Ni-catalyzed fixation of heterocumulenes into organic matter and c-h functionalization reactions

Identificador:  TDX:2479

Handle: https://hdl.handle.net/20.500.11797/TDX2479

Autors:  Wang, Xueqiang

Resum:
During my PhD studies, I have focus my attention primary on 4 projects, two of these dealing with the ability to promote catalytic CO2 fixation techniques, and the last two using isocyanates in reductive hydroamidation and C-H functionalization. The interest of my studies for carbon dioxide relies primarily on the synthesis of carboxylic acids, molecules that despite their tremendous simplicity are incredibly prevalent in a wide number of pharmaceuticals. The utilization of abundant, cheap and non-toxic CO2 as C1 synthon represents an elegant alternative for preparing carboxylic acids. However, the classical methods are limited to stoichiometric, well-defined and air-sensitive metal species that ultimately need to be prepared from the corresponding organic halide. Challenged by such perception, we would like to develop mild, user-friendly catalytic reductive carboxylation protocols with CO2, thus avoiding the need for stoichiometric organometallic reagents. In line with our studies in reductive electrophile-electrophile cross coupling reactions, we developed a convenient hydroamidation reaction of alkynes with isocyanates that utilizes simple alkyl bromides as hydride source. Following up with our interest in selective reaction, we established a C(sp2)-H or C(sp3)-H functionalization/C-O bond forming process catalyzed by in situ generated I(III) reagent. The reactions occurred under mild conditions and with an intriguing selectivity switch depending on the catalyst used.