3385-34-0Relevant articles and documents
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Anschuetz,Bendix,Kerp
, p. 181 ()
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Catalytic asymmetric tamura cycloadditions
Manoni, Francesco,Connon, Stephen J.
supporting information, p. 2628 - 2632 (2014/03/21)
In the presence of a novel, tert-butyl-substituted squaramide-based catalyst, enolizable anhydrides react with alkylidene oxindoles to generate spirooxindole products of significant synthetic interest with excellent enantio- and diastereocontrol. The methodology is of wide scope and encompasses both homophthalic and glutaconic anhydride derivatives, which lead to structurally diverse products. Glutaconic acid-derived anhydrides undergo a clean post-cyclization decarboxylation process which is not a feature of reactions involving homophthalic acid-derived anhydrides. The unusual influence of reaction temperature on diastereocontrol has been probed, with reactions occurring at 30 °C and -30 °C delivering products epimeric at one stereocenter only, in near optical purity. Squared away: The first strategy for bringing about enantioselective Tamura reactions is reported. In the presence of a squaramide-based catalyst, enolizable anhydrides react with alkylidene oxindoles to generate spirooxindole products with excellent enantio- and diastereocontrol. The methodology is of wide scope and leads to structurally diverse products.
MECANISMO DE LA REACCION DE COMPUESTOS 1,3-DICARBONILICOS CON ANHIDRIDO TRIFLICO. CICLACION ANOMALA DEL ESTER ACETILACETICO A 3-ETOXICARBONIL-2,6-DIMETIL-4-PIRONA.
Martinez, A. Garcia,Fernandez, A. Herrera,Vilchez, D. Molero,Ubeda, A Herrera,Hanack, M.,Subramian, L. R.
, p. 121 - 123 (2007/10/02)
The reaction of ethyl acetoacetate (1) with triflic anhydride (Tf2O) in excess, in the presence of nitriles (3) affords 3-ethoxycarbonyl-2,6-dimethyl-4-pyrone (10), instead of 5-ethoxycarbonyl-4,6-dimethyl-2-pyrone (5), which is the usual product formed in the cyclization of 1 catalyzed by protic or Lewis acids.Palabras clave: 2-pirona, 4-pirona, anhidrido triflico, ester acetylacetico.
