Linear and Cyclic Amides with a Thiophene Backbone: Ultrasound Promoted Synthesis and Crystal Structures
Thien Huynh Ngo , Huelya Berndt , Dieter Lentz , and Hans-Ulrich Reissig
J. Org. Chem., Just Accepted Manuscript
Full synthetic study of linear and cyclic oligoamides with thiophene backbone has been carried out. The combination of ultrasonic technique to diminish the intramolecular backfolding of longer oligoamide chain, therefore enhancing the accessibility of carboxylic acid, and T3P® as coupling reagent led to shorter reaction time and higher yields for both linear and cyclic oligoamides. By controlling the degree of dilution macrocyclic amides with different sizes can selectively be prepared. Different crystal structures of cyclic thiophenyl backboned oligoamides were analyzed.