Acetyl chloride → 3-acetyl-2-(2,5-diacetyloxyphenyl)-1,3-thiazolidine-4-carboxylic Acid

HRID 1069042Notes

Reaction equation

[OH:1][C:2]1[CH:7]=[CH:6][C:5]([OH:8])=[CH:4][C:3]=1[CH:9]1[NH:13][CH:12]([C:14]([OH:16])=[O:15])[CH2:11][S:10]1.[C:17](Cl)(=[O:19])[CH3:18]>N1C=CC=CC=1>[C:17]([N:13]1[CH:12]([C:14]([OH:16])=[O:15])[CH2:11][S:10][CH:9]1[C:3]1[CH:4]=[C:5]([O:8][C:2](=[O:1])[CH3:3])[CH:6]=[CH:7][C:2]=1[O:1][C:5](=[O:8])[CH3:4])(=[O:19])[CH3:18]

Participants

Conditions

Temperature: -30 °C

Procedure

To a solution of 0.241 g (0.85 mmol) of 2-(2,5-dihydroxyphenyl)-1,3-thiazolidine-4-carboxylic acid (1:1 mixture of isomers at C2) was added 3 mL of pyridine, and the solution was cooled to −30° C. with a dry ice acetone bath. To the heterogeneous mixture was added 0.34 mL of acetyl chloride under constant stirring. The cooling bath was removed and the reaction mixture was allowed to warm up gradually to room temperature. After overnight stirring at room temperature, the solvent was removed under high vacuum. To the remaining oily residue were added 19 mL of water and 1 mL concentrated HCl. The precipitate was filtered and washed with 2×5 mL of water. After drying at high vacuum, 0.13 g of acetylated product (5) was obtained (34%), as a mixture of diastereoisomers and rotamers. 1H NMR (DMSO-d6) δ; 1.76 s, 1.79 s, 1.99 s, 2.03 s, 2.06 s, 2.26 s, 2.33 s, 2.34 s, 9H; 3.2-3.4m, 3H; 5.11 d, J=8 Hz and 5.36 d, J=8 Hz, 1H; 6.10 s, 6.20 s, 6.33 s and 6.36 s, 1H; 6.99-7.22 m, 2H; 12.95 bs, 1H.

Workup

customThe cooling bath was removed
temperatureto warm up gradually to room temperature
customthe solvent was removed under high vacuum
additionTo the remaining oily residue were added 19 mL of water and 1 mL concentrated HCl
filtrationThe precipitate was filtered
washwashed with 2×5 mL of water
customAfter drying at high vacuum

Sources & evidence

ORD record: ord-0173f7f9d80c4e1ca8114bbe66f05435
Source dataset: uspto-grants-2001_06
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US06251927B1

Reaction notes

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