Enantiopure 4‐oxazolin‐2‐ones and 4‐methylene‐2‐oxazolidinones as chiral building blocks in a divergent asymmetric synthesis of heterocycles
| Autor: | R. Israel Hernández-Benitez, Edson Barrera, Vanessa Pelayo, Julio López, Miguel A. Vázquez, Joaquín Tamariz, Hugo A. Jiménez-Vázquez, Aydeé Fuentes-Benites, Blanca M. Santoyo, Carlos H. Escalante, Guadalupe Martínez‐Morales, Francisco Delgado, Daniel Zárate-Zárate, Carlos González-Romero |
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| Rok vydání: | 2019 |
| Předmět: |
Pharmacology
Chiral auxiliary 010405 organic chemistry Chemistry Stereochemistry Organic Chemistry Enantioselective synthesis 010402 general chemistry 01 natural sciences Asymmetric induction Catalysis Cycloaddition 0104 chemical sciences Analytical Chemistry Stereocenter chemistry.chemical_compound Enantiopure drug Nucleophile Drug Discovery Electrophile Spectroscopy |
| Zdroj: | Chirality. 31:719-749 |
| ISSN: | 1520-636X 0899-0042 |
| Popis: | 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. |
| Databáze: | OpenAIRE |
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