82959-87-3Relevant articles and documents
One-Pot Reductive 1,3-Dipolar Cycloaddition of Secondary Amides: A Two-Step Transformation of Primary Amides
Huang, Pei-Qiang,Lang, Qi-Wei,Hu, Xiu-Ning
, p. 10227 - 10235 (2016/11/17)
The one-pot reductive 1,3-dipolar cycloaddition of secondary aromatic N-(trimethylsilylmethyl)amides with reactive dipolarophiles is reported. The method relies on the in situ generation of nonstabilized NH azomethine ylide dipoles via amide activation with triflic anhydride, partial reduction with 1,1,3,3-tetramethyldisiloxane (TMDS), and desilylation with cesium fluoride (CsF). Running under mild conditions, the reaction tolerated several sensitive functional groups and provided cycloadducts in 71-93% yields. The use of less reactive dipolarophile methyl acrylate led to the cycloadduct in only 40% yield. A (Z) geometric intermediate of NH-azomethine 1,3-dipole was postulated to account for the observed higher yields and higher cis diastereoselectivity for the substrates bearing an electron-withdrawing group. This model features an unconventional cyclic transition state via carbanion-aryl ring interaction. Because the starting secondary amides can be prepared from common primary amides, the current method also constitutes a two-step transformation of primary amides.
Rhodium-Catalyzed Intramolecular C-H Bond Activation with Triazoles: Preparation of Stereodefined Pyrrolidines and Other Related Cyclic Compounds
Senoo, Masato,Furukawa, Ayana,Hata, Takeshi,Urabe, Hirokazu
supporting information, p. 890 - 895 (2016/01/16)
On treatment of triazoles having an N-sulfonyl-protected benzylamine moiety with [Rh2(C7H15CO2)4], intramolecular C-H bond insertion takes place at the benzylic position to give cis-N-sulfonyl-2-aryl-3-[(sulfonylimino)methyl]pyrrolidines in good yields and with highly stereoselectivities. Analogously, the similar treatment of triazoles having an ether or even an alkyl moiety affords 2-alkyl- or 2-aryl-3-[(sulfonylimino)methyl]tetrahydrofurans or a 2-alkyl-3-[(sulfonylimino)methyl]cyclopentane in good yields. Three is a magic number: On treatment of triazoles with [Rh2(C7H15CO2)4], the rhodium catalyst plays three roles, denitrogenation, C-H bond activation, and stereoselective cyclization, providing a new method for heterocycle synthesis. Intramolecular C-H bond insertion takes place at the benzylic position to give pyrrolidines and related heterocycles in good yields.
Synthesis of cis-2-aryl-3-pyrrolidine carboxylic esters via diastereoselective cyclization of γ-imino esters using a TiCl 4/Et3N reagent system
Suresh, Surisetti,Periasamy, Mariappan
, p. 6291 - 6293 (2007/10/03)
Facile synthesis of cis-2-aryl-3-pyrrolidine carboxylates from readily accessible γ-imino esters by intramolecular cyclization mediated by a TiCl4/Et3N reagent system is described.