Facile catalyst-free pseudo five-component domino reactions in the expedient synthesis of 5-aroyl-1,3-diarylhexahydropyrimidines

A catalyst-free multicomponent domino sequence for the diastereoselective synthesis of (E)-3-[2-arylcarbonyl-3-(arylamino)allyl]chromen-4-ones

“…It is noteworthy, that a similar reaction, in which the less hindered, more reactive formaldehyde was employed as the aldehyde component, took a completely divergent course and afforded 5-arylcarbonyl-1,3-diarylhexahydropyrimidines arising from pseudo five-component reactions of ( E )-3-(dimethylamino)-1-arylprop-2-en-1-ones, two molecules of formaldehyde and two molecules of aniline [55]. …”

“…All the subsequent reactions of 3-formylchromone ( 1 ), ( E )-3-(dimethylamino)-1-arylprop-2-en-1-ones 2 and substituted anilines 3 were performed under the optimal conditions (equimolecular amounts, DMF at 130 °C) and were completed in 6–7 h. After completion of the reaction, removal of the solvent and purification of the residue by column chromatography, ( E )-3-[2-arylcarbonyl-3-(arylamino)allyl]-4 H -chromen-4-ones 5 were obtained in pure form in 78–94% yields ( Scheme 2 and Table 2 ). It is noteworthy, that a similar reaction, in which the less hindered, more reactive formaldehyde was employed as the aldehyde component, took a completely divergent course and afforded 5-arylcarbonyl-1,3-diarylhexahydropyrimidines arising from pseudo five-component reactions of ( E )-3-(dimethylamino)-1-arylprop-2-en-1-ones, two molecules of formaldehyde and two molecules of aniline [ 55 ].…”

“…General procedure for the synthesis of ( E )-3-(2-arylcarbonyl-3-(arylamino)allyl)-4 H -chromen-4-one derivatives 5a–5p . In a similar manner as described in [ 55 ], a mixture of 3-formylchromone ( 1 , 1 mmol), enaminone 2 (1 mmol) and aniline 3 (1 mmol) in DMF (5 mL) was heated at 130 °C for 6–7 h. The reaction progress was monitored by TLC. After completion of the reaction, the solvent was removed and the product was purified by column chromatography with a petroleum ether–ethyl acetate mixture (4:1 v/v) as an eluent to afford compounds 5 .…”

Domino Reactions Based on Combinatorial Bond Transformations in Electron-Deficient Tertiary Enamines

“…Beside the efforts made by us, it should be noted that new methods involving the partial cleavage of the tertiary enaminones were also known in literature reported by other groups. Perumal et al39 developed the multicomponent reaction of tertiary enaminones 1 , primary amines 2 , and formaldehyde 75 , which yielded fully hydrogenated pyrimidines 76 wherein the C=C double bond of the enaminones had been reduced by the excess amount of formaldehyde (Eq. 1 in Scheme ).…”

An eco-friendly three-component regio- and stereoselective synthesis of highly functionalized dihydroindeno[1,2-b]pyrroles under grinding

“…14,15 β-Enaminones are readily accessible versatile synthons and their chemistry has received considerable attention in recent years. 16,17 Enaminones and related compounds with the basic structural unit N-C(3)vC( 2)-Z possessing a nitrogen functionality and an electron-withdrawing group Z (= COAr, CO 2 R, CN, etc.) on adjacent alkene carbons display both the nucleophilicity of enamines and the electrophilicity of enones (Fig.…”