Triphenylphosphine → 6-Chloro-5-(1-isopropyl-piperidin-4-yloxy)-1H-indole-2-carboxylic acid ethyl ester

Participants

Reaction Steps

To a cold (0° C.) mixture of 6-chloro-5-hydroxy-1H-indole-2-carboxylic acid ethyl ester (625 mg, 1.0 eq.), 1-Isopropyl-piperidin-4-ol (448 mg, 1.2 eq.) and triphenylphosphine (846 mg, 1.2 eq.) in tetrahydrofuran (8 mL) was added dropwise a solution of di-tert-butylazodicarboxylate (725 mg, 1.2 eq.) in tetrahydrofuran (7 mL). The reaction mixture was stirred for 20 h at room temperature. The volatile components were evaporated under reduced pressure and the residue was purified by flash chromatography on silica gel with a gradient of dichloromethane/methanol/ammonia from 98:2:0 to 90:9:1 as eluant to afford 635 mg (67%) of the tide compound as a light-yellow foam.

Provenance & Evidence