Iodine → racemic-3,4-dihydro-6-(3-iodopropoxy)2,5,7,8-tetramethyl-2H-1-benzopyran-2-acetic acid methyl ester

HRID 2232481Notes

Reaction equation

HRID 2232481 reaction equation
[CH3:1][O:2][C:3](=[O:23])[CH2:4][C:5]1([CH3:22])[CH2:10][CH2:9][C:8]2[C:11]([CH3:21])=[C:12]([O:17][CH2:18][CH:19]=[CH2:20])[C:13]([CH3:16])=[C:14]([CH3:15])[C:7]=2[O:6]1.C([O-])(=O)C.[Na+].[I:29]I.S([O-])([O-])(=O)=S.[Na+].[Na+]>O1CCCC1.CCOCC.O>[CH3:1][O:2][C:3](=[O:23])[CH2:4][C:5]1([CH3:22])[CH2:10][CH2:9][C:8]2[C:11]([CH3:21])=[C:12]([O:17][CH2:18][CH2:19][CH2:20][I:29])[C:13]([CH3:16])=[C:14]([CH3:15])[C:7]=2[O:6]1

Participants

8

Reactant 4

HCID 807IodineHCID 24477Sodium ThiosulfateHCID 517045Sodium AcetateHCID 54012058racemic-3,4-dihydro-2,5,7,8-tetramethyl-6-(2-propenyloxy)-2H-1-benzopyran-2-acetic acid methyl ester

Product 1

HCID 53954860racemic-3,4-dihydro-6-(3-iodopropoxy)2,5,7,8-tetramethyl-2H-1-benzopyran-2-acetic acid methyl esterYield 76.7%

Reagents, catalysts & solvents 3

HCID 962WaterSolventHCID 3283Diethyl EtherSolventHCID 8028TetrahydrofuranSolvent

Procedure

To a stirred, ice-cold solution of 1M borane in tetrahydrofuran (10 ml) was added, dropwise, a solution of 2 ml (1.64 g) of cyclohexene in 6 ml of dry tetrahydrofuran. The mixture was allowed to stir at 0°-5° C. for 1.5 hours. Tothe resulting slurry of dicyclohexylborane was added, dropwise a solution of 1.59 g of the allyl ether from Example 18 in 4 ml of tetrahydrofuran. The mixture was stirred at 0°-5° C. for 1 hour and at room temperature for 18 hours at which point 20 ml of 1M methanolic sodium acetate was added dropwise followed by 23.8 ml of 0.4M methanolic iodine. The resulting mixture was stirred at room temperature for 4 hours whereupon 3.1 ml of aqueous sodium thiosulfate was added. The reaction mixture was poured into water worked-up with ether in the usual manner. Chromatography of the crude product (4.4 g) on 100 g of silica gel afforded 1.71 g (76.7%) of racemic-3,4-dihydro-6-(3-iodopropoxy)2,5,7,8-tetramethyl-2H-1-benzopyran-2-acetic acid methyl ester as an oil, eluted with 19:1 and 9:1 hexane-ethyl acetate.

Workup

  1. additionwas added
  2. additionwas added dropwise
  3. additionwas added

Sources & evidence

ORD record
ord-b48ae380d19e4656b4edd451bd661032
Source dataset
uspto-grants-1988_11
Patent number
US04788214

Reaction notes

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