2,3-Dimethyl-1,3-butadiene → 2H-Pyran-2,2-dicarboxylic acid, 3,6-dihydro-4,5-dimethyl-, diethyl ester

HRID 2396118Notes

Reaction equation

HRID 2396118 reaction equation
[CH2:1]([O:3][C:4](=[O:12])[C:5](=[O:11])[C:6]([O:8][CH2:9][CH3:10])=[O:7])[CH3:2].[CH3:13][C:14]([C:16]([CH3:18])=[CH2:17])=[CH2:15]>C(#N)C>[CH3:13][C:14]1[CH2:15][C:5]([C:4]([O:3][CH2:1][CH3:2])=[O:12])([C:6]([O:8][CH2:9][CH3:10])=[O:7])[O:11][CH2:17][C:16]=1[CH3:18]

Participants

4

Reactant 2

HCID 105662,3-Dimethyl-1,3-butadieneHCID 691051,3-Diethyl 2-oxopropanedioate

Product 1

HCID 109561712H-Pyran-2,2-dicarboxylic acid, 3,6-dihydro-4,5-dimethyl-, diethyl esterYield 325.8%

Reagents, catalysts & solvents 1

HCID 6342AcetonitrileSolvent

Procedure

Part A. The method of Bonjouklian and Ruden, J. Org. Chem., v. 42, p. 4095 (1977), was used here. Thus, a solution of diethylketomalonate (10.0 mL, 65.6 mmol) and 2,3-dimethyl-1,3-butadiene (16.3 mmol, 144 mmol) in acetonitrile (22 mL) was heated in a sealed tube at 140° C. for 6 hours. The contents of the tube was cooled, extracted with methylene chloride washing, evaporated and separated by flash chromatography (1:9 ethyl acetate-hexane) to afford diethyl 3,6-dihydro-4,5-dimethyl-2H-pyran-2,2-dicarboxylate as an oil (13.6 g, 53.1 mmol, 81%). 1H NMR (CDCl3): δ 4.26 (4H, q, J=7.0 Hz); 4.15 (2H, br s); 2.57 (2H, br s); 1.69 (3H, s); 1.51 (3H, s); 1.28 (6H, t, J=7.0 Hz). Mass spectrum (NH3 -CI/DDIP): m/z 275 (14%); 274 (100%); 257 (23%); 183 (1%).

Workup

  1. temperatureThe contents of the tube was cooled
  2. extractionextracted with methylene chloride washing
  3. customevaporated
  4. customseparated by flash chromatography (1:9 ethyl acetate-hexane)

Sources & evidence

ORD record
ord-ab346d92cefe4ce39181e173a0bac1b6
Source dataset
uspto-grants-1996_02
Patent number
US05491152

Reaction notes

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