Sodium borohydride → 4,5,6,7-Tetrahydro-alpha,4,4,7,7-pentamethylbenzo[b]thiophene-methanol

HRID 485032Notes

Reaction equation

HRID 485032 reaction equation
[C:1]([C:4]1[S:8][C:7]2[C:9]([CH3:16])([CH3:15])[CH2:10][CH2:11][C:12]([CH3:14])([CH3:13])[C:6]=2[CH:5]=1)(=[O:3])[CH3:2].[BH4-].[Na+]>C(O)C>[CH3:2][CH:1]([C:4]1[S:8][C:7]2[C:9]([CH3:15])([CH3:16])[CH2:10][CH2:11][C:12]([CH3:14])([CH3:13])[C:6]=2[CH:5]=1)[OH:3]

Participants

4

Reactant 2

HCID 4311764Sodium borohydrideHCID 230492331-(4,4,7,7-Tetramethyl-4,5,6,7-tetrahydro-1-benzothiophen-2-yl)ethan-1-one

Product 1

HCID 867402444,5,6,7-Tetrahydro-alpha,4,4,7,7-pentamethylbenzo[b]thiophene-methanolYield 92.3%

Reagents, catalysts & solvents 1

HCID 702EthanolSolvent

Procedure

21.7 g of 2-acetyl-4,5,6,7-tetrahydro-4,4,7,7-tetramethylbenzo[b]thiophene are dissolved in 250 ml of ethanol and the solution is treated gradually with 5.5 g of sodium borohydride. The mixture is left to come to room temperature and is stirred for a further 2 hours. The mixture is poured on to ice, extracted with ether, the organic phase is washed once with saturated sodium chloride solution, dried and evaporated. The crude product is filtered over silica gel (eluting agent hexane/ether 3:1) and recrystallized from hexane. There are obtained 20.2 g of 4,5,6,7-tetrahydro-α,4,4,7,7-pentamethylbenzo[b]thiophene-methanol in the form of colorless crystals, m.p. 53°-55° C.

Workup

  1. waitThe mixture is left
  2. customto come to room temperature
  3. additionThe mixture is poured on to ice
  4. extractionextracted with ether
  5. washthe organic phase is washed once with saturated sodium chloride solution
  6. customdried
  7. customevaporated
  8. filtrationThe crude product is filtered over silica gel (eluting agent hexane/ether 3:1)
  9. customrecrystallized from hexane

Sources & evidence

ORD record
ord-835fbc43c1ce4bb4b1acb6f65ed23bc7
Source dataset
uspto-grants-1985_08
Patent number
US04535086

Reaction notes

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