Magnesium → alpha-Tocopherol

HRID 465142Notes

Reaction equation

HRID 465142 reaction equation
[CH3:1][C:2]1([CH2:16][CH2:17]Br)[CH2:11][CH2:10][C:9]2[C:4](=[C:5]([CH3:15])[C:6]([CH3:14])=[C:7]([OH:13])[C:8]=2[CH3:12])[O:3]1.C([Mg]Cl)=C.Cl[CH:24]([Mg]Cl)[CH:25]([CH3:37])[CH2:26][CH2:27][CH2:28][CH:29]([CH3:36])[CH2:30][CH2:31][CH2:32][CH:33]([CH3:35])[CH3:34].[Mg].ClCC(C)CCCC(C)CCCC(C)C>C1COCC1>[CH3:14][C:6]1[C:7]([OH:13])=[C:8]([CH3:12])[C:9]2[CH2:10][CH2:11][C@:2]([CH2:16][CH2:17][CH2:35][C@@H:33]([CH2:32][CH2:31][CH2:30][C@@H:29]([CH2:28][CH2:27][CH2:26][CH:25]([CH3:37])[CH3:24])[CH3:36])[CH3:34])([CH3:1])[O:3][C:4]=2[C:5]=1[CH3:15]

Participants

7

Reactant 5

HCID 5462224MagnesiumHCID 13175608(2RS,6RS)-1-chloro-2,6,10-trimethyl-undecaneHCID 133751842-(2-Bromoethyl)-2,5,7,8-tetramethylchroman-6-olHCID 178443148HCID 178443148, compoundHCID 178461836HCID 178461836, compound

Product 1

HCID 14985alpha-TocopherolYield 38%

Reagents, catalysts & solvents 1

HCID 8028TetrahydrofuranSolvent5×

Procedure

6.26 g (20 millimoles) of (2RS)-2,5,7,8-tetramethyl-6-hydroxy-2-(2-bromoethyl)-chroman were dissolved in 20 ml of absolute THF. 16.2 ml of a 1.5-molar solution of vinyl-magnesium chloride in THF were added to the above solution at -20° C. and the mixture was stirred for 1 hour at the same temperature. Thereafter, a solution of (2RS,6RS)-1-chloro-2,6,10-trimethylundecyl-magnesium chloride, which had been prepared by reacting a solution of 0.86 g (35.8 millimoles) of magnesium in 10 ml of absolute THF with a solution of 8.16 g (34 millimoles) of (2RS,6RS)-1-chloro-2,6,10-trimethyl-undecane in 10 ml of THF and stirring the mixture for 2 hours at +70° C. was added dropwise to the above solution at -20° C., followed by dropwise addition of 1.4 ml of an 0.5-molar solution of di-lithium tetrachlorocuprate in absolute THF. The reaction mixture was then stirred for 3 hours at -20° C. and 15 hours at room temperature. After it had been worked up by the method of Example 1c, 3.3 g of α-tocopherol were isolated by distillation at 210° C./0.2 mbar. This corresponds to a yield of 38% of theory.

Workup

  1. stirringstirring the mixture for 2 hours at +70° C.
  2. additionwas added dropwise to the above solution at -20° C.
  3. stirringThe reaction mixture was then stirred for 3 hours at -20° C. and 15 hours at room temperature

Sources & evidence

ORD record
ord-c5b0c06698524e3f942edd6c2b99dd2f
Source dataset
uspto-grants-1985_10
Patent number
US04550182

Reaction notes

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