Dong-Ha Lee

Highly regio-, (E)-stereo-, and diastereoselective SN2′ addition of organocuprates to chiral allylic cyclic carbonates

Abstract Reaction of the cyclic carbonates of acyclic vinyl diols with RCu(CN)Li· BF 3 , RCu(CN)MgBr·BF 3 , or RMgBr·CuI (cat) in THF at −78 °C proceeded in S N 2′ fashion and resulted in the formation of alkylated ( E )-allylic alcohols with remarkably high diastereoselectivity. This reaction represents an efficient 1, 3-chirality transfer method.

Addition of organocopper reagents to cyclic sulfites or carbonates of γ,δ-dihydroxy (E)-α,β-enoates

Abstract Reaction of cyclic sulfites or carbonates of γ,δ-dihydroxy ( E )-α,β-enoates with R 2 Cu(CN)Li 2 , BF 3 ; RCu(CN)Li, BF 3 (R = Me-, n -Bu-) afforded either diastereoselective S N 2′products or reductive elimination product depending on reaction conditions. Addition of R 2 Cu(CN)Li 2 , BF 3 (R = Me-, n -Bu-) to cyclic sulfite ( 1 ) or cyclic carbonate ( 3 ) (inverse addition) afforded highly regio-, ( E )-stereo- and diastereoselectively α-alkylation products ( 6 and 8 ). By using this methodology, (2 S , 5 S )- trans -2-methyl-5-hexanolide, the pheromone of the carpenter bee Xylocopa hirutissima was synthesized.

Synthesis of Optically Active (E)-γ-Hydroxy-α, β-unsaturated Nitriles

Abstract Treatment of (2S, 3S)- or (2R, 3S)-1-cyano-2, 3-alkanediols with carbonyldiimidazole or thionyl chloride resulted in one-pot preparation of (E, S)-γ-hydroxy-α, β-unsaturated nitriles based on the elimination of the cyclic carbonates or sulfites formed in situ