4-(2′-bromoethyl)-3-chloro-2-indolinone 3.00g (10.93 mmol) and Pd-C 300mg [10% Pd on charcoal, Aldrich] was suspended in ethyl acetate 50 mL in a round flask and the mixture was brought to reflux on a 100C bath with vigorous stitting. A solution of NaH2PO2.H2O 3.0g in water 12ml was gradually added through the condenser over a 30 min period. After the complete hypophosphite addition the mix was stirred at reflux for additional 2 hours, then cooled to about 40C and filtered while warm to remove the catalyst. (The spent catalyst was washed with additional water 100mL and EtOAc 100mL). The combined filtrates were separated, the aqueous phase was re-extracted with another portion of EtOAc (100mL). The combined organic extracts were dried (MgSO4) and evaporated. The solid residue was suspended in EtOAc 20mL, the solids were collected by filtration, washed with freezer-chilled EtOAc and dried by suction and on highvac, to provide the 1.428g of a pure product. A second crop 0.850g (95% pure by HPLC) was obtained by evaporating the supernatants and re-crystallizing the residue from EtOAc 10mL (reflux, then RT, then 0C fridge overnight). The combined Y=2.278g of a white crystalline solid (87% th)
1H-NMR (d6-DMSO, 400MHz): 10.360(s, 1H), 7.123(t, 7.8Hz, 1H), 6.848(d, 7.6Hz, 1H), 6.702(d, 7.7Hz, 1H), 3.720(t, 7.4Hz, 2H), 3.505(s, 2H), 3.054(t, 7.3Hz, 2H)
Note: Sodium hypophosphite is on the DEA-watched precursors list in US because it could be supposedly used as a red P replacement in home manufacture of meth. Since hypophosphite has only limited chemistry uses and the chemistry supplier may not be familiar with its application in the transfer hydrogenation, the shipment can be held up. So put it on a separate order, prepare an explanation with a literature reference, and expect that the order shipment can be delayed for 1-2 weeks until the baloney gets sorted out. (To speed things along be ready to complain to the supplier that they are concerned with pleasing the government instead of their customers).