Synthesis of New Aza- and Thia-Crown Ether Based Amino Acids

Abstract

Crown ethers have been known since the middle of the 20th century as metal chelating agents with numerous applications. For example, amino acids functionalized with crown ethers have been used to create artificial ion channels. However, only a few of those crown amino acids are known, all of which contain exclusively oxygen as heteroatoms in the crown ether moiety. Alternative structures may be desirable to explore new biological or pharmaceutical applications. Hence, we aim to expand the scope of available crown ether amino acids - in particular those with heteroatoms other than oxygen. Herein we describe the synthesis of three previously unknown amino acids bearing a crown ether moiety. We use two distinct synthetic routes to avoid the use of hazardous reagents. Two of these three amino acids bear sulfur atoms in the crown ether, while the third contains a nitrogen atom.