Methanesulfonic Acid → Ethyl 5-methyl-4-oxo-2,3,7,8-tetrahydro-4H-1-benzothiopyran-6-carboxylate
Reaction equation
[CH2:1]([O:3][C:4]([C:6]1[CH2:11][CH2:10][C:9]([S:12][CH2:13][CH2:14][C:15]([OH:17])=O)=[CH:8][C:7]=1[CH3:18])=[O:5])[CH3:2].CS(O)(=O)=O.FC(F)(F)C(OC(=O)C(F)(F)F)=O>C1(C)C=CC=CC=1>[CH3:18][C:7]1[C:8]2[C:15](=[O:17])[CH2:14][CH2:13][S:12][C:9]=2[CH2:10][CH2:11][C:6]=1[C:4]([O:3][CH2:1][CH3:2])=[O:5]Participants
Reactant 3
Product 1
Reagents, catalysts & solvents 1
Conditions
- Temperature
- 20 °C
Procedure
A mixture of ethyl-4-β-carboxyethylthio-2-methyl-1,3-cyclohexadiene-1-carboxylate (121.3 g, 0.449 mole) in toluene is stirred at 20° C., treated sequentially with 5.0 ml methanesulfonic acid and portionwise over a 5 minute period with trifluoroacetic anhydride (94.3 g, 0.449 mole) and allowed to stir at ambient temperatures for 18 hours. The resultant reaction mixture is quenched with a 1:1 mixture of ethyl acetate and water and stirred for 15 minutes. The phases are separated. The organic phase is washed with water and concentrated in vacuo to give a residue. Crystallization of the residue from isopropanol/heptane affords the title product as a yellow solid, 90.1 g, (79.5% yield), mp 99°-100° C., identified by 1HNMR and mass spectral analyses.
Workup
- stirringto stir at ambient temperatures for 18 hours
- customThe resultant reaction mixture
- customis quenched with a 1:1 mixture of ethyl acetate and water
- stirringstirred for 15 minutes
- customThe phases are separated
- washThe organic phase is washed with water
- concentrationconcentrated in vacuo
- customto give a residue
- customCrystallization of the residue from isopropanol/heptane
Sources & evidence
- ORD record
- ord-018684c72cea4fbf84c379506e2e8857
- Source dataset
- uspto-grants-1999_12
- Patent number
- US06008402
Reaction notes
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