A Single-Step Synthesis of 4-Oxazolin-2-ones and Their Use in the Construction of Polycyclic Structures Bearing Quaternary Stereocenters
作者:Blanca M. Santoyo、Carlos González-Romero、Omar Merino、Rafael Martínez-Palou、Aydeé Fuentes-Benites、Hugo A. Jiménez-Vázquez、Francisco Delgado、Joaquín Tamariz
DOI:10.1002/ejoc.200900114
日期:2009.5
for the synthesis of 4-oxazolin-2-ones by a one-pot MW-promoted condensation of α-ketols and isocyanates is reported. An alternative thermal approach using the same starting materials is also described. These cyclic enamides were efficient nucleophiles, reacting with Michael acceptors and prenyl bromide to give a variety of polycyclicstructuresbearing one or two quaternarystereocenters. The selectivity
1,2-Oxazolidines. Part V. Spiro and condensed biheterocyclic isomers from nitrones and 1,3-oxazolidin-2-ones
作者:Maria C. Aversa、Giampietro Cum、Placido D. Giannetto、Giovanni Romeo、Nicola Uccella
DOI:10.1039/p19740000209
日期:——
The cycloaddition reaction between nitrones and substituted 1,3-oxazolidin-2-ones yields condensation products and spiro-compounds, each type of product containing a 1,2-oxazolidine nucleus. Their stereochemistry was elucidated by lanthanide shift analysis. The main spectrometric characteristics and the chemical behaviour of these new systems are discussed. Evidence is reported that the formation of
Divergent Pd-catalyzed Functionalization of 4-Oxazolin-2-ones and 4-Methylene-2-oxazolidinones and Synthesis of Heterocyclic-Fused Indoles
作者:Daniel Yescas-Galicia、Rodrigo A. Restrepo-Osorio、Ailyn N. García-González、Roberto I. Hernández-Benítez、José C. Espinoza-Hicks、Carlos H. Escalante、Edson Barrera、Blanca M. Santoyo、Francisco Delgado、Joaquín Tamariz
DOI:10.1021/acs.joc.2c01563
日期:2022.10.7
Palladium-catalyzed functionalization was presently performed on two building blocks: 4-oxazolin-2-ones and 4-methylene-2-oxazolidinones. Direct Heck arylation of 4-oxazolin-2-ones led to a series of 5-aryl-4-oxazolin-2-ones, including analogues with N-chiral auxiliary, in an almost quantitative yield. The Pd(II)-catalyzed homocoupling reaction of 4-oxazolin-2-ones provided novel heterocyclic across-ring
Versatile synthesis of quaternary 1,3-oxazolidine-2,4-diones and their use in the preparation of α-hydroxyamides
作者:Omar Merino、Blanca M. Santoyo、Luisa E. Montiel、Hugo A. Jiménez-Vázquez、L. Gerardo Zepeda、Joaquín Tamariz
DOI:10.1016/j.tetlet.2010.05.034
日期:2010.7
A new approach to the synthesis of 1,3-oxazolidine-2,4-diones, via a two-step reaction sequence, starting from the readily available alpha-ketols and isocyanates, is reported. The condensation of the latter led to the key precursors 4-methylene-2-oxazolidinones, which are converted into the diones by an oxidative cleavage of the exocyclic double bond. Thus, 5,5-disubstituted 1,3-oxazolidine-2,4-diones can be accessed in good yields from the appropriate functionalized alpha-ketols. Moreover, two alternative routes are also described either by functionalization of 4-oxazolin-2-ones or by alkylation of the 1,3-oxazolidine-2,4-dione core previously prepared. Upon hydrolysis of the 1,3-oxazolidine-2,4-diones, a series of alpha-hydroxyamides bearing a quaternary stereocenter were obtained. (C) 2010 Elsevier Ltd. All rights reserved.
Regioselective Synthesis of N-Substituted 4-Methylene-2-oxazolidinones and 4-Oxazolin-2-ones. Study of Reactivity in Thermal Michael Conjugate Additions
作者:Rafael Martı́nez、Hugo A. Jiménez-Vázquez、Joaquı́n Tamariz
DOI:10.1016/s0040-4020(00)00311-2
日期:2000.6
N-Substituted 4-methylene-2-isoxazolidinones 9a–9e have been prepared from the tandem condensation of isocyanates 3 with α-ketol 7. In a more polar solvent (DMF) the same reaction led to stereoisomeric alcohols 11 and 12, which could be transformed to the thermodynamically more stable isomers 4-oxazolin-2-ones 10 in good yield. Thermal conjugate additions of both heterocycles 9a and 10a to enone 13