Rhodium-Catalyzed Oxygenative [2 + 2] Cycloaddition of Terminal Alkynes and Imines for the Synthesis of β-Lactams
作者:Insu Kim、Sang Weon Roh、Dong Gil Lee、Chulbom Lee
DOI:10.1021/ol500856z
日期:2014.5.2
which gives β-lactams as products with high trans diastereoselectivity. In the presence of a Rh(I) catalyst and 4-picoline N-oxide, a terminal alkyne is converted to a rhodium ketene species via oxidation of a vinylidene complex and subsequently undergoes a [2 + 2] cycloaddition with an imine to give rise to the 2-azetidinone ring system. Mechanistic studies suggest that the reaction proceeds through
Staudinger reactions of unsymmetrical cyclic ketenes: a synthetically useful approach to spiro β-lactams and derivatives. Reaction mechanism and theoretical studiesElectronic supplementary information (ESI) available: Spectral data for compounds 4b–4m and 5b–5d and Cartesian coordinates and energies (hartrees) of zwitterionic intermediates (IZ1, IZ2, IZ3, and IZ4) and transition structures (TS1, TS2, TS3 and TS4). See http://www.rsc.org/suppdata/p1/b1/b103279h/
作者:Eduardo Alonso、Carlos del Pozo、Javier González
DOI:10.1039/b103279h
日期:2002.2.6
efficient and operationally simple synthesis of tetrahydrofuran-derived spiro-β-lactamsusing the ketene–imine cycloaddition route is described. Also the preparation of spiro-N-sulfonyl-β-lactam derivatives, which are analogs of monobactams, is reported. As far as we know, this is the first time that an unsymmetrical cyclic ketene is used in a Staudinger-type reaction. The experimental evidence suggests
Chloride ion promoted nucleophilic pentafluorophenylation of imines
作者:Vitalij V. Levin、Alexander D. Dilman、Pavel A. Belyakov、Marina I. Struchkova、Vladimir A. Tartakovsky
DOI:10.1016/j.tetlet.2006.10.019
日期:2006.12
Nucleophilic addition of the pentafluorophenyl group from (C6F5)3SiF to non-activated imines affording α-C6F5-substituted secondary amines in high yield has been described. The reaction proceeds via simultaneous activation of imines and the silane reagent by means of a proton and chlorideion, respectively.
已经描述了将来自(C 6 F 5)3 SiF的五氟苯基亲核加成到未活化的亚胺上,从而以高收率提供α- C6 F 5取代的仲胺。通过分别借助于质子和氯离子同时活化亚胺和硅烷试剂来进行反应。
A Highly Efficient Carbon−Carbon Bond Formation Reaction via Nucleophilic Addition to <i>N</i>-Alkylaldimines without Acids or Metallic Species
A nucleophilic additionreaction to N-methylaldimines without acid or metal species is described. A novel reagent, dicyanomethyl acetate, is used as a nucleophile to give alpha-(N-methyl-N-acetyl)amino acid methyl esters in excellent yield.
Synthesis of C<sub>6</sub>F<sub>5</sub>-Substituted Aminoethanols via Acetate Ion Mediated C<sub>6</sub>F<sub>5</sub>-Group Transfer Reaction
作者:Alexander D. Dilman、Vitalij V. Levin、Pavel A. Belyakov、Alexander A. Korlyukov、Marina I. Struchkova、Mikhail Y. Antipin、Vladimir A. Tartakovsky
DOI:10.1055/s-2006-926278
日期:——
A new approach for the synthesis of N-(pentafluorophenylmethyl)aminoethanols is developed. The method includes alkylation of imines with 2-tris(pentafluorophenyl)silyloxyethyl triflate, prepared from ethylene oxide and (C6F5)3SiOTf, to give 2-silyloxyethyliminium ions. Their treatment with sodium acetate induces C-C bond formation proceeding as transfer of the C6F5 group from the five-coordinate silicate intermediate to the iminium center.