that has been neutralized with potassium carbonate about 15 ml of final solution and the mixture is stirred at room temperature for three hours the yellow brown solution is acidified with 10 potassium bisultate and extracted with ethyl acetate the organic layers are combined dried mgso 4 and evaporated in vacuo to yield 1 1 39 diseleno bis 2 methyl 3 oxo 3 1 propanediyl bis l proline as a yellow glass 2 3 g anal calc 39 d for c 18 h 28 n 2 o 6 se 2 c 41 08 h 5 37 n 5 33 found c 41 13 h 5 62 n 5 12 to a suspension of 1 7 g of dibenzyldiselenide in 50 ml of dry acetonitrile under nitrogen there is added 0 2 g sodium borohydride and the mixture is heated until all yellow color disappears the mixture is cooled 2 6 g of 1 3 bromo 2 methyl 1 oxopropyl l proline is added and the mixture is stirred at room temperature overnight the solvent is removed in vacuo water is added ph 10 and the mixture is extracted with ethyl ether the aqueous layer is then acidified hcl and extracted three times with ethyl acetate the ethyl acetate fractions are combined dried mgso 4 and evaporated to yield 2 1 g of 1 2 methyl 1 oxo 3 phenylmethyl selenyl propyl l proline as a yellow oil anal calc 39 d for c 16 h 21 no 3 se c 54 24 h 5 97 n 3 96 found c 53 98 h 6 00 n 4 04 to a solution of 1 6 g of diphenyl.