Lactamization of 11-Azidoundecanoic Acid Derivatives – DMAP as Catalyst

I. Bosch, P. Romea, F. Urpi, and J. Vilarrasa, Tetrahedron Lett., 34, 4671 (1993)

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1. A solution of tributylphosphine (10 mmol), DMAP (6 mmol) in benzene (200 mL) is heated under reflux.  To this solution is added the azido acid (1) (1 mmol) dissolved in THF (5 mL) and benzene (50 mL) via a syringe pump over 6 h.  Reflux is maintained for a further 1 h; the solution cooled, washed, dried, and concentrated.  The residue is subject to "flash" chromatography (eluent dichloromethane/methanol), and the lactam is obtained in 51% yield.