392668-22-3Relevant academic research and scientific papers
Chiral amino ether-controlled catalytic enantioselective arylthiol conjugate additions to α,β-unsaturated esters and ketones: Scope, structural requirements, and mechanistic implications
Nishimura, Katsumi,Tomioka, Kiyoshi
, p. 431 - 434 (2007/10/03)
Asymmetric conjugate addition reaction of 2-trimethylsilylbenzenethiol with enoates and enones is catalyzed by a chiral amino ether-lithium thiolate complex and affords adducts with high enantioselectivity. Both the s-cis conformation and a steric wall at one side of the carbonyl group are structural requirements in substrates yielding adducts with high enantioselectivity. Reactions with tert-butyl enones gave addition products with high enantioselectivity. Construction of two contiguous chiral centers was possible by this addition-protonation sequence. Methyl tiglate was stereoselectively converted to a single syn-adduct of 95% enantiomeric excess (ee) bearing two contiguous chiral centers. Methyl 2-phenyl-2-butenoate was converted to a single syn-adduct of 95% ee, which was desulfurized to methyl 2-phenylbutanoate of 95% ee. These additions generate a transient lithium enolate that is protonated by a thiol anti to the C-S bond, giving the corresponding product having two adjacent stereocenters.
