Dimethyl Sulfoxide → Methyl 3-formyl-4-nitrobenzoate

Participants

Reaction Conditions

Reaction Steps

In a 5-liter four-necked round-bottomed flask 1.5 l of methylene chloride was cooled to -78° C. Oxalyl chloride (164 g, 1.29 moles) was added slowly, followed by dropwise addition of 202 g (2.59 moles) of dry dimethylsulfoxide in 125 mL of methylene chloride, keeping the temperature below -70° C. After the addition was complete the reaction mixture was stirred at -78° C. for 30 minutes and 273 g (1.29 moles) of previously prepared methyl 3-hydroxymethyl-4-nitrobenzoate dissolved in 250 mL of methylene chloride was added dropwise. The reaction mixture was stirred an additional 30 minutes. Triethylamine (392 g 3.88 moles) in 125 mL of methylene chloride was added dropwise keeping the temperature below -65° C. The reaction mixture was warmed up slowly to room temperature and stirred overnight. The solvent was removed using a rotary evaporator and the resulting solid treated with a mixture of 2 l of ethyl acetate and 1 l of water. The organic phase was separated, filtered through diatomaceous earth, and washed sequentially with dilute aqueous hydrochloric acid (2×250 mL), water (2×250 mL), saturated aqueous sodium bicarbonate (2×250 mL), water (2×200 mL), brine (1×200 mL) and dried over anhydrous magnesium sultate. The solvent was removed using a rotary evaporator. The crude reaction mixture was triturated with hexane and filtered yielding 234.1 g of the expected methyl 3-formyl-4-nitrobenzoate as a yellow solid. This compound was used as such in the next step.

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