3-(1-Methylpyrrolidin-2-ylidene)-3H-indole sesquihydrate

Abstract

The asymmetric unit of the title compound, C13H14N2·1.5H2O, contains two similar mol­ecules of 3-(1-methyl­pyrrolidin-2-yl­idene)-3H-indole, (I), and three water mol­ecules. (I) is the product of reacting indole with 1-methyl­pyrrolidin-2-one in the presence of phospho­rus oxychloride. Both organic molecules are almost completely planar; the maximum distances above and below the least-squares plane through all the atoms of mol­ecule 1 are 0.050 (8) and −0.045 (8) Å, respectively, and the deviations for mol­ecule 2 are 0.096 (8) and −0.059 (8) Å, respectively. In the crystal, the two crystallographically different mol­ecules alternate in π-stacked columns [centroid–centroid distances = 3.729 (5) and 3.858 (5) Å], which are linked by O—H⋯N hydrogen bonds to a network of hydrogen-bonded water mol­ecules. O—H⋯O inter­actions are also present.

Tertiary cyclic amides in Vilsmeier type reaction with indoles

“…This compound has a high level of basicity and reactivity. The overall synthesis pathway of this compound is similar to that of Youngdale and its colleagues [4], but we managed to achieve higher efficiencies by controlling the temperature, time and pHand which provide more complete spectral data [9].…”

“…For example, it was shown to be a remarkably strong base, pKa 10.6, for an imine, as compared to that of 4a-methyl-1,2,3,4-tetrahydro-4a(i)H-carbazole with a pKa of 3.6 [5]. The structure, reactions and crystallographic analysis of this compound have been discussed [5][6][7][8][9]. We have found that 5-bromo-3-(1-methylpyrrolidine)ylidene-3H-indole (4) is obtained from the reaction of 5-bromoindole with 1methylpyrrolidine-2-one and phosphorus oxychloride in 95% yield [10].…”

“…We have found that 5-bromo-3-(1-methylpyrrolidine)ylidene-3H-indole (4) is obtained from the reaction of 5-bromoindole with 1methylpyrrolidine-2-one and phosphorus oxychloride in 95% yield [10]. The reaction of this compound with acidic organic compounds was studied with our group [9,11]. We have reported the reaction of indole with the combination of 1-cyclohexyl-2-pyrrolidinone and phosphorus oxychloride giving the hydrochloride of 3-(1cyclohexylpyrrolidin-2-ylidene)-3H-indole.…”

3-(1-Cyclohexylpyrrolidin-2-ylidene)-3H-indole and 4-(cyclohexylamino)-1-(1H-indol-3-yl)butan-1-one – the balance between enaminimine and ring-opened forms

“…We have expended considerable and rewarding efforts on investigations of the properties and reactions of 3-(1-methylpyrrolidin-2-ylidene)-3H-indole (5): we have examined its crystal structure, 9 its UV spectrum and basicity 10 (it is a remarkably strong base, pK a 10.6, which can be compared to the pK a of 4a-methyl-1,2,3,4-tetrahydro-4aH-carbazole, a simple indolenine, of 3.6), and its intriguing reactivity with 1,3-diketones, 11,12 and malonates. 13,14 Our continuing interest involves using alternatives to 1-methyl-2-pyrrolidinone in Vilsmeier-type reactions with indoles.…”

“…The chloroform layer was dried (Na 2 SO 4 ) and evaporated under reduced pressure. The residue was crystallized from n-hexane to give 3-(1-cyclohexylpyrrolidin-2-ylidene)-3H-indole (9). m.p.…”