Construction of Optically Active Quaternary Propargyl Amines by Highly Enantioselective Zinc/BINOL‐Catalyzed Alkynylation of Ketoimines. Issue 36 (15th July 2013)

• Record Type: Journal Article
• Authors: Huang, Gaochao; Yin, Zengsheng; Zhang, Xingang
• Is Part Of: Chemistry. Volume 19:Issue 36(2013)
• Page Start: 11992
• Page End: 11998
• Publication Date: 2013-07-15
• Subjects: Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.201301479
• Languages: English
• ISSNs: 0947-6539

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>A general and efficient method for the highly enantioselective alkynylation of ketoimines through a zinc/1, 1′‐bi‐2‐naphthol (BINOL)‐catalyzed process has been developed. A variety of ketoimines, including α‐fluoroalkyl α‐imine esters, α‐aryl α‐imine esters, and trifluoromethyl aryl ketoimines, are applicable and provide their corresponding quaternary propargyl amines in excellent yields with high <italic>ee</italic> values (up to 99 % <italic>ee</italic>). Both the steric and electronic effects of substituents at the 3, 3′ positions of BINOL are critical for the reaction efficiency and enantioselectivity. To demonstrate the usefulness of the method, (<italic>R</italic>)‐α‐CF₃ α‐proline has been prepared in a highly efficient manner. The notable features of this protocol are its broad substrate scope, high reaction efficiency (up to 99 %) and enantioselectivity (up to 99 % <italic>ee</italic>), low catalyst loading (5 mol % of BINOL derivative), and mild reaction conditions.</p> </abstract>