Compounds with bridgehead nitrogen. Part 49. The synthesis and stereochemistry of perhydropyrido[3,2,1-j,k][3,l]benzoxazepines and of r-3a,t-11a,c-14a, t-14b, t-22a,t-22b-perhydrodiquino[1,8a,8-c,d:1′,8a′,8′-j,k][1,8,3,10]dioxadiazacyclotetradecine

Abstract

Ring closure of the diastereoisomeric 2-decahydroquinolin-8-ylethanols with formaldehyde gave r-4a,c-7a,t-11a-, r-4a,t-7a,t-11a, and r-4a, c-7a, c-11a-perhydropyrido[3,2,1-j,k][3,1]benzoxazepines, but instead of the fourth isomer a dimer, r-3a,t-11a,c-14a,t-14b,t-22a,t-22b-perhydrodiquino[1,8a,8-c,d:1′,8a′,8′-j,k][1,8,3,10]dioxadiazacyclotetradecine, was obtained. Comparison of ¹³C n.m.r. shifts of the conformationally locked isomers with those of perhydropyrido[1,2-c][1,3]oxazepine showed different average perhydro-1,3-oxazepine ring conformations in the various structures so that an estimate of the position of conformational equilibrium (CDCl₃, solution) of the bicyclic compound from this data could not be made. The ¹³C n.m.r. spectrum of perhydropyrido[1,2-c][1,3]oxazepine in CDCl₃—CFCl₃, however, showed a ratio of ca. 5:1 trans-fused: O-inside-cis-fused conformers at –80 °C.