A stannous chloride-induced deacetalisation–cyclisation process to prepare the ABC ring system of ʹupenamide

A stannous chloride-induced deacetalisation–cyclisation approach to the ABC core of the macrocyclic alkaloid, ʹupenamide is reported. The use of a substituted β-lactone to prepare a C-2 substituted ʹupenamide analogue is also disclosed.