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

HRID 2163439Notes

Reaction equation

HRID 2163439 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>[OH:21][C:20]1[C:15]2[CH:14]=[CH:13][S:12][C:16]=2[S:17][CH2:18][C:19]=1[C:6](=[O:11])[C:7]([O:9][CH3:10])=[O:8]

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 (CHCl 3) 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. Anal. Calcd. for C10H8O4S2 : C, 46.86; H, 3.15; S, 25.02. Found: C, 46.92; H, 3.23; S, 24.58, 24.64.

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-d5238486f4a34f6aa5bd0968304ca699
Source dataset
uspto-grants-1979_01
Patent number
US04134896

Reaction notes

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