Artículo
Enantiopure 4‐oxazolin‐2‐ones and 4‐methylene‐2‐oxazolidinones as chiral building blocks in a divergent asymmetric synthesis of heterocycles
Autor
Santoyo, Blanca M.
González Romero, Carlos
Zárate‐Zárate, Daniel
Hernández‐Benitez, R. Israel
Pelayo, Vanessa
Barrera, Edson
Escalante, Carlos H.
Fuentes Benítes, Aydeé
Martínez‐Morales, Guadalupe
López, Julio
MENDOZA DELGADO, FRANCISCO JAVIER
Vázquez Guevara, Miguel Angel
Jiménez‐Vázquez, Hugo A.
Tamariz, Joaquín
Institución
Resumen
En este trabajo se describe la reactividad de las oxazolidin-2-onas en un ambiente quiral obteniéndose resultados novedosos, los cuales se describen extensamente. Enantiopure 3‐((R)‐ and 3‐((S)‐1‐phenylethyl)‐4‐oxazoline‐2‐ones were evaluated as chiral building blocks for the divergent construction of heterocycles with stereogenic quaternary centers. The N‐(R)‐ or N‐(S)‐1‐phenylethyl group of these compounds proved to be an efficient chiral auxiliary for the asymmetric induction of the 4‐ and 5‐positions of the 4‐oxazolin‐2‐one ring through thermal and MW‐promoted nucleophilic conjugated addition to Michael acceptors and alkyl halides. The resulting adducts were transformed via a cascade
process into fused six‐membered carbo‐ and heterocycles. The structure of the reaction products depended on the electrophiles and reaction conditions used. Alternative isomeric 4‐methylene‐2‐oxazolidinones served as chiral precursors
for a versatile and divergent approach to highly substituted cyclic carbamates. DFT quantum calculations showed that the formation of bicyclic pyranyl compounds was generated by a diastereoselective concerted hetero‐Diels‐Alder cycloaddition. Instituto Politécnico Nacional, Secretaria de Investigación y Estudios Avanzados de la Universidad Autónoma del Estado de México, Universidad de Guanajuato y CONACYT.