Synthesis and Conformational Behaviour of Enantiomeric Naphthoxazinoquinoxalinone Derivatives

New non-racemic naphth[1,3]oxazino[3,2-a]quinoxalinones have been synthesized starting from an enantiomeric hexahydroquinoxalinone and 1-aminoalkyl-2-naphthols or 2-aminoalkyl-1-naphthols. The enantiopure annelational analogues naphth[1,3]oxazino[3,4-a]quinoxalinone derivatives were also synthesized from the reactions of naphthols and the non-racemic quinoxalinone followed by a ring-closing reaction with formaldehyde. In addition to the study of the conformational behaviour of the new heteropolycycles, the diastereoselectivity and formation of the possible diastereomers were examined by NMR analysis. Theoretical calculations were performed to confirm the experimental results.