Formaldehyde → Formaldehyde

Participants

Reaction Conditions

Reaction Steps

A solution of LDA (280 mmol) was prepared by addition of n-BuLi (1.6 M in THF, 175 mL, 280 mmol) to a solution of diisopropylamine (39.3 mL, 280 mmol) in THF (400 mL) at −40° C. and stirring the resulting solution at −15° C. for 30 min. Subsequently the solution was cooled down to −78° C. and a solution of the starting material (50.0 g, 233 mmol) in THF (400 mL) was added dropwisely. After 1 h, gaseous formaldehyde (1.05 mol), which was prepared by heating paraformaldehyde (31.5 g, 1.05 mol) in a separate flask connected by a polyethylene tube to the reaction flask, was passed at −78° C. through this solution over a period of 1 h. After being stirred at −78° C. for additional 30 min and allowed to reach 25° C. over 3 h, the reaction was quenched (saturated aqueous NH4Cl) and extracted (3×EtOAc). The combined organic layers were washed (brine), dried (Na2SO4), and concentrated under reduced pressure. Flash chromatography (SiO2, 30-60% EtOAc/hexanes, gradient elution) gave the product as a pale yellow oil.

Provenance & Evidence