Highly Enantioselective Addition of Phenylacetylene to Aldehydes Catalyzed by a β-Sulfonamide Alcohol–Titanium Complex

✍ Scribed by Zhaoqing Xu; Rui Wang; Jiangke Xu; Chao-shan Da; Wen-jin Yan; Chao Chen

• Publisher: John Wiley and Sons
• Year: 2003
• Tongue: English
• Weight: 89 KB
• Volume: 42
• Category: Article
• ISSN: 0044-8249
• DOI: 10.1002/anie.200352572

✦ Synopsis

The enantioselective formation of C À C bonds is an area of intense research. [1,2] The asymmetric addition of alkynyl reagents to aldehydes is very useful for the synthesis of chiral secondary propargyl alcohols, which are important building blocks for many chiral organic compounds. [3] Several studies into the alkynylation of aldehydes with amino alcohol ligands have led to methods that give moderate to good yields and enantioselectivities. [4] Carreira and co-workers reported the addition of terminal acetylenes to aliphatic aldehydes in the presence of stoichiometric or catalytic amounts of amino alcohol 1 to give the desired products in high yields and enantioselectivities. However, this method was not suitable for the addition reaction to aromatic aldehydes because of significant competition from the Cannizzaro reaction. [5] Recently, Chan and co-workers reported that binol (2) can catalyze the addition of alkynyl zinc reagents to aromatic aldehydes with high ee values. However, the reaction also requires 1 equivalent of a sulfonamide ligand and must be run at 0 8C for 1-2 days. [6] Pu and co-workers reported that a