ChemicalBook CAS DataBase List 4,5,6,7-Tetrahydro-4-oxo-1H-indole-1-carboxylic acid 1,1-dimethylethyl ester

4,5,6,7-Tetrahydro-4-oxo-1H-indole-1-carboxylic acid 1,1-dimethylethyl ester synthesis

4synthesis methods

Product Name:4,5,6,7-Tetrahydro-4-oxo-1H-indole-1-carboxylic acid 1,1-dimethylethyl ester
CAS Number:877170-76-8
Molecular formula:C13H17NO3
Molecular Weight:235.28

Ethanamine, N-[(3,5-dichlorophenyl)methylene]-2,2-diethoxy-

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108-22-5 Synthesis

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4,5,6,7-Tetrahydro-4-oxo-1H-indole-1-carboxylic acid 1,1-dimethylethyl ester

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Yield: 26%

Reaction Conditions:

with toluene-4-sulfonic acid for 5 h;Heating / reflux;

Steps:

3
Tert-butyl 4,5,6,7-tetrahydro-4-oxoindole-1-carboxylate 4,5,6,7-tetrahydro-4-oxoindole-1-carboxylate (1) was prepared using a modified literature procedure (Maekawa, which is hereby incorporated by reference). To a dry 250 mL round bottom flask charged with a magnetic stir bar was added tert-butyl 4,5,6,7-tetrahydro-4-oxoindole-1-carboxylate (4.619 g, 19.6 mmole), 150 mL isopropenyl acetate and p-toluenesulfonic acid monohydrate (67 mg, 0.35 mmole). The solution was refluxed for 5 hours while the solvent was slowly distilled off at the rate of 20 mL/hour. After cooling the solution to ambient temperature, 100 mL of a 1:1 solution of diethyl ether and saturated aqueous NaHCO₃was added. The layers were separated and the aqueous layer extracted with 30 mL diethyl ether. The combined ether extracts were washed with saturated aqueous NaHCO₃(2×30 mL), brine (30 mL), and dried over anhydrous MgSO₄. The solution was then filtered through a plug of silica gel and concentrated in vacuo. The residue was purified via flash chromatography (silica gel, 5:1 pentane:diethyl ether) to give the product as a white solid (1.40 g, 26% yield), mp 79-80° C.; R_f0.26 (5:1 pentane:diethyl ether); FTIR (neat): 2978, 1736 cm^-1; ¹H NMR (500 MHz, CDCl₃) δ 7.09 (d, J=3.5 Hz, 1H), 5.95 (d, J=3.5 Hz, 1H), 5.24 (t, J=4.5 Hz, 1H), 3.10 (t, J=9.5 Hz, 2H), 2.56 (dt, J=9.5, 4.5 Hz, 2H), 2.23 (s, 3H), 1.58 (s, 9H); ¹³C NMR (75 MHz, CDCl₃) δ 169.1 (C), 149.0 (C), 143.3 (C), 130.8 (C), 119.9 (CH), 118.9 (C), 106.8 (CH), 105.4 (CH), 83.8 (C), 27.9 (CH₃), 23.1 (CH₂), 21.7 (CH₂), 20.7 (CH₃); LCMS (ESI) m/z (relative intensity): 250.0 (100), 236.0 (90); HRMS (EI) Calcd for C₁₅H₁₉NO₄277.1309, Found 277.1309.