Synthesis of 2,3‐dihydrospiro[benzofuran‐2,4′ ‐piperidines] and 2,3‐dihydrospiro[benzofuran‐2,3′‐pyrrolidines]

The synthesis of 2,3‐dihydrospiro[benzofuran‐2,4′‐piperidines] 3 and 2,3‐dihydrospiro[benzofuran‐2,3′]‐pyrrolidine] 6 is described. The synthesis was achieved by a Grignard reaction of a 2‐fluorobenzylhalide with an appropriate cycloazaalkyl ketone to yield the tertiary alcohols 1 and 4 . Subsequent intramolecular displacement of the aromatic fluoride by the derived alkoxides provided the novel system. Nitration of 1′‐acetyl‐2,3‐dihydrospiro[benzofuran‐2,4′‐piperidine] 7 resulted in a 5‐nitro derivative.