Tetrafluoroboric acid → HCID 57907588, compound

Ethyl 2-amino-5,6-dihydro-4H-cyclopenta[d][1,3]thiazole-4-carboxylate (2.0 g, 9.4 mmol), (see i-13, step A) was dissolved in fluoroboric acid (5.17 g, 28.3 mmol) and the mixture cooled to the point just above it freezes (˜5° C.). Nitrosonium tetrafluoroborate (1.1 g, 9.4 mmol) was added portionwise and mixture stirred at 0° C. for 20min. Diethyl ether (60 ml) added and mixture stirred at −50° C. for 30 min. Filtered and the solid washed with diethyl ether and air dried. The solid was taken up in toluene (70 ml) and warmed to 90° C. for 30 min. The mixture was cooled and evaporated, and the crude residue purified by MPLC (eluent: gradient rising from 100% Hexanes to 40% EtOAc in Hexanes) to give the title compound 390mg (19%) as a yellow oil. 1H NMR (500 MHz CDCl3) δ; 4.22 (q, J=7.1, 2H), 3.93 (dd, J=7.0 and 5.0, 1H), 3.08 (m, 1H), 2.91 (m, 1H), 2.71 (m, 2H), 1.31 (t, J=7.1, 3H).

1. temperaturethe mixture cooled to the point just above it
2. custom(˜5° C.)
3. stirringmixture stirred at −50° C. for 30 min
4. filtrationFiltered
5. washthe solid washed with diethyl ether and air
6. customdried
7. temperaturewarmed to 90° C. for 30 min
8. temperatureThe mixture was cooled
9. customevaporated
10. customthe crude residue purified by MPLC (eluent: gradient rising from 100% Hexanes to 40% EtOAc in Hexanes)

ORD record

ord-bb956d81bd14459baca8a51cd9671a46

Source dataset

uspto-grants-2013_08

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08501786B2