Acetic Acid → Dimethyl-(8-phenyl-1,4-dioxa-spiro[4.5]dec-8-ylmethyl)-amine

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Reaction Steps

The title compound of step 4 (5.40 g, 21.8 mmol) was dissolved in acetonitrile (150 mL), and a cloudy solution was formed. Aqueous 37% formalin solution (30.6 mL, 407 mmol) was added. The batch was stirred for 20 min at RT and then mixed with sodium cyanoboron hydride (5.76 g, 91.7 mmol). The reaction was followed by DC in chloroform/methanol (9:1). After 4 h the solution was adjusted to pH 7 with acetic acid and concentrated to low volume in a vacuum. The residue was taken up in chloroform, washed with NaHCO3 solution and the aqueous phase extracted with ether. The combined organic phases were dried over Na2SO4 and concentrated to low volume in a vacuum. The raw product was purified by flash chromatography with chloroform/methanol (50:1→20:1→9:1).

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