A range of mechanisms then were explored for the catalytic borylation of 2-methyl-thiophene that proceed via C-H zincation, -bond metathesis and protonolysis and a computed profile that is consistent with the VTNA analysis (1 st order in (H-BBN)2 dimer) is shown in Figure (a). Here [NacNacZn(DMT)] + ([9] + ) and 2-methyl-thiophene are taken as the starting point of the cycle.