Sodium Iodide → 9-[(cyclopentyl)methyl]-5-carbomethoxy-1,2-dihydrocarbazol-4(3H)-one

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Reaction Steps

A suspension of 5-carbomethoxy-1,2-dihydro-9H-carbazol-4(3H)-one (820 g, 3.37 mmol), a catalytic amount of NaI (ca. 10 mg) and K2CO3 (930 mg, 6.74 mmol) in 6 mL of DMF was treated with cyclopentylmethyl chloride (JOC, 1964, 29, 421-423; 400 mg, 3.37 mmol). After stirring overnight at ambient temperature, an additional 800 mg of cyclopentylmethyl chloride and 1 g of NaI were added, and the resulting mixture was heated at 80° C. overnight. An additional 800 mg of cyclopentylmethyl chloride and 2.2 g of Cs2CO3 were added, and the reaction mixture was heated at 80° C. for 24 h. An additional 1.6 g of cyclopentylmethyl chloride was added, and the reaction mixture was heated at 80° C. for 3 d The mixture was poured into H2O (30 mL) and extracted with EtOAc (3×10 mL). The combined organic layers were dried over anhydrous Na2SO4, filtered, and concentrated in vacuo. The residue was purified by radial chromatography on silica gel (elution with gradient of 10% to 40% EtOAc/hexanes) to afford 775 mg (2.38 mmol; 71%) of 9-[(cyclopentyl)methyl]-5-carbomethoxy-1,2-dihydrocarbazol-4(3H)-one as a brown foam. MS (ES) m/e 326 (M+1), 384 (M+AcO−).

Provenance & Evidence