2',3'-Difluoroacetophenone → (NZ,R)-N-[1-(2,3-difluorophenyl)ethylidene]-2-methylpropane-2-sulfinamide

Participants

Reaction Steps

To a solution of 2,3-difluoroacetophenone (25.0 g, 160 mmol) in THF (500 mL) was added (R)-(+)-2-methyl-2-propanesulfinamide (38.8 g, 320 mmol) followed by tetraisopropoxytitanium (142 mL, 480 mmol). The reaction was heated to reflux for 3 days. The mixture was allowed to cool to room temperature and then treated with brine (550 ml). The resulted suspension was stirred for 15 min and filtered through celite. The filter cake was washed with EtOAc. The filtrate was extracted with EtOAc (2×). The organic extracts were washed with brine, dried over Na2SO4 and filtered. The filtrate was concentrated and purified by silica gel column (10-35% EtOAc/hexane) to afford (R,Z)-N-(1-(2,3-difluorophenyl)ethylidene)-2-methylpropane-2-sulfinamide (35.6 g, 137 mmol, 86% yield) as yellow oil. MS m/z=260.1 [M+H]+ calculated for C12H15F2NOS: 259.3

Provenance & Evidence