Reactions Of Diazo Compounds Research Articles

Cyclopropanation Reactions Mediated by Group 9 Metal Porphyrin Complexes

AbstractThe one‐pot reaction of diazo compounds with olefins represents a useful strategy to synthesise cyclopropanes, which are important both as starting materials for the synthesis of organic compounds and because of their intrinsic pharmaceutical properties. Herein we describe the catalytic activity of group 9 metal porphyrin complexes to cyclopropanate olefins that present different electronic behaviour. All the most important porphyrin‐based methodologies have been reviewed, stressing the stereocontrol of the reactions achieved in each case. Moreover, mechanism investigations have provided data that can help greatly to elaborate more efficient catalytic systems in the future.

ChemInform Abstract: Recent Developments in Pd‐Catalyzed Reactions of Diazo Compounds

AbstractReview: ca. 150 refs.

Recent Developments in Pd‐Catalyzed Reactions of Diazo Compounds

AbstractPd‐catalyzed reactions of diazo compounds result in unique transformations that are distinct from those of traditional processes catalyzed by RhII or CuI catalysts. Pd carbene migratory insertion was deemed to be the key step in a series of Pd‐catalyzed reactions of diazo compounds. The combination of this unique reaction and classic Pd‐catalyzed cross‐coupling provides new potential for the development of novel Pd‐catalyzed transformations, in particular for C=C double bond formation.

ChemInform Abstract: The Reactions of Diazo Compounds with Lactones. Part 2. The Reaction of Cyclic 2-Diazo-1,3-dicarbonyl Compounds with Diketene: Benzofuran Formation.

Cyclic 2-diazo-1,3-dicarbonyl compounds react with diketene in the presence of rhodium(II) salts to give benzofurans as the major isolated products. The formation of intermediate products with exocyclic double bonds which isomerise to benzofurans provides support for the proposed mechanism which involves initial formation of a dioxaspirooctenone by a formal dipolar cycloaddition reaction of a carbenoid to the exocyclic double bond of diketene followed by the loss of carbon dioxide. Acyclic 2-diazo-1,3-dicarbonyl compounds give furans in poor yield.

Reactions of Diazo Compounds with Alkenes Catalysed by [RuCl(cod)(Cp)]: Effect of the Substituents in the Formation of Cyclopropanation or Metathesis Products

The reaction of diazo compounds with alkenes catalysed by complex [RuCl(cod)(Cp)] (cod = 1,5-cyclooctadiene, Cp = cyclopentadienyl) has been studied. The catalytic cycle involves in the first step the decomposition of the diazo derivative to afford the reactive [RuCl(Cp){=C(R(1))R(2)}] intermediate and a mechanism is proposed for this step based on a kinetic study of the simple coupling reaction of ethyl diazoacetate. The evolution of the Ru-carbene intermediate in the presence of alkenes depends on the nature of the substituents at both the diazo N(2)=C(R(1))R(2) (R(1), R(2) = Ph, H; Ph, CO(2)Me; Ph, Ph; C(R(1))R(2) = fluorene) and the olefin substrates R(3)(H)C=C(H)R(4) (R(3), R(4) = CO(2)Et, CO(2)Et; Ph, Ph; Ph, Me; Ph, H; Me, Br; Me, CN; Ph, CN; H, CN; CN, CN). A remarkable reactivity of the complex was recorded, especially towards unstable aryldiazo compounds and electron-poor olefins. The results obtained indicate that either cyclopropanation or metathesis products can be formed: the first products are favoured by the presence of a cyano substituent at the double bond and the second ones by a phenyl.

ChemInform Abstract: Cooperative Catalysis with Chiral Broensted Acid‐Rh2(OAc)4: Highly Enantioselective Three‐Component Reactions of Diazo Compounds with Alcohols and Imines.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Generation and Cyclization of Thiocarbonyl S‐Ylides by Reaction of Diazocompounds with C‐Sulfonyldithioformates.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Generation and cyclization of thiocarbonyl S‐ylides by reaction of diazocompounds with C‐sulfonyldithioformates

AbstractThe unexpected 1,3‐benzodithiine derivatives 5b,c were obtained from the reactions of trimethylsilyldiazomethane 2 with C‐sulfonyldithioformates, bearing pentachlorophenylthio group, 1b,c via unprecedented cyclization of the transient thiocarbonyl ylides 4b,c. While the corresponding reaction with C‐sulfonyldithioformates, bearing phenylthio group, afforded 5a via [2 + 3]‐cycloadditive dimerization of a transient thiocarbonyl ylides 4a. Under the same reaction condition, C‐sulfonyldithioformates 1d–f react with diazomethane and/or phenyldiazomethane to afford the unsymmetrical 1,3‐dithiolane 7d,e and thiirane 8e,f derivatives, respectively. © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:28–33, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20246

Tandem Catalytic Carbene Addition/Bicyclization of Enynes. One‐Step Synthesis of Fluorinated Bicyclic Amino Esters by Ruthenium Catalysis.

The reaction of diazo compounds with enynes, containing a fluorinated amino acid moiety, in the presence of the precatalyst Cp*(Cl)Ru(COD) leads to fluorinated alkenyl bicyclo[3.1.0]hexane and [4.1.0]heptane amino acid derivatives. It is remarkable that the catalyst, in situ generated from ruthenium complex and diazo compound, completely inhibits the ring closing metathesis of enyne to the profit of tandem alkenylation/cyclopropanation with high stereoselectivity. The study shows that the Cp*(Cl)Ru moiety in ruthenacyclobutane favors reductive elimination versus expected alkene metathesis.

Tandem Catalytic Carbene Addition/Bicyclization of Enynes. One-Step Synthesis of Fluorinated Bicyclic Amino Esters by Ruthenium Catalysis

The reaction of diazo compounds with enynes, containing a fluorinated amino acid moiety, in the presence of the precatalyst Cp(Cl)Ru(COD) leads to fluorinated alkenyl bicyclo[3.1.0]hexane and [4.1.0]heptane amino acid derivatives. It is remarkable that the catalyst, in situ generated from ruthenium complex and diazo compound, completely inhibits the ring closing metathesis of enyne to the profit of tandem alkenylation/cyclopropanation with high stereoselectivity. The study shows that the Cp(Cl)Ru moiety in ruthenacyclobutane favors reductive elimination versus expected alkene metathesis. [reaction: see text]

First attempts at differential diastereoselection in catalytic reactions of N-chirally substituted dirhodium(II) tetrakis[methyl 2-oxoimidazolidine-4(S)-carboxylates] with diazoacetates

Chiral attachments on 2-oxoimidazolidine-4(S)-carboxylate ligands for dirhodium(ii) can provide differential diastereoselection in catalytic reactions of diazo compounds. The synthesis of these heterocyclic ligands from the readily available amino acid asparagine is reported. Reactions with diazoacetates offering intramolecular carbon—hydrogen insertion provide evaluative data that demonstrate differential diastereoselection. Surprisingly, placement of a carbonyl group within the chiral attachment removes enantiocontrol from the catalyst, presumably because of intramolecular ylide formation.

ChemInform Abstract: The Reactions of Diazo Compounds with Lactones. Part 1. Cyclopropanespiro-β-lactones from Diketene: Synthesis and Reactions.

The cyclopropanespiro-β-lactones 3, 4 and 12 can be prepared by the metal catalysed, or photochemically promoted decomposition reactions of diazocompounds in the presence of diketene. The thermal reactions of these compounds give a variety of products depending on the nature of the spirolactone; these include a furan 9a, 1,4-dicarbonyl compounds 18a–c and 19b, a pyranone 20b, furanones 21a, 21f and 22a and the enol 16. The boron trifluoride promoted reaction of a mixture of 3b and 4b gives a β-ketoacid. Mechanisms are proposed for the formation of these products. The rearrangment of the cyclopropanespiro-β-lactones to furan-2(5H)-ones and furan-2-(3H)-ones 6–8, 21a, 21f, 22a and 24 is shown to be a general reaction that involves metal catalysis. A mechanism based on formation of a metallocycle by a novel insertion of the metal into the C–O bond of the β-lactone ring is proposed for this rearrangement. This accounts for the observed features of the reaction.

The reactions of diazo compounds with lactones. Part 2.† The reaction of cyclic 2-diazo-1,3-dicarbonyl compounds with diketene: benzofuran formation

Cyclic 2-diazo-1,3-dicarbonyl compounds react with diketene in the presence of rhodium(II) salts to give benzofurans as the major isolated products. The formation of intermediate products with exocyclic double bonds which isomerise to benzofurans provides support for the proposed mechanism which involves initial formation of a dioxaspirooctenone by a formal dipolar cycloaddition reaction of a carbenoid to the exocyclic double bond of diketene followed by the loss of carbon dioxide. Acyclic 2-diazo-1,3-dicarbonyl compounds give furans in poor yield.

ChemInform Abstract: Reactions of Diazo Compounds with Imines.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform Abstract: Reactions of Diazo Compounds with Isatin and Its Derivatives.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Reactions of Diazo Compounds with Imines. Preliminary communication

AbstractThe [Rh2(OAc)4]‐catalyzed addition of methyl diazoacetate to N‐benzylideneaniline (1a) afforded the imine cis‐2 in 35% yield. Under catalysis by chiral RhII catalysts, however, only racemic 1a was produced, and the yield was low. In the presence of dimethyl maleate, aziridine formation was suppressed, and an intermediate ylide 6 was trapped as cycloadduct 7. No aziridines were obtained, however, from 1b, 1c, and 3. The iminium salt 8 reacted with (trimethylsilyl)diazomethane in the absence of [Rh2(OAc)4] via dipolar cycloaddition followed by extrusion of N2 to 10.

Formation and Cycloreversion of Dioxadiazole Intermediates in the Reaction of Diazo Compounds with Singlet Oxygen

Abstract Product ratios of N2/N2O as an indicator for carbonyl oxide formation in the 1O2 oxygenation of phenyl diazomethanes were not affected by protic solvents but were significantly increased by electron-donating substituents. A mechanism is suggested in which 1,2,3,4-dioxadiazole intermediates are formed by the cycloaddition of 1O2 and diazomethanes and its cycloreversion is controlled by the relative stability of resulting carbonyl oxides.

Reactions of Diazo Compounds and Chiral Rhenium Alkylidene Complexes of the Formula [(η5‐C5H5)Re(NO)(PPh3)(CHR)]+ PF A Versatile and Highly Stereoselective Route to Alkene Complexes

AbstractThe methylidene complex [(η5‐C5H5)Re(NO)(PPh3)(CH2)]+ PF or the ReCD2 analog react with diazo compounds N2CHR [R  H, Si(CH3)3, COPh, CO2C2H5] in CH2Cl2 at −80°C to give alkene complexes [(η5‐C5H5)Re(NO)(PPh3)(η2‐H2CCHR)]+ PF or D2CCHR analogs. The two ReC geometric isomers of benzylidene complex [(η5‐C5H5)Re‐(NO)(PPh3)(CHPh)]+ PF and CH2N2 react to give opposite configurational diastereomers of styrene complex [(η5‐C5H5)Re(NO)(PPh3)(η2‐H2CCHPh)]+ PF. Stereochemical features of these reactions are analyzed in detail, and are interpreted in terms of models involving (a) attack of the diazo compound upon the ReC face opposite to the bulky PPh3 ligand, (b) an antiperiplanar disposition of the ReC and CN2 bonds in the transition state, utilizing the diazo carbon face that minimizes interactions of the substitutent (R) and cyclopentadienyl ligand, and (c) N2 loss from the resulting intermediate [(η5‐C5H5)Re(NO)(PPh3)(CHR′CHRN2)]+ PF via a conformer with antiperiplanar PReCHR′C and ReCHR′CHRN linkages, with anchimeric assistance of the rhenium fragment d orbital HOMO from the backside.

Highly Reactive Platinum(0) Carbene Intermediates in the Reactions of Diazo Compounds. A Fast Atom Bombardment Mass Spectrometric Study

Highly Reactive Platinum(0) Carbene Intermediates in the Reactions of Diazo Compounds. A Fast Atom Bombardment Mass Spectrometric Study

ChemInform Abstract: Trifluoromethanesulfonic Acid‐Catalyzed Reaction of Diazo Compounds (I) with Dialkyl Phosphites (II) to Give Phosphonates (III).

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.