M554 - 2-[(2-Hydroxy-benzylidene)-amino]-5,6-dihydro-4H-cyclopenta [b] Thiophene-3-carboxylic Acid Methyl Ester

Molbank 2007, M554

http://www.mdpi.org/molbank/

2-[(2-Hydroxy-benzylidene)-amino]-5,6-dihydro-4H-cyclopenta [b] Thiophene-3-carboxylic Acid Methyl Ester

Abdullah Mohamed Asiri *

Chemistry Department, Faculty of Science, King Abdul-Aziz University, Jeddah 21413, P.O. Box 9028, Saudi Arabia

* Author to whom correspondence should be addressed. Tel: (+966)-2-6952293; Fax: (+966)-2-6952293; E-mail: [email protected]

Received: 3 January 2006 / Accepted: 24 June 2006 / Published: 30 May 2007

Keywords: 2-Aminothiophen, Anils, 2-hydroxy naphthaline, Schiff base

Schiff bases from 2-hydroxy-1-naphthaldehyde have often been used as chelating ligands in the field coordination chemistry [1]. The Schiff base compounds can be classified by their photochromic and thermochromic characteristics [2].

scheme m554

A solution of 2-Amino-5,6-dihydro-4H-cyclopenta[b]thiophene-3-carboxylic acid methyl ester 1 (2.5g, 0.0125mol) and 2-hydroxynaphthaldehyde 2 (1.53g, 0.0125 mol) in absolute ethanol (50 mL) was heated under reflux for 3 hrs. Cooling the mixture, filtering the precipitate and recrystallization from ethanol gave the Schiff base 3 as brown crystals (3.76g, 99%).

Melting Point: 135-137ºC. (EtOH).

IR (KBr; cm^-1); 1706.1 (C=O), 1602.1 (C=N), 1445.1 (C=C), 1209.3 (C-O) and 1033 (C-N).

¹H NMR (400 MHz;CDCl₃) δ; 12.67 (s, 1H, OH), 9.19 (s, 1H, CH _olefinic), 7.58 (d, 1H, CH _aromatic), 7.27 (dd, 1H, CH _aromatic), 6.92 (d, 1H, CH _aromatic), 6.84 (dd, 1H, CH _aromatic), 3.88 (s, 3H, COOMe), 3.05-3.04 (t, 2H, CH₂), 2.93-2.60 (t, 2H, CH₂), and 2.52-2.45 (m, 2H, CH₂).

References

Garnovski, A.D.; Nivorozhkin, A.L.; Minkin, V.I. Coord. Chem. Rev. 1993, 126, 1.
Hadjoudis, E.; Vittorakis, M.; Maustakali-Mavridis, I. Tetrahedron 1987, 43, 1345.