Hydrochloric Acid → (+/-) 1-Benzyloxycarbonyl-2-(1-hydroxy-2-aminoethyl)-indoline

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Reaction Steps

Borane-dimethylsulfide (2M, 0.85 ml) is added to a mixture of (±) 1-benzyloxycarbonyl-2-(1-cyano-1-hydroxymethyl)indoline [VI diastereomer B, EXAMPLE 6, 0.431 g] in refluxing tetrahydrofuran (5 ml) slowly over 6 minutes. After one hour additional borane-dimethyl sulfide (2M, 0.5 ml) is added over 2 minutes. The mixture is continued to stir at reflux for 30 minutes then hydrochloric acid (3N, 1.8 ml) is added slowly with much effervescence over 2 minutes. The mixture is stirred for 15 minutes at reflux then cooled to 0° in an ice bath and sodium hydroxide (5N, 1.6 ml) is added slowly over 2 minutes. The solvent layers are separated and the aqueous layer is saturated with potassium carbonate and extracted with ethyl acetate (4×, 30 ml total). The organic layers are combined, dried over magnesium sulfate and then concentrated to give the title compound, NMR (methanol-d4, 300 MHz) 7.35, 7.15, 6.96, 5.26, 4.64, 3.87, 3.22, 3.03 and 2.43 δ; CMR (methanol-d4, 75.47 MHz) 30.5, 62.90, 68.8, 117.2, 124.48, 125.8, 128.24, 129.34, 129.68, 132.9 and 138.1 δ.

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