Carbon Dioxide → Lithium diisopropylamide

Participants

Reaction Steps

LDA was prepared by adding via syringe 2.0 ml nBuLi (1.5 M, hexane) to a solution of 0.324 g (3.2 mmol) of diisopropylamine in 6 ml of abs. THF at −10°. After cooling to −78°, 0.802 g of N-(diphenylmethylene)glycine ethyl ester (3.0 mmol), dissolved in 2 ml of abs. THF, was added dropwise and the mixture kept for 15 Min. at that temperature to ensure complete deprotonation. 0.81 g of crude 4-[2-(4-bromomethyl-naphthalen-1-yloxy)-ethyl]-5-methyl-2-phenyl-oxazole (<0.20 mmol, prepared as described above [example 7a] on a 2.06 mmol scale), dissolved in 12 ml of abs. THF, was then added, followed by 5 ml of DMPU. After stirring for 30 Min. at dry ice temperature and 90 Min. at 0°, the homogeneous reaction mixture was poured onto crashed ice/NH4Cl, extracted twice with AcOEt, washed with NH4Cl to pH 7, dried over sodium sulfate, and evaporated to dryness. Flash chromatography (SiO2, hexane/AcOEt=8/2) yielded 0.829 g of the title compound as colorless, sticky oil.

Provenance & Evidence