“…Syntheses and the conformational assignments of 1,4,6,7,8,8a‐hexahydropyrrolo[1,2‐ d ]1,3,4,2‐oxadiazaphosphinine 3‐oxides ( 1 and 2 ), 1,6,7,8,9,9a‐hexahydro‐4 H ‐pyrido[1,2‐ d ]1,3,4,2‐oxadiazaphosphinine 3‐oxides ( 3 , 4 and 8 ), 1,6,11,11a‐tetrahydro‐4 H ‐1,3,4,2‐oxadiazaphosphino[4,5‐ b ]isoquinoline‐3‐oxides ( 5 and 6a ) and 1,6,7,11b‐tetrahydro‐4 H ‐1,3,4,2‐oxadiazaphosphino‐[5,4‐ a ]isoquinoline‐3‐oxides ( 7 ) (Table 1) were reported previously 5, 6. In addition to the basic fragmentations of the compounds mentioned above, our main interest was in the detection of parallels and dissimilarities (caused by differences in ring size, ring fusion, P substitution and bridgehead N atom) relative to the 3,1,2‐O,N,P‐ and 1,3,2‐N,N,P‐heterocycles studied previously 7, 8…”