ethyl(4'-chloro-2'-oxo-5,6-dihydrospiro[benzo[1,2-b:5,4-b']difuran-3,3'-indol]-1'(2'H)-yl)acetate → (4'-chloro-2'-oxo-5,6-dihydrospiro[benzo[1,2-b:5,4-b']difuran-3,3'-indol]-1'(2'H)-yl)acetic acid

Participants

Reaction Steps

Following the procedure as described in EXAMPLE 2, and making non-critical variations using ethyl (4′-chloro-2′-oxo-5,6-dihydrospiro[benzo[1,2-b:5,4-b′]difuran-3,3′-indol]-1′(2′H)-yl)acetate to replace ethyl (2′-oxospiro[furo[2,3-f][1,3]benzodioxole-7,3′-indol]-1′(2′H)-yl)acetate, the title compound was obtained in 92% yield as a colorless solid: mp 228-229° C.; 1H NMR (300 MHz, CDCl3) δ 7.26-7.21 (m, 1H), 7.03 (dd, 1H), 6.71 (dd, 1H), 6.52 (s, 1H), 6.36 (s, 1H), 4.93 (dd, 2H), 4.69-4.63 (m, 1H), 4.54-4.51 (m, 3H), 2.95 (t, 2H); 13C NMR (75 MHz, CDCl3) δ 177.8, 170.9, 162.1, 162.1, 143.1, 131.7, 130.0, 128.6, 124.7, 119.6, 118.7, 117.0, 106.7, 92.8, 77.2, 72.3, 58.1, 41.2, 28.9; MS (ES−) m/z 370.4 (M−1).

Provenance & Evidence