Reaction #1265396

Reaction equation

iodopentane

(2S)-2-hydroxy-4-methylpentanoic acid

NaH

water

→

compound 9

(2S)-pentyl 4-methyl-2-pentyloxypentanoate

Solvents

DMF

Conditions

Workup

1. 1
   workup.STIRRINGThe reaction mixture was stirred at rt for additional 16 h
2. 2
   Otherthe layers separated
3. 3
   ExtractionThe aqueous layer was extracted with methylene chloride
4. 4
   Washthe combined extracts were washed with sat'd NaHCO3
5. 5
   Dryingdried over magnesium sulfate
6. 6
   Concentrationconcentrated to a crude product
7. 7
   OtherUpon further purification

Procedure

To a solution of (2S)-2-hydroxy-4-methylpentanoic acid 8 (1 g, 7.6 mmol) in 50 mL DMF at 0° C. was added NaH (0.6 g, 15.2 mmol) and stirred for 20 min, followed by the addition of iodopentane (1.5 g, 7.6 mmol). The reaction mixture was stirred at rt for additional 16 h. The solution was poured into water and the layers separated. The aqueous layer was extracted with methylene chloride and the combined extracts were washed with sat'd NaHCO3, dried over magnesium sulfate, and concentrated to a crude product. Upon further purification, compound 9 was obtained as an oil (80 mg, 4%). MS [M+H]+ 273. Step 2: Preparation of (2S)-4-methyl-2-pentyloxypentanoic acid 10. To a solution of (2S)-pentyl 4-methyl-2-pentyloxypentanoate 9 (80 mg, 0.3 mmol) in 20 mL of THF cooled to 0° C. was added dropwise a solution of lithium hydroxide monohydrate (25 mg, 0.6 mmol) in 5 mL of water. The reaction mixture was stirred at rt for 16 h. THF was removed under reduced pressure to give an yellow oil which was diluted with 10 mL of 1 N HCl. The aqueous phase was extracted with CH2Cl2 (8×15 mL), and the extracts were combined, dried over Na2SO4, and concentrated to afford compound 10 (45 mg, 74%). MS [M+H]+ 203. Step 3: Preparation of (7S)-[(2S)-1-oxo-2-pentyloxy-(4-methylpentyl)]amino-5-methyl-5H,7H-dibenzo[b,d]azepin-6-one, 12. To a solution of (2S)-4-methyl-2-pentyloxypentanoic acid 10 (45 mg, 0.22 mmol) in CH2Cl2/DMF (5:1, 15 mL) at 0° C. was added HOBT (40 mg, 0.26 mmol) and EDC (50 mg, 0.26 mmol). The mixture was stirred for 10 min then the amine 11 (52 mg, 0.22 mmol) was added and stirring was continued for 1 h. The solution was poured into water and the layers separated. The aqueous layer was extracted with methylene chloride and the combined extracts were washed with water, 1 N HCl, sat'd NaHCO3, dried over magnesium sulfate, and concentrated to a glassy solid compound 12 (80 mg, 86%). MS [M+H]+ 423.

Source