ChemicalBook CAS DataBase List 5-PHENYL-3,4-DIHYDRO-2H-PYRROLE

5-PHENYL-3,4-DIHYDRO-2H-PYRROLE synthesis

11synthesis methods

Product Name:5-PHENYL-3,4-DIHYDRO-2H-PYRROLE
CAS Number:700-91-4
Molecular formula:C10H11N
Molecular Weight:145.2

108-86-1 Synthesis

108-86-1
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628-20-6 Synthesis

628-20-6
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700-91-4
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Yield: 47%

Reaction Conditions:

Stage #1:bromobenzene with magnesium in diethyl ether at 40; for 2 h;
Stage #2:4-Chlorobutyronitrile in diethyl ether at 20 - 40; for 1.5 h;

Steps:

1 General procedure for the synthesis of 2-aryl-1-pyrrolines
General procedure: This procedure was adapted from the literature.²⁸ Unless stated otherwise, the Grignard reagent was prepared by adding dropwise the corresponding aryl bromide to a suspension of excess of magnesium turnings and a few iodine crystals in diethyl ether. The solution was kept for 2h at 40°C. The heating was turned off and a solution of an equimolar amount of 4-chlorobutyronitrile in diethyl ether was added dropwise to the in situ prepared Grignard reagent. The reaction mixture was refluxed for 1.5h and the temperature was then increased up to 110°C to distil off the diethyl ether while xylene was added to keep the total volume constant. The mixture was allowed to cool to room temperature, and a saturated aqueous solution of NH₄Cl was added, which caused phases separation. The aqueous phase was repeatedly washed with diethyl ether and the combined organic phases were acidified with a 10% HCl aqueous solution. After extraction, the aqueous acidic solution was neutralised with a NaOH 1M aqueous solution, in an ice bath. Diethyl ether was added and the organic layer extracted and washed with distilled water. After drying over anhydrous MgSO₄, the diethyl ether was removed under vacuum and the remaining product purified by trap-to-trap distillation, column chromatography or recrystallization in the appropriate solvent.
4.2.1
2-Phenyl-1-pyrroline (1a)
The phenyl Grignard reagent was prepared from bromobenzene (39.5 mL, 375 mmol) and magnesium turnings (9.24 g, 380 mmol) in diethyl ether (250 mL).
Addition of a solution of 4-chlorobutyronitrile (23.2 mL, 375 mmol) in diethyl ether (250 mL) and subsequent reaction afforded a dark-brown oil, which was purified by trap-to-trap distillation (80 °C and 10^-1 mbar).
The resulting light yellow oil was stored at 4 °C, yielding 25.8 g (47%) of 1a as colourless crystals. ¹H NMR (300 MHz, CDCl₃): δ=7.83-7.80 (m, 2H, Ph-H_ortho), 7.38-7.35 (m, Ph-H_meta and Ph-H_para), 4.09-4.03 (m, 2H, H5 pyrr), 2.97-2.90 (m, 2H, H3 pyrr), 2.08-1.96 (m, 2H, H4 pyrr) ppm.