1 H - NMR ( DMSO - d 6 ) δ : 1 . 07 ( 6 H , s ) , 4 . 11 ( 2 H , s ) , 4 . 73 ( 1 H , s ) , 7 . 00 ( 1 H , m ) , 7 . 18 ( 1 H , m ) , 7 . 56 ( 1 H , m ) , 7 . 66 ( 1 H , m ) , 8 . 13 ( 1 H , s ) , 8 . 20 ( 1 H , m ) , 8 . 54 ( 1 H , m ) .