Triphenylphosphine → tert-butyl (3S)-3-{[1'-(diphenylmethyl)-2'-oxo-1,2'-dihydrospiro[1-benzofuran-3,3'-indol]-6-yl]oxy}pyrrolidine-1-carboxylate

Participants

Reaction Steps

To a solution of 1′-(diphenylmethyl)-6-hydroxyspiro[1-benzofuran-3,3′-indol]-2′(1′H)-one (0.45 g, 1.07 mol), tert-butyl (3R)-3-hydroxypyrrolidine-1-carboxylate (0.60 g, 3.22 mmol) and triphenylphosphine (0.70 g, 2.68 mmol) in tetrahydrofuran (50 mL) was added diethyl azodicarboxylate (0.42 mL, 2.68 mmol) slowly at 0° C. The mixture was stirred to 16 h at ambient temperature, then concentrated in vaccuo. The residue was purified by column chromatography (ethyl acetate/hexanes-1:2) to afford tert-butyl (3S)-3-{[1′-(diphenylmethyl)-2′-oxo-1′,2′-dihydrospiro[1-benzofuran-3,3′-indol]-6-yl]oxy}pyrrolidine-1-carboxylate as an oil (0.52 g, 83%): 1H NMR (300 MHz, CDCl3) δ7.43-7.25 (m, 10H), 7.16-7.06 (m, 1H), 7.07-6.91 (m, 3H), 6.58-6.43 (m, 3H), 6.38-6.25 (m, 1H), 5.00 (d, J=9.0 Hz, 1H), 4.80 (s, 1H), 4.73 (d, J=9.0 Hz, 1H), 3.65-3.36 (m, 4H), 2.22-1.95 (m, 2H), 1.45 (s, 9H); MS (ES+) m/z 611.3 (M+23).

Provenance & Evidence