SYNTHESIS AND NOE AND 2D-NOESY SPECTROSCOPIC STUDIES OF N-PROPIONYL DERIVATIVES OF OXAZOLIDIN-2-ONE AND 1,3-OXAZIN-2-ONE CHIRAL AUXILIARIES DERIVED FROM TERPENE-ALCOHOL [(1S)-ENDO]-(-)-BORNEOL

A variant method was employed for the synthesis of N-propionyl derivatives of oxazolidin-2-one and 1,3- oxazin-2-one chiral auxiliaries derived from [(1S)-endo]-(-)-borneol via the use of sodium hydride as a base and cheap and readily available acylation reagent, propionic anhydride. This procedure led to excellent yields 96% and 99% of N-propionyl derivatives of oxazolidin-2-one and 1,3-oxazin-2-one chiral auxiliaries, respectively. Attempts to distinguish between the prochiral methylene protons in the Npropionyl group, and all other diastereotopic protons and methyl groups in these two N-propionyl derivatives of chiral auxiliaries were carried out by using 1H NMR nOe difference spectra and 2DNOESY spectroscopic studies.