2685978 4-MPBA 4-mercaptophenylboronic acid 68 3047512 MPBA 4-mercaptophenylboronic acid 46 1210215 MBA 4-mercaptophenylboronic acid 12 1261798 MPA 4-mercaptophenylboronic acid 3 3714091 4-MBA 4-mercaptophenylboronic acid 2 2660197 4-MBPA 4-mercaptophenylboronic acid 1 3714502 4-MPB 4-mercaptophenylboronic acid 1