Preparation of Sulfur-Containing Optically Active Secondary Alcohols Based on Pichia farinosa-Catalyzed anti-Prelog-Rule Reduction as the Key Step
A Pichia farinosa IAM 4682 mediated reduction of sulfur containing ketones afforded secondary alcohols with (R)-absolute configuration. For example, 4-(phenylthio)-2-butanone and 4-(phenylsulfonyl)-2-butanone afforded (R)-4-(phenylthio)-2-butanol (91%ee) in 90% yield and (R)-4-(phenylsulfonyl)-2-butanol (97%ee) in 94% yield, respectively. In the case that the ee of the product was not satisfactory, any contaminating (S)-enantiomer was selectively oxidized by Rhodococcus rhodochrous IFO 15564 to leave pure (R)-enantiomer. The substrate specificity of Pichia farinosa-mediated reduction and Rhodococcus rhodochrous-mediated oxidation was further examined.
Diastereoselectivity of the conjugate addition of organocopper reagents to (E)-γ-hydroxy-α,β-unsaturated sulfones
The conjugate addition of organocopper reagents, mainly the higher order cuprates R3CuLi2 to (E)-γ-hydroxy-α,β-unsaturated phenyl sulfones takes place with excellent yields and high anti-selectivity.
Dominguez,Carretero
p. 5803 - 5806
(2007/10/02)
Synthesis and conjugate additions to (E)-γ-alkoxy-α-substituted-α,β-unsaturated sulfones
(E)-γ-hydroxy-α,β-unsaturated sulfones have been readily functionalized at α-position via protection of hydroxyl group, metalation with n-BuLi and subsequent reaction with electrophiles. The conjugate addition of organolithiums to (E)-γ-methoxymethoxy-α-trimethylsilyl-α,β-unsaturated phenyl sulfones in Et2O is highly syn-stereoselective
Alcaraz,Carretero,Dominguez
p. 1385 - 1388
(2007/10/02)
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