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Dirhodium acetate di(cyclohexylisocyanide) [Rh2(O2CCH3)4(C≡NCy)2] is prepared by treating Rh2(OAc)4 with cyclohexylisocyanide. The crystal structure of [Rh2(O2CCH3)4(C≡NCy)2] is determined by a single crystal X-ray diffraction (XRD) analysis. The title compound crystallizes in the orthorhombic system (space group Ibam). According to the single crystal XRD analysis data, the Rh atom exhibits a slightly distorted octahedral coordination geometry. The Rh1—Rh1—C1 fragment is almost linear (177.87°); ORhO angles are 88.28°, 88.79°, and 91.25°. In addition, the structure of the title compound is unambiguously confirmed by the aggregation of elemental analysis (C, H, N), ESI+—MS, and IR spectroscopy data.

Transformation of N-alkylated anilines to N-aryloxamates was studied using ethyl 2-diazoacetoacetate as an alkylating agent and dirhodium tetraacetate (Rh2(OAc)4) as the catalyst. The general applicability of the reaction as a synthetic method for N-aryloxamates was studied with a number of substituted N-alkylated anilines. The results revealed that the oxamate was formed by a radical reaction with molecular O2 and Rh2(OAc)4 as initiator.

Coordination of 2,8-Ar2-5-phenylanthyridines (Ar = 2-thienyl, 1a; Ar = 2-ClC6H4–, 1b) with dirhodium tetraacetate yielded the cyclometalated complexes [Rh2(OAc)3(metalated-1a)] (3a) and [Rh2(OAc)3(...

The asymmetric dirhodium(II)-catalyzed intramolecular CH insertion of α-diazo acetamides in water is described for the first time. The use of natural α-amino acids as chiral ligands allowed the preparation of novel dirhodium(II) homochiral complexes by a simple procedure consisting of the in situ ligand exchange starting from dirhodium tetraacetate. The catalytic system was further reused up to 7 cycles and β-lactams were obtained in good yields and enantiomeric excess.

A new strategy for the synthesis of N-alkoxycarbonyl aryl α-imino esters in the presence of dirhodium tetraacetate [Rh2(OAc)4] is reported to produce the desired compounds in high yield (up to 96%) under mild reaction conditions. The application of the synthetic method is demonstrated in enantioselective reduction and Friedel–Crafts reaction of indoles to afford the corresponding chiral arylglycines and indole derivatives, respectively, in high yield and excellent ee.

Approach was developed underlain by the use of fluorinated diazocompounds to the synthesis of derivatives of α-trifluoromethyl-α-hydroxycarboxylic acids and their phosphorus-containing analogs, α-trifluoromethyl-α-hydroxyphosphonic acids. Methyl 2-diazo-3,3,3-trifluoropropionate and diethyl 1-diazo-2,2,2-trifluoroethylphosphonate under the action of catalytic quantities of dirhodium tetraacetate Rh2(OAc)4 easily inserted into the O-H bond leading to the formation of the corresponding products in high yields.

An appropriately substituted α-diazo β-keto ester, prepared from D-glucose, on treatment with a catalytic amount ot dirhodium tetraacetate gave a strained 1,5-dioxabicyclo[3.3.0]octane ring system with concomitant diastereoselective formation of a quaternary carbon substituted with both an ethoxycarbonyl group and a 2-ethoxy-2-oxoethyl group; the product is a key intermediate in the synthesis of a new griseolic acid analogue.

The addition of diazoacetoacetates to aromatic imines derived from p-methoxyaniline is achieved using dirhodium tetraacetate as the catalyst. Highly functionalized aziridines are obtained in good yield and with excellent stereoselectivity. 2-Diazo-1,3-diketones also provide good yields of aziridines, but dimethyl diazomalonate is inactive in the transformation. The diazoacetoacetates of chiral alcohols are also examined in the reaction and moderate diastereoselectivity is achieved with (R)-pantolactone-derived diazoacetoacetate. A reaction mechanism through metal-carbene and azomethine ylide is proposed.

Catalytic decomposition of diazoacetylacetone, ethyl diazoacetate, and diethyl diazomalonate effected by dirhodium tetraacetate in the presence of 3(2H)-oxoisothiazole-1,1-dioxides resulted in O-alkylation of amide carbonyl of the heterocycle affording the corresponding enol ethers in preparative yield. The reaction occurred chemoselectively. The 1,3-dicarbonyl derivatives of 3-hydroxyisothiazole-1,1-dioxides obtained in contrast to analogous N-alkylated products are not enolized in solutions and in crystals.

Cyclopropane analogs of aspartic and adipic acids were prepared by catalytic cyclopropanation of dehydro amino acid derivatives with alkyl diazoacetates in the presence of catalyst (dirhodium tetraacetate).

The Kanematsu transformation was employed for the preparation of tetrahydroisobenzofuran-4-carboxylic acid (12), α-methylation, subsequent conversion into the diazoethanone 14, and, finally, treatment with dirhodium tetraacetate of which furnished the hydrindanone 1 of the steroid C-D ring structure.

Dirhodium tetraacetate is an antitumor active compound that is known to inhibit cellular DNA synthesis, but relatively little is known about its interactions with nucleic acids. A combination of ma...

The in situ formed complexes of dirhodium(II) tetraacetate with optically active derivatives of the 1,2-amino alcohols ephedrine and adrenaline show circular dichroism spectra suitable for determination of their absolute configuration. According to the M- or P-helicity of the N–C–C–O moiety the investigated compounds generate negative or positive Cotton effects at around 300 and 440 nm, respectively. The third prominent CE of an opposite sign to the first two occurs at ca. 380 nm. It is demonstrated that the in situ method allows fast and easy configurational assignment based on the helicity rule that connects the signs of the Cotton effects at around 300 and 440 nm with the sign of the N–C–C–O torsional angle.

(4′-Polystyrylmethyloxy)-3-carboxylatomethyloxy-1-phenylacetate bis-μ-coordinated rhodium(II) diacetate complex, a resin-bound analogue of dirhodium tetraacetate in which two adjacent μ-bridging acetate moieties are covalently linked, serves as an efficient, stable and re-useable immobilised alkene hydrofomylation and hydrogenation catalyst. 4-(4′-Polystyrylmethyloxy)-3-carboxylatomethyloxy-1-phenylacetate bis-μ-coordinated rhodium(II) diacetate complex (3) serves as a polymer-supported catalyst for alkene hydroformylation and hydrogenation

We have investigated the reaction of dirhodium tetraacetate with the phosphine P( o -CH 3 OH 6 H 4 )Ph 2 (P) under different experimental conditions. From these reactions we have been able to isolate the dirhodium tetraacetate phosphine mono-adduct. The crystal structure shows that in the solid state this compound forms a centrosymmetric dimer of the dimer, {Rh 2 (O 2 CCH 3 ) 4 ·P(0-CH 3 OC 6 H 4 )Ph 2 } 2 , in which we oxygen atom from one acetate group in one Rh 2 (O 2 CCH 3 ) 4 ·P unit is axially coordinating one Rh atom on another Rh 2 (O 2 CCH 3 ) 4 · P unit (Rh⋯) 2.347(3) A intermolecular versus Rh⋯O 2.455(3) A intermolecular), and vice versa. The RhRh bond distance is 2.414(1) A while the intermolecular Rh⋯Rh distance is 3.45592) A.

A new strategy for the synthesis of N-alkoxycarbonyl aryl α-imino esters in the presence of dirhodium tetraacetate [Rh2(OAc)4] is reported to produce the desired compounds in high yield (up to 96%) under mild reaction conditions. The application of the synthetic method is demonstrated in enantioselective reduction and Friedel–Crafts reaction of indoles to afford the corresponding chiral arylglycines and indole derivatives, respectively, in high yield and excellent ee.

Benzaldehyde p-Anisidine Benzaldehyde-p-anisidine imine 9-Anthracenemethanol 9-Anthraldehyde R-(+)-1,1’-Bi-2-naphthol, (R)-BINOL (R)-2,2’-(9-Phenanthryl)-BINOL phosphoric acid Dirhodium tetraacetate dehydrate Methyl (4-methoxyphenyl)diazoacetate 4-Methoxyphenylacetic acid (2S, 3S)-Methyl-2-(9-anthryloxy-methyl)-2-(4-methoxyphenyl)-3-(4-methoxy-phenylamino)-3-phenylpropanoate Keywords: Rh2(OAc)4; chiral Bronsted acid; electrophiles; enantioselective Mannich-type reaction; BINOL phosphates; β-amino-α-hydroxy esters

A new regio- and stereo- specific synthesis of a useful intermediate (7) for aphidicolane and stemodane diterpenoids is reported. The formation of ring C from 6b is achieved by Rh(II) catalyzed intramolecular carbon-hydrogen insertion.

Dirhodium tetraacetate catalyzed decomposition of trifluoromethyl acetyl diazoacetates 6a and 6b in ethyl vinyl ether gives rise to the dihydrofuroates 7a and 7b , respectively, which can be converted into the corresponding 2-(trifluoromethyl)pyrroles. This two step pyrrole synthesis is also suitable for the preparation of ethyl 2,3-bis(ethoxycarbonyl)-1H-pyrrole-1-propinate, an important intermediate for the synthesis of necin bases.

Diazomethyl ketones, prepared from Diels-Alder adducts of methyl oxindolylideneacetic acid ester (methyl 2-oxo-3(2H)-indolylideneacetate) and 1,3-butadiene as well as 1,3-cyclohexadiene by standard means, were decomposed over dirhodium tetraacetate, in the hope of carbon-hydrogen insertion leading to cyclopentanone formation. However, in every case studied the diazo ketone underwent interaction with the neighboring benzene ring, resulting in the creation of a norcaradiene

Treatment of a series of β,γ-unsaturated α-diazo-β-ketoesters with dirhodium tetraacetate results in the formation of rhodium carbenoids which undergo further skeletal rearrangement to produce substituted malonates.

The Kanematsu transformation was employed for the preparation of tetrahydroisobenzofuran-4-carboxylic acid (12), α-methylation, subsequent conversion into the diazoethanone 14, and, finally, treatment with dirhodium tetraacetate of which furnished the hydrindanone 1 of the steroid C-D ring structure.

Treatment of tertiary propargylic alcohols 13 with 3-diazo-2-butanone 6 and catalytic dirhodium tetraacetate in benzene gave good yields of the diastereomeric allenic hydroxyketones 14, with, in some cases, good diastereocontrol. These products are presumably formed via the [2,3]-sigmatropic rearrangement of an α-propargyloxy enol derivative. This reaction has been extended to the preparation of homoallylic hydroxyketones from allylic alcohols by reaction with 6 and the rhodium catalyst.

Dirhodium tetraacetate catalyzed reaction of α-diazo-β-keto-carboxylates and -phosphonates with arenecarboxamides gives 2-aryloxazole-4-carboxylates and 4-phosphonates by carbene N−H insertion and cyclodehydration. In stark contrast, dirhodium tetrakis(heptafluorobutyramide) catalysis results in a dramatic change of regioselectivity to give oxazole-5-carboxylates and 5-phosphonates. α-Diazo-β-ketosulfones behave similarly and give 5-sulfonyloxazoles upon dirhodium tetrakis(heptafluorobutyramide) catalyzed reaction with carboxamides. The analogous reactions of thiocarboxamides give the corresponding thiazole-5-carboxylates, -phosphonates, and -sulfones.

Dirhodium tetraacetate catalysed reaction of α-diazo-β-keto-carboxylates and -phosphonates with arenecarboxamides gives 2-aryloxazole-4-carboxylates and 4-phosphonates by carbene N–H insertion and cyclodehydration; in stark contrast, dirhodium tetrakis(heptafluorobutyramide) catalysis results in a dramatic change of regioselectivity to give oxazole-5-carboxylates and 5-phosphonates.

Dirhodium tetraacetate catalysed reaction of alpha-diazo-beta-keto-carboxylates and -phosphonates with arenecarboxamides gives 2-aryloxazole-4-carboxylates and 4-phosphonates by carbene N-H insertion and cyclodehydration; in stark contrast, dirhodium tetrakis(heptafluorobutyramide) catalysis results in a dramatic change of regioselectivity to give oxazole-5-carboxylates and 5-phosphonates.

The addition of diazoacetoacetates to aromatic imines derived from p-methoxyaniline is achieved using dirhodium tetraacetate as the catalyst. Highly functionalized aziridines are obtained in good yield and with excellent stereoselectivity. 2-Diazo-1,3-diketones also provide good yields of aziridines, but dimethyl diazomalonate is inactive in the transformation. The diazoacetoacetates of chiral alcohols are also examined in the reaction and moderate diastereoselectivity is achieved with (R)-pantolactone-derived diazoacetoacetate. A reaction mechanism through metal-carbene and azomethine ylide is proposed.

The synthesis of reverse pyrrole ribonucleosides methyl 5-C-(4-acetyl-5-methyl-pyrrol-1-yl)-2,3-O-isopropylidene-5-deoxy- beta-D-ribofuranoside (10), methyl 5-C-(4-ethoxycarbonyl-5-methyl-pyrrol-1-yl)-2,3-O-isopropylidene-5-deoxy- beta-D-ribofuranoside (11), methyl 5-C-(4-acetyl-5-methyl-pyrrol-1-yl)-5-deoxy-beta-D-ribofuranoside (12), methyl 5-C-(4-ethoxycarbonyl-5-methyl-pyrrol-1-yl)-5-deoxy- beta-D-ribofuranoside (13), methyl 5-deoxy-5-C-(3'-formyl-4'-hydroxypropyl-pyrrol-1'-yl)-2,3-O-isopropylidene- beta-D-ribofuranoside (16) and methyl 5-deoxy-5-C-(3'-formyl-pyrrol-1'-yl)-2,3-O-isopropylidene- beta-D-ribofuranoside (18) are described starting from readily available methyl 5-amino-5-deoxy-2,3-O-isopropylidene-beta-D-ribofuranoside (9). The synthetic strategy for the construction of the heterocyclic ring was based on the nucleophilic attack of (9) to 4-acetyl-2-n-butoxy-5-methyl-4,5-dihydrofuran (4), 4-carbetoxy-2-n-butoxy-5-methyl-4,5-dihydrofuran (5), 4-formyl-2-n-butoxy-4,5-dihydrofuran (6) and 4-formyl-1-methyl dioxabyciclo[3.3.0]oct-3-en (8, in situ). The later compounds were obtained from reaction between 3-diazo-2,4-pentadione (1), ethyl 2-diazoacetoacetate (2) or diazomalonaldehyde (3) and enol ethers using dirhodium tetraacetate as a catalyst. Neste trabalho estão descritas as sínteses dos ribonucleosídeos pirrólicos reversos 5-C-(4-acetil-5-metil-pirrol-1-il)-2,3-O-isopropilideno-5-desoxi- beta-D-ribofuranosídeo de metila (10), 5-C-(4-etoxicarbonil-5-metil-pirrol-1-il)-2,3-O-isopropilideno-5-desoxi- beta-D-ribofuranosídeo de metila (11), 5-C-(4-acetil-5-metil-pirrol-1-il)-5-desoxi-beta-D-ribofuranosídeo de metila (12), 5-C-(4-etoxicarbonil-5-metil-pirrol-1-il)-5-desoxi- beta-D-ribofuranosídeo de metila (13), 5-desoxi-5-C-(3'-formil-4'-hidroxipropil-pirrol-1'-il)-2,3-O-isopropilideno- beta-D-ribofuranosídeo de metila (16) e 5-desoxi-5-C-(3'-formil-pirrol-1'-il)-2,3-O-isopropilideno- beta-D-ribofuranosídeo de metila (18) a partir do 5-amino-5-desoxi-2,3-O-isopropilideno-beta-D-ribofuranosídeo de metila (9), matéria-prima de fácil preparação. A estratégia sintética para a construção do anel heterocíclico baseou-se no ataque nucleofílico da amina 9 aos diidrofuranos: 4-acetil-2-n-butoxi-5-metil-4,5-diidrofurano (4), 4-carbetoxi-2-n-butoxi-5-metil-4,5-diidrofurano (5), 4-formil-2-n-butoxi-4,5-diidrofurano (6) e 4-formil-1-metil dioxabiciclo[3.3.0]oct-3-eno (8, in situ), obtidos através da reação dos diazo compostos 3-diazo-2,4-pentadiona (1), 2-diazoacetoacetato de etila (2) e diazomalonaldeído (3) com enol-éteres, sob catálise de tetraacetato de di-ródio.

[formula: see text] Treatment of tertiary propargylic alcohols 13 with 3-diazo-2-butanone 6 and catalytic dirhodium tetraacetate in benzene gave good yields of the diastereomeric allenic hydroxyketones 14, with, in some cases, good diastereocontrol. These products are presumably formed via the [2,3]-sigmatropic rearrangement of an alpha-propargyloxy enol derivative. This reaction has been extended to the preparation of homoallylic hydroxyketones from allylic alcohols by reaction with 6 and the rhodium catalyst.

Treatment of a series of β,γ-unsaturated α-diazo-β-ketoesters with dirhodium tetraacetate results in the formation of rhodium carbenoids which undergo further skeletal rearrangement to produce substituted malonates.

Catalytic decomposition of diazoacetylacetone, diazoacetoacetic, diazomalonic, and diazoacetic esters using dirhodium tetraacetate in the presence of isothiazol-3(2H)-one 1,1-dioxides and a number of N-(arenesulfonyl)carboxamides in solutions of methylene chloride or dichloroethane gives rise to O-alkylation of the imidic carbonyl groups by Rh(II)-carbenoids and the formation of O-alkylimidates as the final products. The reaction proceeds with high chemoselectivity via carbonyl ylides and offers a powerful method for the synthesis in good yields of the imidates with polyfunctional O-alkyl groups. On the basis of X-ray analysis and 1H- and 13C-NMR studies it was shown that the resulting acyclic O-alkylimidates have the E-configuration in the solid state and in solution. Unlike acyclic analogues, the cyclic carbonyl ylide derived from substituted diazosaccharin by intramolecular cyclization of the appropriate diketocarbenoid is capable of reacting with DMAD in a 1,3-cycloaddition process.

On prepare une serie de β-cetoesters possedant 2 sites competitifs d'insertion de C-H et on en etudie la cyclisation intramoleculaire

Realizing a need for labeled dirhodium tetraacetate [Rh2/OAc/4] for binding studies by the equilibrium dialysis procedure, we have established a method for the preparation and purification of [3H]Rh2/OAc/4. This is obtained with a tritium label of a sufficiently high specific activity in the methyl group of acetate residues. The method consists of replacement of the existing acetate bridge by [3H]OAc−. A typical preparation involves refluxing Rh2/OAc/4 with [3H]NaOAc in dry ethanol at 80°C for 6 h. The reaction time is critical for obtaining the product with a high specific activity. A simple purification of reaction products yields the compound of interest with a high specific activity, i. e., 315±10 Ci per mol of Rh2/OAc/4 and in satisfactory yield /87% of the starting material., This labeled material can be synthesized with greatly increased specific activity /of tritium in acetate groups/ by employing [3H]NaOAc without prior dilution. The labeled Rh2/OAc/4 is stable and yields a characteristic product with adenylic acid.

The E-configurated allylic methyl ethers (I) are coupled with the α-diazocarbonyl compounds (II) in the presence of dirhodium tetraacetate to give the diastereomeric γ,δ-unsaturated α-methoxy carbonyl compounds (III) and (IV) with predominance of the erythro-isomers (III), together with the cyclopropanes (V).

A crystalline complex of yeast tRNAphe and dirhodium tetraacetate (DRTA) was prepared and its X-ray structure determined. The bifunctional DRTA forms an intermolecular crosslink between the N(1) position of adenine A36 in the anticodon triplet and possibly a ribose hydroxyl group of residue A76 at the 3′ terminus of a symmetry related tRNA molecule. The rhodium complex apparently shows a preference for binding to the N(l) position of adenine in a single strand region of the tRNA molecule.