Deacetalisation–bicyclisation routes to novel polycyclic heterocycles using stannous chloride dihydrate

The stannous chloride dihydrate-mediated deprotection–bicyclisation of a range of amides possessing a pendant acetal group is reported. These mild reaction conditions have been used to prepare a number of ring-fused heterocyclic compounds, some in enantiomerically pure form, which should be of interest both in their own right and as building blocks for the production of more complex target molecules.