Source of free-radical or positive bromine. For examples of radical benzylic bromination (Wohl-Ziegler), see: Org. Synth. Coll., 4, 921 (1963); 5, 145, 329, 825 (1973). The use of the ozone depleting solvent CCl4 has been avoided by the use of the ionic liquid 1-n-Butyl-3-methyl-imidazolium hexafluorophosphate, L19086: Synlett, 702 (2003). Cleavage of carbohydrate benzyl ethers: J. Org. Chem., 55, 378 (1990), and of benzyl esters: Synlett, 219 (1994), occur under mild conditions; the benzyl group is converted to benzaldehyde. For allylic bromination, see e.g.: Org. Synth. Coll., 4, 108 (1963);.9, 112, 191 (1998) review: Chem. Rev., 43, 271 (1948). For free-radical ɑ-bromination of a Boc glycine ester, see: Org. Synth. Coll., 9, 526 (1998).
