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

HRID 839770Notes

Reaction equation

HRID 839770 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 P2 O5 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. customdried over P2 O5

Sources & evidence

ORD record
ord-75fc21e00683419ca8951d2e2e92e1bb
Source dataset
uspto-grants-1978_06
Patent number
US04097441

Reaction notes

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