Asymmetric Michael Addition of 5 H-Oxazol-4-ones to Vinyl Sulfones:
- TCHLab
- Oct 24, 2014
- 1 min read
Stereoselective Synthesis of Monofluorinated Analogs of 2‐Tertiary Hydroxyl‐3‐Methyl‐Substituted Carboxylic Acidl Derivatives
Qian Liu, Baokun Qiao, Kek Foo Chin, Choon‐Hong Tan and Zhiyong Jiang
Advanced Synthesis and Catalysis, 2014, 356, 3777-3783
Abstract: An asymmetric Michael addition of 5H‐oxazol‐4‐ones to vinyl sulfones has been developed. In the presence of 10 mol % of quinine‐based benzyl‐substituted thiourea as catalyst at 0 °C, the products could be obtained with excellent enantio‐ and diastereoselectivity (up to>99 % ee and>20:1 dr). 1.0 mol % of catalyst also produced the corresponding adducts with similar stereoselective results when the temperature was increased to 25 °C. The obtained adducts have been demonstrated as significant synthetic fragments to conveniently access the monofluorinated analogs of biologically important 2‐tertiary hydroxyl‐3‐methyl‐substituted carboxylic acid derivatives.
Paper download: https://doi.org/10.1002/adsc.201400649
Commenti