methyl (E)-4-methoxybut-2-enoate

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

Procedure: A mixture of 54 g of methyl 4-bromocrotonate and 30.2 g of calcium carbonate in 200 mL of methanol was refluxed for 5 days. The mixture was filtered and the solvent was removed from the filtrate. The residue was dissolved in ether and washed with water containing a trace of hydrochloric acid. The ether solution was dried over magnesium sulfate. The solvent was removed and the residue was distilled to give 30.6 g of methyl 4-methoxycrotonate. This material was stirred in 170 mL of 1N sodium hydroxide for 3 min. The solution was washed with ether and the aqueous layer was acidified with sulfuric acid. The mixture was extracted several times with ether. The combined extracts were washed with brine and dried over magnesium sulfate. The solvent was removed to give 4-methoxycrotonic acid as a crystalline solid. A 10 g portion of this acid was stirred in 50 mL of benzene at 0° C. and 8.3 mL of oxalyl chloride was added. The mixture was stirred at room temperature for 6 hr. The solvent was removed and the residue was distilled to give 4-methoxycrotonyl chloride as a colorless liquid. was refluxed for 5 days The mixture was filtered the solvent was removed from the filtrate The residue was dissolved in ether washed with water containing a trace of hydrochloric acid The ether solution was dried over magnesium sulfate The solvent was removed the residue was distilled

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

Procedure: Methyl 4-methoxy-trans-crotonate (6.5 g, 50 m.mole) and N-bromoacetamide (7.6 g, 55 m.mole) were dissolved together in peroxide-free dioxane (30 ml) and water (12 ml) was added. The solution was kept at room temperature in the dark for 7 days. The resulting clear, colourless solution was diluted with ether (150 ml) and washed three times with water (50 ml portions). The solution was dried (MgSO4) and the solvent removed under reduced pressure to yield a colourless oil (9.47 g) which was chromatographed on silica-gel (elution with ethyl acetate/petroleum ether) to give the erythro bromohydrin (e2) as a colourless oil (3.46 g, 30.5%). washed three times with water (50 ml portions) The solution was dried (MgSO4) the solvent removed under reduced pressure

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

Procedure: A mixture of 54 g of methyl 4-bromocrotonate and 30.2 g of calcium carbonate in 200 mL of methanol was refluxed for 5 days. The mixture was filtered and the solvent was removed from the filtrate. The residue was dissolved in ether and washed with water containing a trace of hydrochloric acid. The ether solution was dried over magnesium sulfate. The solvent was removed and the residue was distilled to give 30.6 g of methyl 4-methoxycrotonate. This material was stirred in 170 mL of 1N sodium hydroxide for 3 min. The solution was washed with ether and the aqueous layer was acidified with sulfuric acid. The mixture was extracted several times with ether. The combined extracts were washed with brine and dried over magnesium sulfate. The solvent was removed to give 4-methoxycrotonic acid as a crystalline solid. A 10 g portion of this acid was stirred in 50 mL of benzene at 0° C. and 8.3 mL of oxalyl chloride was added. The mixture was stirred at room temperature for 6 hr. The solvent was removed and the residue was distilled to give 4-methoxycrotonyl chloride as a colorless liquid. was refluxed for 5 days The mixture was filtered the solvent was removed from the filtrate The residue was dissolved in ether washed with water containing a trace of hydrochloric acid The ether solution was dried over magnesium sulfate The solvent was removed the residue was distilled