Substrate (0.56 mmol)
KOH (powdered, 0.7 mmol)
1,3-dibromopropane (1.7 mmol)
DMF (3 ml)
hexane / ether (for chromatography)
Silica Gel (for chromatography)

To the substrate in DMF added the electrophile and then the KOH, stirred overnight at room temperature. Standard aqueous work up using ether for extraction. Purification by silica-gel chromatography using gradient elution (hexane:ether, 50:1, 20:1, 10:1, 5:1, 2:1) gave the product as a white solid (51%)

We have used this type of reaction many times and although the yields are generally only in the range 40 - 70 ^oC it is generally quite applicable. It is important not to use too much base otherwise elimination can be a problem and dimerisation can be an issue. An alternative is to use a chloro-bromo substrate and convert the chloro compound into the bromide or iodide using NaBr or NaI.

¹H NMR 7.85, 2H, d, J = 8.4 Hz; 7.71, 1H, d, J = 8.02 Hz; 7.44-7.37, 2H, m; 7.34-7.31 Hz, 2H, m; 7.22-7.16, 2H, m; 4.44, 2H, t, J = 7.8 Hz; 3.4, 2H, t, J = 6.25 Hz; 2.4, 3H, s; 2.22, 2H, p, J = 7.0 Hz

S. Caddick, K. Aboutayab, K. Jenkins, R. I. West, J. Chem. Soc. Perkin Trans 1. 1996, 675

W. Dehaen, A. Hassner, J. Org. Chem. 1991, 56, 896