Experimental⁸

α-Chloro-α-(methylthio)acetone (4)

This compound was prepared according to the procedure described by Böhme.⁹ N-Chlorosuccinimide (13.9 g, 0.104 mol) was added to a stirred solution of α-(methylthio)acetone¹⁰ (10.4 g, 0.1 mol) in carbon tetrachloride (150 ml) in small portions at 0°C and stirring was continued at room temperature for 3 h. The precipitated succinimide was filtered off and the solvent was removed in vacuo. The residual oil was distilled to give 4 (8.82 g, 64%), bp 77.5°C (16 mmHg), lit.⁹ 76-77°C (15 mmHg).

α-(Methylthio)phenylacetone (5a)

SnCl₄ (1.03 g, 3.96 mmol) was added to a stirred solution of 4 (549 mg, 3.96 mmol) in benzene (9 ml) at 0°C, and stirring was continued at room temperature for 40 min. The reaction was quenched by the addition of water, and the mixture was extracted with benzene and dried (MgSO₄). The solvent was removed in vacuo and the residue was chromatographed on silica gel using benzene an eluent to give 5a (630 mg, 88%), which was identified by comparison of its spectroscopic data with those reported.¹¹ The data are given in Table III.

α-(Methylthio)arylacetones (5b, c, d, e, f, g, h, and i); General Procedure

SnCl₄ or ZnCl₂ (for furan) (1.78- 1.89 mmol) was added to a stirred solution of 4 (1.78-1.89 mmol) and an aromatic compound [1.78-1.89 mmol except for the case of the reaction of thiophene or furan (2 eq)] in CH₂Cl₂ (10-15 ml) at 0°C, and stirring was continued under the conditions described in Table I. The reaction was quenched by the addition of water, then the mixture was extracted with CH₂Cl₂, and the extract was dried (MgSO₄). The solvent was removed in vacuo and the residue was chromatographed on silica gel using benzene as an eluent to give 5b, c, d, e, f, g, h, or i oil. The yields and physical data are listed in Table I and III.

Arylacetones (6a, c, e, f, g, h, and i): General Procedure

Zinc dust (1 g) was added to a solution of 5a, c, e, f, g, h, or i (200-300 mg) in acetic acid (2-3 ml), and the resultant mixture was heated with vigorous stirring at 100°C for 1 h, then cooled. Water (20 ml) and CH₂Cl₂ (30 ml) were added, and the inorganic materials were filtered off. The organic layer was separated and the aqueous layer was further extracted with CH₂Cl₂). The combined organic layer was dried (MgSO₄) and the solvent was evaporated off. The residue was chromatographed on silica gel using benzene as an eluent to give 6a, c, e, f, h, or i as an oil. The yields and physical data are listed in Table II. The compounds (6a),¹² (6c)¹², (6g),⁵ (6h),¹³ and (6i)¹⁴ were identified by comparison of their ¹H-NMR spectra with those reported. The compound (6e) was identified by comparison of its IR and ¹H-NMR spectra with those of a commercial sample. The compound (6f) was characterized as the 2,4-dinitrophenylhydrazone, mp 143-144°C (from ethanol).

α-Chloro-α-(methylthio)acetonitrile (7)

This compound was prepared according to the procedure described by Böhme.⁹ N-Chlorosuccinimide (11.07 g, 0.083 mol) was added to a stirred solution of α-(methylthio)acetonitrile¹⁵ (7.2 g, 0.083 mol) in carbon tetrachloride (45ml) in small portions at 0°C and stirring was continued at room temperature for 4.5 h. The precipitated succinimide was filtered off and the solvent was removed in vacuo. The residual oil was distilled to give 7 (5.52 g, 55%), by 67-69°C (12-14 mmHg), lit.⁹ 65.5°C (12 mmHg).

α-(Methylthio)phenylacetonitrile (8a)

SnCl₄ (1.09 g, 4.18 mmol) was added to a stirred solution of 7 (508 mg, 4.18 mmol) in benzene (2 ml) at 0°C, and stirring was continued at room temperature for 40 min. Work-up as described for the preparation of 5a gave 8a (560 mg, 82%), whose physical data are given in Table III.

α-(2- and 4-Methoxyphenyl)-α-(methylthio)acetonitriles (8b) and α,α-bis(4-Methoxyphenyl)- acetonitrile (10)

TiCl4 (412 mg, 2.17 mmol) was added to a stirred solution of anisole (234 mg, 2.17 mmol) and 7 (263 mg, 2.17 mmol) in CH₂Cl₂ (15 ml) at 0°C, and stirring was continued at the same temperature for 1h. The reaction was quenched by the addition of water, then the mixture was extracted with CH₂Cl₂, and dried (MgSO₄). The solvent was removed in vacuo and the residue was chromatographed on silica gel using benzene as an eluent to give 8b (235 mg, 56%) as an oil, whose physical data are given in Table III. Further elution with the same solvent gave 10 (38.3 mg, 7% based on 7), mp 153-154°C (from n-hexane).

α-(Methylthio)arylacetonitriles (8c, d, and e) General Procedure

SnCl₄ or TiCl₄ (for 1,2-methylenedioxybenzene) (3 mmol) was added to a stirred solution of 7 (3 mmol) and an aromatic compound (3 mmol) in CH₂Cl₂ (15 ml) at 0°C, and stirring was continued under the conditions described in Table I. The reaction was quenched by the addition of water, then the mixture was extracted with CH₂Cl₂, and dried (MgSO₄). The solvent was removed in vacuo and the residue was chromatographed on silica gel using benzene as an eluent to give 8c, d, or e as an oil. The yields and physical data are listed in Table I and III.

Arylacetonitriles (9a, c, d, and e); General Procedure

Zinc dust (1 g) was added to a solution of 8a, c, d, or e (100-200 mg) in acetic acid (2-3 ml), and the mixture was heated with vigorous stirring at 100°C for 1 h, then cooled. Work-up as described for the preparation of 6 gave 9a, c, d, or e, which was identified by comparison of its physical data with those of a commercial sample. Yields and spectral data are given in Table III.