A New Way to the Synthesis of Tricyclic Compounds via Nitrone 1,3- cycloaddition Dipolar Reaction

This study aimed at developing new methodologies for 1,3-dipolar cycloaddition.

A new series of tricyclic derivatives (13a-d) were synthesized via 1, 3-dipolar cycloaddition of nitrones (8a-c) and (9a-c) using intramolecular cyclisation at the reflux of toluene and radical intramolecular cyclisation in the presence of tributyltin hydride and AIBN as an initiator in benzene, which are two techniques to prepare cycloadducts (11a-d), followed by cleavage of the N-O bond performed using Sml in THF.

The structures of these new tricyclic derivatives have been confirmed by Mass, 1H-NMR (1d, 2d), 13C-NMR, and IR spectral data.

In summary, we have investigated the possibility of synthesizing some new and straightforward methods to access an A-C-D tricyclic skeleton of morphinans from symmetrical arylcyclohexadienes.