1,2-Dichloroethane → 2-[(4-benzylpiperidin-1-yl)methyl]-1H-benzimidazole

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Reaction Steps

A mixture of 0.5 g of 4-benzyl-piperidine, 0.5 g of 1-(2-trimethylsilylethoxymethyl)-1H-benzoimidazole-2-carbaldehyde, 5 mL of 1,2-dichloroethane and 0.5 g of sodium triacetoxyborohydride was stirred at room temperature for 48 h. The reaction mixture was diluted with 50 mL chloroform and 10 mL saturated aqueous Na2CO3 and the layers separated. The aqueous layer was extracted with 2×25 mL of chloroform and the combined organic layers dried over magnesium sulfate and concentrated under reduced pressure. The crude SEM ether was heated to reflux in 50 mL of ethanol containing 5 mL of 3N HCl for 2 h, cooled, concentrated and partitioned between 10 mL of saturated aqueous sodium carbonate and 3×25 mL of chloroform. The chloroform extracts were dried over magnesium sulfate and concentrated. Purification by chromatography eluting with 90:10 CHCl3: MeOH gave 0.8 g of 2-[4-benzyl-piperidin-1-ylmethyl]-1H-benzimidazole: MS (m+1)=: 1H NMR (400MHz, CDCl3).

Provenance & Evidence