Sodium hydride → Benzyl 1-(tert-butoxycarbonylmethyl)-2-indolecarboxylate

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Reaction Steps

50.25 g of benzyl 2-indolecarboxylate (Preparation 2.1, step A) are dissolved in 140 ml of anhydrous DMF, followed by addition over 30 minutes, under a stream of dry nitrogen, of a solution of 6.6 g of NaH at 80% in oil, in 100 ml of DMF. The reaction medium is stirred for 90 minutes at RT and is then cooled on an ice bath and 42.91 ml of tert-butyl bromoacetate are added dropwise. After stirring at RT overnight, the DMF is evaporated off and the residue is taken up in DCM and then in water. After stirring, the phases are separated by settling and the aqueous phase is then extracted twice-with DCM; the combined organic phases are washed with saturated NaCl solution and then dried over MgSO4. After filtration and evaporation, the residue is taken up in a mixture of 100 ml of ethyl ether and 100 ml of heptane. After stirring for 2 hours, the crystals formed are filtered off and then washed with 50 ml of a heptane/ethyl ether mixture (70/30; v/v) and dried in an oven. 58 g of the expected product are obtained: m.p. 95-96° C.

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