Reactions of diazoalkanes with transition metal complexes

Putala, Martin; Lemenovśkii, D. A.

doi:10.1070/rc1994v063n03abeh000080

Cited by 40 publications

(34 citation statements)

References 141 publications

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“…Complex 2 experiences two different transformations, which are competitive in dichloromethane at 60 °C (Scheme ). The migration of the methyl group from the C α atom of the alkylidene ligand to the metal center and a subsequent methylidene extrusion , yield the hydride alkylidyne derivative OsHCl 2 {C(CH 2 ) 3 CONHPh}(P i Pr 3 ) 2 ( 5 ), containing a linear spacer between the alkylidyne C α atom and the amide (pathway a in Scheme ). On the other hand, the activation of one of the C–H bonds of the C β H 2 group and a concerted 1,2-methyl shift in the resulting osmacyclopropene give OsHCl{CCH(CH 3 )(CH 2 ) 2 C(O)NHPh}(P i Pr 3 ) 2 ( 6 ), with a branched spacer between the alkylidyne C α atom and the amide (pathway b in Scheme ).…”

Section: Resultsmentioning

confidence: 99%

Amide-Directed Formation of Five-Coordinate Osmium Alkylidenes from Alkynes

et al. 2015

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The amide-directed synthesis of five-coordinate osmium alkylidene derivatives from alkynes is reported. These types of complexes, which have been elusive until now because of the tendency of osmium to give hydride alkylidyne species, are prepared by reaction of the dihydride OsH2Cl2(PiPr3)2 (1) with terminal alkynes containing a distal amide group. Complex 1 reacts with N-phenylhex-5-ynamide and N-phenylhepta-6-ynamide to give OsCl2{=C(CH3)(CH2)nNH(CO)Ph}(PiPr3)2 (n = 3 (2), 4 (3)). The relative position of carbonyl and NH groups in the organic substrates has no influence on the reaction. Thus, treatment of 1 with N-(pent-4-yn-1-yl)benzamide leads to OsCl2{=C(CH3)(CH2)3NHC(O)Ph}(PiPr3)2 (4). The new compounds are intermediate species in the cleavage of the C–C triple bond of the alkynes. Under mild conditions, they undergo the rupture of the Cα–CH3 bond of the alkylidene, which comes from the alkyne triple bond, to afford six-coordinate hydride–alkylidyne derivatives. In dichloromethane, complex 2 gives a 10:7 mixture of OsHCl2{≡C(CH2)3C(O)NHPh}(PiPr3)2 (5) and OsHCl2{≡CCH(CH3)(CH2)2C(O)NHPh}(PiPr3)2 (6). The first complex contains a linear separation between the alkylidyne Cα atom and the amide group, whereas the spacer is branched in the second complex. In contrast to the case for 2, complex 4 selectively affords OsHCl2{≡C(CH2)3NHC(O)Ph}(PiPr3)2 (7). In spite of their instability, these compounds give the alkylidene–allene metathesis, being a useful entry to five-coordinate vinylidene complexes, including the dicarbon-disubstituted OsCl2(=C=CMe2)(PiPr3)2 (8) and the monosubstituted OsCl2(=C=CHCy)(PiPr3)2 (9).

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Section: Resultsmentioning

confidence: 99%

Amide-Directed Formation of Five-Coordinate Osmium Alkylidenes from Alkynes

et al. 2015

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“…Those substrates that react to form N−C, S−C, and O−C single bonds (i.e., amines, thiols, and alcohols) can be thought of doing so by nucleophilic attack at the new Re−C bond. It is well known that atoms become more electrophilic upon coordination to a high oxidation-state metal. ,, Indeed, were there neither these nor other examples, the conversion of the normally nucleophilic peroxide ion into an electrophilic center upon coordination to MTO would provide a convincing illustration. The nucleophilic center (the heteroatom) of RNH 2 , RSH, and ROH will attack the carbon atom of A C .…”

Section: Discussionmentioning

confidence: 99%

Organic Reactions Catalyzed by Methylrhenium Trioxide: Reactions of Ethyl Diazoacetate and Organic Azides

1996

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Methylrhenium trioxide (CH 3 ReO 3 or MTO) catalyzes several classes of reactions of ethyl diazoacetate, EDA. It is the first high valent oxo complex for carbene transfer. Under mild conditions and in the absence of other substrates, EDA was converted to a 9:1 mixture of diethyl maleate and diethyl fumarate. In the presence of alcohols, R-alkoxy ethyl acetates were obtained in good yield. The yields dropped for the larger and more branched alcohols, the balance of material being diethyl maleate and fumarate. An electron-donating group in the para position of phenols favors the formation of R-phenoxy ethyl acetates. The use of EDA to form R-thio ethyl acetates and N-substituted glycine ethyl esters, on the other hand, is hardly affected by the size or structure of the parent thiol or amine, with all of these reactions proceeding in high yield. MTO-catalyzed cycloaddition reactions occur between EDA and aromatic imines, olefins, and carbonyl compounds. Three-membered ring products are formed: aziridines, cyclopropanes, and epoxides, respectively. The reactions favor the formation of trans products, and provide a convenient route for the preparation of aziridines. Intermediate carbenoid and nitrenoid species have been proposed.In the presence of an oxygen source such as an epoxide, ethyl diazoacetate and azibenzil are converted to an oxalic acid monoethyl ester and to benzil; at the same time the epoxide was converted to an olefin. These results provide further support for the proposed intermediate, a cyclic species containing Re, O, and CHCO 2 Et (or, occasionally, CPhC(O)Ph) in a three-membered ring.

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“…10−13 Many stable σ-coordinated diazoalkane complexes have been isolated without extrusion of the N 2 fragment, although thermolysis often leads to N 2 elimination to form metallacarbene complexes or decomposition products. [10][11][12][13]19,20 Previous success promoting η 2 -coordination of ligands such as nitriles, ketones, and aldehydes to the W(CO)(acac) 2 moiety led us to ask whether η 2 -coordination of diazoalkane ligands might be possible with this d 4 fragment.…”

Section: ■ Introductionmentioning

confidence: 99%

Bis(acetylacetonate) Tungsten(IV) Complexes Containing a π-Basic Diazoalkane or Oxo Ligand

et al. 2012

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Tungsten(IV) bis(acetylacetonate) (acetylacetonate = acac) complexes were synthesized by incorporating either a diazoalkane or an oxo ligand into the coordination sphere of a tungsten(II) reagent. The reaction of free diazoalkane (N 2 CRR′) with W(CO) 3 (acac) 2 leads to loss of two carbon monoxide ligands and coordination of the diazoalkane reagent through the terminal nitrogen to produce W(CO)(acac) 2 (N 2 CRR′). This monomer is best formulated as a tungsten(IV) complex. A second example of converting a d 4 tungsten carbonyl complex to a d 2 product involves oxidation of W(CO)(acac) 2 (PhCN) with m-chloroperoxybenzoic acid (MCPBA) to replace the CO ligand with an oxygen atom. This increase in metal oxidation state causes rotation of the nitrile ligand by 90°relative to the two bidentate acac ligands. Electrophilic addition at the nitrogen of the π-bound nitrile ligand using methyl triflate (MeOTf) and subsequent nucleophilic addition at carbon with sodium trimethoxyborohydride, Na[HB(OMe) 3 ], reduces the CN bond stereoselectively and produces the neutral imine complex W(O)(acac) 2 (PhHCNMe) with a diastereomeric ratio of 11:1.

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Reactions of diazoalkanes with transition metal complexes

Cited by 40 publications

References 141 publications

Amide-Directed Formation of Five-Coordinate Osmium Alkylidenes from Alkynes

Amide-Directed Formation of Five-Coordinate Osmium Alkylidenes from Alkynes

Organic Reactions Catalyzed by Methylrhenium Trioxide: Reactions of Ethyl Diazoacetate and Organic Azides

Bis(acetylacetonate) Tungsten(IV) Complexes Containing a π-Basic Diazoalkane or Oxo Ligand

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