1. Intramolecular Chiral Relay at Stereogenic Nitrogen: Design, Synthesis, and Application of Oxadiazinones as Chiral Auxiliaries
Shawn R. Hitchcock, Department of Chemistry, Illinois State University, Normal, IL
Our research program has been focused on refining the chemistry of the oxadiazinones. We have employed the oxadiazinones as chiral auxiliaries in the asymmetric aldol reaction and we have determined that the N4-position of the heterocycle is responsible for inducing the stereochemistry of the addition reaction. In this context we sought to increase the diastereoselectivities beyond the capacity of
N4-methyl substituent by introducing substituents that were more sterically demanding.
We have prepared a variety of oxadiazinones with
differing substituents (benzyl, neopentyl, cyclohexyl, and phenyl) and applied these derivatives in application reactions. The diastereoselectivities ranged from 88:12 to 99:1. However, the hydrolysis component of this project remains a challenge.
Our most current efforts are directed at electronically tuning the N4-nitrogen to effect the high diastereoselectivity in the aldol reaction and to facilitate the hydrolysis process.