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Enantiopure 4‐oxazolin‐2‐ones and 4‐methylene‐2‐oxazolidinones as chiral building blocks in a divergent asymmetric synthesis of heterocycles
Author(s) -
Santoyo Blanca M.,
GonzálezRomero Carlos,
ZárateZárate Daniel,
HernándezBenitez R. Israel,
Pelayo Vanessa,
Barrera Edson,
Escalante Carlos H.,
FuentesBenites Aydeé,
MartínezMorales Guadalupe,
López Julio,
Vázquez Miguel A.,
Delgado Francisco,
JiménezVázquez Hugo A.,
Tamariz Joaquín
Publication year - 2019
Publication title -
chirality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.43
H-Index - 77
eISSN - 1520-636X
pISSN - 0899-0042
DOI - 10.1002/chir.23109
Subject(s) - enantiopure drug , chemistry , methylene , chirality (physics) , enantioselective synthesis , combinatorial chemistry , stereochemistry , organic chemistry , catalysis , chiral perturbation theory , particle physics , pion , physics , nambu–jona lasinio model
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.