Stereochemical studies. 81. Saturated heterocycles. 69. Preparation of methylene‐bridged 3,1‐benzoxazines, 3,1‐benzoxazin‐2‐ones and 3,1‐benzoxazine‐2‐thiones

Abstract 3‐exo‐Aminobicyclo[2.2.1]hept‐5‐ene‐2‐exo‐carboxylic acid and ethyl 3‐endo‐aminobicyclo[2.2.1]heptane‐2‐endo‐carboxylate (6) were reduced with lithium aluminum hydride to the corresponding bicyclic aminoalcohols 3 and 4. These and the saturated endo‐endo and exo‐exo N‐methylaminoalcohols 16 and 22, respectively, were converted to methylene‐bridged tetrahydro‐ (11) and hexahydro‐3,1‐benzoxazin‐2‐ones 12, 17, 23 and 3,1‐benzoxazin‐2‐thiones 13, 14, 18, 24. The exo‐exo 3 and endo‐endo 4 aminoalcohols were cyclized by means of ethyl arylimidates to tricyclic dihydro‐1,3‐oxazines 7a‐d, 8a‐d. The structures were confirmed by ir, 1H and 13C nmr spectroscopy.