Syntheses & reactions of azabicycles
Several novel nitrogen containing bicyclic systems have been synthesised and their chemistry investigated. The kinetic and thermodynamic invertomer ratios of N-chloro-1,2,3,4-tetrahydro-2-keto-l, 4-iminonaphthalene derivatives were determined. The results suggested that a repulsive interaction existed between the positive end of the carbonyl dipole and the incoming electrophilic chlorine. Despite reaction under favourable solvolytic conditions, it appeared that homolysis of the N-chloroamines was favoured over heterolysis. Under conditions of negligible inversion, N-chloro-1,4-dihydro-1-methyl-l,4-iminonaphthalenes underwent heterolytic rearrangement to form 4-inethyIquinclines. From these experiments it was deduced that the quinoline products must be derived from the anti-N-chloroamines with loss of a bridgehead carbon atom. A mechanism for the formation of these products was proposed. Nortropane was synthesised in high overall yield and the first synthesis of a simple derivative of nortrop-6-ene which has been achieved in significant yield was also accomplished. The procedure demonstrated the viability of an intramolecular cyclisation approach given an appropriately nucleophilic nitrogen. Investigation of the reactions of chlorosulphonyl isocyanate with 7-substituted cycloheptatrienes provided evidence that choice of solvent and reaction time along with careful monitoring exerts control over the addition of either the C=0 or C=N moiety across the termini of the triene unit.