Ninhydrin → (R)-tert-butyl 1-bromopropan-2-ylcarbamate

HRID 521625Notes

Reaction equation

HRID 521625 reaction equation
O[CH2:2][C@H:3]([NH:5][C:6](=[O:12])[O:7][C:8]([CH3:11])([CH3:10])[CH3:9])[CH3:4].C(Br)(Br)(Br)[Br:14].C1(P(C2C=CC=CC=2)C2C=CC=CC=2)C=CC=CC=1.C1C=C2C(C(O)(O)C(=O)C2=CC=1)=O>>[Br:14][CH2:2][C@H:3]([NH:5][C:6](=[O:12])[O:7][C:8]([CH3:11])([CH3:10])[CH3:9])[CH3:4]

Participants

5

Reactant 4

HCID 10236NinhydrinHCID 11205Carbon tetrabromideHCID 11776TriphenylphosphineHCID 13200309tert-butyl N-((2R)-1-hydroxypropan-2-yl)carbamate

Product 1

HCID 57081792(R)-tert-butyl 1-bromopropan-2-ylcarbamateYield 49.3%

Procedure

A solution of (R)-tert-butyl 1-hydroxypropan-2-ylcarbamate (100 mg, 571 μmol) and carbon tetrabromide (303 mg, 913 μmol) was cooled on an ice bath. Triphenylphosphine (299 mg, 1141 μmol) was added and the reaction was stirred for 10 min. The reaction was then allowed to warm to r.t. and stirred for 18 hours. After this time, a TLC suggested that the reaction was complete (silica, 50% EtOAc/Hexanes, Ninhydrin stain). The solvent was removed and the product purified by column chromatography (0, 5, 10, 15, 20% EtOAc/Hexanes) to yield (R)-tert-butyl 1-bromopropan-2-ylcarbamate (67.1 mg, 0.28 mmol, 49.3%) as a colorless oil that turned solid upon standing. LCMS 238.1 (M+H); 1H NMR (400 MHz, MeOH-d4) δ ppm 1.23 (d, J=6.57 Hz, 3H), 1.46 (s, 9H), 3.44 (dd, J=5.56, 1.77 Hz, 2H), 3.71-3.92 (m, 1H).

Workup

  1. stirringstirred for 18 hours
  2. customThe solvent was removed
  3. customthe product purified by column chromatography (0, 5, 10, 15, 20% EtOAc/Hexanes)

Sources & evidence

ORD record
ord-34ca8f0ae86a475cafd318e06f66d105
Source dataset
uspto-grants-2016_05
Patent number
US09328107B2

Reaction notes

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