Dimethyl oxalate → Methyl 4-hydroxy-alpha-oxo-6H-thieno[2,3-b]-thiopyran-5-acetate

HRID 866322Notes

Reaction equation

HRID 866322 reaction equation
C[O-].[Na+].CO[C:6](=[O:11])[C:7]([O:9][CH3:10])=[O:8].[S:12]1[C:16]2[S:17][CH2:18][CH2:19][C:20](=[O:21])[C:15]=2[CH:14]=[CH:13]1>C1C=CC=CC=1>[CH3:10][O:9][C:7](=[O:8])[C:6](=[O:11])[C:19]1[CH2:18][S:17][C:16]2[S:12][CH:13]=[CH:14][C:15]=2[C:20]=1[OH:21]

Participants

5

Reactant 3

HCID 11120Dimethyl oxalateHCID 10942334Sodium MethoxideHCID 110302745,6-Dihydro-4H-thieno[2,3-b]thiopyran-4-one

Product 1

HCID 22751985Methyl 4-hydroxy-alpha-oxo-6H-thieno[2,3-b]-thiopyran-5-acetateYield 91%

Reagents, catalysts & solvents 1

HCID 241BenzeneSolvent2×

Procedure

A mixture of sodium methoxide (21.6 g, 0.4 mole) and dimethyloxalate (47.2 g, 0.4 mole) in benzene (300 ml) is refluxed for 5 min. in order to dissolve most of the solid. To the cooled solution is added a solution of 5,6-dihydro-4H-thieno[2,3-b]-thiopyran-4-one (34 g, 0.2 mole) in benzene (300 ml) and the mixture is stirred for 3 hrs. to give a yellow suspension. The mixture is poured into ice-water mixture (1750 ml). After separating the aqueous layer from the benzene layer, the benzene layer is extracted with 1(N) NaOH solution (250 ml), and the combined aqueous solution is washed once with ether (100 ml) and acidified with (N) HCl. The yellow crystalline glyoxalate is filtered off and dried over P2O5 to give 45.8 g (91%) of the desired product; m.p. 53°-56° C. IR (CHCl3) 3120-3040 (b, OH), 1735 (C=O), 1605 (C=C-C=O) cm-1. NMR (CDCl3) δ 10.6 (s, 1, OH, exchangeable); 7.35 (d, 1, C2 ); 7.05 (d, 1, C3); 4.4 (s, 2, C6 ); 3.9 (s, 3, OCH3). λmaxEtOH 320 (5,600), 238 (10,800) mμ

Workup

  1. temperatureis refluxed for 5 min. in order
  2. dissolutionto dissolve most of the solid
  3. customto give a yellow suspension
  4. customAfter separating the aqueous layer from the benzene layer
  5. extractionthe benzene layer is extracted with 1(N) NaOH solution (250 ml)
  6. washthe combined aqueous solution is washed once with ether (100 ml)
  7. filtrationThe yellow crystalline glyoxalate is filtered off
  8. dry with materialdried over P2O5

Sources & evidence

ORD record
ord-f10fdbdd0d454e6d83f1311c8e635b12
Source dataset
uspto-grants-1978_07
Patent number
US04098794

Reaction notes

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