Figure 3 The potential energy surface for Pd(II)-catalyzed
tranformation from 7 to products PR11and PR12 with L1 as the ligand. The
free energies are given in kcal/mol.
From Figure 3, it can be clearly seen that TS8-9 andTS13-14 are the chemodivergence-determining transition states
towards alkenyl chloride product (PR11) and
trisubstituted olefin (PR12 ), respectively. The
overall barrier for 13→TS8-9 associated with oxidative addition
is lowered by 1.8 kcal/mol in comparison to 13→TS13-14 related
to protonation process, which means that alkenyl chloride
(PR11) is the major product. The calculated
chemoselectivity is 9.4:1 in 298 K. The result is well consistent with
the experimentally observed a 82:9 (9.1:1) ratio for the L1ligand-promoted Pd II -catalyzed C-H activation of
arene with alkyne (entry 1 in Scheme 2). As seen from Figures 2 and 3,
the rate-determining step of the whole catalytic cycle is CMD process
via TS3-4 after the formation of active catalyst K .
The reaction energy barrier for this step is 24.8 kcal/mol, which is
comparable with the observed yield (81%) of major productPR11 under experimental conditions.