Organocatalytic Stereoselective Synthesis of Acyclic γ-Nitrothioesters with All-Carbon Quaternary Stereogenic Centers

摘要: A method for the stereoselective synthesis of acyclic thioesters bearing adjacent quaternary and tertiary stereogenic centers under mild organocatalytic conditions was developed. α-Substituted monothiomalonates (MTMs) were used as thioester enolate equivalents. They reacted cleanly with nitroolefins in presence 1–6 mol % cinchona alkaloid urea derivatives, provided access to γ-nitrothioesters stereocenters high yields diastereo- enantioselectivities. Mechanistic investigations insight into parameters that determine stereoselectivity showed diastereoselectivity can be controlled by nature MTM substrate. The different reactivities three functional groups (oxoester, thioester, nitro moieties) within conjugate addition products allowed straightforward other compounds centers, such γ-nitroaldehydes γ-butyrolactams.