A 1,3-dipolar cycloaddition–annulation protocol for the expedient regio-, stereo- and product-selective construction of novel hybrid heterocycles comprising seven rings and seven contiguous stereocentres

An expedient regio-, stereo- and product-selective synthesis of novel hybrid heterocyclic systems comprising [1,2-c]oxazolidine, pyrrolidine and piperidine units, in good to excellent yields, has been developed via three-component 1,3-dipolar cycloaddition/annulation domino reactions and concomitant trifluoroacetic acid mediated condensative annulation with paraformaldehyde. These novel structurally complex heterocyclic hybrids, accessed by a two-step protocol, possess seven rings and seven contiguous stereocentres.