l-Prolinamides 2, prepared from l-proline and simple aliphatic and aromatic amines, have been found to be active catalysts for the direct aldol reaction of 4-nitrobenzaldehyde with neat acetone at room temperature. They give moderate enantioselectivities of up to 46% enantiomeric excess (ee). The enantioselectivity increases as the amide N-H becomes a better hydrogen bond donor. l-Prolinamides ...

Structure, and consequently properties, of ionic liquids can be easily tailored by changing cation/anion combinations and/or attaching functional groups. By grafting enantiopure moieties to the framework liquid it is possible prepare bioinspired chiral molecules that serve as a reaction medium, additive or even asymmetric catalyst. In this context, new (CILs), based on biomolecules, such aminoa...

This paper gives a review of research work in the synthesis of higher alcohols over catalysts based on Cu/ZnO/Al,O,, emphasizing three main topics: (i) the effect on selectivity of the addition of several compounds to this catalyst, (ii) the effect on selectivity of the reaction conditions used, and (iii) the reaction network leading to the different products found. Although the use of aLkali c...

An efficient formal synthesis of (-)-englerin A (1) is reported. The target molecule is a recently isolated guaiane sesquiterpene that possesses highly potent and selective activity against renal cancer cell-lines. Our enantioselective strategy involved the construction of the BC ring system of compound 1 through a Rh(II)-catalyzed [4+3] cycloaddition reaction followed by subsequent attachment ...

The glyceraldehyde conversion in terms of dehydration, keto-enol tautomerism, and retro-aldol reaction has been discussed by means of ab initio density functional theory calculation to elucidate the catalytic water molecule influence on the pathways. The optimized structures of reactants, products, and transition state structure on the glyceraldehyde conversion pathways were fully optimized wit...

High oxidation-state carbonyl coupling partners including esters and lactones were reacted with enones to give aldol-type products directly using two-fold organoborane catalysis. This new retrosynthetic disconnection is compatible enolisable partners, without self-condensation, couples the high reactivity of secondary dialkylboranes stability pinacolboronic esters. Excellent chemoselectivity, s...

Chalcones 1~8 and 5-deoxyflavonoids 9~22 were synthesized in good yields by aldol condensation, Algar-Flynn-Oyamada reaction, glycosidation, and deacetylation reaction, respectively, starting from 2-acetyl phenols substituted by methoxy or methoxymethoxy group and appropriately benzaldehydes substituted by methoxy, methoxymethoxy group, or chlorine. Among them, 13 and 17~22 are new compounds. T...

Extensive NMR investigation of the compounds revealed a complex spiroketal core capped at one end by a tetrasubstituted g-pyrone, residing in an anomerically favored configuration wherein all but the substituents are positioned equatorially except for the C10 methyl and the C11 acyloxy groups. Auripyrones A (1) and B (2) showed cytotoxicity against HeLa S3 cells with IC50 values of 260 and 480 ...

Five quaternary ammonium ionic liquid (IL) and two tetrabutylphosphonium ILs were prepared and characterized. An environmentally benign and convenient functionalized ionic liquid catalytic system was thus explored in the aldol condensation reactions of aromatic aldehydes with acetone. The aldol reactions proceeded more efficiently through microwave-assisted heating than through conventional the...

The first examples of the directed, boron-mediated aldol reaction between different ketones are presented. Transformation of a variety of ketones to their corresponding boron enolates with Chx2BCl/Et3N, followed by reaction with acceptor ketones in diethyl ether, and oxidation of the resultant boron aldolate (H2O2, MeOH/pH 7 buffer), provided the aldol addition products. The reaction was most f...