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

Abstract

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, 1 H and 13 C nmr spectroscopy.