Download PDF
Synlett 2008(1): 105-107  
DOI: 10.1055/s-2007-992387
LETTER
© Georg Thieme Verlag Stuttgart · New York

Applications of Lanthanide Trichloride Hydrates, Prepared from Mischmetall, in the Biginelli Reaction

Marie-Isabelle Lannou, Florence Hélion, Jean-Louis Namy*
Laboratoire de Catalyse Moléculaire CNRS, ICMMO, Bât 420, Université Paris-Sud, 91405 Orsay, France
Fax: +33(1)69154680; e-Mail: flohelion@icmo.u-psud.fr;
Further Information

Publication History

Received 6 July 2007
Publication Date:
03 December 2007 (online)

    Permissions and Reprints All articles of this category

Abstract

An inexpensive alloy of light lanthanides, called misch­metall, has been used in the preparation of a mixture of lanthanide trichloride hydrates. The use of this new type of material is described in Biginelli reactions.

Key words

mischmetall - lanthanide trichlorides - Biginelli-type reaction

15

Typical Experimental Procedure for Biginelli Reaction: A mixture of ethyl acetoacetate (638 µL, 5 mmol), urea (451 mg, 7.5 mmol) or thiourea (571 mg, 7.5 mmol), aldehyde (5 mmol), LnCl3·7H2O (Ln = mischmetall, 373 mg, 1 mmol, 0.2 equiv) and 12 M HCl acid (1 drop) in absolute EtOH (10 mL) was placed under magnetic stirring and refluxed in EtOH for 5 h. The reaction mixture was then cooled to r.t. and poured onto an ice-water mixture (25 g). The solution was stirred for 5 min until a solid appeared. The precipitate was then filtered and the solid was washed with cold H2O (2 ×), then with an EtOH-H2O mixture (1:1, 2 ×) and finally dried under vacuum. The crude product was then purified by recrystallization in absolute EtOH.
Selected Spectral Data for 6-Methyl-2-oxo-4-phenyl-1,2,3,4-tetrahydropyrimidine-5-carboxylic Acid Ethyl Ester (1): colorless crystals; mp 207-209 °C (lit.8 mp 206-209 °C); yield: 1.954 g, 92% (cat.: 0.5 equiv); yield:1.106 g, 85% (cat.: 0.2 equiv). 1H NMR (250 MHz, CDCl3): δ = 1.16 (t, J CH3-CH2 = 7.1 Hz, 3 H, OEt), 2.35 [s, 3 H, C(6)Me], 4.07 (q, J CH2-CH3 = 7.1 Hz, 2 H, OEt), 5.40 [d, J 4,3 = 2.9 Hz, 1 H, C(4)H], 5.65 [br s, 1 H, N(3)H], 7.31 (m, 5 H, Har), 7.97 [br s, 1 H, N(1)H]. 13C NMR (62.9 MHz, DMSO): δ = 15.0, 18.7, 54.9, 60.2, 100.2, 127.2, 128.2, 129.3, 145.8, 149.3, 153.1, 166.3. FTIR (NaCl, nujol): 3233, 3110, 1728, 1704, 1644, 1378, 1309, 1290, 1232, 1220, 1090, 779, 758, 681 cm-1. GC-MS(electrospray): m/z (%) = 543.3 (89) [2 × M + Na]+, 315.2 (60), 283.1 (100) [M + Na]+. 4-(4-Methoxy-phenyl)-6-methyl-2-thioxo-1,2,3,4-tetrahydro-pyrimi­-dine-5-carboxylic Acid Ethyl Ester (4): colorless crystals; mp 149-151 °C (lit.17 mp 150-152 °C); yield: 1.347 g, 88%. 1H NMR (250 MHz, CDCl3): δ = 1.10 (t, J CH3-CH2 = 7.1 Hz, 3 H, OEt), 2.26 [s, 3 H, C(6)Me], 3.71 (s, 3 H, OMe), 4.00 (q, J CH2-CH3 = 7.1 Hz, 2 H, OEt), 5.28 [d, J 4,3 = 2.9 Hz, 1 H, C(4)H)], 5.80 [br s, 1 H, N(3)H], 6.76 [d, J 3 ′,2 ′ = J 5 ′,6 ′ = 8.6 Hz, 2 H, C(3′)H, C(5′)H)], 7.16 [d, J 2 ′,3 ′ = J 6 ′,5 ′ = 8.6 Hz, 2 H, C(2′)H, C(6′)H], 8.26 [br s, 1 H, N(1)H]. 13C NMR (62.9 MHz, DMSO): δ = 15.0, 18.0, 54.4, 56.0, 60.5, 101.9, 114.8, 128.5, 136.6, 145.7, 159.7, 166.1, 174.9. FTIR (NaCl, nujol): 3305, 3161, 3097, 1666, 1574, 1510, 1331, 1270, 1120, 1023 cm-1. GC-MS(electrospray): m/z (%) = 636.2 (25) [(2 × M + 1) + Na]+, 635.2 (68) [2 × M + Na]+, 330.1 (18), 329.1 (100) [M + Na]+, 307.1 (35).