Hydrochloric Acid → 2-Methyl-7-oxo-4,5,6,7-tetrahydro-1,3-benzothiazole-6-carbaldehyde

HRID 2102781Notes

Reaction equation

HRID 2102781 reaction equation
[H-].[Na+].C([O:5][CH2:6][CH3:7])=O.[CH3:8][C:9]1[S:10][C:11]2[C:17](=[O:18])C[CH2:15][CH2:14][C:12]=2[N:13]=1.Cl>CCOCC.CO.CCCCCC>[CH3:8][C:9]1[S:10][C:11]2[C:17](=[O:18])[CH:7]([CH:6]=[O:5])[CH2:15][CH2:14][C:12]=2[N:13]=1

Participants

8

Reactant 4

HCID 313Hydrochloric AcidHCID 8025Ethyl formateHCID 24758Sodium hydrideHCID 149133692-Methyl-5,6-dihydrobenzo[d]thiazol-7(4H)-one

Product 1

HCID 248876322-Methyl-7-oxo-4,5,6,7-tetrahydro-1,3-benzothiazole-6-carbaldehydeYield 66%

Reagents, catalysts & solvents 3

HCID 887MethanolSolventHCID 3283Diethyl EtherSolvent2×HCID 8058HexaneSolvent

Procedure

To a suspension of hexane-washed NaH (1.1 g, 44.8 mmol) in dry Et2O (70 mL) was added dry MeOH (6.1 mL). After evolution of H2 had subsided, freshly distilled ethyl formate (7.3 mL, 6.7 g, 89.7 mmol) was added, followed by 2-methyl-5,6-dihydro-4H-benzothiazol-7-one (3.0 g, 17.9 mmol) in dry Et2O (12 mL). The reaction mixture was stirred at room temperature for 16 h. 10% aq HCl solution was added (150 mL) and the product was extracted with EtOAc (5×150 mL). The combined organic extracts were dried, filtered, and concentrated under vacuum to leave a brown oily crude product. Purification by flash column chromatography (20% EtOAc:hexane) afforded the pure title product as a yellow solid (2.30 g, 66%): mp 107-108° C. Anal. RP-HPLC: tR 12.6 min (0-60% MeCN, purity 100%). 1H-NMR (CDCl3): δ 9.90 (s, CHO), 7.20 (s, 1H, CH), 2.91 (t, 2H, J 7.1, CH2), 2.67 (s, 3H, CH3), 2.58 (t, 2H, J 7.1, CH2). 13C-NMR (CDCl3): δ 198.6, 186.3, 174.2, 165.7, 162.6, 131.0, 108.4, 27.0, 24.5, 20.7. MS: (ESI−) m/z 193.98 (M−H)+.

Workup

  1. extractionthe product was extracted with EtOAc (5×150 mL)
  2. customThe combined organic extracts were dried
  3. filtrationfiltered
  4. concentrationconcentrated under vacuum
  5. customto leave a brown oily crude product
  6. customPurification by flash column chromatography (20% EtOAc:hexane)

Sources & evidence

ORD record
ord-da016d91ee464113b06870fb537032af
Source dataset
uspto-grants-2009_08
Patent number
US07576091B2

Reaction notes

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