- Exploiting Continuous Processing for Challenging Diazo Transfer and Telescoped Copper-Catalyzed Asymmetric Transformations
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Generation and use of triflyl azide in flow enables efficient synthesis of a range of α-diazocarbonyl compounds, including α-diazoketones, α-diazoamides, and an α-diazosulfonyl ester, via both Regitz-type diazo transfer and deacylative/debenzoylative diazo-transfer processes with excellent yields and offers versatility in the solvent employed, in addition to addressing the hazards associated with handling of this highly reactive sulfonyl azide. Telescoping the generation of triflyl azide and diazo-transfer process with highly enantioselective copper-mediated intramolecular aromatic addition and C-H insertion processes demonstrates that the reaction stream containing the α-diazocarbonyl compound can be obtained in sufficient purity to pass directly over the immobilized copper bis(oxazoline) catalyst without detrimentally impacting the catalyst enantioselectivity.
- Crowley, Daniel C.,Brouder, Thomas A.,Kearney, Aoife M.,Lynch, Denis,Ford, Alan,Collins, Stuart G.,Maguire, Anita R.
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p. 13955 - 13982
(2021/09/02)
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- Asymmetric Intramolecular Buchner Reaction: From High Stereoselectivity to Coexistence of Norcaradiene, Cycloheptatriene, and an Intermediate Form in the Solid State
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Bicyclic compounds bearing a quaternary stereogenic center have been obtained using asymmetric intramolecular Buchner reaction with excellent yields and level of enantioselectivity. X-ray crystallography determination of the absolute configuration of one product has led to the serendipitous observation of an unusual behavior within the crystal structure, with equilibrating norcaradiene and cycloheptatriene valence isomers at the solid state, as well as an even more unexpected intermediate form. DFT calculations were performed to support these observations.
- Darses, Benjamin,Maldivi, Pascale,Philouze, Christian,Dauban, Philippe,Poisson, Jean-Fran?ois
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supporting information
p. 300 - 304
(2021/01/26)
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- 3-Alkylperoxy-3-cyano-oxindoles from 2-Cyano-2-diazo-N-phenyl-acetamides via Cyclizing Carbene Insertion and Subsequent Radical Oxidation
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A transition-metal-free one-pot sequence for the synthesis of 3-peroxy-substituted oxindoles from readily prepared 2-cyano-2-diazo-acetamides is reported. The two-step tandem process includes a highly efficient thermal intramolecular C-H-carbene insertion
- Kischkewitz, Marvin,Daniliuc, Constantin-Gabriel,Studer, Armido
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supporting information
p. 1206 - 1209
(2016/03/15)
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- In situ-generated iodonium ylides as safe carbene precursors for the chemoselective intramolecular buchner reaction
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A chemoselective intramolecular Buchner reaction employing iodonium ylides as safe carbene precursors has been developed. Iodonium ylides are generated in situ from N-benzyl-2-cyanoacetamides and PhI(OAc)2 in the presence of base and undergo intramolecular Buchner reaction under catalysis from Cu(OAc)2·H2O, affording fused cyclohepta-1,3,5-triene derivatives in up to 85% yield. The N,N-dibenzyl-2-cyanoacetamides with two different benzyl groups undergo intramolecular Buchner reaction on their electron-rich benzyl groups selectively. The reaction is not sensitive to air and moisture and uses a safe alternative version of the corresponding diazo starting materials. The overall transformation involving the carbene pathway has been verified.
- Mo, Shanyan,Li, Xinhao,Xu, Jiaxi
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p. 9186 - 9195
(2014/12/11)
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- 2-Amino-3-benzoylthiophene allosteric enhancers of A1, adenosine agonist binding: New 3, 4-, and 5-modifications
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2-Amino-3-aroylthiophenes are agonist allosteric enhancers (AE) at the A1, adenosine receptor (A1AR). Here we report the syntheses of three kinds of novel 2-aminothiophenes and assays of their AE activity at the human A1AR (hA1AR), namely, (1) 2-amino-4,5-diphenylthiophene-3-carboxylates, 3a-h, (2) 2-amino-3-benzoyl-4,5-diphenylthiophenes, 7a-p, and (3) 2-amino-5-bromo-3-benzoyl-4-phenylthiophenes, 10a-h. An in vitro assay employing the A1AR agonist [125I]ABA and membranes from CHO-K1 cells stably expressing the hA1AR measured an index of AE activity, the ability of a candidate AE to stabilize the agonist-A1AR-G protein ternary complex, scored as the percentage of ternary complex remaining after 10 min of dissociation initiated by CPX and GTPγS. The AE activity score of 2-amino-4,5-dimethyl-3-(3-trifluoromethylbenzoyl)thiophene (PD 81,723), which was 19%, served as a standard for comparison. Two 3-carboxythiophene 3-trifluoromethylbenzyl esters, 3d (49%) and 3f (63%), had substantial AE activity. The 3-(1-naphthoyl) substituent of 7e (52%) also supported AE activity. Compounds in series 3 tended to be more potent, 10a and 10c having scores of 91 and 80%, respectively. The activity of 2-amino-5-bromo-3-ethoxycarbonyl-4-(3-nitrophenyl)thiophene, 10h (26%), is an exception to the rule that a 3-ethoxycarbonyl substituent cannot support AE activity.
- Lütjens, Henning,Zickgraf, Andrea,Figler, Heidi,Linden, Joel,Olsson, Ray A.,Scammells, Peter J.
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p. 1870 - 1877
(2007/10/03)
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