A novel series of 2-amino-6-carboxamidobenzothiazole was discovered to have potent Lck inhibitory properties. A highly efficient chemistry was developed. Many potent analogues were generated with urea, carbamate, heteroarylamine or alkylamine at the C-2 position. The SAR for the middle ring and the right side aryl group was also explored. The selectivity profile was herein included. ... Developing small molecule Lck inhibitors has been the focus of major ...