Base Mediated Intramolecular Cyclization of Betti-propargyl Precursors: An Efficient Approach to 1,4-oxazepine Derivatives.

Introduction: 1,4-oxazepine is a significant structural motif found in several bio-active molecules used in the treatment of diseases such as psychotic disorders.

Methods: Therefore, developing novel methodologies for its preparation is of great interest to medicinal chemists.

Results: These seven-membered heterocycles are generated through the intramolecular cy-clization of Betti bases, which are propargylated using propargyl bromide as the source of the triple bond in the presence of a base.

Conclusion: This efficient and straightforward protocol proceeds under mild, metal-free conditions and has been shown to be applicable to a broad range of aldehydes and 2-aminopyridines.