Oxalyl chloride → HCID 10613711, compound

Participants

Reaction Steps

Oxalyl chloride (13.6 g) and DMF (3 drops) were successively added dropwise to a solution of methyl 2-(1-carboxyethyl)thio-3-(3,4-methylenedioxyphenyl)propionate (27.8 g) in tetrahydrofuran (THF) (200 ml), followed by stirring for 1.5 hours at room temperature and concentrated under reduced pressure. The residual oil was dissolved in dichloromethane (250 ml). To the solution was added dropwise tin(IV) tetrachloride (SnCl4)(51.0 g) under ice-cooling. The mixture was stirred for an hour under ice-cooing, to which 2NHCl (100 ml) was added dropwise. The dichloromethane layer was separated, washed with water, dried (MgSO4) and distilled off the solvent. The residual oil was dissolved in methanol (250 ml), to which a solution of sodium methoxide in methanol (28%, 10 ml) was added. The resultant solution was stirred for 1.5 hours at room temperature to which 2N--HCl (250 ml) was added. The precipitated crystals were collected by filtration to give methyl trans-7,8-methylenedioxy-4-methyl-5-oxo-1,2,4,5-tetrahydro-3-benzothiepine-2-carboxylate (19.0 g, 73%). Recrystallization from ethyl acetate gave colorless prisms.

Provenance & Evidence