(1,2-Diaminoethane-1,2-diyl)bis(N-methylpyridinium) Salts as a Prospective Platform for Designing Recyclable Prolinamide-Based Organocatalysts

Tripeptide-Catalyzed Asymmetric Aldol Reaction Between α-ketoesters and Acetone Under Acidic Cocatalyst-Free Conditions

Here, we report the tripeptide-catalyzed asymmetric aldol reaction between α-ketoesters and acetone under acidic cocatalysts-free conditions. H-Pro-Tle-Gly-OH 3g-catalyzed reactions between α-ketoesters and acetone resulted in up to 95% yield and 88% ee. Analysis of the transition state using density functional theory (DFT) calculations revealed that the tert-butyl group in 3g played an important role in enantioselectivity.

Сhiral and Racemic Fields Concept for Understanding of the Homochirality Origin, Asymmetric Catalysis, Chiral Superstructure Formation from Achiral Molecules, and B-Z DNA Conformational Transition

The four most important and well-studied phenomena of mirror symmetry breaking of molecules were analyzed for the first time in terms of available common features and regularities. Mirror symmetry breaking of the primary origin of biological homochirality requires the involvement of an external chiral inductor (environmental chirality). All reviewed mirror symmetry breaking phenomena were considered from that standpoint. A concept of chiral and racemic fields was highly helpful in this analysis. A chiral gravitational field in combination with a static magnetic field (Earth’s environmental conditions) may be regarded as a hypothetical long-term chiral inductor. Experimental evidences suggest a possible effect of the environmental chiral inductor as a chiral trigger on the mirror symmetry breaking effect. Also, this effect explains a conformational transition of the right-handed double DNA helix to the left-handed double DNA helix (B-Z DNA transition) as possible DNA damage.

Probing the Synergistic Catalytic Model: A Rationally Designed Urea-Tagged Proline Catalyst for the Direct Asymmetric Aldol Reaction

A urea tag was incorporated at the C-4 position of proline, cis to its COOH group, in order to explore the prospect of a synergistic effect between the two functional groups in the transition state of the enamine route to the asymmetric aldol reaction. The catalyst proved to be an excellent performer, delivering aldols in high yields and with excellent enantio- and diastereoselectivities using just 2 mol % loading in the presence of water; it also exhibited good levels of recyclability under aqueous conditions. The favorable results reveal the interesting possibility of an intramolecular host-guest interaction between the urea and the amino acid moieties, exerting a beneficial effect on catalysis. The concept could certainly offer a new direction toward more efficient catalyst design.

Catalytic enantioselective aldol reactions

Recent developments in catalytic asymmetric aldol reactions have been summarized.

Stereospecific diaza-Cope rearrangement as an efficient tool for the synthesis of DPEDA pyridine analogs and related C2-symmetric organocatalysts

Enantiomerically pure trans-1,2-di-(pyridinyl)ethylene-1,2-diamines were synthesized via a stereospecific diaza-Cope rearrangement and converted to prolinamide-based recyclable organocatalysts.

C 2-Symmetric pyrrolidine-derived squaramides as recyclable organocatalysts for asymmetric Michael reactions

Novel sustainable organocatalysts applicable to asymmetric synthesis of active pharmaceutical ingredients are developed.