Multicomponent Biginelli Reaction And Pd-catalyzed Aldol Condensation Reaction In The Presence Of TMSCI

Biginelli reactions are ranked as one of the most powerful tools for the facile synthesis of complex heterocyclic scaffolds due to their wide range of therapeutical and pharmacological properties. In this paper, Biginelli reaction was extensively investigated in the presence of trimethylsilyl chloride (TMSC1) as a Lewis acid, it contains:1, TMSC1 was used to efficiently perform Biginelli reactions of aldehydes, 1,3-dicarbonyl compounds and urea or thiourea. This resulted in simple one-pot synthesis of the corresponding 3,4-dihydropyrimidin-2(1H)-ones at room temperature.2, One-pot chemoselective condensation of 1, 3-cyclohexanedione, urea or thiourea with aldehydes has been performed by using TMSC1. This extended Biginelli-type reaction afforded two families of fused heterobicyclic and spiro-fused heterobicyclic compounds in excellent yields. para-Substituted benzaldehydes exhibited different chemical behaviors to ortho- or meto-substituted benzaldehydes and aliphatic aldehydes.3, The Biginelli reaction is considerably extended by cycloalkanones instead of 1,3-dicarbonyl compounds. In the presence of TMSC1, the presented reaction provided one-pot Biginelli reactions between cycloalkanones, urea or thiourea and aldehydes. Under similar reaction conditions, thiourea exhibited different behaviors and showed lower reactivity to urea, aliphatic aldehyde exhibited different behaviors to aromatic aldehydes.4, The Biginelli-type reactions between 3,4-dihydro-2(H)-pyran or styrenes, urea or thiourea and aromatic aldehydes proceeded to furnish a variety of substituted-phenyl-octahydro-pyrano[2,3-d]pyrimidin-2-(thi)ones or tetrahydropyri-midinone compounds. This is the first reported example in which styrenes other than 1,3-dicarbonyl compounds can participate in the Biginelli-type reaction.5, In the reaction system of Pd-TMSC1-CH3CN-DMF, the presented reaction provided one-pot condensation between aromatic ketones instead of 1,3-dicarbonyl compounds, urea/thiourea and aromatic aldehydes, thiourea exhibited analogical behaviors to urea under similar reaction conditions.Aldol condensation is one of the most useful reactions in organic chemistry. Bis(arylmethyllidene)cycloalkanones were a particularly interesting class of compounds which were used as precursors for the synthesis of bis(arylmethyllidene)cycloalkanones with bioactive pyrimidine derivatives and as intermediates to form compounds with particular qualities. In this paper we present a new approach to aldol condensation reactions where palladium catalyzed the cross and self aldol condensation reactions of varies ketones with varies aldehydes in the presence of TMSC1. The following reactions were investigated: (1) aromatic aldehydes with cycloalkanones, (2) aromatic aldehydes with aromatic ketones, (3) cycloalkanones with aliphatic aldehydes, and (4) the self-condensation reactions of aliphatic aldehydes and cycloalkanones.