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Novel Chiral Bifunctional L-Thiazoline-Thiourea Derivatives: Design and Application in Enantioselective Michael Reactions.

Novel Chiral Bifunctional L-Thiazoline-Thiourea Derivatives: Design and Application in Enantioselective Michael Reactions.

Chirality (2015-10-03)

Qi Lai, Yang Li, Zhiyong Gong, Qingwen Liu, Chiyu Wei, Zhiguang Song

ABSTRACT

Several novel chiral bifunctional L-thiazoline-thiourea derivatives were easily synthesized from commercially available L-cysteine in high yield. These catalysts were subsequently applied to the enantioselective Michael addition of acetylacetone to β-nitrostyrenes. The products with S configuration were obtained in 98% enantiomeric excess (ee) when the L-thiazoline-thiourea derivatives were used. A plausible transition state model is proposed to explain the observed enantioselectivities.

MATERIALS

Product Number

Brand

Product Description

Sigma-Aldrich

Ethyl alcohol, Pure 190 proof, for molecular biology

Sigma-Aldrich

Tetrahydrofuran, contains 250 ppm BHT as inhibitor, puriss. p.a., ACS reagent, reag. Ph. Eur., ≥99.9%

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Tetrahydrofuran, anhydrous, contains 250 ppm BHT as inhibitor, ≥99.9%

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2-Propanol, SAJ first grade, ≥99.0%

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2-Propanol, JIS special grade, ≥99.5%