Bond Insertion Reaction Research Articles

Enantioselective iron-catalysed O–H bond insertions

The ready availability, low price and environmentally benign character of iron mean that it is an ideal alternative to precious metals in catalysis. Recent growth in the number of iron-catalysed reactions reported reflects an increasing demand for sustainable chemistry. Only a limited number of chiral iron catalysts have been reported and these have, in general, proven less enantioselective than other transition-metal catalysts, thus limiting their appeal. Here, we report that iron complexes of spiro-bisoxazoline ligands are highly efficient catalysts for asymmetric O-H bond insertion reactions. These complexes catalyse insertions into the O-H bond of a wide variety of alcohols and even water, with exceptional enantioselectivities under mild reaction conditions. The selectivities surpass those obtained with other transition-metal catalysts. This study should inspire and encourage the use of iron instead of traditional precious metals in the development of greener catalysts for catalytic asymmetric synthesis.

Palladium- and Nickel-Catalyzed Carbon−Carbon Bond Insertion Reactions with Alkylidenesilacyclopropanes

Palladium and nickel catalysts promoted highly selective carbon-carbon bond insertion reactions with di-tert-butyl-alkylidenesilacyclopropanes. Pd(PPh(3))(4) was demonstrated to be the optimal catalyst, allowing for a variety of carbon-carbon pi-bond insertion reactions. Depending on the nature of the carbon-carbon pi bond, the insertion reaction proceeded with either direct insertion into the carbon(sp(2))-silicon bond or with allylic transposition. Ring-substituted alkylidenesilacyclopropanes required a nickel catalyst to afford insertion products. Using Ni(cod)(2) as the carbon-carbon bond insertion catalyst, new double alkyne insertion products and alkene isomerization products were observed.

Highly functionalized, enantiomerically pure furo[ x, y- c]pyrans via alkylidenecarbenes derived from sugar templates: synthesis and mechanism study via computational chemistry

The new method for the generation of alkylidenecarbenes based on the reaction of trimethylsilylazide/Bu 2SnO with α-cyanomesylates has been applied to readily available sugar derivatives for the synthesis of highly functionalized, enantiomerically pure furo[ x, y- c]pyrans. The furo[ x, y- c]pyran heterocyclic ring system is present in a number of natural or non-natural products of biological interest such as the miharamycins, and deserve particular attention. The scope and extent of the present new methodology has been investigated by systematic modification of the starting sugar precursor ( d-glucose, d-galactose, etc.) in the hexo-α(β)- d-pyranoside forms, bearing also different O-protecting groups, the effect of the absolute configuration of the substituent at the anomeric position, the location (C-2, -3 and -4) of the alkylidenecarbene species on the pyran nucleus, as well as the substitution (H or Ph) at the ‘carbon donor’ in the 1,5 C–H bond insertion process. In overall, using these key 1,5 C–H bond insertion reactions a simple protocol results for the synthesis of the furo[ x, y- c]pyrans, difficult to be prepared by other methodologies, from moderate to good yields. To examine the reactivity of the alkylidenecarbene, we have undertaken a systematic investigation of the insertion reactions of various alkylidenecarbene derivatives into C–H bonds using density functional theory.

Copper(0)-Induced Deselenative Insertion of N,N-Disubstituted Selenoamides into Acetylenic C−H Bond Leading to Propargylamines

Upon heating at 110 degrees C in the presence of copper(0) powder, terminal acetylenes undergo a novel deselenative C-H bond insertion reaction of N,N-disubstituted selenoamides, affording the corresponding propargylamines in good to excellent yields, selectively.

Copper-catalyzed enantioselective carbenoid insertion into S–H bonds

An asymmetric carbenoid insertion into S-H bonds catalyzed by copper-chiral spiro bisoxazoline complexes has been developed, in which a series of alpha-mercaptoesters were produced in high yields with moderate to good enantioselectivities (up to 85% ee); this result represents the best enantioselectivity in the catalytic asymmetric carbenoid S-H bond insertion reaction.

Copper‐Catalyzed Highly Enantioselective Carbenoid Insertion into SiH Bonds

Complete control: A highly efficient, copper-catalyzed, asymmetric carbenoid insertion into SiH bonds, using chiral spiro diimine (SIDIM) ligands (see scheme, Ar=2,6-Cl2C6H3, OTf=trifluoromethanesulfonate), produces a wide range of α-silylesters, in high yields with excellent enantiomeric excesses. This catalytic system offers unprecedented levels of enantiocontrol for the SiH bond insertion reaction.

The facile insertion of β-keto sulfones to arynes: The direct preparation of polysubstituted ortho-keto benzyl sulfones

One novel carbon–carbon bond insertion reaction of arynes has been developed. By this reaction β-keto sulfones can insert the triple bond of arynes to prepare polysubstituted ortho-keto benzyl sulfones.

Density functional theory calculation on the C-H bond insertion reaction of dibromocarbene with acetaldehyde

The insertion reaction mechanism of CBr2 with CH3CHO has been studied by using the B3LYP/6-31G(d) method. The geometries of reactions, transition state and products were completely optimized. All the energy of the species was obtained at the CCSD(T)/6-31G(d) level. All the transition state is verified by the vibrational analysis and the internal reaction coordinate (IRC) calculations. The results show that the propionaldehyde (HP1) is the main product of CH2 insertion with CH3CHO. The calculated results indicated that all the major pathways of the reaction were obtained on the singlet potential energy surface. The singlet CBr2 not only can insert the Cα-H [reaction I(1)]) but also can react with Cβ-H [reaction II(1)]. The statistical thermodynamics and Eyring transition state theory with Wigner correction are used to study the thermodynamic and kinetic characters of I(1) and II(1) in temperature range from 100 to 2200 K. The results show that the appropriate reaction temperature rang is 250 to 1750 K and 250 to 1600 K at 1.0 atm for I(1) and II(1) respectively. The rate constant and equilibrium constant are distinct in the range from 250 to 1000 K so that I(1) more easily occurs, while the reactions are not selected in the temperature range of 1000–1600 K.

Photoinduced FeCp Bond Cleavage and Insertion Reactions of Strained Silicon- and Sulphur-Bridged [1]Ferrocenophanes in the Presence of Transition-Metal Carbonyls

The photochemical reactions of the moderately strained sila[1]ferrocenophane [Fe(eta-C(5)H(4))(2)SiPh(2)] (1) and the highly strained thia[1]ferrocenophane [Fe(eta-C(5)H(4))(2)S] (8) with transition-metal carbonyls ([Fe(CO)(5)], [Fe(2)(CO)(9)] and [Co(2)(CO)(8)]) have been studied. The use of metal carbonyls has allowed the products of photochemically induced Fe-cyclopentadienyl (Cp) bond cleavage reactions in the [1]ferrocenophanes to be trapped as stable, characterisable products. During the course of these studies the synthesis of 8 from [Fe(eta-C(5)H(4)Li)(2)TMEDA] (TMEDA=N,N,N',N'-tetramethylethylenediamine) and S(SO(2)Ph)(2) has been significantly improved by a change of reaction solvent and temperature. Photochemical reaction of 1 with excess [Fe(CO)(5)] in THF gave the dinuclear complex [Fe(2)(CO)(2)(mu-CO)(2)(eta-C(5)H(4))(2)SiPh(2)] (9). The analogous photolytic reaction of 8 with [Fe(CO)(5)] in THF gave cyclic dimer [Fe(eta-C(5)H(4))(2)S](2) (10) and [Fe(2)(CO)(2)(mu-CO)(2)(eta-C(5)H(4))(2)S] (11), with the former being the major product. Photolysis of 1 with [Co(2)(CO)(8)] afforded the remarkable tetrametallic dimer [(CO)(2)Co(eta-C(5)H(4))SiPh(2)(eta-C(5)H(4))Fe(CO)(2)](2) (13). The corresponding photochemical reaction of 8 with [Co(2)(CO)(8)] gave a trimetallic insertion product in high conversion, [Co(CO)(4)(CO)(2)Fe(eta-C(5)H(4))S(eta-C(5)H(4))Co(CO)(2)] (14). These reactivity studies show that UV light promotes Fe-Cp bond cleavage reactions of both of the [1]ferrocenophanes 1 and 8. We have found that, whereas the less strained sila[1]ferrocenophane 1 requires photoactivation for Fe-Cp bond insertions to occur, the highly strained thia[1]ferrocenophane 8 undergoes both irradiative and non-irradiative insertions, although the latter occur at a slower rate. Our results suggest that such photoinduced bond cleavage reactions may be general and applicable to other related strained organometallic rings with pi-hydrocarbon ligands.

Cationic Aryl Complexes of the Rare-Earth Metals

Neutral rare-earth metal tri(aryl) complexes [Ln(C6H4-p-R)3(THF)2] (Ln = Lu, Sc; R = H, Me, Et), synthesized by reacting anhydrous metal trichloride with 3 equiv of the corresponding aryllithium, react with 1 or 2 equiv of [NR‘3H][BPh4] (R‘ = Et; R‘3 = PhMe2) to yield monocationic di(aryl) complexes [Ln(C6H4-p-R)2(THF)4]+[BPh4]- and dicationic mono(aryl) complexes [Ln(C6H4-p-R)(THF)5]2+[BPh4]-2, respectively. Single-crystal X-ray diffraction studies of the mono- and dicationic compounds [Sc(C6H5)2(THF)4]+[BPh4]- and [Lu(C6H5)(THF)5]2+[BPh4]-2 show distorted octahedral coordination geometry around the metal center in the cation. Kinetic studies for the reaction of the dicationic complex [Lu(C6H4-p-Me)(THF)5]2+[BPh4]-2 with pyridine suggest competition between C−H bond activation and insertion reactions.

Transition-Metal-Catalyzed Group Transfer Reactions for Selective C−H Bond Functionalization of Artemisinin

Three types of novel artemisinin derivatives have been synthesized through transition-metal-catalyzed intramolecular carbenoid and nitrenoid C-H bond insertion reactions. With rhodium complexes as catalysts, lactone 11 was synthesized via carbene insertion reaction at the C16 position in 90% yield; oxazolidinone 13 was synthesized via nitrene insertion reaction at the C10 position in 87% yield based on 77% conversion; and sulfamidate 14 was synthesized via nitrene insertion reaction at the C8 position in 87% yield.

A Convergent and Enantioselective Synthesis of (+)‐Amurensinine via Selective C—H and C—C Bond Insertion Reactions.

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A convergent and enantioselective synthesis of (+)-amurensinine via selective C-H and C-C bond insertion reactions.

A convergent and enantioselective synthesis of the natural product amurensinine is described. The synthetic strategy takes advantage of mild and selective C-H and C-C bond insertion reactions, in addition to the palladium-catalyzed aerobic oxidative kinetic resolution recently developed in these laboratories.

Matrix Isolation Infrared Spectroscopic and Theoretical Study of the Reactions of Beryllium Atoms with Methanol

Laser-ablated beryllium atoms have been reacted with methanol molecules during condensation in excess argon at 12 K. Absorptions due to CH3OBeH, CH3BeOH, and CH3BeOBeH were observed and identified on the basis of isotopic IR studies with 13CH3OH, CH318OH, and CH3OD, as well as quantum chemical calculations. The beryllium atoms were observed to insert spontaneously into the O−H bond of methanol to form the CH3OBeH molecule, while the C−O bond insertion reaction to give the more stable CH3BeOH product requires activation energy. The CH3BeOH or CH3OBeH molecules could further react with a beryllium atom to form the CH3BeOBeH molecule.

Redox activation of dicarbonyl(η 5-cyclopentadienyl)methyl iron within the cavity of β-cyclodextrin: carbon monoxide insertion in iron–methyl bond

The organometallic complex CpFe(CO) 2CH 3 is included in a β-cyclodextrin cavity, retains its redox activity and undergoes CO insertion into the methyl–metal bond. The reaction inside the cavity suppresses undesirable loss of released CO from the reaction site. This simplifies the mechanism of the bond-insertion reaction in the presence of cyclodextrin. Further enhancement is observed in presence of free CO, which can penetrate to the reaction site inside the cyclodextrin cavity.

Dipyridylketone binding and subsequent C–C bond insertion reactions at cyclopentadienylrhodium

UV irradiation of a solution of (eta5-C5H5)bis(ethene)rhodium in the presence of 2,2'-dipyridylketone yields (eta5-C5H5)Rh(kappa2-N,O-2,2'-dipyridylketone) which inserts ethene to yield a bicyclic oxametallacyclopentane.

Linear Free Energy Relationship Studies of the Dimethyldioxirane C-H Bond Insertion Reaction

Linear Free Energy Relationship Studies of the Dimethyldioxirane C-H Bond Insertion Reaction

N-hydroxysuccinimide ester functionalized perfluorophenyl azides as novel photoactive heterobifunctional cross-linking reagents. The covalent immobilization of biomolecules to polymer surfaces.

The synthesis of N-hydroxysuccinimide (NHS) functionalized perfluorophenyl azides (PFPAs) 2 and 3 is described together with a general method for the covalent modification of polymer surfaces using heterobifunctional, photoactivable cross-linking reagents 1 and 3. The NHS-active ester group becomes covalently attached to the polymer surface via an efficient CH bond insertion reaction of the photogenerated, highly reactive nitrene intermediate derived from the PFPA. The NHS ester is capable of further reaction with a variety of primary amine-containing reagents including biomolecules by way of amide formation. The method is illustrated as follows. Photolysis of polystyrene (PS) and poly-(3-octylthiophene) (P3OT) thin films spin-coated with NHS PFPA ester 1 or 3 gave films 8 or 9, respectively. Each film was then exposed to an aqueous solution of horseradish peroxidase (HRP), giving films 10 or 11, respectively. The amounts of HRP immobilized on PS and P3OT were calculated from enzyme activity assays to be 0.5 +/- 0.1 ng/mm2 for 10a, 1.0 +/- 0.2 ng/mm2 for 11a, 0.2 +/- 0.1 ng/mm2 for 10b, 0.3 +/- 0.1 ng/mm2 for 11b. Using this surface functionalization methodology, biotin-streptavidin-biotin-HRP was constructed on the PS film. The storage stability of HRP thus immobilized through the extended linker, biotin-streptavidin-biotin, was enhanced as compared to that of HRP directly immobilized on the PS surface.

Dioxirane chemistry. Part 25. The effect of solvent on the dimethyldioxirane carbon–hydrogen bond insertion reaction

Second order rate coefficients for the insertion reaction of dimethyldioxirane with cis-1,2-dimethylcyclohexane have been measured in several binary solvents. The reaction proceeds stereospecifically with retention to give a single alcohol product as reported earlier. The data were treated with the Kamlet–Taft α parameter taken from the multi-parameter solvent effect equation devised by these authors. The α parameter measures the hydrogen bond donor capacity of the solvent. An excellent correlation was observed between the rate coefficients and the α values indicating that the insertion reaction is facilitated by solvents with hydrogen bond donor properties. A spiro type transition state is proposed for the insertion reaction.

Carbene rearrangements. Part. 42. Intramolecular addition versus novel carbon-hydrogen bond insertion reactions of n-alkenyl-substituted cyclopropylidenes

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCarbene rearrangements. Part. 42. Intramolecular addition versus novel carbon-hydrogen bond insertion reactions of n-alkenyl-substituted cyclopropylidenesThomas Miebach, Hartmut Wuster, and Udo H. BrinkerCite this: J. Org. Chem. 1993, 58, 23, 6520–6523Publication Date (Print):November 1, 1993Publication History Published online1 May 2002Published inissue 1 November 1993https://doi.org/10.1021/jo00075a067RIGHTS & PERMISSIONSArticle Views114Altmetric-Citations10LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (505 KB) Get e-Alerts Get e-Alerts