Diisobutylaluminum hydride → 6-Chloro-2,2-dimethylchroman-8-carbaldehyde

HRID 402803Notes

Reaction equation

HRID 402803 reaction equation
[Cl:1][C:2]1[CH:3]=[C:4]2[C:9](=[C:10]([C:12]([O-])=[O:13])[CH:11]=1)[O:8][C:7]([CH3:16])([CH3:15])[CH2:6][CH2:5]2.CC(C[AlH]CC(C)C)C.[OH-].[Na+].CC(OI1(OC(C)=O)(OC(C)=O)OC(=O)C2C=CC=CC1=2)=O>ClCCl.O>[Cl:1][C:2]1[CH:3]=[C:4]2[C:9](=[C:10]([CH:12]=[O:13])[CH:11]=1)[O:8][C:7]([CH3:16])([CH3:15])[CH2:6][CH2:5]2

Participants

7

Reactant 4

HCID 14487Diisobutylaluminum hydrideHCID 14798Sodium HydroxideHCID 159087TriacetoxyperiodinaneHCID 866768156-Chloro-2,2-dimethyl-3,4-dihydro-2H-chromene-8-carboxylate

Product 1

HCID 772308536-Chloro-2,2-dimethylchroman-8-carbaldehyde

Reagents, catalysts & solvents 2

HCID 962WaterSolventHCID 6344DichloromethaneSolvent2×

Conditions

Temperature
-78 °C

Procedure

6-Chloro-2,2-dimethyl-3,4-dihydro-2H-chromene-8-carboxylate (350 mg, 1.37 mmol) was dissolved in dichloromethane (6.87 mL) and cooled to −78° C. DIBAL-H (4.12 mL, 4.12 mmol) was added dropwise. The reaction mixture was warmed to room temperature and stirred for 1 hour. It was then cooled to 0° C., diluted with dichloromethane (10.0 mL) and water (2.00 mL) was added slowly, followed by a 15% aqueous NaOH solution (5.00 mL). The mixture was warmed to room temperature and stirred for 15 minutes. The organic layer was separated, dried over Na2SO4, filtered, and concentrated under vacuum. The crude alcohol was used directly in the next step without further purification. The crude alcohol was dissolved in dichloromethane (7.00 mL), and Dess-Martin periodinane (1.20 g, 2.75 mmol) was added in one portion at room temperature. The reaction mixture was stirred at room temperature for 30 minutes and then concentrated under vacuum on silica gel. It was then purified by silica gel chromatography eluting with 0-15% EtOAc/hexanes to give the desired product as a white solid.

Workup

  1. temperatureThe reaction mixture was warmed to room temperature
  2. temperatureIt was then cooled to 0° C.
  3. additionwas added slowly
  4. temperatureThe mixture was warmed to room temperature
  5. stirringstirred for 15 minutes
  6. customThe organic layer was separated
  7. dry with materialdried over Na2SO4
  8. filtrationfiltered
  9. concentrationconcentrated under vacuum
  10. customThe crude alcohol was used directly in the next step without further purification
  11. dissolutionThe crude alcohol was dissolved in dichloromethane (7.00 mL)
  12. stirringThe reaction mixture was stirred at room temperature for 30 minutes
  13. concentrationconcentrated under vacuum on silica gel
  14. customIt was then purified by silica gel chromatography
  15. washeluting with 0-15% EtOAc/hexanes

Sources & evidence

ORD record
ord-eb00497ab7304ad08319006f22f0e54f
Source dataset
uspto-grants-2014_06
Patent number
US08742110B2

Reaction notes

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