Dimethyl Sulfoxide → 2,7-Dibromo-9-(bis-methylsulfanyl-methylene)fluorene

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Reaction Steps

Sodium tert-butoxide (31.1 g, 0.32 mol) was added portionwise over 5 min to a solution of 2,7-dibromofluorene (50 g, 0.154 mol) in DMSO (1000 ml) at RT (22° C.) under nitrogen. To the resulting red solution was added carbon disulfide (13 g, 0.17 mol) via a syringe causing an exotherm to 35° C. The reaction was stirred for 10 min until the internal temperature was 30° C. Methyl iodide (46 g, 0.32 mol) was added over 2 min, causing an exotherm to 42° C. The reaction was stirred for 1 h and quenched by the addition of ice water (1000 ml) and conc. ammonia (20 ml). The reaction was stirred for 10 min and then filtered under reduced pressure and washed with further water (500 ml). After drying the crude yield was 64.8 g (98%, purity (HPLC) 97.8%). Recrystallization from ethyl acetate/THF (2:1) afforded 55.2 g (purity (HPLC) 99.2%).): 1H and 13C NMR spectra as expected; M+=428 (t). Anal. Calcd. For C16H12Br2S2: C, 44.9; H, 2.8, N, 0.0. Found C, 44.7; H, 3.1; N, <0.3.

Provenance & Evidence