Triphosgene → methyl (2S)-2-isocyanato-3,3-dimethylbutanoate
Reaction equation
[CH3:1][C:2]([CH3:10])([CH3:9])[C@@H:3]([C:5]([O:7][CH3:8])=[O:6])[NH2:4].[C:11]([O-])(O)=[O:12].[Na+].ClC(Cl)(OC(=O)OC(Cl)(Cl)Cl)Cl>C(Cl)Cl>[CH3:1][C:2]([CH3:10])([CH3:9])[C@@H:3]([C:5]([O:7][CH3:8])=[O:6])[N:4]=[C:11]=[O:12]Participants
5
Reactant 3
Product 1
Reagents, catalysts & solvents 1
Procedure
A solution (0.39 M) of methyl 3-methyl-L-valinate in a 2:1 mixture of saturated aqueous NaHCO3 and CH2Cl2 was cooled in an ice bath and stirred rapidly. The mixture was treated with triphosgene (0.45 eq) in one portion, and the resulting mixture was stirred for 0.5 h. The reaction was diluted with CH2Cl2, and the layers were separated. The aqueous phase was extracted with CH2Cl2, then the combined organics were washed with brine and dried. Removal of the solvent gave the title compound as clear oil that was kept for 12 h under vacuum (0.1 mbar) then used directly in the subsequent step. 1H NMR (400 MHz, CDCl3) δ 3.79 (s, 3H), 3.75 (s, 1H), 1.00 (s, 9H).
Workup
- temperaturewas cooled in an ice bath
- stirringthe resulting mixture was stirred for 0.5 h
- customthe layers were separated
- extractionThe aqueous phase was extracted with CH2Cl2
- washthe combined organics were washed with brine
- customdried
- customRemoval of the solvent
Sources & evidence
- ORD record
- ord-11250b12ec064952a2df53915cb00e36
- Source dataset
- uspto-grants-2011_12
- Patent number
- US08080654B2
Reaction notes
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