Imidazole → 5-t-Butyldiphenylsilyloxy-4-(R)-iodopentanoic acid, methyl ester

HRID 653976Notes

Reaction equation

HRID 653976 reaction equation
[Si:1]([O:18][CH2:19][C@@H:20](O)[CH2:21][CH2:22][C:23]([O:25][CH3:26])=[O:24])([C:14]([CH3:17])([CH3:16])[CH3:15])([C:8]1[CH:13]=[CH:12][CH:11]=[CH:10][CH:9]=1)[C:2]1[CH:7]=[CH:6][CH:5]=[CH:4][CH:3]=1.C1(P(C2C=CC=CC=2)C2C=CC=CC=2)C=CC=CC=1.N1C=CN=C1.[I:52]I>C1(C)C=CC=CC=1>[Si:1]([O:18][CH2:19][C@H:20]([I:52])[CH2:21][CH2:22][C:23]([O:25][CH3:26])=[O:24])([C:14]([CH3:17])([CH3:16])[CH3:15])([C:8]1[CH:13]=[CH:12][CH:11]=[CH:10][CH:9]=1)[C:2]1[CH:7]=[CH:6][CH:5]=[CH:4][CH:3]=1

Participants

6

Reactant 4

HCID 795ImidazoleHCID 807IodineHCID 11776TriphenylphosphineHCID 110254905-t-Butyldiphenylsilyloxy-4-(S)-hydroxypentanoic acid, methyl ester

Product 1

HCID 151260955-t-Butyldiphenylsilyloxy-4-(R)-iodopentanoic acid, methyl ester

Reagents, catalysts & solvents 1

HCID 1140TolueneSolvent

Procedure

To a solution of 7 (4.33 g, 11.2 mmol) in 250 mL toluene was added triphenylphosphine (5.9 g, 22.4 mmol), imidazole (2.3 g, 33.6 mmol), and iodine (4.26 g, 16.8 mmol) under a nitrogen atmosphere. The reaction mixture was lowered into a preheated heating mantle and refluxed for 1 hour. The reaction mixture was quenched by pouring into 200 mL saturated NaHCO3 solution. Excess triphenylphosphine was destroyed by the addition of iodine until an iodine coloration remained in the organic phase. The organic phase was then washed with 5% sodium thiosulfate solution (2×100 mL) and 2×200 mL water. The product was purified by flash chromatography with 6:1 hexane/ethyl acetate yield 4.75 g (85%) of a viscous oil; [α]D25 +6.5° (C=1, CHCl3); FAB MS 497 (M+H)+, 439 (M-t-butyl)+ ; 1H NMR (CDCl3) δ 7.89 (m, 4, ArH), 7.4 (m, 6, ArH), 4.15 (m, 1, H-4), 3.85 (m, 2, CH ), 3.7 (s, 3, OCH3), 2.5 (m, 2, CH2), 2.25 (m, 1, H-2), 2.1 (m, 1, H-2), 1.1 (s, 9, t-butyl).

Workup

  1. temperaturerefluxed for 1 hour
  2. customThe reaction mixture was quenched
  3. additionby pouring into 200 mL saturated NaHCO3 solution
  4. customExcess triphenylphosphine was destroyed by the addition of iodine until an iodine coloration
  5. washThe organic phase was then washed with 5% sodium thiosulfate solution (2×100 mL) and 2×200 mL water
  6. customThe product was purified by flash chromatography with 6:1 hexane/ethyl acetate yield 4.75 g (85%) of a viscous oil

Sources & evidence

ORD record
ord-ec4dabde2d3f4a60b31f814b5b5c2c7c
Source dataset
uspto-grants-1992_07
Patent number
US05128458

Reaction notes

Loading…