It is surveyed that the amination of the Baylis-Hillman acetates with primary amines can be dramatically promoted in improved yields and shortened reaction time under ultrasound irradiation than those under conventional stirring. The extensive scope of both amines and acetates are screened to investigate the relationship between substituents and their performance in such transformation.

The title compound, C21H14BF2NO, was synthesized by the reaction of 3-[(E)-(naphthalen-1-ylimino)methyl]naphthalen-2-ol, diisopropylethylamine and boron trifluoride etherate. The mean planes of the two naphthalene systems make a dihedral angle of 71.97 (4)°. The crystal packing is stabilized by π–π stacking interactions and van der Waals forces.

A novel tetracyclic frameworks of dispiropyrrolizidines can be obtained in moderate to good yields via the 1,3-dipolar cycloaddition of azomethine ylides with dipolarophiles derived from aza-Claisen rearrangement of Baylis-Hillman amines. The transformations are highly regioselective and stereoselective, affording the desired compounds in reduced time and increased yields under ultrasound irradiation at room temperature. All the products are confirmed by 1H, 13C NMR, IR and MS spectra, while their molecular structures are elucidated by X-ray crystallography of a selected sample.

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