Dioxa-adamantanes

By the approach B Stetter and coworkers successfully synthesized in 1966 the first 2,6-dihetero-adamantane, the 2,6-dioxa-adamantane (14). Oxymercuration of 

The diiodide 5 as sole product was obtained by reaction of 9-oxabicyclo[3.3.1 ]-nona-2,6-diene (1) with mercuric oxide and iodine. Treatment of the diiodides 

5 and 6 with silver acetate in acetic acid yielded, depending on the reaction time, among others the monoacetates 7 and 8 or the diacetates 9 and 10 (see 3.2.2.2.). 

Further syn-4,8-disubstituted 2,6-dioxa-adamantanes were prepared from diene 1 applying pathway B by Cuthbertson and MacNicol dibromide 11 14 and by Averina - dibromide 11, dichloride 12 and diol 13. The latter 13 was 

---

Pioneering work on the desulphonylation of jS-ketosulphones was carried out by Corey and Chaykovsky - . This reaction was part of a sequence which could be used in the synthesis of ketones, as shown in equation (53). The main thrust of this work was in the use of sulphoxides, but Corey did stress the merits of both sulphones and sulphonamides for different applications of this type of reaction. The method soon found application by Stetter and Hesse for the synthesis of 3-methyl-2,4-dioxa-adamantane , and by House and Larson in an ingenious synthesis of intermediates directed towards the gibberellin skeleton, and also for more standard applications . Other applications of the method have also been madealthough it does suffer from certain limitations in that further alkylation of an a-alkyl- -ketosulphone is a very sluggish, inefficient process. Kurth and O Brien have proposed an alternative, one-pot sequence of reactions (equation 54), carried out at — 78 to — 50°, with yields better than 50%. The major difference between the two routes is that the one-pot process uses the desulphonylation step to generate the enolate anion, whereas in the Corey-House procedure, the desulphonylation with aluminium amalgam is a separate, non-productive step. 

Treatment of exo,exo-2,3-epoxy-9-oxabicyclo[3.3.1 ]non-6-ene (15) with mercuric acetate yielded the 2,6-dioxa-adamantane derivative 16, which was directly demer-... 

In both cases studied using G 56-adamantanes as starting materials rearranged products were observed where oxonium ions occurred as intermediates, namely on treatment of 4°l l,8°l l-diiodo-2,6-dioxa-adamantane (J 2.1.2.1.) and N(6)-phenylsulfonyl-4N(6)8N(S),diiodo.2 -oxa-6-aza-adamantane (47 2.1.5.2.) with silver acetate in acetic acid, see G 36 - G 38 (oxonium ion) - G 39 (adamantane) + G 40 (isotwistane) ... 

To obtain an equal turnover,the following reaction conditions had to be applied 16 hrs at 95° with the 2,6-dioxa-adamantane J and 230 hrs at 70-75° with the 2-oxa>-... 

Cl2H20O6 f 1,3,5,7-Tetramethoxy-2,6-dioxa-adamantane, 33B, 135 Ci2H2oOef 1,4,7,10,13,16-Hexaoxa-2,6-cyclooctadecanedione, 45B, 330 C12H22N2OU, Cyclobisurethane, 42B, 242... 

The relative and absolute configurations of diepoxydicarbazoles involving the 2,6-dioxa-4,8-diazaadamantane system were determined in the course of a study on indole and indole alkaloids.242 Water-soluble azo, anthraquinone, and phthalocyanine dyes which are substituted by a 4-chloro-s-triazin-2-ylamino group can be quaternized with a l-aza-3-methyl-4,6,10-trioxa-adamantane unit in aqueous medium at 40 50"C.243 Dyes mixed with... 

Dioxa-, 1,3-dithia,, 3-diaza-2,4,6-triarsinanes with adamantane structures... 

---