2-(2-bromophenyl)-1,3-dioxane

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:80.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Acetal (5a) (9.04 g, 37.22 mmol) was dissolved in 50 ml of dry THF under an inert atmosphere in a two necked flask equipped with a condenser. Magnesium (1.8 g, 74.44 mmol) and one drop of 1,2 dibromoethane were added. This mixture was stirred at 80° C. for 45 min, and cooled to room temperature. A 50 ml solution of 2.74 g of nitrochromene (3a) (12.41 mmol) in THF was cannulated into this flask. This mixture was stirred for 30 min, and water was added to quench the reaction. The mixture was extracted with CH2Cl2 (100 ml×3), the extracts washed with brine (100 ml), dried over MgSO4 filtered, and the solvent evaporated to a brown oil from which (6a) precipitated spontaneously. The precipitate was filtered, rinsed with 30 ml of EtOAc and dried to give 2.91 g (61.4% yield). The remaining liquor was purified by flash column chromatography to give an additional 550 mg (72% combined yield): mp 207° C.; 1H-NMR (CDCl3) δ 7.50 (m, 1, ArH); 7.29 (m, 2, ArH); 6.99 (m, 1, ArH); 6.47 (s, 1, ArH); 6.38 (s, 1, ArH); 5.90 (d, 2, ArOCH2); 5.70 (s, 2, OCH2O); 4.97 (s, 1, O2CHAr); 4.71 (dq, 1, Ar2CH, J=10 Hz); 4.23 (m, 2+1, CH2(CH2O)2, CHNO2); 3.98 (m, 2, CH2(CH2O)2); 2.22 (m, 1, CH2); 1.43 (d, 1, CH2); Low resolution CIMS: m/z (rel. intensity) 386 (MH+, 100). Anal. Calcd. for C20H19NO7: C, 62.33; H, 4.97; N, 3.63. Found: C, 62.18; H, 5.37; N, 3.38. equipped with a condenser cooled to room temperature This mixture was stirred for 30 min to quench the reaction The mixture was extracted with CH2Cl2 (100 ml×3) the extracts washed with brine (100 ml) dried over MgSO4 filtered the solvent evaporated to a brown oil from which (6a) precipitated spontaneously The precipitate was filtered rinsed with 30 ml of EtOAc dried to give 2.91 g (61.4% yield) The remaining liquor was purified by flash column chromatography to give an additional 550 mg (72% combined yield)

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: ortho-Bromobenzaldehyde (4a) (8 g, 43.24 mmol) was stirred with 1,3 propanediol (4.7 ml, 64.86 mmol) and p-toluenesulfonic acid monohydrate (164 mg, 0.86 mmol) in benzene (150 ml) in a flask equipped with a Dean-Stark trap and a condenser. The mixture was heated at reflux for 12 hrs, cooled, and extracted with 2 M NaOH (100 ml), and brine (100 ml×3). The solution was dried over MgSO4, and the solvent evaporated to the title compound in quantitative yield. equipped with a Dean-Stark trap and a condenser The mixture was heated at reflux for 12 hrs cooled extracted with 2 M NaOH (100 ml), and brine (100 ml×3) The solution was dried over MgSO4 the solvent evaporated to the title compound in quantitative yield