The mechanism of the proline-catalyzed aldol reaction has stimulated considerable debate, and despite limited experimental data, at least five different mechanisms have been proposed. Complementary to recent theoretical studies we have initiated an experimental program with the goal of clarifying some of the basic mechanistic questions concerning the proline-catalyzed aldol reaction. Here we su...

nano-graphene oxide was synthesized by the oxidation of graphite powders. the structural nature of the nano-graphene oxide was characterized by a variety of techniques including xrd, tem, ft-ir and uv/vis. the functional groups on its basal planes and edges of nano-grahene oxide play important role in catalytic activity. the catalytic activity of nano-graphene oxide was investigated on crossed-...

Axially chiral 5-methyl-2-(o-aryl)imino-3-(o-aryl)-thiazolidine-4-ones have been subjected to aldol reactions with benzaldehyde to produce secondary carbinols which have been found to be separable by HPLC on a chiral stationary phase. Based on the reaction done on a single enantiomer resolved via a chromatographic separation from a racemic mixture of 5-methyl-2-(α-naphthyl)imino-3-(α-naphthyl)-...

Nanotubes formed by the aqueous assembly of a proline-lysine dipeptide (1) were used to create the hydrophobic microenvironments required to catalyze the aldol reaction in water. The self-assembly process occurred most efficiently in the presence of the substrates, producing an array of homogeneous nanotubes under the reaction conditions. The nanotubes formed by dipeptide 1 served as an efficie...

A new method for enolate generation via the gold-catalyzed addition of boronic acids to alkynes is reported. The formation of boron enolates from readily accessible ortho-alkynylbenzeneboronic acids proceeds rapidly with 2 mol % PPh(3)AuNTf(2) at ambient temperature. The enolates undergo aldol reaction with an aldehyde present in the reaction mixture to give cyclic boronate esters, which can be...

In a synthetic approach to the completely protected C1-C12 fragment of the macrocyclic cytotoxic agent tedanolide 1, we carried out the tin-catalyzed Mukaiyama aldol reaction between the 2,3-dialkoxypropanal 5 and the silyl enol ether 6 derived from the ketone 7, which gave, unexpectedly, the anti aldol isomer, rather than the expected syn isomer 4, as the major diastereomer formed.

The report by List, Lerner, and Barbas1 in 2000 of an intermolecular direct aldol reaction catalyzed by proline became an unexpected watershed for the field of organocatalysis.2-4 Pihko and co-workers4b,c were the first to observe significantly higher yields with addition of water to intermolecular aldol reactions, even allowing employment of stoichiometric substrate ratios in some cases. This ...

Simple and effective multi-component one-pot aldol addition/protection reactions of β-ketoesters to a series of aldehydes in the presence Me(3)SiCl and i-Pr(2)EtN have been described. The analysis of the scope of the reaction revealed a dramatic dependence of the reactivity on the substrates used. Thus the effect of a catalytic amount of DMF and different reaction conditions was widely investig...

The synthesis of the marine neurotoxin azaspiracid-1 has been accomplished. The individual fragments were synthesized by catalytic enantioselective processes: A hetero-Diels-Alder reaction to afford the E- and HI-ring fragments, a carbonyl-ene reaction to furnish the CD-ring fragment, and a Mukaiyama aldol reaction to deliver the FG-ring fragment. The subsequent fragment couplings were accompli...

Mukaiyama aldol reactions in aqueous media have been surveyed. While the original Mukaiyama aldol reactions entailed stoichiometric use of Lewis acids in organic solvents under strictly anhydrous conditions, Mukaiyama aldol reactions in aqueous media are not only suitable for green sustainable chemistry but are found to produce singular phenomena. These findings led to the discovery of a series...