Disubstituted 2,6-Dihetero-adamantanes

8-Disubstituted 2,6-Dihetero-adamantanes The methylene groups H2—C(9) and Hj—C(10) in 4,8-disubstituted 2,6-dihetero-adamantanes appear generally independent of the nature of X and Y 

In this section several characteristic NMR-data of 2-oxa-6-aza-adamantanes [X(2) = O, Y(6) = NR] diall be discussed standing as typical examples for the rather large number of 4,8-disubstituted 2,6-dihetero-adamantanes known so far. 

H-atoms connected by lines). This reflects the influence of the heteroatoms X(2) [or Y(6), resp.] to reduce Jvic between a bridgehead H-atom geminal and a methylene H-atom vicinal to X(2) [or Y(6), resp.]. The effect becomes larger if X(2) [or Y(6), resp.] is arranged trans-coplanar to the methylene H-atom (approx. 

5 Hz) and smaller if the angle between X(2) [or Y(6), resp.] and the methylene H-atom is approx. 60° (approx. 3.5—4.5 Hz) The vicinal coupling constants of diacetate 80 as an illustrative example are listed in Table 14. 

From the data in Table 14 it further can be seen that the same is also caused by the electronegative atoms 0(2) and N(6) on the vicinal coupling constants between the bridgehead H-atoms and the corresponding H-atoms H—0(4) and H—C(8) geminal to an acetoxy group, independent of the latter substituents. 

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