Carboxylicacids and their corresponding carboxylate anions are generally utilized as Brønsted acids/bases and oxygen nucleophiles in organic synthesis. However, a few asymmetric reactions have used carboxylicacids as electrophiles. Although chiral thioureas bearing both arylboronic acid and tertiary amine were found to promote the aza-Michael addition of BnONH2 to α,β-unsaturatedcarboxylic acids
作者:Stephen G. Davies、Ai M. Fletcher、Linlu Lv、Paul M. Roberts、James E. Thomson
DOI:10.1016/j.tetlet.2012.04.025
日期:2012.6
The asymmetricsynthesis of (−)-(R)-sitagliptin was achieved in seven steps from commercially available starting materials using the highly diastereoselective conjugate additions of either lithium (R)-N-benzyl-N-(α-methylbenzyl)amide or lithium (R)-N-benzyl-N-(α-methyl-p-methoxybenzyl)amide to tert-butyl 4-(2′,4′,5′-trifluorophenyl)but-2-enoate to install the correct stereochemistry. Subsequent sequential