Phosphorus oxychloride → Methyl 3-chlorothieno[2,3-b]pyrazine-6-carboxylate

Reaction equation

O=[C:2]1[NH:7][C:6]2[S:8][C:9]([C:11]([O:13][CH3:14])=[O:12])=[CH:10][C:5]=2[N:4]=[CH:3]1.P(Cl)(Cl)([Cl:17])=O>>[Cl:17][C:2]1[N:7]=[C:6]2[S:8][C:9]([C:11]([O:13][CH3:14])=[O:12])=[CH:10][C:5]2=[N:4][CH:3]=1

Participants

Reactant 2

HCID 24813Phosphorus oxychloride

HCID 67125580Methyl 3-oxo-3,4-dihydrothieno[2,3-b]pyrazine-6-carboxylate

Product 1

HCID 86680178Methyl 3-chlorothieno[2,3-b]pyrazine-6-carboxylateYield 40%

Procedure

A mixture of 91 (6.66 mmol, 1.4 g) in phosphorus oxychloride (21.46 mmol, 2 mL) was heated to reflux for 5 days. Reaction mixture was concentrated under reduced pressure and co-evaporated with toluene (3×). The crude product was purified by chromatography (heptane/ethyl acetate 9/1) to give methyl 3-chlorothieno[2,3-b]pyrazine-6-carboxylate 92 (0.6 g, 40%). NMR (400 MHz, CDCl3) 4.01 (s, 3H), 8.18 (s, 1H), 8.71 (s, 1H). (m/z)=229 (M+H)+.

Workup

temperaturewas heated
temperatureto reflux for 5 days
customReaction mixture
concentrationwas concentrated under reduced pressure and co-evaporated with toluene (3×)
customThe crude product was purified by chromatography (heptane/ethyl acetate 9/1)

Sources & evidence

ORD record: ord-e8d5500034004bae9bd8c732f0693f82
Source dataset: uspto-grants-2014_03
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US08669256B2

Reaction notes

Loading…