Diazocarbonyl Compounds Research Articles

Recent Advances in Catalytic Selective Synthesis of Epoxide and Aziridine via Diazocarbonyl Compound

Recent Advances in Catalytic Selective Synthesis of Epoxide and Aziridine via Diazocarbonyl Compound

Chiral Dirhodium(II) Catalysts for Selective Metal Carbene Reactions

Dirhodium(II) catalysts have proven effectiveness in controlling selectivity in metal carbene reactions of diazocarbonyl compounds. Over the years many dirhodium(II) paddlewheel derivatives with chiral ligands have been advanced, but three structural classes have emerged as being most effective for inducing high stereocontrol: chiral dirhodium carboxamidates derived from cyclic chiral carboxamides and chiral dirhodium carboxylic acids derived from sybstituted chiral prolinates or from phthalimide-protected α-amino acids. This review focuses on describing which of these classes of chiral dirhodium(II) catalysts have provided the highest levels of stereocontrol in intramolecular and intermolecular reactions of diazoacetates, diazoacetoacetates and diazomalonates, vinyl- and aryldiazoacetates, and enoldiazoacetates. Assessment is taken from published results that compare catalyst results for cyclopropanation, cyclopropenation, C-H insertion, ylide formation and reactions, as well as cycloaddition reactions, especially [3+3]- and [4+3]-cycloaddition. Keywords: Chiral durhodium(II) catalysts, acceptor-acceptor metal carbenes, donor-acceptor metal carbenes, enoldiazoacetates, enantioselectivity, cycloaddition, insertion, cyclopropanation.

Total Synthesis of the Posttranslationally Modified Polyazole Peptide Antibiotic Plantazolicin A.

The power of rhodium-carbene methodology in chemistry is demonstrated by the synthesis of a structurally complex polyazole antibiotic. Plantazolicin A, a novel soil-bacterium metabolite, comprises a linear array of 10 five-membered rings in two pentacyclic regions that derive from ribosomal peptide synthesis followed by extensive posttranslational modification. The compound possesses potent antimicrobial activity, and is selectively active against the anthrax-causing organism. A conceptually different synthesis of plantazolicin A is reported in which the key steps are the use of rhodium(II)-catalyzed reactions of diazocarbonyl compounds to generate up to six of the seven oxazole rings of the antibiotic. NMR spectroscopic studies and molecular modeling reveal a likely dynamic hairpin conformation with a hinge region around the two isoleucine residues. The compound has modest activity against methicillin-resistant Staphylococcus aureus (MRSA).

Reactions of (1E)‐Buta‐1,3‐dien‐1‐yl Acetate with Diazocarbonyl Compounds

AbstractCarbene transfer to appropriate substrates is a highly versatile tool for the construction of carbon frameworks with increased functional and structural complexity. In this study, some novel cyclopropane derivatives were synthesized via carbenoid reactions and their further reactivities were investigated. (1E)‐Buta‐1,3‐dien‐1‐yl acetate was reacted with four different diazocarbonyl compounds, ethyl diazoacetate, dimethyl diazomalonate, 1‐diazo‐1‐phenylpropan‐2‐one, and methyl (3E)‐2‐diazo‐4‐phenylbut‐3‐enoate, in the presence of two catalysts. All synthesized substituted cyclopropanes were obtained chemoselectively with respect to less‐hindered CC bonds. Under the applied conditions, while cyclopropanes 7a and 7d underwent further reactions, cyclopropanes 7b and 7c were stable enough. Cyclopropanes 7a and an additional equivalent of ethyl diazoacetate yielded polyfunctionalized cyclohexenes. Cyclopropanes from methyl (3E)‐2‐diazo‐4‐phenylbut‐3‐enoate yielded polyfunctionalyzed cycloheptadiene isomers by Cope rearrangement.

The insertion reaction of diazocarbonyl compounds at С–Н bonds in the synthesis of biologically active nitrogen- and oxygen-containing heterocycles

This review offers a systematic analysis of literature data about intramolecular C–H insertion reactions of diazocarbonyl compounds, applicable to the synthesis of biologically active nitrogen- and oxygen-containing heterocyclic systems.

Redox-neutral rhodium-catalyzed C-H functionalization of arylamine N-oxides with diazo compounds: primary C(sp(3))-H/C(sp(2))-H activation and oxygen-atom transfer.

An unprecedented rhodium(III)-catalyzed regioselective redox-neutral annulation reaction of 1-naphthylamine N-oxides with diazo compounds was developed to afford various biologically important 1H-benzo[g]indolines. This coupling reaction proceeds under mild reaction conditions and does not require external oxidants. The only by-products are dinitrogen and water. More significantly, this reaction represents the first example of dual functiaonalization of unactivated a primary C(sp(3) )H bond and C(sp(2) )H bond with diazocarbonyl compounds. DFT calculations revealed that an intermediate iminium is most likely involved in the catalytic cycle. Moreover, a rhodium(III)-catalyzed coupling of readily available tertiary aniline N-oxides with α-diazomalonates was also developed under external oxidant-free conditions to access various aminomandelic acid derivatives by an O-atom-transfer reaction.

Redox‐Neutral Rhodium‐Catalyzed CH Functionalization of Arylamine N‐Oxides with Diazo Compounds: Primary C(sp3)H/C(sp2)H Activation and Oxygen‐Atom Transfer

AbstractAn unprecedented rhodium(III)‐catalyzed regioselective redox‐neutral annulation reaction of 1‐naphthylamine N‐oxides with diazo compounds was developed to afford various biologically important 1H‐benzo[g]indolines. This coupling reaction proceeds under mild reaction conditions and does not require external oxidants. The only by‐products are dinitrogen and water. More significantly, this reaction represents the first example of dual functiaonalization of unactivated a primary C(sp3)H bond and C(sp2)H bond with diazocarbonyl compounds. DFT calculations revealed that an intermediate iminium is most likely involved in the catalytic cycle. Moreover, a rhodium(III)‐catalyzed coupling of readily available tertiary aniline N‐oxides with α‐diazomalonates was also developed under external oxidant‐free conditions to access various aminomandelic acid derivatives by an O‐atom‐transfer reaction.

Advances in the Enantioselective Metal-catalyzed N-H and O-H Insertion Reactions with Diazocarbonyl Compounds

Advances in the Enantioselective Metal-catalyzed N-H and O-H Insertion Reactions with Diazocarbonyl Compounds

Stereoselective Synthesis of Highly Substituted Tetrahydrofurans through Diverted Carbene OH Insertion Reaction

AbstractCopper‐ or rhodium‐catalyzed reactions of diazocarbonyl compounds with β‐hydroxyketones give highly substituted tetrahydrofurans with excellent diastereoselectivity. Under mild conditions, the single‐step process starts as a carbene OH insertion reaction, but is diverted by an intramolecular aldol reaction.

Stereoselective Synthesis of Highly Substituted Tetrahydrofurans through Diverted Carbene O-H Insertion Reaction.

Copper- or rhodium-catalyzed reactions of diazocarbonyl compounds with β-hydroxyketones give highly substituted tetrahydrofurans with excellent diastereoselectivity. Under mild conditions, the single-step process starts as a carbene O-H insertion reaction, but is diverted by an intramolecular aldol reaction.

ChemInform Abstract: Pseudopericyclic 1,5‐ versus Pericyclic 1,4‐ and 1,6‐Electrocyclization in Electron‐Poor 4‐Aryl‐2‐azabuta‐1,3‐dienes: Indole Synthesis from 2H‐Azirines and Diazo Compounds.

AbstractThe Rh(II)‐catalyzed coupling reactions of azirines with diazocarbonyl compounds is found to depend on the nature of the azirine and diazocarbonyl substituents.

Structures and Reactivity of Group 9 Metalloporphyrin Complexes

The importance of metalloporphyrins is highlighted by their wide occurrence and use in nature. Essential biological roles of metalloporphyrins include electron-, energy-, and oxygen-transfer, oxygen activation, and diverse functions in enzyme active sites. Due to a broad range of physical and chemical properties, metalloporphyrins have been modified for a variety of applications such as novel components in advanced materials, sensors, medical research, and synthetic chemistry. Metalloporphyrins are also of great utility for non-biological chemical catalysis, spanning reactions such as aziridination,1 C-H activation,1 and olefination.2 Moreover, metalloporphyrins are useful, atom-efficient catalysts for the generation of new carbon-carbon and heteroatom bonds using diazo carbonyl compounds.1 Thus, understanding the structures and reactivities of metalloporphyins is vital for developing and optimizing new uses. Our current work focuses on group 9 (Rh, Ir) metalloporphyrins. This includes probing the reactivity of coordination complexes and determining the structures of the subsequent products.3 Recently, tetratolylporphyrinato (TTP) methyliridium, Ir(TTP)CH3, was shown to be an active and robust catalyst for the cyclopropanation of olefins using diazo reagents as carbene sources.4 Ir(TTP)CH3 also catalyzes N–H insertion reactions between ethyl diazoacetate (EDA) or methyl phenyldiazoacetate (MPDA) and a variety of aryl, aliphatic, primary, and secondary amines.5 Reactions with aryl amines produce the highest yields with up to 105 catalyst turnovers and without the need for slow addition of the diazo reagent. Mechanistic aspects of diazo insertion reactions are examined. In addition, a comparison of the molecular structures of RhIII(TTP) and IrIII(TTP) carbene complexes provides insights for understanding reactivity differences for the two metals complexes.6

Intramolecular Insertions into Unactivated C(sp³)-H Bonds by Oxidatively Generated β-Diketone-α-Gold Carbenes: Synthesis of Cyclopentanones.

Generation of reactive α-oxo gold carbene intermediates via gold-catalyzed oxidation of alkynes has become an increasing versatile strategy of replacing hazardous diazo carbonyl compounds with benign and readily available alkynes in the development of efficient synthetic methods. However, one of the hallmarks of metal carbene/carbenoid chemistry, i.e., insertion into an unactivated C(sp(3))-H bond, has not be realized. This study reveals for the first time that this highly valuable transformation can be readily realized intramolecularly by oxidatively generated β-diketone-α-gold carbenes using ynones as substrates. Substrate conformation control via the Thorpe-Ingold effect is the key design feature that enables generally good to excellent efficiencies, and synthetically versatile cyclopentanones including spiro-, bridged, and fused bicyclic ones can be readily accessed.

ChemInform Abstract: Azide Trapping of Metallocarbenes: Generation of Reactive C‐Acylimines and Domino Trapping with Nucleophiles.

AbstractThe reactive intermediate C‐acylimines are generated from azide‐tethered diazocarbonyl compounds under Cu catalyzed conditions.

Elusive 2H-1,2-oxasiletes through reactions of an isolable dialkylsilylene with diazocarbonyl compounds.

The reactions of isolable dialkysilylene 1 with 2-diazo-1,2-diphenylethanone and ethyl 2-diazo-2-phenylacetate gave elusive silacycles, 2H-1,2-oxasiletes 2 and 3, respectively, in high yields. Because these reactions occur at low temperatures of ca.-30 °C, initial complexation of the silylene to the carbonyl oxygen of the diazocarbonyl compounds is suggested to trigger dinitrogen elimination followed by cyclization. In contrast, a six-membered cyclic diazo compound 8 and 1-sila-2,3-diazabicyclo[3.3.0]oct-3-ene 10 were obtained in good yields by the reaction of 1 with less reactive ethyl 2-diazo-3-oxo-3-phenylpropanoate 7 and trimethylsilyldiazomethane 9. Molecular structures of 2, 3, 8 and 10 were determined by X-ray crystallography.

Pd錯体を開始剤とするジアゾカルボニル化合物の重合

Pd錯体を開始剤とするジアゾカルボニル化合物の重合

Rh(III)-catalyzed chelation-assisted intermolecular carbenoid functionalization of α-imino Csp(3)-H bonds.

A Rh(iii)-catalyzed cross-coupling/cyclization cascade of α-imino Csp(3)-H bonds with donor/acceptor α-acyl diazocarbonyl compounds has been developed. This novel transformation involves ligand-directed Csp(3)-H bond functionalization with carbenoids under the pyridine-chelation assistance, and offered an efficient access to synthetically versatile polysubstituted N-(2-pyridyl)pyrroles with a broad range of functional group tolerance.

Domino reactions of diazodicarbonyl compounds with α,β-unsaturated δ-amino esters: a convenient way towards 2-oxopiperidines, dihydropyridinones and isoquinolinediones.

Thermal decomposition of a series of diazodicarbonyl compounds in the presence of α,β-unsaturated δ-amino esters and sodium hydride gives rise to a variety of nitrogenous heterocycles. The direction of these processes is highly dependent on the structure of the initial reagents giving rise to the formation of multi-functionalized 2-oxopiperidines, 5,6-dihydropyridin-2(1H)-ones or tetrahydroisoquinoline-1,6(2H,8aH)-diones. The reactions occur in domino processes involving the Wolff rearrangement of diazocarbonyl compounds, NaH-catalyzed anti-stereoselective intramolecular Michael addition to the α,β-unsaturated system of amino esters, and in some cases also cycloelimination and intramolecular Claisen condensation of the initial products formed.

Pseudopericyclic 1,5- versus Pericyclic 1,4- and 1,6-Electrocyclization in Electron-Poor 4-Aryl-2-azabuta-1,3-dienes: Indole Synthesis from 2H-Azirines and Diazo Compounds.

Transformations of 2-azabuta-1,3-dienes, formed in Rh2(OAc)4-catalyzed reactions of diazo carbonyl compounds with 2H-azirines, dramatically depend on the nature of substituents. 4,4-Diphenyl-2-azabuta-1,3-dienes with two electron-acceptor substituents at C(1) undergo thermal 1,5-cyclization to give indoles in good yields. The increase in electron-withdrawing ability of C(1)-substituents facilitates the reaction that proceeds via pseudopericyclic 1,5-electrocyclization of 2-azabutadiene into 7aH-indolium ylide followed by prototropic shift. 3,4-Diphenyl-2-azabuta-1,3-dienes, resulting from reaction of 2,3-diphenyl-2H-azirine and diazo compounds, do not produce indoles via 1,5-cyclization due to the trans-configuration of the 4-Ph-group and the nitrogen, but undergo 1,4-cyclization to 2,3-dihydroazetes. 1,6-Cyclization into 2H-1,4-oxazines with participation of the oxygen of ester or amide group at C(1) of corresponding 2-azabuta-1,3-dienes does not take place due to kinetic and thermodynamic reasons. Instead of this, 1,6-electrocyclization with participation of phenyl substituent at C(4) of the 2-azabuta-1,3-dienes, providing isoquinoline derivatives, can occur at elevated temperatures. The DFT-calculations (mPWB1K/6-31+G(d,p)) confirm the dependence of 2-azabuta-1,3-diene transformation type on the nature of substituents.

ChemInform Abstract: Diastereoselective Formation of Aziridines from Diazocarbonyl Compounds and N‐(O‐Pivaloylated D‐Galactosyl)benzylideneamines and Ring‐Opening Reactions with P‐Toluenethiol.

N-Galactosyl aziridines were synthesized via BF3·OEt2 promoted addition of carbenes generated from diazocarbonyl compounds with O-pivaloylated β-D-galactosylimines in good yields and high diastereoselectivity. The ring-opening reactions with p-toluenethiol of the aziridines provided enantiometrically pure β-S-substituted phenylalanine derivatives in a highly regioselective manner.