Síntese do monastrol e novos compostos de Biginelli promovida por In(OTf)3

Abstract

Recebido em 5/10/04; aceito em 30/3/05; publicado na web em 10/8/05 SYNTHESIS OF MONASTROL AND OF NEW BIGINELLI COMPOUNDS PROMOTED BY In(OTf) 3 . In this paper, we describe a practical route for the synthesis of Biginelli compounds using In(OTf) 3 . To study the generality of this catalyst, several examples using aromatic aldehydes, 1,3-dicarbonyl compounds, urea, and thiourea were investigated. The present procedure provides an efficient modification of the classical Biginelli reaction, namely short reaction times and simple work-up, that not only preserves the simplicity of the original protocol but also produces excellent yields of 3,4-dihydropyridin-2(1H)-ones. Thiourea was used with similar success to provide the corresponding 3,4-dihydropyridin-2(1H)-thiones. In this case, the (+/-)-monastrol, antimitotic agent, was obtained in 92% yield and new thio analogues were synthesized.

N-Alkylated Sulfamic Acid Derivatives as Organocatalyst in Multicomponent Synthesis of Fatty Dihydropyrimidinones

“…IR, 1 H and 13 C NMR spectroscopies. 23,24 The results are showed in Table 2. The fatty-DHPM 1c was formed in good yields, with NSA 04 and NSA 01 catalysts showing the most relevant results ( Table 2, entries 2 and 5, respectively).…”

“…Initially, the Biginelli reaction was carried out reacting methyl acetoacetate, benzaldehyde and urea in the presence of 10 mol% of SA as pattern, under reflux of methanol. 23 The reaction was monitored by thin-layer chromatography (TLC) and the aldehyde consumption was observed after 4 h. In this case, the dihydropyrimidinone 1 was formed in 84% yield. The result is shown in Table 1 (entry 2).…”

“…After completion of the reaction, the mixture was evaporated under reduced pressure and the crude product was recrystallized from ethyl acetate to obtain pure fatty 3,4-dihydropyrimidin-2(1H)-one/thiones according to literature. 23,24…”

Synthesis, crystal structure and antibacterial studies of 2,4,6-trimetoxybenzaldehyde based dihydropyrimidine derivatives

“…[Hmim]HSO4-NaNO3 [62], TMSCl/CAN [63], GaI3 [64], CAN [65], Sm(ClO4)3 [66], La(OTf)3 [67], RuCl3 [68], HBF4-SiO2 [69], H3PMo12O40 [70], Sc(OTf)3 [71], MgCl2×6H2O [72], In(OTf)3 [73] and NH4Cl [16] did not lead to the desired effect. Only improving the [74] procedure by performing the reaction in the presence of Cu(OTf)2 in microwave conditions allowed us to obtain targeted dihydropyrimidine with 80% yield.…”

Tuning the Biginelli reaction mechanism by the ionic liquid effect: the combined role of supported heteropolyacid derivatives and acidic strength

“…40 This MCR (Scheme 1) allows the direct synthesis of bioactive DHMPs (3,4-dihydropyrimidin-2(1H)ones or -thiones) such as monastrol, piperastrol, and enastron. [41][42][43][44][45] HPAs and their derivatives have been previously used to promote the Biginelli reaction; however, in general, only moderate yields were achieved using organic solvents and no mechanistic elucidation was described. 46 The need for excess reagents and other drawbacks, such as organic solvent contamination, low yields, long reaction times and no mechanistic evaluation, were also noted.…”