Synthesis and Analysis
Professor M. Cristina White has developed iron-based small molecule catalysts which, in conjunction with hydrogen peroxide, can selectively oxidize aliphatic C-H...
Professor M. Cristina White has developed iron-based small molecule catalysts which, in conjunction with hydrogen peroxide, can selectively oxidize aliphatic C-H bonds in complex natural products.
Organic synthetic strategies are typically designed around the use of protecting or activating groups to yield desired products. While the use of these types of groups is well developed and widely used, this approach often generates waste and introduces unwanted complexity into the synthetic sequence. Methods which allow introduction of functionalities without activating or protecting groups can significantly impact synthetic methods. In particular, reactions which can predictively and selectively oxidize isolated, unactivated sp3 C-H bonds in complex substrates are of particular value as they enable introduction of functionalities in the later stages of synthetic sequences.
White has developed catalyst systems which achieve this oxidation of C-H bonds based solely on electronic and steric properties of the bond. With the additional use of carboxylate directing groups, diastereoselective lactonizations can be achieved.
A compelling example of the selective oxidation of a C-H bond is the conversion of the antimalarial compound artemisinin which contains five potential C-H sites for oxidation and a cleavage-sensitive peroxide functional group. Using White's iron-based catalyst and its designed selectivity, the targeted C-H bond is oxidized preferentially to give the desired product in higher yields, with shorter reaction times, and in higher volume throughputs compared to enzymatic reactions.
White's catalyst systems open powerful methods to greatly streamline synthetic methods by offering predictive and selective aliphatic C-H oxidation in complex substrates.
Dr. John Katzenellenbogen from the University of Illinois has designed Pathway preferential estrogens (PaPEs) that are novel synthetic compounds that...
Dr. John Katzenellenbogen from the University of Illinois has designed Pathway preferential estrogens (PaPEs) that are novel synthetic compounds that structurally resemble the natural estrogen but with its reduced binding affinity, form ER-PaPE complex with a short lifetime of seconds. This short binding is sufficient to selectively activate the ER non-genomic pathway and not the ER genomic pathway. PaPEs are shown in animal models to promote health of metabolic tissues and vasculature; reduces body weight gain and fat accumulation after ovariectomy and accelerates repair of endothelial damage; no stimulation on breast and endometrial cancerous cells.