2 research outputs found
Catalytic Asymmetric 1,6-Michael Addition of Arylthiols to 3-Methyl-4-nitro-5-alkenyl-isoxazoles with Bifunctional Catalysts
Diastereoselective Corey–Chaykovsky 9‑Epoxymethylation of <i>Cinchona</i> Alkaloids: Access to Chiral Scaffolds with Diverse Functionalities
Reaction of dimethylsulfonium methylide
with <i>Cinchona</i> alkaloid ketones proceeds with complete
diastereoselectivity to
give epoxides of 8,9-<i>like</i> configuration. The reaction
of dimethylsulfoxonium methylide gives different isomers, albeit with
lower (4:1) selectivity. α-Epimerization of the alkaloid ketones
resulted in formation of two separable diasteromeric products. The
configurations of the epoxides were elucidated on the basis of NMR
data combined with DFT calculations. Models explaining observed selectivity
are discussed. The epoxides were efficiently transformed to a number
of derivatives through selective S<sub>N</sub>2-type ring-opening
reactions with various nucleophiles, often without the need of additional
purification steps