Selective aromatic chlorination of activated arenes with sodium chlorite, (salen)manganese(III) complex, and alumina in dichloromethane

Abstract

The reaction of alkyl phenyl ethers with sodium chlorite in dichloromethane in the presence of a (salen)manganese(III) complex and alumina preloaded with a small amount of water afforded monochlorination products with unusually high para selectivities under mild conditions. The NaClO2-based biphasic system can also be successfully used for the regioselective monochlorination of substituted anisoles and polymethoxybenzenes. Keywords: aromatic chlorination, alkyl aryl ethers, sodium chlorite, (salen)manganese(III) complex, alumina.

Origin of 13C complexation shifts in the adduct formation of 2‐butyl phenyl ethers with a dirhodium tetracarboxylate complex

“…Most of the ethers, namely 1, [8] 2a, [9] 2b, [10] 2c, [11] 2d, [12] 2e, [13] 3a, [9] 3b, [14] 3c, [15] and 5d, [16] are described in the literature; 3d, 4c and 5c are new. In nearly all cases, spectral data are not well documented in the literature.…”

Iron(III)-Catalyzed Chlorination of Activated Arenes

“…4-Chloro-2-methylanisole (7b). 25 The reaction was performed as described in general procedure A using 2-methylanisole (6b) (124 μL, 1.00 mmol). The reaction mixture was heated to 60 °C for 24 h. Purification by flash column chromatography (petroleum ether/ethyl acetate, 4:1) gave 4-chloro-2-methylanisole (7b) (133 mg, 85%) as a yellow oil.…”

Transition Metal-Catalyzed Oxidations. 11.Para-selective chlorination and bromination of phenols with tert-butyl hydroperoxide and TiX(OiPr)3

“…: Ph 2 S, AlCl 3 [10] 8.7 : 91.3 -89 b ) 2,3,4,4,5,6-hexachlorocyclohexa-2,5-dienone [11] 5.6 : 94.4 a ) 10 a ) 85 a ) sodium chlorite, cat. : (salene)-mangan(III)-complex [7] -a ) 0 a ) 98 a ) a ) selectivity for the chlorination of anisol; b ) based on chlorination equivalent were formed when lithium bromide was added to the TiCl(OiPr) 3 /TBHP system. To exclude the simultaneous formation of chlorides, we later used TiBr(OiPr) 3 that was prepared by mixing TiBr 4 with three parts of Ti(OiPr) 4 similarly as described for TiCl(OiPr) 3 .…”

“…For comparison, the most successful reagents for regioselective para-chlorination are listed in Table 1. With exception of a recent procedure of Hirano et al [7] using sodium chlorite and a manganese(III)-salen complex in the chlorination of anisol some orthochlorination products (3 -8.7%) were always formed in the described procedures.Next, we turned our attention to the bromination of the phenols 1-4. Initially, we observed that bromination products halides 5-11 with the TiX n (OiPr) m /TBHP system (X = Cl or Br).…”