Reactions of Cupric Bromide in Dioxane. Formation of ι-Bromo-o-hydroxyacetophenone

In Vitro Action of ent-Manoyl Oxides against Leishmania donovani

“…Compound 16 (500 mg) was dissolved in dioxane (50 mL), and CuBr 2 (1.2 g) was added. 21 The reaction was stirred and heated under reflux for 3 h. The CuBr was filtered off, and dioxane was removed under reduced pressure. The mixture was chromatographed over a Si gel column to give the starting product (16, 90 mg) and ent-3 -acetoxy-11R-bromo-12-oxo-13-epi-manoyl oxide (17, (Md-NNN).…”

“…Compound 16 (500 mg) was dissolved in dioxane (50 mL), and CuBr 2 (1.2 g) was added. 21 The reaction was stirred and heated under reflux for 3 h. The CuBr was filtered off, and dioxane was removed under reduced pressure. The mixture was chromatographed over a Si gel column to give the starting product (16, 90 mg) and ent-3β-acetoxy-11Rbromo-12-oxo-13-epi-manoyl oxide (17, 380 mg, 66%): mp 124-126 °C; [R] D -55°(c 1, CHCl 3 ); IR (KBr) ν max 3095 (CdC), 1725 (CdO, ester and ketone), 1640, 1247 (C-O-C, ester), 1126, 1087, 1032, 901 cm -1 ; 1 H NMR (CDCl 3 , 300 MHz) δ 6.38 (1H, dd, J 1 ) 17.3, J 2 ) 10.8, H-14), 5.40 (1H, dd, J 1 ) 17.3, J 2 ) 1.5 Hz, H-15), 5.34 (1 H,dd, J 1 ) 10.8, J 2 ) 1.5 Hz, H-15), 4.51 (1H, dd, J 1 ) 11.4, J 2 ) 4.7 Hz, H-3), 4.20 (1H, d, J ) 8.9 Hz, H-11), 2.48 (1H, d, J ) 8.9 Hz, H-9), 2.05 (3H, s, AcO) and 1.71, 1.02, 0.90, 0.88, 0.85 (3H each, s, 5 × Me); 13 Dehydrobromation of Compound 17.…”

“…Bromation of Ketone 16 . Compound 16 (500 mg) was dissolved in dioxane (50 mL), and CuBr 2 (1.2 g) was added . The reaction was stirred and heated under reflux for 3 h. The CuBr was filtered off, and dioxane was removed under reduced pressure.…”

“…The ketone 15 was obtained from ent -3β-acetoxy-12-oxo-13- epi -manoyl oxide ( 16 ), previously obtained from varodiol 2 . The treatment of ketone 16 with CuBr 2 in dioxane at reflux gave rise to compound 17 (66%), not previously described in literature (Figure ). The mass spectrum of 17 indicated that it was a monobrominated derivative ( m/z 443/441 [M + 1] + , CI).…”

Versatile Reactivity and Catalytic Effects of Copper(II) Halides in Organic Syntheses

“…The reaction proceeded rapidly with the evolution of HBr and with conversion of the black CuBr 2 to the white CuBr. For the bromination of o-hydroxyacetophenone or 6-or 7-acetylcoumarin, the application of CuBr 2 in dioxane was likewise successful [33]. 9-Acetylanthracene reacts with CuBr 2 in ethyl acetate to give the 9-bromoacetyl derivative; other 9-acylated (formyl and benzoyl) derivatives resulted in 9-acyl-10-haloanthracene via a ligand-transfer radical reaction [34].…”