Abstract
AbstractNonstabilized α‐O‐substituted tertiary organolithium species are difficult to generate, and the α‐S‐substituted analogues are configurationally unstable. We now report that they can both be generated easily and trapped with a range of electrophiles with high enantioselectivity, providing ready access to a range of enantioenriched tertiary alcohols and thiols. The configurational stability of the α‐S‐organolithium species was enhanced by using a less coordinating solvent and short reaction times.
Highlights
Chiral a-heteroatom (O, N, and S)-substituted organolithium compounds are a versatile class of nucleophiles that are useful in the asymmetric synthesis of chiral alcohols, amines, and thiols.[1]
Nonstabilized tertiary a-O-organolithium compounds are configurationally stable but are difficult to generate owing to their reduced kinetic acidity (Scheme 1 B);[1e,2] tertiary a-Sorganolithium species are formed but are not configurationally stable (Scheme 1 A)
Boronic esters represent a niche class of electrophiles,[6] and we initially embarked on a study of the trapping of tertiary a-O-substituted organolithium species, which were generated by lithiation of the enantioenriched TIB esters 1 a–1 e, with a range of electrophile classes (Scheme 2)
Summary
Chiral a-heteroatom (O, N, and S)-substituted organolithium compounds are a versatile class of nucleophiles that are useful in the asymmetric synthesis of chiral alcohols, amines, and thiols.[1]. We have discovered reaction conditions for the generation of enantioenriched, tertiary, nonstabilized a-Sorganolithium compounds and report their subsequent trapping with electrophiles in high enantioselectivity (Scheme 1 C).
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