Triethylamine → Phthalimide

Participants

Reaction Steps

To a solution, stirred at room temperature, of 0.9 g (5.4 mmol) of 3,4-dimethoxybenzylamine in 100 ml of methylene chloride are added 3 g of molecular sieve 4 Å and after 20 minutes 0.7 g (5.4 mmol) of isopropylidene-L-gylceraldehyde and 5 g of anhydrous magnesium sulphate. The mixture is subsequently stirred at room temperature for 1 hour. The resulting organic solution of isopropylidene-L-glyceraldehyde (3,4-dimethoxybenzyl)imine is cooled to -20° under argon and treated while stirring with 0.88 ml (5.4 mmol) of triethylamine. Then, a solution of 1.25 g (5.6 mmol) of phthaloylglycyl chloride in 20 ml of dry methylene chloride is added dropwise thereto within 1 hour and the mixture is subsequently stirred overnight at room temperature. The mixture is worked-up as described in Example 1 and there are obtained after chromatography 1.56 g (62%) of N-(3S,4S)-cis-1-(3,4-dimethoxybenzyl)-4-[(R)-2,2-dimethyl-1,3-dioxolan-4-yl]-2-oxo-3-azetidinyl]phthalimide as a foam; [α ]D =+16.2° (c=1.0 in methanol); MS: 466 (M+).

Provenance & Evidence