Thiochroman-4-one → Methyl 4-oxothiochromane-3-carboxylate

HRID 478655Notes

Reaction equation

[Li+].C[Si]([N-][Si](C)(C)C)(C)C.[S:11]1[C:20]2[C:15](=[CH:16][CH:17]=[CH:18][CH:19]=2)[C:14](=[O:21])[CH2:13][CH2:12]1.C([C:24]([O:26][CH3:27])=[O:25])#N.[NH4+].[Cl-]>C1COCC1>[CH3:27][O:26][C:24]([CH:13]1[C:14](=[O:21])[C:15]2[C:20](=[CH:19][CH:18]=[CH:17][CH:16]=2)[S:11][CH2:12]1)=[O:25]

Participants

Conditions

Temperature: -78 °C

Procedure

LHMDS (1.12 g, 6.7 mmol) dissolved in anhydrous THF (7 ml) was cooled to −78° C. under N2. Thiochroman-4-one (1.00 g, 6.1 mmol) in anhydrous THF (20 ml) was added dropwise under 20 minutes. After an additional 60 minutes methyl cyanoformate (0.62 g, 7.3 mmol) in anhydrous THF (1.5 ml) was added dropwise under 5 minutes and the suspension was then stirred at −78° C. for 80 minutes. The suspension was poured onto 10% NH4Cl and extracted with ether. The organic phase was washed with water, dried (Na2SO4), filtered and the solvent evaporated. The crude product was purified by chromatography on silica gel (heptane-ethyl acetate 10:1) to yield 4-oxo-thiochroman-3-carboxylic acid methyl ester (0.65 g): 1H NMR (400 MHz, CDCl3; enol tautomer) δ 12.64 (1H, s), 7.83 (1H, d), 7.25-7.29 (2H, m), 7.16-7.20 (1H, m), 3.84 (3H, s), 3.71 (2H, s).

Workup

extractionextracted with ether
washThe organic phase was washed with water
dry with materialdried (Na2SO4)
filtrationfiltered
customthe solvent evaporated
customThe crude product was purified by chromatography on silica gel (heptane-ethyl acetate 10:1)

Sources & evidence

ORD record: ord-fec4faf86a7348a3ae3b23f47bf3f75f
Source dataset: uspto-grants-2003_11
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US06642249B2

Reaction notes

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