aryl Iodides with Alkenylaluminum Reagents
Chen, Bo,Wu, Xiao-Feng
supporting information, p. 7624 - 7629 (2019/10/02)
A highly reactive catalytic system for the carbonylative coupling of aryl iodides with alkenylaluminum reagents has been developed. Various β-substituted γ,δ-unsaturated ketones were produced under mild conditions in good to excellent yields even under ppm level of palladium catalyst. Notably, this also represents the first example on carbonylative transformation of alkenylaluminum compounds. Additionally, by the addition of zinc salt, the selectivity of the product can be modified.
Iron-Catalyzed Oxyalkylation of Terminal Alkynes with Alkyl Iodides
Deng, Weili,Ye, Changqing,Li, Yajun,Li, Daliang,Bao, Hongli
supporting information, p. 261 - 265 (2019/01/10)
A general oxyalkylation of terminal alkynes enabled by iron catalysis has been developed. Primary and secondary alkyl iodides acted as the alkylating reagents and afforded a range of α-alkylated ketones under mild reaction conditions. Acetyl tert-butyl peroxide (TBPA) was used as the radical relay precursor, providing the initiated methyl radical to start the radical relay process. Preliminary mechanistic studies were conducted, and late-stage functionalizations of natural product derivatives were performed.
Halogen-bonded iodonium ion catalysis: A route to α-hydroxy ketones: Via domino oxidations of secondary alcohols and aliphatic C-H bonds with high selectivity and control
Guha, Somraj,Kazi, Imran,Mukherjee, Pranamita,Sekar, Govindasamy
supporting information, p. 10942 - 10945 (2017/10/13)
A domino synthesis of α-hydroxy ketones has been developed from benzylic secondary alcohols employing catalytic iodonium ions stabilized by DMSO. The reaction proceeds through an unprecedented sequential oxidation of alcohols to ketone and its α-hydroxylation in a controlled manner. The spectroscopic evidence establishes the possibility of formation of a stable halogen-bonded adduct between DMSO and iodonium ions.
DECARBOXYLATIVE CROSS-COUPLING AND APPLICATIONS THEREOF
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Page/Page column 31; 32; 35; 36, (2015/12/09)
Methods described herein enable the production of numerous molecular species through decarboxylative cross-coupling via use of photoredox and transition metal catalysts. For example, methods described herein enable the production of numerous molecular species through decarboxylative cross-coupling via use of photoredox and transition metal catalysts. A method described herein, in some embodiments, comprises providing a reaction mixture including a photoredox catalyst, a transition metal catalyst, a coupling partner and a substrate having a carboxyl group. The reaction mixture is irradiated with a radiation source resulting in cross-coupling of the substrate and coupling partner via a mechanism including decarboxylation, wherein the coupling partner is selected from the group consisting of a substituted aromatic compound and a substituted aliphatic compound.
Merging Photoredox and Nickel Catalysis: The Direct Synthesis of Ketones by the Decarboxylative Arylation of α-Oxo Acids
Chu, Lingling,Lipshultz, Jeffrey M.,Macmillan, David W. C.
supporting information, p. 7929 - 7933 (2015/06/30)
The direct decarboxylative arylation of α-oxo acids has been achieved by synergistic visible-light-mediated photoredox and nickel catalysis. This method offers rapid entry to aryl and alkyl ketone architectures from simple α-oxo acid precursors via an acyl radical intermediate. Significant substrate scope is observed with respect to both the oxo acid and arene coupling partners. This mild decarboxylative arylation can also be utilized to efficiently access medicinal agents, as demonstrated by the rapid synthesis of fenofibrate. The direct decarboxylative arylation of α-oxo acids has been achieved by synergistic visible-light-mediated photoredox and nickel catalysis. This method offers rapid entry to aryl and alkyl ketone architectures from simple α-oxo acid precursors via an acyl radical intermediate. Significant substrate scope is observed with respect to both the oxo acid and arene coupling partners.
Role of sterically demanding chiral dirhodium catalysts in site-selective C-H functionalization of activated primary C-H bonds
Qin, Changming,Davies, Huw M. L.
supporting information, p. 9792 - 9796 (2014/07/22)
The influence of sterically demanding dirhodium tetracarboxylate catalysts on the site selectivity of C-H functionalization by means of rhodium carbene-induced C-H insertion is described. The established dirhodium tetraprolinate-catalyzed reactions of aryldiazoacetates cause preferential C-H functionalization of secondary C-H bonds as a result of competing steric and electronic effects. The sterically more demanding dirhodium tetrakis(triarylcyclopropanecarboxylate) catalysts, exemplified by dirhodium tetrakis[(R)-(1-(biphenyl)-2,2-diphenylcyclopropanecarboxylate)] [Rh 2(R-BPCP)4], favor C-H functionalization of activated primary C-H bonds. Highly site-selective and enantioselective C-H functionalization of a variety of simple substrates containing primary benzylic, allylic, and methoxy C-H bonds was achieved with this catalyst. The utility of this approach has been demonstrated by the late-stage primary C-H functionalization of (-)-∝-cedrene and a steroid.
A heterogeneous Ru/CeO2 catalyst effective for transfer-allylation from homoallyl alcohols to aldehydes
Miura, Hiroki,Wada, Kenji,Hosokawa, Saburo,Sai, Masahiro,Kondo, Teruyuki,Inoue, Masashi
scheme or table, p. 4112 - 4114 (2009/12/25)
A simple heterogeneous Ru/CeO2 catalyst was found to be effective for transfer-allylation from homoallyl alcohols to aldehydes, followed by isomerization to give the saturated ketones in high yields.
PROCESS FOR PREPARING KETONES FROM ALPHA-OXO CARBOXYLATES AND ARYL BROMIDES
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Page/Page column 3-4, (2009/09/08)
A process for preparing ketones of the general formula (III) where R is an optionally substituted carbocyclic aromatic radical having 6 to 24 carbon atoms or an optionally substituted alkyl radical or an optionally substituted heteroaromatic radical having 5 to 24 carbon atoms, andR1 is an optionally substituted carbocyclic aromatic radical having 6 to 24 carbon atoms or an optionally substituted heteroaromatic radical having 5 to 24 carbon atoms, by reacting alpha-oxo carboxylates of the general formula (I) wherein n and m is a number in the range from 1 to 6, M(m+) is a cation, and R has the meaning indicated for formula (III), with aryl bromides of the general formula (II) [in-line-formulae]R1—Br ??(II)[/in-line-formulae] where R1 has the meaning indicated for formula (III), in the presence of two transition metals or compounds thereof as catalyst, is described.
