Trifluoroacetic acid → cyclohexylmethyl-[2-(1H-thieno[3,2-c]pyrazol-3-yl)-1H-indol-5-ylmethyl]-amine

Participants

Reaction Steps

A mixture of 2-(1-tert-butoxycarbonyl-1H-thieno[3,2-c]pyrazol-3-yl)-5-formyl-indole-1-carboxylic acid tert-butyl ester [200 mg, 1 eq, Intermediate (11) prepared as described in Step 1 of Example 24], aminomethylcyclohexane (1.1 eq), MP-cyanoborohydride (macroporous triethylammonium methylpolystyrene cyanoborohydride, 1.5 eq), and acetic acid (0.5 ml) in dimethyl formamide (10 ml) at room temperature was shaken overnight. The resin was filtered and the filtrate was poured into water. The mixture was extracted twice with ethyl acetate; the extract was dried over magnesium sulfate and concentrated. The residue was purified by silica gel column (eluted by 20% methanol in ethyl acetate) to yield a mixture of 2-(1-tert-butoxycarbonyl-1H-thieno[3,2-c]pyrazol-3-yl)-5-[(cyclohexylmethyl-amino)-methyl]-indole-1-carboxylic acid tert-butyl ester [major product, LC/MS: 565 (M+H), RT=3.5 minutes], 5-[(cyclohexylmethyl-amino)-methyl]-2-(1H-thieno[3,2-c]pyrazol-3-yl)-indole-1-carboxylic acid tert-butyl ester and 3-{5-[(cyclohexylmethyl-amino)-methyl]-1H-indol-2-yl}-thieno[3,2-c]pyrazole-1-carboxylic acid tert-butyl ester. This mixture was treated with trifluoroacetic acid in dichloromethane (10 ml, 1:1) at room temperature for 2 hours and the reaction mixture was passed through SCX column eluting with 7N ammonia in methanol affording cyclohexylmethyl-[2-(1H-thieno[3,2-c]pyrazol-3-yl)-1H-indol-5-ylmethyl]-amine [Example 52]. LC/MS: 365 (M+H), RT=2.5 minutes; 1H NMR [(CD3)2SO)]: δ 11.4 (1H, s), 7.8 (d, 2H), 7.5 (1H, s), 7.4 (1H, d), 7.2 (1H, d), 7.0 (1H, d), 6.6 (1H, s), 3.8 (2H, s)2.2 (2H, d), 1.8-2.0 (4H, m), 1.0-1.2(4H, m), 0.8-1.0(3H, m).

Provenance & Evidence