Solution phase synthesis of β-peptides using micro reactors

The synthesis of β-peptides has been successfully performed using a borosilicate glass micro reactor, in which a network of channels has been produced using a photolithographic and wet etching method. The reagents were mobilised by electroosmotic flow (EOF). The micro reactor was initially evaluated using a carbodiimide coupling reaction to form a dipeptide. The methodology has been extended such that the peptides may also be produced via the pentafluorophenyl ester derivatives of amino acids. It was found that performing the pentafluorophenyl ester reactions in the micro reactor resulted in an increase in the reaction efficiency over the traditional batch method. We postulate that the enhancement in rate of reaction is an electrochemical phenomenon, due to the reaction being performed in an electric field, which is unique to micro reactor systems. It has also been demonstrated that selective deprotection of the resultant dipeptides can be achieved. This approach has been used in the synthesis of a tripeptide.