- The Generation of Carbene Anion Radicals from Diazo Compounds. Factors Influencing the Unimolecular Decomposition of the Anion Radicals of Diazo Compounds in Solution
-
Anion radicals of two diazo compounds, azibenzil and diethyl diazomalonate, had previously been reported to undergo unimolecular decomposition in aprotic solvents to generate the corresponding carbene anion radicals.These processes have been examinated in detail by transient electrochemical techniques.The rate constants for the loss of dinitrogen in DMF at 273.2 K are 407 and 125 s-1 for the anion radicals of diethyl diazomalonate and azibenzil, respectively.There is little difference in the rate constants in the two solvents.The activation enthalpies fall in the range 10.6-12.7 kcal/mol, and the entropies of activation are close to -6 cal/(K*mol).Hydrogen bonding to water (i) (Ki = 0.8 M-1) facilitates unimolecular decomposition. The hydrogen bonded complex, Ph(PhCO)C=N2.-/HOH, undergoes first-order decomposition with a rate constant in acetonitrile at 273.2 K equal to 1700 s-1.This rate enhancement is attributed to the localization of charge away from nitrogen.The carbonyl group adjacent to the diazo function in both substrates also facilitates loss of dinitrogen.It is concluded that unimolecular loss of nitrogen is a more favorable process than previously thought, especially at higher temperatures and when the charge is delocalized.
- Bethell, Donald,Parker, Vernon D.
-
-
Read Online
- Reactions of α-diazoketones with indolinone imines: Synthesis of new 1,3,3-triaryl-1′-methylspiro[azetidine-2,3′-indoline]-2′, 4-diones
-
The paper describes the synthesis of new 1,3,3-triary-1′- methylspiro[azetidine-2,3′-indoline]-2′,4-diones from reaction of the 2-diazo-1,2-diarylethanones with 3-arylimino-1-methyl-2-indolinones. The compounds have been characterized by satisfactory anal
- Singh, Girija S.,Mmolotsi, Boycie J.
-
-
Read Online
- Bis-Rhodamines Bridged with a Diazoketone Linker: Synthesis, Structure, and Photolysis
-
Two fluorophores bound with a short photoreactive bridge are fascinating structures and remained unexplored. To investigate the synthesis and photolysis of such dyes, we linked two rhodamine dyes via a diazoketone bridge (?COCN2?) attached to p
- Belov, Vladimir N.,Bossi, Mariano L.,Hell, Stefan W.,Shojaei, Heydar
-
-
- Gold-Catalyzed [3+2]-Annulations of α-Aryl Diazoketones with the Tetrasubstituted Alkenes of Cyclopentadienes: High Stereoselectivity and Enantioselectivity
-
This work reports gold-catalyzed [3+2]-annulations of α-diazo ketones with highly substituted cyclopentadienes, affording bicyclic 2,3-dihydrofurans with high regio- and stereoselectivity. The reactions highlights the first success of tetrasubstituted alkenes to undergo [3+2]-annulations with α-diazo carbonyls. The enantioselective annulations are also achieved with high enantioselectivity using chiral forms of gold and phosphoric acid. Our mechanistic analysis supports that cyclopentadienes serve as nucleophiles to attack gold carbenes at the more substituted alkenes, yielding gold enolates that complex with chiral phosphoric acid to enhance the enantioselectivity.
- Chen, Ching-Nung,Cheng, Wei-Min,Wang, Jian-Kai,Chao, Tzu-Hsuan,Cheng, Mu-Jeng,Liu, Rai-Shung
-
supporting information
p. 4479 - 4484
(2021/01/21)
-
- Blue Light-Promoted N?H Insertion of Carbazoles, Pyrazoles and 1,2,3-Triazoles into Aryldiazoacetates
-
Blue light irradiation of aryldiazoacetates leads to the formation of free carbenes, which can react with carbazoles, pyrazoles and 1,2,3-triazoles to afford the corresponding N?H inserted products. These reactions are performed under air and at room temperature, allowing the mild preparation of a variety of motifs found in biologically relevant targets. (Figure presented.).
- Stivanin, Mateus L.,Fernandes, Alessandra A. G.,da Silva, Amanda F.,Okada, Celso Y.,Jurberg, Igor D.
-
supporting information
p. 1106 - 1111
(2020/01/25)
-
- Copper-Catalyzed Carbenoid Insertion Reactions of α-Diazoesters and α-Diazoketones into Si-H and S-H Bonds
-
An efficient copper-catalyzed carbenoid insertion reaction of α-diazo carbonyl compounds into Si-H and S-H bonds was developed. A wide range of α-silylesters and α-thioesters was obtained in high yields (up to 98%) from α-diazoesters using 5 mol% of a simple copper(I) salt as catalyst. Using 0.05 mol% of the same catalyst, α-diazoketones led to α-silylketones in low to good yields (up to 70%).
- Keipour, Hoda,Jalba, Angela,Delage-Laurin, Léo,Ollevier, Thierry
-
p. 3000 - 3010
(2017/03/23)
-
- Alkyl halide-free heteroatom alkylation and epoxidation facilitated by a recyclable polymer-supported oxidant for the in-flow preparation of diazo compounds
-
Highly reactive metal carbenes, generated from simple ketones via diazo compounds, including diazoamides and -phosphonates, using a recyclable reagent inflow, are transient but versatile electrophiles for heteroatom alkylation reactions and for epoxide formation. The method produces no organic waste, with the only byproducts being water, KI and nitrogen, without the attendant hazards of isolation of intermediate diazo compounds.
- Nicolle, Simon M.,Hayes, Christopher J.,Moody, Christopher J.
-
supporting information
p. 4576 - 4579
(2015/03/18)
-
- Potassium N-iodo p-toluenesulfonamide (TsNIK, iodamine-T): A new reagent for the oxidation of hydrazones to diazo compounds
-
A new reagent for the oxidation of hydrazones to diazo compounds is described. N-Iodo p-toluenesulfonamide (TsNIK, iodamine-T) allows the preparation of α-diazoesters, α-diazoamides, α-diazoketones and α-diazophosphonates in good yield and in high purity after a simple extractive work-up. α-Diazoesters were also obtained in high yield from the corresponding ketones through a one-pot process of hydrazone formation/oxidation. Diazo compounds: N-Iodo p-toluenesulfonamide (TsNIK, iodamine-T), readily prepared from p-toluenesulfonamide and iodine in aqueous KOH, is a new reagent for the oxidation of hydrazones to diazo compounds in good yields and high purity (see scheme).
- Nicolle, Simon M.,Moody, Christopher J.
-
supporting information
p. 4420 - 4425
(2014/05/06)
-
- Enantioselective N-H insertion reaction of α-aryl α-diazoketones: An efficient route to chiral α-aminoketones
-
A highly enantioselective N-H insertion reaction of α-diazoketones was developed by using cooperative catalysis by dirhodium(II) carboxylates and chiral spiro phosphoric acids. The insertion reaction provides a new access route to diverse chiral α-aminoketones, which are versatile building blocks in organic synthesis, with fast reaction rates, good yields and high enantioselectivity under mild and neutral conditions. Spiro inspiration: A highly enantioselective N-H insertion reaction of α-diazoketones was developed by using cooperative catalysis by dirhodium(II) carboxylates and chiral spiro phosphoric acids. The insertion reaction provides a new access route to diverse chiral α-aminoketones, which are versatile building blocks in the organic synthesis, with fast reaction rates, good yields and high enantioselectivity under mild and neutral conditions.
- Xu, Bin,Zhu, Shou-Fei,Zuo, Xiao-Dong,Zhang, Zhi-Chao,Zhou, Qi-Lin
-
supporting information
p. 3913 - 3916
(2014/05/06)
-
- Synthesis of 2-aminofurans and 2-unsubstituted furans via carbenoid-mediated [3 + 2] cycloaddition
-
An efficient dual synthetic manifold for 2-aminofurans and 2-unsubstituted furans has been developed. The carbenoid-mediated [3 + 2] cycloaddition of copper carbenoids with enamines provides 2-amino-2,3-dihydrofurans which serve as common intermediates for both 2-aminofurans and 2-unsubstituted furans. The Royal Society of Chemistry 2012.
- Jiang, Yaojia,Khong, Vanessa Zhong Yue,Lourdusamy, Emmanuvel,Park, Cheol-Min
-
experimental part
p. 3133 - 3135
(2012/05/04)
-
- Synthesis of α,α-diarylacetamides from benzyl aryl ketones using 2-azido-1,3-dimethylimidazolinium hexafluorophosphate
-
Benzyl aryl ketones reacted with 2-azido-1,3-dimethylimidazolinium hexafluorophosphate (ADMP, 1) to give migratory amidated compounds, which were transformed into the corresponding diarylacetamides by treating with LiAlH 4.
- Kitamura, Mitsuru,Miyagawa, Satoshi,Okauchi, Tatsuo
-
scheme or table
p. 3158 - 3161
(2011/06/28)
-
- Synthesis and antimicrobial activity of new 1-alkyl/cyclohexyl-3,3-diaryl-1′-methylspiro[azetidine-2,3′-indoline]-2′,4-diones
-
The paper describes the synthesis of new 1-alkyl/cyclohexyl-3,3-diaryl-1′-methylspiro[azetidine-2,3′-indoline]-2′,4-diones from the reactions of the 2-diazo-1,2-diarylethanones with 1-methyl-3-(alkyl/cyclohexylimino)indolin-2-ones under thermal condition.
- Singh, Girija S.,Luntha, Patrick
-
experimental part
p. 2265 - 2269
(2009/10/02)
-
- Enantioselective reactions of donor/acceptor carbenoids derived from α-aryl-α-diazoketones
-
The reaction of a variety of α-aryl-α-diazo ketones with activated olefins, catalyzed by the adamantyl glycine-derived dirhodium complex Rh2(S-PTAD)4, generates cyclopropyl ketones with high diastereoselectivity (up to >95:5 dr) and enantioselectivity (up to 98% ee). Intermolecular C-H functionalization of 1,4-cyclohexadiene by means of carbenoid-induced C-H insertion was also possible with this type of carbenoid.
- Denton, Justin R.,Davies, Huw M. L.
-
supporting information; experimental part
p. 787 - 790
(2009/09/06)
-
- Diazo preparation via dehydrogenation of hydrazones with "activated" DMSO
-
We report that "activated" dimethyl sulfoxide efficiently dehydrogenates hydrazones to the respective diazo species at -78°C. Under optimized conditions, triethylamine hydrochloride is removed quantitatively by vacuum filtration to provide solutions of diazo compounds. Stable diazo species can be isolated in high yield, or alternatively, the direct treatment of these solutions with carboxylic acids provides esters.
- Javed, Muhammad I.,Brewer, Matthias
-
p. 1789 - 1792
(2008/02/02)
-
- o-Iodoxybenzoic Acid (IBX) as a Viable Reagent in the Manipulation of Nitrogen- and Sulfur-Containing Substrates: Scope, Generality, and Mechanism of IBX-Mediated Amine Oxidations and Dithiane Deprotections
-
o-Iodoxybenzoic acid (IBX), a highly versatile hypervalent iodine(V) reagent, was found to efficiently mediate the dehydrogenation of amines in addition to facilitating the oxidative cleavage of dithioacetals and dithioketals. Through the development of relevant IBX-based protocols, a plethora of useful synthetic intermediates, including imines, oximes, ketones, and aromatic N-heterocycles, were found to be readily accessible under notably mild conditions. Further investigation of these transformations led to the elucidation of valuable mechanistic details, resulting in the conclusion that they proceed via ionic rather than single electron transfer (SET) pathways.
- Nicolaou,Mathison, Casey J. N.,Montagnon, Tamsyn
-
p. 5192 - 5201
(2007/10/03)
-
- Anodic oxidation of benzil hydrazones in the presence of halide ions
-
Benzil hydrazones were subjected to electrolytic oxidation in MeOH containing halide ion source, such as KI and KBr. The results show that the reaction products were dependent on both the electrolytes and the substituents. In the presence of KI, benzoylphenyldiazomethanes were obtained, whereas in the presence of KBr, benzil dimethyl acetals were obtained.
- Okimoto, Mitsuhiro,Takahashi, Yukio
-
p. 2059 - 2060
(2007/10/03)
-
- New insertion reactions of some carbenoids into amide- and sulfonamide-NH bonds
-
In the presence of catalytic amounts of Rh2(OAc)4 in toluene, dimethyl diazomalonate (1) decomposed with evolution of N2 to form a carbenoid of type 8 which reacted with carboxamides 2 and toluenesulfonamide (4) to give 2-(acylamino)- and 2-(sulfonylamino)malonates 3 and 5, respectively. In an analogous reaction, α-diazo ketone 6 and 4 yielded N-(2-oxo-1,2-diphenylethyl)toluenesulfonamide (7).
- Mloston,Celeda,Swiatek,Kaegi,Heimgartner
-
p. 1907 - 1914
(2007/10/03)
-
- Dihydrofurans from α-diazoketones due to facile ring opening - Cyclization of donor-acceptor cyclopropane intermediates
-
A series of α-diazoketones, 8, 25, 28, 31, and 34, have been synthesized and their reaction with ethyl vinyl ether examined under various reaction conditions. In the presence of metal salts (Rh2(OAc)4, Pd(OAc)2, CuCl) the ethoxydihydrofurans 12, 37, 39, 41, and 43 are produced. Sensitized irradiation of the α-diazoketone 8 afforded the dihydrofuran 12 plus cyclobutanone 7, while direct photolysis of α-diazoketones 8, 25, 28, 31, and 34 gave the cyclobutanones 7, 38, 40, 42, and 44, respectively. A sample of the cyclopropylketone 45 was isolated from the rhodium(II) acetate mediated reaction of 34 and its facile rearrangement to dihydrofuran 43 demonstrated. Collectively, these results indicate that the initial product from the reaction of an α-diazoketone with an electron-rich alkene such as ethyl vinyl ether is a cyclopropylketone. The donnor-acceptor substitution pattern of this intermediate results in spontaneous rearrangement to a dihydrofuran. Thus a direct dipolar cycloaddition mechanism is not involved when α-diazoketones react with enol ethers under metal-mediated conditions. Instead, these reactions follow a cyclopropanation rearrangement or, more accurately, cyclopropanation - ring opening - cyclization pathway.
- Lund, Elizabeth A.,Kennedy, Isaac A.,Fallis, Alex G.
-
p. 2401 - 2412
(2007/10/03)
-
- Diazo-Transfer Reaction with Diphenyl Phosphorazidate
-
Diphenyl phosphorazidate (DPPA) was used as the azide source in a one-pot synthesis of 2,2-disubstituted 3-amino-2H-azirines 1 (Scheme 1).The reaction with lithium enolates of amides of type 2, bearing two substituents at C(2), proceeded smoothly in THF at 0 degree C; keteniminium azides C and azidoenamines D are likely intermediates.Under analogous reaction conditions, DPPA and amides of type 3 with only one substituent at C(2) gave 2-diazoamides 5 in fair-to-good yield (Scheme 2).The corresponding 2-diazo derivatives 6-8 were formed in low yield by treatment of the lithium enolates of N,N-dimethyl-2-phenylacetamide, methyl 2-phenylacetate, and benzyl phenyl ketone, respectively, with DPPA.Thermolysis of 2-diazo-N-methyl-N-phenylcarboxamides 5a and 5b yielded 3-subdtituted 1,3-dihydro-N-methyl-2H-indol-2-ones 9a and 9b, respectively (Scheme 3).The diazo compounds 5-8 reacted with 1,3-thiazole-5(4H)-thiones 10 and thiobenzophenone (13) to give 6-oxa-1,9-dithia-3-azaspironona-2,7-dienes 11 (Scheme 4) and thiirane-2-carboxylic acid derivatives 14 (Scheme 5), respectively.In analogy to previously described reactions, a mechanism via 1,3-dipolar cycloaddition, leading to 2,5-dihydro-1,3,4-thiadiazoles, and elimination of N2 to give the 'thiocarbonyl ylides' of type H or K is proposed.These dipolar intermediates with a conjugated C=O group then undergo either a 1,5-dipolar electrocyclization to give spiroheterocycles 11 or a 1,3-dipolar electrocyclization to thiiranes 14.
- Villalgordo, Jose M.,Enderli, Adelheid,Linden, Anthony,Heimgartner, Heinz
-
p. 1983 - 1998
(2007/10/02)
-
- Formation of diazoketones and azines by improved oxidation of ketohydrazones using Cu(acac)2 as a catalyst
-
An efficient Cu(acac)2-catalyzed oxidation of ketohydrazones afforded the corresponding α-diazeketones or ketazines in high yields depending on the reaction conditions. However, the reaction of benzophenone hydrazone gave benzophenone azine without affording diphenyldiazomethane. The formation of azines is explained by intermediacy of carbenoid generated by the Cu(acac)2-catalyzed decomposition of diazo compounds.
- Ibata, Toshikazu,Singh, Girija S.
-
p. 2581 - 2584
(2007/10/02)
-
- The mechanism of the reaction of diphenylketene with bases in aqueous solution: Nucleophilic attack versus general base catalysis of ketene hydration
-
Diphenylketene was generated in aqueous solution by flash photolysis, and rates of its decay accelerated by 30 bases of various structure were determined. The rate constants so obtained did not show the regular dependence on basic strength expected if the bases were serving as general base catalysts assisting the attack of water on the ketene, but they did vary with polarizability and steric bulk of the base in the way expected for direct nucleophilic attack of the base on the carbonyl carbon atom of the ketene. Assignment of a direct nucleophilic role to the bases is supported by the formation of amide products in addition to diphenylacetic acid in the reaction of diphenylketene accelerated by ammonia and morpholine, and quantitative analysis of the product ratios shows that these two bases serve only as nucleophiles and that the diphenylacetic acid is formed by uncatalyzed reaction of diphenylketene with solvent water.
- Andraos,Kresge
-
p. 5643 - 5646
(2007/10/02)
-
- A convenient preparation of diazo carbonyl compounds under tri-phase phase-transfer catalysis conditions
-
A simple and convenient one-pot preparation method for pure diazo carbonyl compounds under tri-phase phase-transfer catalysis conditions is described.
- Madan Kumar
-
p. 2121 - 2127
(2007/10/02)
-
- STUDIES ON THE OXIDATION OF HYDRAZONES WITH IODINE AND WITH PHENYLSELENENYL BROMIDE IN THE PRESENCE OF STRONG ORGANIC BASES; AN IMPROVED PROCEDURE FOR THE SYNTHESIS OF VINYL IODIDES AND PHENYL-VINYL SELENIDES
-
The oxidation of hydrazones by iodine in the presence of strong organic bases (guanidines) has been studied.Improved yields of vinyl iodides can be obtained by inverse addition using dry solvents and with a final heating period where appropriate.The reaction has been extended to various dihydrazones with interesting results.In complementary studies hydrazones have been oxidized by phenylselenyl bromide in the presence of strong organic bases to give the corresponding phenyl vinyl selenides in good yield.
- Barton, Derek H. R.,Bashiardes, George,Fourrey, Jan-Louis
-
p. 147 - 162
(2007/10/02)
-
- A CONVENIENT SYNTHESIS OF DIAZO COMPOUNDS BY CATALYTIC DEHYDROGENATION OF HYDRAZONES WITH COBALT SCHIFF BASE COMPLEX-OXYGEN SYSTEM
-
Cobalt Schiff base complex catalyzed oxidation of hydrazones is found to be a convenient method for the synthesis of diazo compounds.
- Nishinaga, Akira,Yamazaki, Shigekazu,Matsuura, Teruo
-
p. 505 - 506
(2007/10/02)
-
- Stereo- and Photochemistry of 1,2,3,4,5-Pentaphenyl-1,3,5-heptatriene
-
The stereochemistry of 1,2,3,4,5-pentaphenyl-1,3,5-heptatriene (2) previously isolated from the photolysis of cis-6-methyl-1,2,3,4,5-pentaphenyl-1,3-cyclohexadiene has been shown to be Z,E,Z on the basis of X-ray crystallographic analysis and chemical dat
- Woolsey, Neil F.,Radonovich, Lewis J.,Saad, Fathi M.,Brostrom, Myles
-
p. 1937 - 1941
(2007/10/02)
-
- A COMPARISON OF THE DECOMPOSITION OF A 3-NITRENO-1,3-OXAZOLIN-2-ONE AND THE ISOMERIC 1,3,4-OXADIAZIN-2-ONE
-
The oxidation of 3-amino-4,5-diphenyl-1,3-oxazolin-2-oe (7) affords monodiazobenzyl 10 as the primary decomposition product of N-nitrenolactam 1.In contrast, the oxidation 3,6-dihydro-5,6-diphenyl-1,3,4-oxadiazin-2-one (6) leads to diphenylacetylene (12) via oxadiazin-2-one 2.
- Wilson, R. Marshall,Chow, Tahsin J.
-
p. 4635 - 4636
(2007/10/02)
-
- The Contrast in the Reactions of Toluene-p-sulphonylhydrazones and Semicarbazones with the Acetates of Hg(II), Tl(III) and Pb(IV). Some Useful Regenerations of Carbonyl Compounds: Reactions of Mercuric Acetate with Nitrogen Compounds. Part 7.
-
Thallium triacetate in acetic acid gave a clean regeneration of both aldehydes and ketones from their toluene-p-sulphonylhydrazones.The reagent also cleaved carbonyl compounds from semicarbazones at reflux temperatures in acetic acid with some interference from side reactions due to the vigorous conditions.Treatment of benzil monosemicarbazone with thallium triacetate gave 5,6-diphenyl-1,2,4-triazin-3-one and oxidation of benzil mono- and bis(toluene-p-sulphonyl) hydrazones gave a fragmentation of the hydrazone chain to a diazo species which was isolated in the former case and in the latter case cyclised to 1-(toluene-p-sulphonamido)-4,5-diphenyl-1,2,3-triazole.These reactions are compared with the corresponding reactions of mercuric acetate and lead tetraacetate and the mechanisms are discussed.The essential difference between the behaviour of the three isoelectronic reagents with hydrazone substrates lies in the lability of the hydrazone amino N-metal bond of an N-metallo intermediate and the influence of the charge on the metal on adjacent labile bonds.In the case of Tl(III) the redox step is intermolecular and involves solvent participation.
- Butler, Richard N.,Morris, Gerard J.,O'Donohue, Anne M.
-
p. 808 - 820
(2007/10/02)
-