(2,3-Dihydro-1 H -indol-5-ylmethyl)amine

: New (2,3-dihydro-1 H -indol-5-ylmethyl)amine was synthesized from 2-((1-acetylindolin-5-yl)methyl)isoindoline-1,3-dione by simultaneous deprotection of phthalimide and acetyl groups. The structure of the newly synthesized compounds was established by elemental analysis, high resolution mass-spectrometry, 1 H, 13 C NMR and IR spectroscopy and mass-spectrometry. The resulting compound is a convenient intermediate for various disubstituted 1-(indolin-5-yl)methanamines, which may be of interest as substances with useful pharmacological properties.


Introduction
2,3-Dihydroindoles (indolines) are important structural components presented in many natural products and biologically active compounds [1,2]. In this regard, di-N,1substituted 1-(indolin-5-yl)methanamines are of a great interest. These compounds have been identified by targeted SAR studies as promising structures interacting with RCAR/ (PYR/PYL) receptor proteins [3]. Some of indolinylmethyl sulfonamides showed a strong affinity for RCAR/(PYR/PYL) receptor proteins in wheat, and the binding affinity of several their representatives was at the same level or even better than that of the essential plant hormone abscisic acid (ABA) [3]. All of these heterocyclic compounds were obtained from commercially available indoline in several synthesis steps. (2,3-dihydro-1H-indol-5-ylmethyl)amine 1 can be considered as an important intermediate for the preparation of other disubstituted 1-(indolin-5-yl)methanamines. Herein, we report the synthesis of a previously unknown (2,3-dihydro-1H-indol-5-ylmethyl)amine 1 via its dihydrochloride salt 2.
In conclusion, the first representative of indolines containing a methylamine group-(2,3-dihydro-1H-indol-5-ylmethyl)amine 1, was obtained. This compound opens up possibilities for the synthesis of various functional derivatives of disubstituted 1-(indolin-5yl)methanamines, which may be of interest as compounds with useful pharmacological properties.

Materials and Methods
2-((1-Acetylindolin-5-yl)methyl)isoindoline-1,3-dione 2 was prepared according to the published method [5]. The solvents and reagents were purchased from commercial sources and used as received. Elemental analysis was performed on a 2400 Elemental Analyzer (Perkin ElmerInc., Waltham, MA, USA). Melting point was determined on a Kofler hot-stage apparatus and is uncorrected. 1 H and 13 C NMR spectra were taken with a Bruker AM-300 machine (Bruker AXS Handheld Inc., Kennewick, WA, USA) (at frequencies of 300 and 75 MHz) with TMS as the standard. J values are given in Hz. MS spectrum (EI, 70 eV) was obtained with a Finnigan MAT INCOS 50 instrument (Hazlet, NJ, USA). IR spectrum was measured with a Bruker "Alpha-T" instrument in KBr pellet. Highresolution MS spectrum was measured on a Bruker micrOTOF II instrument (Bruker Daltonik Gmbh, Bremen, Germany) using electrospray ionization (ESI).
A mixture of 2-((1-acetylindolin-5-yl)methyl)isoindoline-1,3-dione 2 (2 g, 6.3 mmol) and hydrazine hydrate (1 mL, 31.6 mmol) in methanol (20 mL) was refluxed for 3 h. Excess of methanol was removed under reduced pressure. Water (10 mL) and concentrated HCl (10 mL) were added to the residue. The mixture was heated with stirring for 3 h at 70 °C. After filtration of the precipitate the aqueous layer was evaporated, the residue was washed with acetone and dried in air. The structure of (2,3-dihydro-1H-indol-5-ylmethyl)amine 1 and its dihydrochoride salt 3 was confirmed by elemental analysis, high resolution mass-spectrometry, 1 H, 13 C NMR and IR spectroscopy, and mass-spectrometry. Compared with disubstituted compound 2, the spectral data of compound 1 contain, in addition to signals characteristic of the indoline ring and CH 2 group, signals characteristic of the NH 2 and NH groups: in 1 H NMR spectrum-2.45 (2H) and 5.28 (1H) ppm, and in IR spectrum-3359, 3282, 3012 cm -1 .
In conclusion, the first representative of indolines containing a methylamine group-(2,3-dihydro-1H-indol-5-ylmethyl)amine 1, was obtained. This compound opens up possibilities for the synthesis of various functional derivatives of disubstituted 1-(indolin-5yl)methanamines, which may be of interest as compounds with useful pharmacological properties.

Materials and Methods
2-((1-Acetylindolin-5-yl)methyl)isoindoline-1,3-dione 2 was prepared according to the published method [5]. The solvents and reagents were purchased from commercial sources and used as received. Elemental analysis was performed on a 2400 Elemental Analyzer (Perkin ElmerInc., Waltham, MA, USA). Melting point was determined on a Kofler hotstage apparatus and is uncorrected. 1 H and 13 C NMR spectra were taken with a Bruker AM-300 machine (Bruker AXS Handheld Inc., Kennewick, WA, USA) (at frequencies of 300 and 75 MHz) with TMS as the standard. J values are given in Hz. MS spectrum (EI, 70 eV) was obtained with a Finnigan MAT INCOS 50 instrument (Hazlet, NJ, USA). IR spectrum was measured with a Bruker "Alpha-T" instrument in KBr pellet. High-resolution MS spectrum was measured on a Bruker micrOTOF II instrument (Bruker Daltonik Gmbh, Bremen, Germany) using electrospray ionization (ESI).