Nitrogen → Aluminum hydride

Participants

Reaction Steps

A solution of AlH3 was prepared by addition of c.H2SO4 (1.59 g) dropwise to a cooled (ice-bath) suspension of LiAlH4 (1.226 g) in dry THF (82 mL) over 20 min. The mixture was them left to stand under dry N2 for 1 hr to allow the solids to settle. A solution of the glyoxamide (0.59 g, 1.926 mmol) in THF (110 mL) was prepared, and in a N2 atmosphere, the AlH3 solution (55 mL) was added over 5 min. The mixture was stirred for 16 hr and then H2O was added dropwise to quench excess reagent, and the THF was evaporated in vacuo. The residue was partitioned between 1M HCl/CH2Cl12 and after re-extraction of the aqueous layer (2×; CH2Cl2), the combined organic layers were washed with 1M HCl and then saturated aqueous NaCl, dried (MgSO4) and evaporated to a solid. Chromatography (silica gel; CH2Cl2 /EtOH containing 2% concentrated aqueous NH3 ; 0-12%), gave the free base: 1-(N,N-dimethylamino)-2-(5-benzylindol-3-yl)ethane, as a gum, 0.246 g (46%). This was treated with oxalic acid (0.07 g) in MeOH (2 mL) and Et2O added until crystallisation commenced. The product: 1-(N,N-dimethylamino)-2-(5-benzylindol-3-yl)ethane oxalate, was obtained as white granular crystals, 0.191 g (27%), m.p.158°-9° C.

Provenance & Evidence