Synthesis
General procedure for the synthesis of 2'-chloro-4-bromoacetophenone from p-bromoacetophenone: [TABLE-US-00002] (18) Acetophenone Derivative R13 R14 1 NO2 H 2 NO2 Cl 3 H Br 4 H H. Acetophenone derivatives shown in Eqn. (18) (2.00 g) was dissolved or suspended in a solvent, and sulfonyl chloride as shown in Table 2 was added in a single addition under stirring (molar concentration M based on acetophenone derivative). The reaction temperature and reaction time are shown in Table 2. [Table-US-00003] Table 2: Acetophenone derivatives, SO2Cl2 (equivalent), solvent (M), temperature, time (hr) and yield (%). Examples: 42 MTBE(0.5)1 3.0 room temperature 4.5 50.8; 43 MTBE(1)1 1.65 reflux 7.0 70.1; 44 IPE(1)1 3.0 room temperature 3.0 77.8; 45 DME(1)1 1.65 room temperature 4.0 71.4; 46 MTBE(1)3 3.0 room temperature 1.0 50.3; 47 MTBE(1)4 1.1 room temperature 7.0 78.9. Note: MTBE is methyl tert-butyl ether; IPE is diisopropyl ether; DME is 1,2-dimethoxyethane.
References
[1] Synthesis, 1988, # 7, p. 545 - 546
[2] Synthetic Communications, 2006, vol. 36, # 2, p. 255 - 258
[3] Green Chemistry, 2009, vol. 11, # 2, p. 275 - 278
[4] Synthetic Communications, 2011, vol. 41, # 10, p. 1508 - 1513
[5] Tetrahedron Letters, 2004, vol. 45, # 1, p. 191 - 193
