15047-76-4Relevant academic research and scientific papers
The condensation of carbonyl compounds with electron-rich arenes: Mercury, thallium, gold or a proton?
Hashmi, A. Stephen K.,Schwarz, Lothar,Rubenbauer, Philipp,Blanco, M. Carmen
, p. 705 - 708 (2006)
Gold(III) chloride, mercury(II) perchlorate, thallium(III) perchlorate and p-toluenesulfonic acid were found to efficiently catalyze the condensation of two furans with aldehydes or acetone. The olefinic unit of α,β- unsaturated carbonyl compounds reacts faster than the carbonyl group, other olefins do not react selectively. The first (addition) step is rate-limiting, the second (substitution) step is much faster.
Dynamic Kinetic Cross-Electrophile Arylation of Benzyl Alcohols by Nickel Catalysis
Guo, Peng,Wang, Ke,Jin, Wen-Jie,Xie, Hao,Qi, Liangliang,Liu, Xue-Yuan,Shu, Xing-Zhong
, p. 513 - 523 (2021/01/12)
Catalytic transformation of alcohols via metal-catalyzed cross-coupling reactions is very important, but it typically relies on a multistep procedure. We here report a dynamic kinetic cross-coupling approach for the direct functionalization of alcohols. The feasibility of this strategy is demonstrated by a nickel-catalyzed cross-electrophile arylation reaction of benzyl alcohols with (hetero)aryl electrophiles. The reaction proceeds with a broad substrate scope of both coupling partners. The electron-rich, electron-poor, and ortho-/meta-/para-substituted (hetero)aryl electrophiles (e.g., Ar-OTf, Ar-I, Ar-Br, and inert Ar-Cl) all coupled well. Most of the functionalities, including aldehyde, ketone, amide, ester, nitrile, sulfone, furan, thiophene, benzothiophene, pyridine, quinolone, Ar-SiMe3, Ar-Bpin, and Ar-SnBu3, were tolerated. The dynamic nature of this method enables the direct arylation of benzylic alcohol in the presence of various nucleophilic groups, including nonactivated primary/secondary/tertiary alcohols, phenols, and free indoles. It thus offers a robust alternative to existing methods for the precise construction of diarylmethanes. The synthetic utility of the method was demonstrated by a concise synthesis of biologically active molecules and by its application to peptide modification and conjugation. Preliminary mechanistic studies revealed that the reaction of in situ formed benzyl oxalates with nickel, possibly via a radical process, is an initial step in the reaction with aryl electrophiles.
A two-phase system for the clean and high yield synthesis of furylmethane derivatives over -SO3H functionalized ionic liquids
Shinde,Rode
, p. 4804 - 4810 (2017/10/19)
A new and effective unique two-phase reaction system is investigated for the high yield production of tri(furyl)methane from furfural and furan. This strategy includes the use of an acidic aqueous phase (water + -SO3H functionalized IL) and furan phase, which significantly suppresses polymer formation, thereby increasing the yield of tri(furyl)methane. Furan serves as a reactant as well as an extraction solvent for the recovery of the condensation products. For comparison, different -SO3H functionalized ionic liquids are prepared and their performances evaluated for the condensation of furan and furfural. The ionic liquids with alkyl chain linkers are found to be more effective and acidic than those with imidazolium linked N-sulfonic acids. In addition, an increase in carbon chain length between imidazole/tri-ethylamine/pyridine and -SO3H, increases the catalytic activity of the respective ionic liquids. Among the several prepared ionic liquids, the strongly acidic imidazolium based butylsulfonic acid 6 shows the best activity with a maximum condensation product yield of 84%. This strategy offers a significantly high yield of the condensation products of furan and furfural compared to the traditional mineral acid route. The activity and stability of the -SO3H functionalized 6 is confirmed from seven successful recycles, in which there is no reduction in its activity. Finally, this new strategy is successfully extended for the condensation of furan derivatives (e.g. furan and 2-methylfuran) with several different aldehydes, ketones and alcohols.
Positional Selectivity in C-H Functionalizations of 2-Benzylfurans with Bimetallic Catalysts
Zhang, Jiadi,Sha, Sheng-Chun,Bellomo, Ana,Trongsiriwat, Nisalak,Gao, Feng,Tomson, Neil C.,Walsh, Patrick J.
supporting information, p. 4260 - 4266 (2016/05/02)
Metal-catalyzed carbon-carbon bond-forming reactions are a mainstay in the synthesis of pharmaceutical agents. A long-standing problem plaguing the field of transition metal catalyzed C-H functionalization chemistry is control of selectivity among inequivalent C-H bonds in organic reactants. Herein we advance an approach to direct site selectivity in the arylation of 2-benzylfurans founded on the idea that modulation of cooperativity in bimetallic catalysts can enable navigation of selectivity. The bimetallic catalysts introduced herein exert a high degree of control, leading to divergent site-selective arylation reactions of both sp2 and sp3 C-H bonds of 2-benzylfurans. It is proposed that the selectivity is governed by cation-π interactions, which can be modulated by choice of base and accompanying additives [MN(SiMe3)2, M = K or Li·12-crown-4].
Organocatalytic Nonclassical Trienamine Activation in the Remote Alkylation of Furan Derivatives
Skrzyńska, Anna,Przydacz, Artur,Albrecht, ?ukasz
supporting information, p. 5682 - 5685 (2015/12/01)
A new approach for the stereoselective remote alkylation of furan derivatives is reported. The reaction of 5-alkylfurfurals with nitroolefins as electrophilic counterparts occurs at their exocyclic ε-position and proceeds through the intermediacy of a non
AsCat and FurCat: New Pd catalysts for selective roomerature Stille cross-couplings of benzyl chlorides with organostannanes
Ronson, Thomas O.,Carney, Jonathan R.,Whitwood, Adrian C.,Taylor, Richard J. K.,Fairlamb, Ian J. S.
supporting information, p. 3466 - 3469 (2015/03/04)
Two novel succinimide-based palladium complexes, AsCat and FurCat, are highly efficient catalysts for roomerature Stille cross-coupling of organostannanes with benzyl chlorides. The air- and moisture-stable catalysts are prepared in one step, and the coupling reactions proceed with a high selectivity for the benzyl position under mild conditions without the need for additives. This journal is
Proton-exchanged montmorillonite-mediated reactions of methoxybenzyl esters and ethers
Chen, Dongyin,Xu, Chang,Deng, Jie,Jiang, Chunhuan,Wen, Xiaoan,Kong, Lingyi,Zhang, Ji,Sun, Hongbin
, p. 1975 - 1983 (2014/03/21)
Proton-exchanged montmorillonite (H-mont) was found to be an eco-friendly and cost-effective catalyst for the generation of O-methylated quinone methides (QM) from the corresponding p or o-methoxybenzyl esters and ethers. Nucleophilic trapping of the O-methylated QM with arenes, alcohols, 1,3-dicarbonyl compounds, silyl enol ethers, and allylsilanes has been carried out, respectively, leading to eco-friendly benzylation reactions. Using this protocol, H-mont-mediated deprotection of PMB-protected esters and ethers have been realized for the first time. This work would pave the way for further exploration in O-alkylated QM that are of chemical and biological significance.
Synthesis of diarylmethanes via metal-free reductive cross-coupling of diarylborinic acids with tosyl hydrazones
Li, Xijing,Feng, Yuanyuan,Lin, Lin,Zou, Gang
, p. 10991 - 10995 (2013/02/22)
This paper describes a practical and efficient procedure that takes advantage of diarylborinic acids as a cost-effective alternative to arylboronic acids for synthesis of diarylmethanes through metal-free reductive cross-coupling with N-tosylhydrazones of aromatic aldehydes and ketones. The procedure tolerates hydroxyl, halide, amine, and allyl functionality, complementary to the transition-metal catalyzed cross-coupling techniques.
Palladium-catalyzed coupling reactions of (ArCH2)Ti(O-i-Pr) 3 with aromatic or heteroaromatic bromides
Chang, Shu-Ting,Li, Qinghan,Chiang, Ruei-Tang,Gau, Han-Mou
experimental part, p. 3956 - 3962 (2012/07/02)
Three benzyltitanium compounds of (ArCH2)Ti(O-i-Pr)3 (Ar = Ph (1a), 4-MeOC6H4 (1b), 4-FC6H 4 (1c)) were prepared and used as benzyl nucleophiles for coupling reactions with aromatic or heteroaromatic bromides. The simple catalytic system of 1 mol % Pd(OAc)2 and 2 mol % PCy3 worked efficiently for a wide variety of aromatic bromides, producing diarylmethanes in good to excellent yields of up to 96%. Coupling reactions of hindered aromatic bromides or aromatic bromides containing electron-withdrawing substituents were slower over longer reaction times of 3-6 h. Reactions of heteroaromatic bromides of bromopyridines, bromofurans, or bromothiophenes with benzyl reagents of 1a or 1b required either longer reaction times of 12-24 h or a higher reaction temperature of 80 °C, producing pyridyl-, furyl-, and thienyl-arylmethanes in moderate yields.
Cross-coupling of grignard reagents with sulfonyl-activated sp3 carbon-nitrogen bonds
Li, Man-Bo,Tang, Xiang-Ling,Tian, Shi-Kai
, p. 1980 - 1984 (2011/10/12)
Sulfonyl-activated sp3 carbon-nitrogen bonds have been found to be cleaved by Grignard reagents in the presence of 5 mol% of copper(I) iodide (CuI). Significantly, a broad range of sulfonyl-activated benzylic, allylic, and propargylic amines smoothly undergo the cross-coupling reaction with Grignard reagents to afford structurally diverse coupling products in good to excellent yields and with high chemo-, regio-, and stereoselectivity. Moreover, an S N2 mechanism has been demonstrated to be involved in the cross-coupling reaction that allows the asymmetric synthesis of chiral hydrocarbons from optically active α-branched amine derivatives. Copyright
