N-HETEROCYCLIZATION IN ELECTROPHILIC HALOAMIDATION REACTIONS OF 1,5-CYCLOOCTADIENE - SYNTHESIS AND REARRANGEMENTS OF THE GRANATANINE AND HOMONORTROPANE SKELETONS

The transannular N-heterocyclization of 1,5-cyclooctadiene using eithe r N-bromo- or N-iodosuccinimide and cyanamide is a preparatively usefu l method for the synthesis of 9-azabicyclononanes 2 and 3. This reacti on failed when N-chlorosuccinimide was employed. The chloro-substitute d derivative 2c was prepared, with retention of configuration, from bo th pure 2a and from an equimolar mixture of 2a and 3a by nucleophilic displacement with chlorine, followed by dehydration of the resulting c arboxamide 4c. Acidic hydrolysis of the cyanamide group in 2a and 3a g ave the ureas 4a and 5a. Reaction of 2a and 3a with tributyltin hydrid e gave the debrominated derivatives 8 and 9, while treatment of the sa me compounds with LiAlH4 afforded a single air-sensitive product which was trapped as the urea 7. Substitution of the halogens in 2a and 3a (or 2b and 3b) by acetoxy groups using silver acetate in acetic anhydr ide gave 12 and 13 as a result of inversion at one side and retention of the configuration on the other side of the starting materials which was accompanied by transamidation at the nitrogen bridge. Treatment o f 2a with dicyclohexylethylamine led to complete dehydrobromination an d the formation of 14.