Methanol → N-(7'-Bromo-3',4'-dihydro-1'H-spiro[cyclopropane-1,2'-naphthalene]-1'-ylidene)-2-methylpropane-2-sulfinamide

Participants

Reaction Steps

Titanium ethoxide (5.9 mL, 28.7 mmol), 2-methyl-2-propanesulfinamide (2.61 g, 21.5 mmol) and 7′-bromo-3′,4′-dihydro-1′H-spiro[cyclopropane-1,2′-naphthalen]-1′-one (Intermediate 6, 3.6 g, 14.3 mmol) in dry 2-Me THF (80 mL) were heated to 100° C. to give an azeotrope. In total 100 mL 2-Me THF was removed and replaced by new 2-Me THF in 50 mL portions over a period of 4 h. The mixture was refluxed overnight. The azeotropic distillation was continued for 9 h and then more 2-methyl-2-propanesulfinamide (2.61 g, 21.5 mmol) and titanium ethoxide (5.9 mL, 28.7 mmol) were added. In total 90 mL 2-Me THF were removed and replaced by new 2-Me THF in 50 mL portions. The mixture was refluxed overnight and the azeotropic distillation was continued for 6 h. The cooled reaction mixture was added to a mixture of MeOH (105 mL), sat. aq. NaHCO3 (41 mL) and EtOAc (430 mL). The resulting slurry was stirred for 2 h and was then filtered through a mixture of diatomaceous earth and Na2SO4 and concentrated. Some material crystallized from the mixture. The solid was triturated with EtOAc/n-heptane and collected by filtration. The mother liquor was purified by flash silica gel chromatography using CHCl3/MeOH 50:1 as eluent and the obtained product was recrystallized from EtOAc/n-heptane. Combining the obtained solids gave 2.02 g (40% yield) of the title compound. 1H NMR (500 MHz, DMSO-d6) δ ppm 1.06 (d, 2 H), 1.14 (s, 9 H), 1.40 (d, 2 H), 1.64-1.84 (m, 2 H), 2.83 (m, 2H), 7.36 (d, 1 H), 7.69 (dd, 1 H), 8.16 (d, 1 H); MS (ES+) m/z 354.0 [M+H]+.

Provenance & Evidence