2,4-Dimethoxybenzylamine → (3R)-tert-Butyl 3-((2,4-dimethoxybenzylamino)methyl)-3,4-dihydroisoquinoline-2(1H)-carboxylate

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Reaction Steps

Sodium triacetoxyborohydride (3.1 g, 15 mm) was added to a mixture of (3R)-tert-butyl 3-formyl-3,4-dihydroisoquinoline-2(1H)-carboxylate (1.3 g, 5.0 mmol theory), 2,4-dimethoxybenzylamine (0.77 ml, 5.5 mmol), and dry 4 A sieves in 1,2-dichloroethane (25 ml) stirring at ambient temperature. After stirring at ambient temperature overnight the reaction solution was transferred to a separatory funnel with EtOAc and saturated NaHCO3. Extraction with EtOAc (2×), washing the combined organic layers with brine and drying over MgSO4 afforded 1.6 g of crude product. Flash chromatography (SiO2, 1 to 10% 2N N3 in MeOH/CH2Cl2) gave pure product (1.3 g, 63% yield over the previous 3 steps). MS (ESI) 413 (M+H).

Provenance & Evidence