On the Reaction of N-Formylbenzotriazole and Norbornene with NAlkylacetonitrilium Salts

Reaction of N-methyl/isopropylacetonitrilium hexachloroantimonate 1a, b with N-formylbenzotriazole 2 afforded the corresponding iminium salts 4a, b; of which 4a reacts with the oxime derivatives 5a-d to give the corresponding N-oxyiminium salts 6a-d in a good yield (60-92 %). Reaction of N-methylacetonitrilium hexachloroantimonate 1a with norbornene (7) furnished the new ring system 1,4,4a,5,6,7,8,8a-octahydro-5,8-methano-4(2-norbornyl)-naphthridinium hexachloroantimonate 10 in 85 % yield. The Treatment of 10 with DDQ oxidized the two bridged protons and afforded 1,4,5,6,7,8-hexahydro-5,8-methano-4(2-norbornyl)-naphthrdinium hexachloroantimonate 11 in 80% yield.