Content area
Full Text
Mol Divers (2010) 14:385392 DOI 10.1007/s11030-009-9184-2
FULL-LENGTH PAPER
The Michael addition of indoles and pyrrole to -, -unsaturated ketones and double-conjugate 1,4-addition of indoles to symmetric enones promoted by pulverization-activation methodand Thia-Michael addition catalyzed by wet cyanuric chloride
Ramin Ghorbani-Vaghei Hojat Veisi
Received: 1 May 2009 / Accepted: 11 July 2009 / Published online: 7 August 2009 Springer Science+Business Media B.V. 2009
Abstract A new, facile, and efcient procedure for conjugate addition of indole and pyrrole with Michael acceptors have been developed for pulverizationactivation reaction catalyzed by wet cyanuric chloride (2,4,6-trichloro-[1,3,5]-triazine or TCT) through grinding under solvent-free conditions at room temperature. Also, double-conjugate 1,4-addition of indoles to dibenzylidenacetones and conjugate addition of thiols with Michael acceptors using wet-TCT as catalyst is reported.
Keywords TCT Conjugate 1,4-addition
-, -unsaturated compounds Solvent-free
Introduction
In recent years, considerable attention has been focused on the development of efcient and operationally simple protocols for carboncarbon and carbonheteroatom bonds formation for the construction of valuable molecules. Addition reactions of indoles, amines, and thiols to -, -unsaturated compounds have received much interest because a number of their derivatives occur in nature and possess a variety of biological activities [1,2]. Thus, the development of facile and environmentally friendly synthetic methods for the preparation of these compounds constitutes an active area of investigation in pharmaceutical and organic synthesis. The
R. Ghorbani-Vaghei (B) H. Veisi
Department of Organic Chemistry, Faculty of Chemistry, Bu-Ali Sina University, 65174 Hamadan, Irane-mail: [email protected]
H. VeisiDepartment of Chemistry, Payame Noor University, Songhor, Kermanshah, Irane-mail: [email protected]
Michael addition is one of the most useful carboncarbon bond-forming reactions and has wide synthetic applications in organic synthesis [3]. This reaction is traditionally catalyzed by strong bases that often lead to undesirable side reactions [4]. A variety of Lewis acids are found to catalyze this reaction, and these procedures are also not free from disadvantages [5]. Thus, a number of milder reagents and Lewis acids catalysts such as Al2O3 [6], K2CO3 [7], rhodium complex [8], ruthenium complex [9], clay-supported nickel bromide [10], quaternary ammonium salt [11], InBr3 [12], InCl3 [13], Bi(NO3)3 [14], I2 [15], Bi(OTf)3 [16], HClO4/SiO2 [17], GaI3 [18], PTSA [19], sulfamic acid [20], Ru(III) [21], NH4Cl [22], and N-phenyltris(dimethylamino)iminophosphorane immobilized on polystyrene resin [23] have been developed over the past few...