Regioselective C-H Alkylation of Aromatic Ethers with Alkenes by a Half-Sandwich Calcium Catalyst

The catalytic ortho-regioselective C-H alkylation of a variety of alkoxy-substituted benzene derivatives with alkenes can be achieved by the use of a half-sandwich calcium alkyl complex [(Cp-Ar5)Ca{CH(SiMe3)(2)}-(THF)] (2) (Cp-Ar5 = C5Ar5, Ar = 3,5-Pr-i-C6H3) as the precatalyst. The potential catalytic reaction intermediates, half-sandwich calcium anisyl complexes [(Cp-Ar5)Ca(o-MeO-m-Ph-C6H3) (THF)(2)] (8) and [(Cp-Ar5)Ca-(o-MeO-2-Np) (THF)(2)] (9) (Np = naphthyl), were isolated and X-ray structurally characterized. DFT calculations were carried out to elucidate the different reaction profiles of sp(2) and sp(3) C-H activations.

Automated summary

This study demonstrated the catalytic ortho-regioselective C-H alkylation of alkoxy-substituted benzene derivatives with alkenes using a half-sandwich calcium alkyl complex as the precatalyst. The potential catalytic reaction intermediates were isolated and X-ray structurally characterized, with DFT calculations elucidating the different reaction profiles of sp(2) and sp(3) C-H activations.