Toluene → Methyl (S)-(-)-2-Isocyanato-3-methylbutyrate

HRID 2393521Notes

Reaction equation

HRID 2393521 reaction equation
[C:1](Cl)(Cl)=[O:2].C1(C)C=CC=CC=1.[NH2:12][C@H:13]([C:17]([O:19][CH3:20])=[O:18])[CH:14]([CH3:16])[CH3:15].Cl>>[CH3:20][O:19][C:17](=[O:18])[C@@H:13]([N:12]=[C:1]=[O:2])[CH:14]([CH3:16])[CH3:15]

Participants

4

Reactant 3

HCID 1140TolueneHCID 6371PhosgeneHCID 111190Methyl valinate hydrochloride

Product 1

HCID 10397066Methyl (S)-(-)-2-Isocyanato-3-methylbutyrate

Procedure

A solution of 1.9M phosgene in toluene (9.41 mL, 17.89 mmol) was added to a suspension of H-Val-OCH3.HCl (1.0 g, 5.96 mmol). The reaction mixture was heated at reflux for 2 h under a dry ice condenser, cooled to room temperature, sparged vigorously with nitrogen for 1.5 h and then concentrated to dryness. Toluene (5 mL) was added to the residue and the resulting solution concentrated to dryness to give (S)-2-isocyanato-3-methylbutanoic acid methyl ester. This product was dried under high vacuum for 5 min and then used in the following step. 1H NMR(CDCl3) δ3.95-3.94 (d, J=3.82 Hz, 1H), 3.81 (s, 3H), 2.35-2.22 (m, 1H), 1.04-1.02 (d, J=6.8 Hz, 3H), 0.91-0.89 (d, J=6.74 Hz, 3H).

Workup

  1. temperatureThe reaction mixture was heated
  2. temperatureat reflux for 2 h under a dry ice condenser
  3. customsparged vigorously with nitrogen for 1.5 h
  4. concentrationconcentrated to dryness
  5. additionToluene (5 mL) was added to the residue
  6. concentrationthe resulting solution concentrated to dryness

Sources & evidence

ORD record
ord-4d02d52e33d6450cac8cc07975305fda
Source dataset
uspto-grants-1998_09
Patent number
US05807870

Reaction notes

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