Thiophene → 4,5-Dimethyl-4,5-dihydro-6H-cyclopenta[b]thiophen-6-one

HRID 1922324Notes

Reaction equation

HRID 1922324 reaction equation
[S:1]1[CH:5]=[CH:4][CH:3]=[CH:2]1.[C:6](O)(=[O:11])/[C:7](=[CH:9]/[CH3:10])/[CH3:8]>C(Cl)Cl>[CH3:10][CH:9]1[C:3]2[CH:4]=[CH:5][S:1][C:2]=2[C:6](=[O:11])[CH:7]1[CH3:8]

Participants

4

Reactant 2

HCID 8030ThiopheneHCID 125468Tiglic acid

Product 1

HCID 585261534,5-Dimethyl-4,5-dihydro-6H-cyclopenta[b]thiophen-6-one

Reagents, catalysts & solvents 1

HCID 6344DichloromethaneSolvent

Procedure

To polyphosphoric acid (prepared from 500 g of P4O10 and 340 g of 85% H3PO4) a mixture of 47.6 ml (50.0 g, 0.60 mol) of thiophene and 59.5 g (0.60 mol) of tiglic acid in 80 ml of CH2Cl2 was added over 2.5 h at 50° C. This mixture was stirred at this temperature for 2 h, and, then, immersed in 1 kg of ice. The product was extracted with 3×300 ml of methyl-tert-butyl ether. The combined extract was washed with the saturated aqueous solution of Na2CO3, dried over K2CO3, and evaporated to dryness. Fractional distillation gave a colorless oil, bp 96-98° C./2 mm Hg. Yield 89.3 g (90%). On the evidence of NMR spectroscopy, the product is a mixture of two diastereomers (ca. 3:1).

Workup

  1. additionwas added over 2.5 h at 50° C
  2. extractionThe product was extracted with 3×300 ml of methyl-tert-butyl ether
  3. extractionThe combined extract
  4. washwas washed with the saturated aqueous solution of Na2CO3
  5. dry with materialdried over K2CO3
  6. customevaporated to dryness
  7. distillationFractional distillation
  8. customgave a colorless oil, bp 96-98° C./2 mm Hg
  9. additiona mixture of two diastereomers (ca. 3:1)

Sources & evidence

ORD record
ord-d00bbc35784f4b918517fd9003b3c2ef
Source dataset
uspto-grants-2012_05
Patent number
US08173828B2

Reaction notes

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