Practical Asymmetric Conjugate Alkynylation of Meldrum's Acid-Derived Acceptors: Access to Chiral β-Alkynyl Acids

The enantioselective conjugate addition of alkynyl nucleophiles has been a long-standing challenge in synthetic chemistry. This paper describes a highly practical asymmetric conjugate alkynylation of Meldrum’s acid-derived acceptors using cinchonidine (<$100/kg) as the chiral mediator. The process provides practical access to chiral β-alkynyl acids. Noteworthy attributes of the method are its broad scope, high functional-group compatibility, and ease of scalability.