4H,5H,6H-cyclopenta(b)thiophen-6-one → 5,6-Dihydrothieno[2,3-c]pyridin-7(4H)-one

Participants

Reaction Conditions

Reaction Steps

Prepare the title compound by essentially following procedures as found in Aparajithan, K.; Thompson, A. C.; Sam, J. J. Heterocyclic. Chem. 1966, 3, 466. Dissolve 4,5-dihydro-cyclopenta[b]thiophen-6-one (Bonini, B. F.; et. al. Eur. J. Org. Chem. 2004, 4442 and references cited therein) (0.658 g, 4.77 mmol) in MeOH (50 mL), and add hydroxylamine hydrochloride (0.365 g, 5.25 mmol) and NaOAc (2.35 g, 28.62 mmol). Stir the reaction at RT overnight. Remove the organic solvent in vacuo, and treat the residue with EtOAc (60 mL). Filter through silica gel, wash with EtOAc, and concentrate. Treat the residue with PPA (30 g), heating to 130° C. in an oil bath and with occasional stirring over 30 min. Allow the reaction to cool to RT and pour into ice water (100 mL). Extract with CH2Cl2 (3×150 mL). Wash the combined organic layers with 0.1 M NaOH (100 mL), dry over Na2SO4 and concentrate. Purify the material by chromatography, eluting with 75% EtOAc/hexanes to give 0.521 g (71%) of the title compound. MS/ES m/z 154.1 [M+H]+.

Provenance & Evidence