Propylamine → 1-benzyl-N,N-dimethyl-N'-propylcyclohexane-1,4-diamine

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Reaction Steps

6.00 g 4-benzyl-4-dimethylamino-cyclohexanone (see example 3) were dissolved in 90 ml analytical grade tetrahydrofuran, and 1.53 g n-propylamine followed by 3.36 ml glacial acetic acid were added, while stirring in an ice-bath. 7.68 g sodium triacetoxyborohydride were then added in portions in the course of 15 minutes and the mixture was subsequently stirred for approx. 65 hours. For working up, 45 ml two molar sodium hydroxide solution were added dropwise (pH>10) and the mixture was extracted three times with 50 ml diethyl ether each time. The combined organic phases were washed twice with 50 ml water each time, dried over sodium sulfate and filtered and the filtrate was concentrated. The crude product obtained (6.43 g) was chromatographed over silica gel with diethyl ether with the addition of five percent by volume of aqueous ammonia solution (25 wt. %). 707 mg of the nonpolar diastereoisomer of 1-benzyl-N,N-dimethyl-N′-propyl-cyclohexane-1,4-diamine were obtained.

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