- Addition of Diazo Compounds ipso -C-H Bond to Carbon Disulfide: Synthesis of 1,2,3-Thiadiazoles under Mild Conditions
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We describe here an operationally simple and straightforward synthesis method for a series of diverse 4,5-disubstituted 1,2,3-thiadiazoles via the nucleophilic addition of α-diazo carbonyl compounds to carbon disulfide. This method features using abundant and inexpensive carbon disulfide under mild reaction conditions.
- Zhang, Lei,Sun, Beiqi,Liu, Qianyi,Mo, Fanyang
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- Ethynylbenziodazolones (EBZ) as Electrophilic Alkynylation Reagents for the Highly Enantioselective Copper-Catalyzed Oxyalkynylation of Diazo Compounds
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Ethynylbenziodoxol(on)e (EBX) cyclic hypervalent iodine reagents are now established reagents for the alkynylation of radicals and nucleophiles, yet they present limited possibilities for further structure and reactivity modification. Herein, the first synthesis is reported for the corresponding ethynylbenziodazolone (EBZ) reagents, in which the oxygen atom in the iodoheterocycle is replaced by a nitrogen atom. The substituent on the nitrogen enables further fine-tuning of the reagent structure and reactivity. EBZ reagents are obtained easily from the corresponding benzamides by using a one-step procedure, and display reactivity comparable to that of EBX reagents. In particular, they are applied in an asymmetric copper-catalyzed oxyalkynylation of diazo compounds, which proceeds in high yield and enantioselectivity for a broad range of substituents on the diazo compounds and the alkyne.
- Hari, Durga Prasad,Schouwey, Lionel,Barber, Verity,Scopelliti, Rosario,Fadaei-Tirani, Farzaneh,Waser, Jerome
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- Enantioselective Copper-Catalyzed Oxy-Alkynylation of Diazo Compounds
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Enantioselective catalytic methods allowing the addition of both a nucleophile and an electrophile onto diazo compounds give a fast access into important building blocks. Herein, we report the highly enantioselective oxyalkynylation of diazo compounds usi
- Hari, Durga Prasad,Waser, Jerome
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p. 8420 - 8423
(2017/07/06)
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- Direct Carboxylation of the Diazo Group ipso-C(sp2)-H bond with Carbon Dioxide: Access to Unsymmetrical Diazomalonates and Derivatives
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The direct carboxylation of the ipso-C(sp2)-H bond of a diazo compound with carbon dioxide under mild reaction conditions is described. This method is transition-metal-free, uses a weak base, and proceeds at ambient temperature under atmospheric pressure in carbon dioxide. The carboxylation exhibits high reactivity and is amenable to subsequent diversification. A series of unsymmetrical 1,3-diester/keto/amide diazo compounds are obtained with moderate to excellent yields (up to 99%) with good functional group compatibility.
- Liu, Qianyi,Li, Man,Xiong, Rui,Mo, Fanyang
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p. 6756 - 6759
(2017/12/26)
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- Catalyzed addition of diazoacetoacetates to imines: Synthesis of highly functionalized aziridines
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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.
- Zhang, Xue-Jing,Yan, Ming,Huang, Dan
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experimental part
p. 187 - 192
(2009/04/07)
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- Stereoselective formation of a chiral ether by intramolecular O-H insertion reaction of a metal carbenoid generated from diazoacetoacetate
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Intermolecular O-H insertion reactions of rhodium carbenoids generated from chiral diazoacetoacetates are less efficient and less stereoselective than the reactions of those generated from the corresponding phenyldiazoacetates. Nevertheless, when the diazoacetoacetate is connected to a phenolic moiety through a 2,4-pentanediol tether, the carbenoid generated shows a high potential in both efficiency and stereoselectivity during the intramolecular O-H insertion reaction to give a cyclic ether in up to 88% diastereomeric excess (de) in quantitative yield. The de value depends on the structure of the tether, but is independent of the catalyst employed. The isomerization of the cyclic ether has been studied under the conditions of equilibrium and kinetic protonation of the corresponding enolate. The similarity between the de values obtained by insertion and those obtained under equilibrium suggests that the rhodium catalyst is eliminated during the early stages of the O-H insertion reaction and that proton transfer, which determines the stereoselectivity, occurs after the elimination of the rhodium metal, independent of the stereochemistry of the initial addition. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
- Chun, Young Im,Okuyama, Tadashi,Sugimura, Takashi
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p. 285 - 294
(2008/09/18)
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- Synthesis of (-)-gleenol via C-H insertion reaction of alkylidenecarbene
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A spiro sesquiterpene alcohol, (-)-gleenol (1) was synthesized from (-)-1-menthol in 16 steps, using the C-H insertion reaction of the alkylidenecarbene as the key step. The absolute configuration of (-)-1 was determined to be IS, 6R, 7S. 10R.
- Ohira, Susumu,Yoshihara, Naoya,Hasegawa, Taisuke
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p. 739 - 740
(2007/10/03)
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- Electronic and steric control in carbon-hydrogen insertion reactions of diazoacetoacetates catalyzed by dirhodium(II) carboxylates and carboxamides
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Carboxylate and carboxamide ligands on dirhodium(II) catalysts can provide enormous regiocontrol in carbon-hydrogen insertion reactions of diazoacetate esters. Whereas 2,3,4-trimethyl-3-pentyl diazoacetoacetate (1) forms γ-lactone products from insertion into primary and tertiary C-H bonds in a statistical distribution (61:39) with dirhodium(II) tetrakis(perfluorobutyrate), only tertiary C-H insertion is observed with dirhodium(II) tetraacetamide. Similar results are obtained with 2-methyl-2-octyl diazoacetoacetate (3), where competition for insertion exists between secondary and primary C-H bonds and electronic factors govern regioselection. However, with 2-methyl-3-isopropyl-3-heptyl diazoacetoacetate (2) and 2-methyl-l-phenyl-2-propyl diazoacetoacetate (4), product distributions from C-H insertion are invariant with the dirhodium(II) ligands; insertion into a secondary C-H bond is favored over tertiary C-H insertion with 2 (95:5), and insertion into a primary C-H bond is preferred to benzylic secondary C-H insertion with 4 (70:30). In such cases, which are amenable to analyses by MM2 calculations, regioselectivity is determined by conformational preferences for which C-H insertion selectivity can be as random as that found with 2 and 4. When only one C-H bond site is available for insertion to form a five-membered ring product, only one γ-lactone is observed from reactions catalyzed by dirhodium(II) tetraacetate, and that product is not necessarily the one predicted by presumed electronic preferences.
- Doyle, Michael P.,Westrum, Larry J.,Wolthuis, Wendelmoed N. E.,See, Marjorie M.,Boone, William P.,Bagheri, Vahid,Pearson, Matthew M.
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p. 958 - 964
(2007/10/02)
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