2-[4-Chloro-3-(4-ethoxybenzyl)phenyl]-1,3-dithiane

In the title compound, C19H21ClOS2, the dithiane ring adopts a chair conformation. The dihedral angle between the benzene rings is 87.88 (4)°. In the crystal, inversion dimmers linked by pairs of C—H⋯O interactions occur.

supplementary materials sup-2 Figures Fig. 1. View of the constituents of (I), showing the atom-labeling scheme and displacement ellipsoids drawn at the 50% probability level. H atoms are represented by circles of arbitrary size.

Special details
Experimental.
To a solution of (2-chloro-5-methyl-phenyl)-(4-ethoxy-phenyl)-methanone (2; 650 mg, 2.37 mmol) and N-bromosuccinimide (465 mg, 2.61 mmol) in carbon tetrachloride (8 ml) was added 2,2'-azobisisobutyronitrile (AIBN, 8 mg, 0.047 mmol) and the reaction mixture was heated to reflux for 26 hours under nitrogen. The reaction was cooled to room temperature, quenched with water (50 ml) and the mixture diluted with dichloromethane (25 ml). The layers were separated and the aqueous layer was extracted two additional times with dichloromethane (25 ml). The combined organic layers were washed with brine, dried over magnesium sulfate, filtered through a pad of celite, and concentrated under reduced pressure. The crude material was chromatographed with an ISCO automated chromatography unit (40 g silica gel column) eluting with a gradient of 0-20% ethyl acetate in heptane to produce 434 mg (52% yield) of the de-
The combined organic layers were successively washed with water, brine, dried over sodium sulfate, filtered and concentrated under reduced pressure. The crude material was chromatographed using an ISCO automated chromatography unit (4.0 g silica gel column) and eluting with a gradient of 0-50% ethyl acetate in heptane yielding 11 mg (51% yield) of an oil that solidified upon standing.
2-(4-Chloro-3-(4-ethoxy-benzyl)phenyl)-1,3-dithiane (1): To a solution of 4-chloro-3-(4-ethoxy-benzyl)benzaldehyde (8.4 g, 31 mmol) in dichloromethane (113 ml) was added 1,3-propanedithiol (3.38 ml, 33.6 mmol) and the solution was stirred at room temperature for 1 hour before cooling down to 0°C. To the solution was added boron trifluoride diethyl etherate (5 ml, 39.7 mmol) and the reaction was warmed up to room temperature over 12 hours. The mixture was diluted with dichloromethane and the reaction was quenched by dropwise addition of saturated aqueous solution of sodium bicarbonate. The organic phase was successively washed with a solution of sodium hydroxide (1M), brine, dried over magnesium sulfate, filtered and concentrated. The crude product was purified by chromatography over silica gel (0% to 30% EtOAc in heptane) to give 1 as a white solid (8.25 g, 74% yield  Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating Rfactors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.