《Highly Diastereoselective Functionalization of Piperidines by Photoredox-Catalyzed α-Amino C-H Arylation and Epimerization》 was published in Journal of the American Chemical Society in 2020. These research results belong to Walker, Morgan M.; Koronkiewicz, Brian; Chen, Shuming; Houk, K. N.; Mayer, James M.; Ellman, Jonathan A.. Synthetic Route of C33H24IrN3 The article mentions the following:
We report a photoredox catalyzed α-amino C-H arylation reaction of highly substituted piperidine derivatives with electron deficient cyano(hetero)arenes. The scope and limitations of the reaction were explored, with piperidines bearing multiple substitution patterns providing the arylated products in good yields and with high diastereoselectivity. In order to probe the mechanism of the overall transformation, optical and fluorescent spectroscopic methods were used. By employing flash-quench transient absorption spectroscopy, we were able to observe electron transfer processes associated with radical formation beyond the initial excited state Ir(ppy)3 oxidation Following the rapid and unselective C-H arylation reaction, a slower epimerization occurs to provide the high diastereomer ratio observed for a majority of the products. Several stereoisomerically pure products were re-subjected to the reaction conditions, each of which converged to the exptl. observed diastereomer ratios. The observed distribution of diastereomers corresponds to a thermodn. ratio of isomers based upon their calculated relative energies using d. functional theory (DFT). Safety: NaCN is a reaction byproduct. The results came from multiple reactions, including the reaction of fac-Tris(2-phenylpyridine)iridium(cas: 94928-86-6Synthetic Route of C33H24IrN3)
fac-Tris(2-phenylpyridine)iridium(cas: 94928-86-6) belongs to pyridine. Pyridine is very deactivated towards electrophilic substitution with respect to benzene. For this reason classical formylation, using methods such as the Gattermann or Vilsmeier reactions, are not generally successful. Synthetic Route of C33H24IrN3