Utilization of Nonionic Bases in Water as a Highly Efficient Organocatalytic System for Michael Addition of β‐Ketoesters

Gas-phase proton affinities of guanidines with heteroalkyl side chains

“…Besides of being a building block of several biomolecules such as arginine, creatine phosphate, and purines [1], the guanidine subunit plays a significant role in the synthesis of a number of drugs [2]. Due to their high intrinsic basicities, guanidine derivatives are also used as powerful non-ionic organic bases or basic catalysts [3][4][5][6] in a number of organic reactions, to mention only the transesterification of vegetable oils [7][8][9][10], which is a key-step in the production of Biodiesel ® . Substituted guanidine salts are also successfully applied as the ionic liquids in modern chemistry approaches [11,12].…”

Lewis Acid Catalyzed Conjugate Addition and the Formation of Heterocycles using Michael Acceptors under Solvent‐Free Conditions

“…The mechanism for the addition of metal enolates to Michael acceptors has been investigated by several authors 6,8,21b. It has been suggested that metal enolates of β‐dicarbonyl compounds of the general structure I (Figure 3), formed in situ, are the actual nucleophilic species 6.…”

“…Therefore, the catalysis by transition metals or lanthanides, which work under neutral and mild conditions, has attracted the attention of the chemical community 3,4. Conjugate addition of β‐dicarbonyl compounds, especially β‐keto esters, to several acceptors catalyzed by LiI,2 zeolite,5 non‐ionic bases such as phosphazenes and guanidines,6 indium metal/TMSCl,7 some copper and nickel compounds,8–10 Yb(OTf) 3 in H 2 O11 or silica gel support,12 clay‐supported NiCl 2 /FeCl 3 13 and Lewis acid/surfactant systems14 have been reported. As a consequence of the ever‐increasing demand for optically active compounds, asymmetric versions have also been investigated using either chiral complexes of metal cations or organo‐catalysts 15,16…”

Non‐Biaryl Atropisomers in Organocatalysis

“…The spectroscopic data were in agreement with the literature. [55] General procedure for the a-fluorination of a-branched aldehydes 24:…”