Ni(II) and Photocatalyzed Functionalization of Carbon-Carbon Double Bonds

Homogenous nickel catalysis is gaining more and more attention of chemist due to a variety of oxidative states resulting from distribution of its external electron in 3d orbital and abundance in the earth crust. Due to difference in diameter and distribution of external electron, nickel complexes possess some unique activities that 4d, 5d noble metals can’t achieve. In this thesis, we described our work on nickel(II) catalyzed Suzuki coupling of electron perturbed allenes to synthesize stereochemically defined enamine and ester. The methodology showed excellent tolerance to variously substituted phenylboronic acids. Additionally, with allenamide, it can also proceed in cascade tricomponent versions with aldehyde wherein dimethylzinc was also compatible. Theoretical computation was conducted to reveal the nature of mechanism. This work realized an umpolung of nucleophilicity of allenamde, extending the reactivity of it. As an expansion of previous work on nickel chemistry, we stretched our sight to photoredox reaction with initial idea of using organonickel as co-catalyst. So, we devoted to develop photocatalyzed synthesis of 1,3,4-trisubstituted pyrrole in a mild, oxidant-free way which was also documented in this thesis. Further work to disclose the mechanism were also done suggesting the azide were reduced through a new pathway. Wacker oxidation is a quite useful transformation from alkene to ketone or aldehyde which always needs palladium catalyst system and theoretically at least one equivalent oxidant. Herein, we disclose a new way to realize Wacker Oxidation through a gentle photoredox process where noble metal, harsh condition, oxidant or other additives are not indispensable any more. At last, the assistant work has been done to realize the Cp*Rh(III) catalyzed enantioselective C-H activation of acrylamide which is not further mentioned in this thesis. In this work, the activated acrylamide coupled with terminal allene affording an annulated 5-member lactam with excellent enantioselectivity. (DOI: 10.1002/anie.201909971)