Synthesis of Methyl 1-Formylcyclopropanecarboxylate utilizing Ti-Claisen Condensation

Abstract

A. Methyl 4-chloro-2-formylbutanoate (1). An oven-dried 500-mL, threenecked (24/40), round-bottomed flask equipped with a Teflon-coated magnetic stirring bar (egg-shaped, 32 mm length x 15 mm diameter), an internal thermometer, a 50-mL pressure-equalizing addition funnel fitted with a nitrogen inlet (central neck), and a second 60-mL pressure-equalizing addition funnel is charged with methyl 4-chlorobutanoate (12 mL, 13.7 g, 100 mmol, 1 equiv) (Notes 1 and 2), HCO2Me (18 mL, 18 g, 300 mmol, 3 equiv) (Note 3), and CH2Cl2 (100 mL) (Notes 4 and 5) (Figure 1). The stirred solution is immersed in an ice bath, cooling the internal temperature to 0 °C, and TiCl4 (24 mL, 41.7 g, 220 mmol, 2.2 equiv) is added dropwise through a 60-mL dropping funnel (Figure 1, right side) (Notes 6 and 7) over a period of 20 min, while maintaining the internal temperature at 5–10 °C (Note 8). A.