Ethyl isocyanate → (+/-)-1-Ethyl-3-[6-fluoro-2,3-dihydro-2',4'-dioxospiro[4H-1-benzopyran-4,5'-thiazolidin]-8-yl]-urea

HRID 279880Notes

Reaction equation

[NH2:1][C:2]1[C:7]2[O:8][CH2:9][CH2:10][C:11]3([S:15][C:14](=[O:16])[NH:13][C:12]3=[O:17])[C:6]=2[CH:5]=[C:4]([F:18])[CH:3]=1.[CH2:19]([N:21]=[C:22]=[O:23])[CH3:20]>O1CCCC1>[CH2:19]([NH:21][C:22]([NH:1][C:2]1[C:7]2[O:8][CH2:9][CH2:10][C:11]3([S:15][C:14](=[O:16])[NH:13][C:12]3=[O:17])[C:6]=2[CH:5]=[C:4]([F:18])[CH:3]=1)=[O:23])[CH3:20]

Participants

Conditions

Temperature: 50 °C

Procedure

268 mg of (±)-8-amino-6-fluoro-2,3-dihydrospiro[4H-1-benzopyran-4,5'-thiazolidine]-2',4'-dione were stirred in 2 ml of tetrahydrofuran with 100 μl of ethyl isocyanate at room temperature for 2.5 hours and the mixture was subsequently heated to 50° C. for an additional 2 hours. The liquid constituents were removed under reduced pressure, he residue was purified by chromatography on a silica gel column using hexane/ethyl acetate (1:2) for the elution, decolorized with active carbon and recrystallized from ethyl acetate/hexane. (±)-1-Ethyl-3-[6-fluoro-2,3-dihydro-2',4'-dioxospiro[4H-1-benzopyran-4,5'-thiazolidin]-8-yl]-urea was obtained in the form of colorless crystals of melting point 197°-199° C.

Workup

customThe liquid constituents were removed under reduced pressure, he residue
customwas purified by chromatography on a silica gel column
washfor the elution
customrecrystallized from ethyl acetate/hexane

Sources & evidence

ORD record: ord-4ddaf572402346b5a5d91e7e729c3ca7
Source dataset: uspto-grants-1986_05
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US04587256

Reaction notes

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