Tetrahydrofuran → Tert-butyl 5-(2-oxo-1-piperidinyl)-1-indolinecarboxylate

Participants

Reaction Steps

Part H. To tert-butyl-5-amino-1-indolinecarboxylate (1.90 g, 8.2 mmol) was added 5-bromovaleryl chloride (1.4 mL, 9.0 mmol) and 18 mL of THF. After stirring for 5 min at rt under N2, potassium tert-butoxide (9 mL, 9 mmol; 1.0 M in THF) was added in one portion, and the resulting brown solution was stirred under N2 for 30 min. A second portion of potassium tert-butoxide (9 mL) was added, and the resulting brown suspension was stirred for 15 min. An additional 0.10 mL-portion of 5-bromovaleryl chloride and a 4.5 mL-portion of potassium tert-butoxide were added, and the mixture was stirred for 30 min. The reaction was then poured into H2O (80 mL). The aqueous layer was washed with EtOAc (3×50 mL), and the combined organic layers were washed with brine, dried over Na2SO4, and filtered. The filtrate was concentrated and the resulting residue was purified by radial chromatography (50% EtOAc in hexanes) to afford tert-butyl 5-(2-oxo-1-piperidinyl)-1-indolinecarboxylate as a pink solid (1.30 g, 50%). LRMS (AP+): 317.2 (M+H)+. 1H NMR (CDCl3) δ 7.40–7.80 (br m, 1H), 7.01 (s, 1H), 6.97 (d, 1H), 3.94 (t, 2H), 3.55 (br m, 2H), 3.09 (t, 2H), 2.49 (br m, 2H), 1.91 (br m, 4 H), 1.52 (s, 9H).

Provenance & Evidence