Heteroaromatic N-Oxides Modified with a Chiral Oxazoline Moiety, Synthesis and Catalytic Applications

Interesting properties of N-oxides and pyridine oxazoline compounds have become the starting point to synthesize compounds connecting both groups. A multi-step synthesis of a series of chiral oxazoline substituted pyridine N-oxides, alkyl derived of pyridine N-oxides, bipyridine N-oxides, and isoquinoline N-oxides, based on amino alcohols derived from natural amino acids or other previously prepared, is presented herein. Various synthetic pathways have been designed and tested according to the properties and limitations imposed by the target products. The encountered problems related to the stability of the products were discussed. The resulting compounds (eighteen structures) were tested as catalysts in th e allylation of benzaldehyde (obtaining up to 79% ee) as well as in nitroaldol reaction (obtaining up to 48% ee).

Automated summary

This study presents a multi-step synthesis of a series of chiral oxazoline substituted pyridine N-oxides compounds, and tests their catalytic properties in allylation and nitroaldol reactions. Various synthetic pathways were designed and potential stability issues were discussed.