Α-diazocarbonyl Compounds Research Articles

Radical addition to carbenoids. Chain reactions of α-diazo carbonyl compounds with triorganotin hydrides, tris(trimethylsilyl)silane and allyltributylstannane

α-Diazo ketones RC(O)CHN2 react with tributyltin hydride at 60 °C in benzene to give the corresponding α-stannyl ketones RC(O)CH2SnBu3, which exist in equilibrium with the stannyl enol ether tautomers R(Bu3SnO)CCH2. The reactions are initiated by di-tert-butyl hyponitrite and follow a freeradical chain mechanism. Triphenyltin hydride and tris(trimethylsilyl)silane [(TMS)3SiH] react similarly, the latter to yield the α-silyl ketone RC(O)CH2Si(TMS)3 which does not isomerise to the more stable silyl enol ether R[(TMS)3SiO]CCH2 under the reaction conditions. This result indicates that TMS3Si˙ reacts at the α-carbon atom of the α-diazo ketone to give R(CO)ĊHSiTMS3, probably via an initial diazenyl radical adduct; triorganotin radicals are assumed to react in the same way. When the group R in the α-diazo ketone is but-3-enyl, the intermediate α-metalloalkyl radical undergoes 5-exo-cyclisation. Allyltributylstannane reacts with α-diazo ketones and with ethyl α-diazoacetate in refluxing benzene, in the presence of 2,2′-azo(2-methylpropionitrile) as initiator, to give butenyl ketones RC(O)CH2CH2CHCH2 and ethyl pent-4-enoate, respectively, after a hydrolytic work-up.

Site- and Enantiocontrol in Intramolecular C-H Insertion Reactions of .ALPHA.-Diazo Carbonyl Compounds Catalyzed by Dirhodium(II) Carboxylates.

The full potential of rhodium (II) -catalyzed intramolecular C-H insertion reactions of α-diazo carbonyl compounds as a powerful tool for the construction of both carbocycles and heterocycles has been developed by variation of the bridging ligands of the dirhodium (II) catalysts : (1) Dirhodium (II) tetrakis (triphenylacetate) featured by the steric bulk of the bridging ligands on the rhodium has been demonstrated to exhibit an exceptionally high order of selectivity for C-H insertion into methylene over methine on a cycloalkane ring as well as for aromatic substitution over aliphatic C-H insertion. (2) Dirhodium (II) complexes incorporating N-phthaloyl- (S) -amino acids as bridging ligands have proven to be the chiral catalysts of choice for allowing high levels of differentiation of enantiotopic methylene C-H bonds and enantiotopic benzene rings, affording optically active cyclopentanone, 2-azetidinone, and 2-indanone derivatives in up to 80%, 96%, and 98% ee, respectively.

Dirhodium(II) Tetrakis[N-phthaloyl-(S)-tert-leucinate]: A Notable Catalyst for Enantiotopically Selective Aromatic Substitution Reactions of α-Diazocarbonyl Compounds

Dirhodium(II) Tetrakis[N-phthaloyl-(S)-tert-leucinate]: A Notable Catalyst for Enantiotopically Selective Aromatic Substitution Reactions of α-Diazocarbonyl Compounds

Formation of Acyl-Substituted Nitrile Ylides by Rh2(OAc)4-Catalyzed Decomposition of α-Diazocarbonyl Compounds in Nitriles

Abstract The Rh2(OAc)4-catalyzed reactions of α-diazocarbonyl compounds in nitrile in the presence of dimethyl acetylenedicarboxylate (DMAD) gave oxazole and pyrrole derivatives. The formation of the oxazole derivatives is explained in terms of the 1,5-cyclization of an acyl-substituted nitrile ylide intermediate, and the formation of the pyrrole derivatives is explained by the 1,3-dipolar cycloaddition of the same intermediate with DMAD. The regiochemistry of the cycloaddition of the acyl-substituted nitrile ylide with methyl propiolate showed that the contribution of an allenyl-type resonance structure plays an important role in the acyl-substituted nitrile ylide reaction.

α‐ジアゾカルボニル化合物の新しい利用法新規炭素骨格構築反応からＤＮＡの光切断まで

We have been interested in the reactions of α-diazocarbonyl compounds which produce reactive intermediates such as ketenes and ketocarbenes under thermal and photochemical conditions. The first part of this report describes the synthesis and reaction of bis(diazoketone)s. The thermal reaction of bis(diazoketone)s produced unpreceedented trans-hydroindenones in a quite good yield. Trans-hydroindenones are sensitive to acid and base to produce well-known cis-hydroindenones. Therefore, it is conceivable that the absolutely neutral conditions for the thermal reactions, which suppress the enolization and isomerization pathway, were indispensable for the formation of trans-hydroindenones. In the second part we focused our attention on molecular design of photoinduced DNA-cleaving agents, which may be useful in molecular biology and cancer photodynamic therapy. The first compound we developed has an a-diazoketone group conjugated with the ene-yne system and was expected to mimic the function of neocarzinostatin chromophore, which cleaves DNA by the hydrogen abstraction of a benzenoid diradical. The second compound we investigated has the dibenzoyldiazomethane (DBDM) system. The Wolff rearrangement of DBDM produces the highly electrophilic benzoylketene, which seemed to react with nucleobase resulting in modification of DNA. These α-diazocarbonyl compounds showed very efficient DNA cleavage under photoirradiation conditions and the latter compound may be used as an artificial DNA photonuclase.

Chemoselectivity and stereoselectivity of cyclisation of α-diazocarbonyls leading to oxygen and sulfur heterocycles catalysed by chiral rhodium and copper catalysts

Good levels of enantioselectivity have been achieved in intramolecular C–H insertion reactions of α-diazocarbonyl compounds leading to six-membered oxygen heterocycles (chromanones) through the use of chiral rhodium(II) carboxylates as catalysts. Competition between C–H insertion and sigmatropic rearrangement, the latter leading to five-membered oxygen heterocycles (furanones), was observed with precursors containing a proximal O-allyl side chain. Whereas rhodium carboxylates produced C-H insertion products predominantly, a copper catalyst produced sigmatropic rearrangement products exclusively. A precursor with an S-allyl side chain exhibited cyclisation via sigmatropic rearrangement with both copper and rhodium catalysts.

Formation and Reaction of Azomethine Ylide by the Reaction of Cu(acac)2- ketocarbenoids with 1,1-Diphenylmethanimine

Abstract The reaction of α-diazocarbonyl compounds with 1,1-diphenylmethanimine in the presence of Cu(acac)2 afforded the corresponding N-substituted imines in general together with pyrrolidine and 1,4,6-dioxazocine derivatives (in the reaction of α diazo-4-chloroacetophenone) and 1,1-diphenyl-2-(4-nitrobenzoyl) ethylene (in the reaction of α-diazo-4-nitroacetophenone) through azomethine ylides.

Formation of 2-Imino-1,3-oxathioles and 2(3H)-Oxazolethione by the Rhodium(II) Acetate-Catalyzed Reaction of α-Diazocarbonyl Compounds with Isothiocyanates

Abstract The rhodium(II) acetate-catalyzed reaction of various α-diazocarbonyl compounds with alkyl, phenyl, and benzoyl isothiocyanates gave 2-imino-1,3-oxathioles in good yields. 2(3H)-Oxazolethione was obtained as a by- product only in the reaction of diazodimedone with methyl isothiocyanate. The mechanism through thiocarbonyl ylide and azomethine ylide was proposed for these reactions, and preferable formation of thiocarbonyl ylide was explained by heat of formation and frontier molecular orbital calculations.

Formation and Reaction of Acyl Substituted Nitrile Ylide through the Rh2(OAc)4-Catalyzed Reaction of α-Diazocarbonyl Compounds with Benzonitrile

Abstract The rhodium(II) acetate-catalyzed reaction of α-diazocarbonyl compounds with benzonitrile and dimethyl acetylenedicarboxylate gave oxazoles and pyrrole-3,4-dicarboxylates through the 1,5-cyclization and 1,3-dipolar cycloaddition of the acyl substituted nitrile ylide intermediates generated by the reaction of ketocarbenoids with benzonitrile.

1,3-Dipolar cycloaddition reactions of α-diazocarbonyl compounds, organoazides, and ethynyl(phenyl)iodonium triflate salts

The electron-poor triple bond of RCCI + -Ph·TfO - ( 1, R = H, SiMe 3, tBuCO) undergoes [2+3] cycloaddition with α-diazocarbonyl compounds. Whereas 1:1 cycloadducts (4a–d,6) are obtained for R = SiMe 3 or tBuCO (X-ray structure analysis of 4b), diazoacetic esters react with two equivalents of the parent alkyne (1, R = H) to form bis-iodonium salts 9. Cycloaddition of methyl or phenyl azide to 1 yields (1,2,3-triazoly-4-yl)iodonium salts ( 13,14) in low yield.

Highly selective insertion into aromatic C–H bonds in rhodium(II) triphenylacetate-catalysed decomposition of α-diazocarbonyl compounds

Rhodium(II) triphenylacetate, which features a bulky bridging ligand, has been demonstrated to exhibit an exceptionally high order of selectivity for aromatic C–H insertion over aliphatic C–H insertion or cyclopropanation in catalytic decompositions of α-diazocarbonyl compounds, thus providing an expedient and general entry to variously substituted indan-2-ones.

Rh 2(OAc) 4-mediated decomposition of diazocarbonyl compounds: A comparison of α-diazo ketones and α-diazo β-keto esters reactivity.

Unsaturated α-diazocarbonyl compounds undergo intramolecular cyclopropanation or carbon-hydrogen bond insertion when catalyzed by Rh 2(OAc) 4: α-diazo ketones react preferentially with carbon-carbon doubled bond, whereas closely related α-diazo-β-keto-esters insert into carbon-hydrogen bond.

Formation of 1,3-Oxathiole-2-thione and 1,2,4-Trithiolane Derivatives by the Catalytic Reaction of α-Diazocarbonyl Compounds with Carbon Disulfide

Abstract The rhodium(II) acetate-catalyzed decomposition of α-diazocarbonyl compounds such as substituted α-diazoacetophenones, cyclic diazoketones, cyclic diazodiketones, and α-diazo-β-ketoesters in carbon disulfide gave 1,3-oxathiole-2-thione derivatives in good yields. Diazomalonates also gave alkyl 5-alkoxy-2-thioxo-1,3-oxathiole-4-carboxylates together with 3,5-bis[bis(alkoxycarbonyl)methylene]-1,2,4-trithiolanes. The formation of 1,3-oxathiole-2-thiones can be explained by the intermediacy of zwitterionic intermediate containing rhodium(II) acetate formed by the reaction of carbon disulfide with ketocarbenoids generated in the catalytic decomposition of the diazocarbonyl compounds.

Enantioselectively catalyzed intramolecular cyclopropanations of unsaturated diazo carbonyl compounds

A series of unsaturated α-diazo carbonyl compounds underwent enantioselective intramolecular cyclopropanation (ee = 4–77%) when treated with an enantiomerically pure chiral copper catalyst. The nature of the diazo substrate was critical: α-diazo ketones gave the best enantioselectivities whereas α-diazo β-keto ester systems showed diminished enantioselectivities.

Efficient Route to γ,δ-Unsaturated Carbonyl Compounds from Allyl Sulfides and α-Diazocarbonyls Using a Rhodium Catalyst

Abstract Functionalized γ,δ-unsaturated carbonyl compounds are efficiently prepared from allyl sulfides and α-diazo carbonyl compounds by catalysis of rhodium (II) acetate.

ChemInform Abstract: A Simple Procedure for Preparation of α‐Diazocarbonyl Compounds.

Chemischer InformationsdienstVolume 17, Issue 47 Preparative Organic Chemistry ChemInform Abstract: A Simple Procedure for Preparation of α-Diazocarbonyl Compounds. Y. K. RAO, Y. K. RAOSearch for more papers by this authorM. NAGARAJAN, M. NAGARAJANSearch for more papers by this author Y. K. RAO, Y. K. RAOSearch for more papers by this authorM. NAGARAJAN, M. NAGARAJANSearch for more papers by this author First published: November 25, 1986 https://doi.org/10.1002/chin.198647075Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume17, Issue47November 25, 1986 RelatedInformation

Bis(α,β-ditrifloxystyryl)mercury: Synthesis and crystal structure

Abstract Reaction of bis(α-diazophenacyl)mercury or its p -methyl derivative with triflic anhydride [(CF 3 SO 2 ) 2 O] leads to three diastereomeric bis(α,β-ditrifloxystyryl)mercury compounds. For ( E , E )-bis(α,β-ditrifloxystyryl)mercury, an X-ray structural determination was carried out. The reaction represents another example of attack of the anhydride on the oxygen atom of an α-diazocarbonyl compound.

Reaction of ketenes. Part 18. Catalysed reactions between α-diazocarbonyl compounds and ketene acetals

In the presence of copper powder or Cu(acac)2, ethyl diazoacetate reacts with dialkylketene acetals to give cyclopropanes (2) whilst with ketene acetals having at least one hydrogen atom at position 2 both cyclopropanes (2) and butenoates (3) are formed. Noteworthy in these reactions is the fact that the α-diazoester fails to give dihydrofurans (1), which are the only reaction products when α-diazoketones are the employed α-diazocarbonyl compounds. The results can be rationalized on the basis of the intermediacy of a species in which α-diazocarbonyl compound, catalyst, and ketene acetal are involved.

Photolysis of α-diazo carbonyl compounds in the presence of imidazole. A new method for the preparation of nor olefins and its application to bile acid side chain degradation

α-Diazomethyl ketones derived from carboxylic acids are photolyzed in the presence of imidazole to give the corresponding nor olefins or, in the case of aryl diazo ketones, the corresponding, stable imidazolides. The application of the method to a novel degradation of bile acid side chain is reported.

ChemInform Abstract: PRIMARY AND SECONDARY ISOTOPE EFFECTS ON PROTON TRANSFERS TO DIAZOCARBONYL COMPOUNDS

The primary solvent isotope effects on the ASE-2 type hydrolyses of α-diazocarbonyl compounds p-XC6H4CN2CH3 (X = NO2, H, OCH3 and C6H5CON(CH3)2) are found to be identical despite large differences in their overall hydrolysis rates. The secondary solvent isotope effects diminish considerably with diminishing substrate reactivity, and for two substrates they are smaller than those normally anticipated for a simple proton transfer from the lyonium species. An analysis is presented of these and other abnormal secondary isotope effects found elsewhere, involving consideration of the solvation of the reaction complex.