ChemicalBook CAS DataBase List 5-Fluoro-2-oxindole

5-Fluoro-2-oxindole synthesis

8synthesis methods

Product Name:5-Fluoro-2-oxindole
CAS Number:56341-41-4
Molecular formula:C8H6FNO
Molecular Weight:151.14

synthesis of 5-fluoro-2-oxindole: 4-fluoroaniline was used as the starting material, reacted with chloral hydrate and hydroxylamine hydrochloride to generate 4-fluoroisonitrosoacetanilide, and then cyclized under the action of concentrated sulfuric acid to form the compound 5-fluoroisatin was finally obtained by wolff-kishner-huang minlon reduction to obtain 5-fluoro-2-oxindole with a total yield of 66%.

443-69-6 Synthesis

443-69-6
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56341-41-4
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Yield:56341-41-4 99.1%

Reaction Conditions:

with hydrazine hydrate in water at 140; for 6 h;Wolff-Kishner-Huang Minlon Reduction;Temperature;

Steps:

5-Fluoroindolin-2-one (2)

To a flask equipped with a thermometer were added 5-fluoroisatin (13, 4.60 g, 27.9 mmol), hydrazine hydrate (80 %, 19.3 mL, 386 mmol), and water (19.3 mL) with full stirring. The reaction mixture was kept at 140 °C in an oil bath for 6 h before cooling down to r.t., to which was added hydrochloride (2.0 mol/L) to pH 2. The reaction mixture was stirred at r.t. for 12 h. Brownish-gray solid was obtained by filtering under vacuum and washing with water as the first portion of compound 2 (2.59 g), m.p. 131-133 °C. Some solid was recovered from the filtration via extracting with ethyl acetate (30 mL 9 3) then evaporating to give the second portion of compound 2 (1.58 g), m.p. 134-135 °C (lit. 134-135 °C [21]). The total amount of 2 was 4.17 g with yield of 99.1 % (lit. yield 80.8 % [21]). R_f = 0.51 (eluent: petroleum ether/ethyl acetate, v/v = 3:1). ¹H NMR (DMSO-d₆) δ: 3.49 (s, 2H, 3-CH2), 6.76-6.79 (m, 1H, aryl-6-H), 6.96-7.01(m, 1H, aryl-4-H), 7.08-7.10 (m, 1H, aryl-7-H), 10.36 (s, 1H, NH-indole).

References:

Meng, Ge;Liu, Chunyan;Qin, Shidong;Dong, Mengshu;Wei, Xiaomi;Zheng, Meilin;Qin, Liwen;Wang, Huihui;He, Xiaoshuang;Zhang, Zhiguo [Research on Chemical Intermediates,2015,vol. 41,# 11,p. 8941 - 8954]