Alternate synthesis of olanexidine base employing phase transfer catalysis

The traditional methods of synthesis of biguanide drugs generally result in the formation of high levels of waste. In this study, we have developed a simple and green route for the synthesis of olanexidine, the novel antimicrobial compound developed by Otsuka Pharmaceutical Factory Inc. This molecule has been clinically explored in Japan for pre-operative skin preparations. The proposed synthesis scheme is beneficial as it has obviated the use of harmful sodium dicyanamide and has employed the readily available dicyandiamide to facilitate cyanoguanidylation of 3,4-dichlorobenzylamine into 3,4-dichlorobenzylbiguanide. This intermediate was further condensed with 1-bromooctane, using tetrabutyl ammonium bromide as the phase transfer catalyst, in a biphasic solvent system comprising of water and ethyl acetate. The developed method resulted in an overall yield of 76% of olanexidine.