The mechansim of the three-component Biginelli dihydropyrimidine synthesis was reinvestigated using (1)H and (13)C NMR spectroscopy. Condensation of benzaldehyde, ethyl acetoacetate, and urea (or N-methylurea) in CD(3)OH according to the procedure described by Biginelli produced the expected 6-methyl-2-oxo-4-phenyl-1,2,3,4-tetrahydropyrimidine-5-carboxylates. According to NMR measurements, ther...

Although aldol condensation is one of the most important organic reactions, capable of forming new C-C bonds, its mechanism has never been fully established. We now conclude that the rate-limiting step in the base-catalyzed aldol condensation of benzaldehydes with acetophenones, to produce chalcones, is the final loss of hydroxide and formation of the C═C bond. This conclusion is based on a stu...

The enantioselective total synthesis of pironetin has been achieved in 11 steps from known aldehyde 2. The synthesis relies on the formation of 5 out of 6 stereocenters through titanium mediated iterative aldol reactions. Key steps in this synthesis include an acetal aldol reaction to establish the stereochemistry at C8 and C9, an acetate aldol reaction, and "Evans" syn aldol reaction.

Thioamides are the preferred pronucleophiles for direct catalytic asymmetric aldol reactions in the context of soft Lewis acid/hard Brønsted base cooperative catalysis. In-depth investigation of this proton-transfer catalysis, which is virtually in equilibrium, revealed that the prominence of the retro-aldol reaction depended on the substrate combination. The retro-aldol reaction is a serious i...

2-ethylhexanal is synthesized directly from crotonaldehyde over a bifunctional acidic resin-supported palladium catalyst via hydrogenation and aldol condensation in supercritical CO2.

chromanone derivatives demonstrate remarkable cytotoxity against a varieties of cancer cell lines. novel 9-[hydroxy(substitutedphenyl)methyl]-2,2-dimethyl-2,3,8,9- tetrahydro-4h,10h-pyrano[2,3-f]chromene-4,10-diones as glyasperin analogues were synthesized in four steps from known 4-chromone 1. the key step was the preparation of chromane dione 5a by regioselective intramolecular cyclization re...

Key words (+)-bufogargarizin B - [5+2] cycloaddition Mukaiyama hydration retro-aldol-aldol reaction Suzuki–Miyaura coupling

Potassium modified acid–base bifunctionalized MgAl-SBA-15 for mild aldol condensation of furfural and acetone to high-quality jet-fuel range or chemical intermediates.