A Practical Aryl Unit for Azlactone Dynamic Kinetic Resolution: Orthogonally Protected Products and A Ligation‐Inspired Coupling Process1. (25th November 2014)

• Record Type: Journal Article
• Authors: Tallon, Sean; Manoni, Francesco; Connon, Stephen J.
• Is Part Of: Angewandte Chemie. Volume 127:Number 3(2015)
• Page Start: 827
• Page End: 831
• Publication Date: 2014-11-25
• Subjects: Chemistry -- Periodicals; 540
• DOI: 10.1002/ange.201406857
• Languages: English
• ISSNs: 0044-8249

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>The first strategy for bringing about enantioselective azlactone dynamic kinetic resolution to generate orthogonally protected amino acids has been developed. In the presence of a C₂<italic>‐</italic>symmetric squaramide‐based catalyst, benzyl alcohol reacts with novel yet readily prepared tetrachloroisopropoxycarbonyl‐substituted azlactones to generate trapped phthalimide products of significant synthetic interest with excellent enantiocontrol. These materials are masked amino acids which are demonstrably orthogonally protected: cleavage of the phthalimide can be achieved in the presence of the ester and vice versa. This process could be utilized to bring about a highly stereoselective ligation‐type coupling of protected serines (at stoichiometric loadings) with racemic azlactones derived from both natural and abiotic amino acids. After deprotection, a subsequent base‐mediated O→N acyl transfer occurs to form a dipeptide.</p> </abstract>