INVESTIGATIONS CONCERNING THE SYNTHESIS OF CONDENSED FURANOPYRAZOLES, FURANODIAZEPINES AND FURANOOXAZEPINES STARTING WITH 3-CHLORO-6-METHOXYBENZOFURAN-2-CARBOXALDEHYDE .4.

3-Chloro-6-methoxybenzofuran-2-carboxaldehyde (2) on condensation with a variety of nitrogen dinucleophiles gave the expected aldimines (3a-d, 4a-d, 5). Attempted intramolecular cyclisation under the influences of acid or base catalysis or thermolysis or even photolysis of these aldimines (3a-d, 4a-d, 5) was however found to be unsuccessful. Even the chloroacetal (12) prepared from the chloroaldehyde (2) failed to undergo substitution of the halogen by the nitrogen nucleophiles in affording the corresponding substituted acetal (13). The tosylate (16) derived from the aldimine (5) also failed to undergo intramolecular cyclisation in furnishing the anticipated seven-membered heterocyclic derivative (17).