Hydrochloric Acid → 5-(5-Hydroxy-pent-1-ynyl)-2,3-dihydro-indole-1-carboxylic acid tert-butyl ester

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Reaction Steps

To 3.73 g (12.5 mmol) 5-Bromo-2,3-dihydro-indole-1-carboxylic acid tert-butyl ester in 25 ml piperidine 722 mg (0.63 mmol) tetrakis-(triphenylphosphine)-palladium and 120 mg (0.625 mmol) CuI were added. The solution was purged with argon and was heated to 80° C. over a period of 45 min, during which 0.9 ml (9.4 mmol) 4-pentynol were added. Additional 0.9 ml (9.4 mmol) 4-pentynol were added and the mixture was stirred for 2 h, poured into ice water and 2M HCl was added. The inorganic phase was extracted with ether, the combined organic phases were washed with water and dried over Na2SO4. Purification on silica gel with hexane/EtOAc 4:1 to 2:1 yielded 3.0 g (79%) 5-(5-Hydroxy-pent-1-ynyl)-2,3-dihydro-indole-1-carboxylic acid tert-butyl ester as light brown solid, MS: 302 (MH+). (See also: Stara, Irena G.; Stary, Ivo; Kollarovic, Adrian; Teply, Filip; Saman, David; Fiedler, Pavel. Coupling reactions of halobenzenes with alkynes. The synthesis of phenylacetylenes and symmetrical or unsymmetrical 1,2-diphenylacetylenes. Collect. Czech. Chem. Commun. (1999), 64(4), 649-672)

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