Sodium borohydride → 3-(4-Bromophenoxy)-6-methoxybenzo[b]thiophene 1,1-dioxide

Participants

Reaction Conditions

Reaction Steps

To a solution of 2-bromo-3-(4-bromophenoxy)-6-methoxy-benzo[b]thiophene 1,1-dioxide (180 g, 403 mmol) in MeOH (150 mL) and DMSO (1300 mL) at 0° C. (internal temperature was at 5° C.) was added the first portion of NaBH4 (15 g, 396.5 mmol). Internal temperature rose quickly to 40° C. and H2 gas release was observed. The mixture was stirred in an ice bath for 30 min (internal temperature cooled down to 10° C.). The second portion of NaBH4 (15.5 g, 409.7 mmol) was added. The resulting mixture was stirred for 30 minutes after which time the reaction was quenched with water (2000 mL) over 1 hour. The resulting precipitate was collected, air dried over 18 hours, then washed with heptane to afford 3-(4-bromophenoxy)-6-methoxybenzo[b]thiophene 1,1-dioxide as an off white solid which was used without further purification. 1H NMR (400 MHz, CDCl3) δ ppm=3.85 (s, 3 H), 5.38 (s, 1 H), 7.02-7.08 (m, 3 H), 7.22 (d, J=2.53 Hz, 1 H), 7.47-7.60 (m, 3 H).

Provenance & Evidence