Isobutyl chloroformate → meso-DAP (D)GlyOH

To a suspension of D-alanine (2.89 g) in a mixture of methylene chloride (30 ml) and dimethylformamide (12 ml) was added bis(trimethylsilyl)acetamide (30 ml) and the mixture was stirred for 15 hours at room temperature to give a clear solution. To a solution of the mixed anhydride of Z-(L)-Boc-(D)-mesoDAP-(D)-NHNHBoc (1) (13.45 g) in methylene chloride (140 ml), prepared by adding N-methylmorphorine (3.03 g) and isobutyl chloroformate (4.10 g) at -15° and stirring the mixture for 40 minutes at the same temperature, was added in one portion the above solution of D-alanine trimethylsilyl ester at -40° C. Then the reaction mixture was allowed to warm up to 0° C. and stirred for 2 hours. The reaction mixture was evaporated and the residue was dissolved in water, acidified with diluted hydrochloric acid and extracted with ethyl acetate. The extract was washed with water, dried over magnesium sulfate and concentrated to give a white powder (12.25 g) of Z-(L)-Boc-(D)-mesoDAP-(D)-NHNHBoc-(L)-D-AlaOH (2).

1. customto give a clear solution
2. stirringstirring the mixture for 40 minutes at the same temperature
3. temperatureto warm up to 0° C.
4. stirringstirred for 2 hours
5. customThe reaction mixture was evaporated
6. dissolutionthe residue was dissolved in water
7. extractionextracted with ethyl acetate
8. washThe extract was washed with water
9. dry with materialdried over magnesium sulfate
10. concentrationconcentrated

ORD record

ord-651a07c5491543abaf89a61623fe0d0e

Source dataset

uspto-grants-1985_09

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US04539155