Szymon Buda

A catalytic enantioselective intramolecular Rauhut-Currier (IRC) reaction has been developed by using a combination of lithium selenolates and a catalytic amount (10 mol %) of an enantiopure BINOL ligand. The study focused particularly on evaluating the influence of BINOL ligands on the reaction's outcome. The reaction conditions were optimized to achieve good yields and enantioselectivities. Screening of lithium organoselenolates identified phenyl lithium selenolate (PhSeLi) as the most efficient nucleophile. A variety of bis-α,β-unsaturated compounds were successfully cyclized under these conditions, demonstrating the broad applicability of the method. Detailed studies revealed the crucial role of water in the reaction and the importance of hydrogen bonding and Bro̷nsted acid catalysis in achieving asymmetric induction.

Simple and efficient carbasugar synthesis from d-aldopentoses via temporary protection of the hydroxyl moieties with TMS groups followed by consecutive intramolecular tandem Michael/aldol cyclisation.

We demonstrate that enantiopreference in the binding of S,S over R,R astaxanthin (AXT) to albumin manifests itself only for racemic (but not enantiopure) carotenoids. The observed enantioselectivity is rationalized using chiroptical spectroscopies supported by molecular docking, molecular dynamics and quantum-chemical calculations. These methods offer a plausible explanation for the observed enantiopreference, as they reveal a unique binding mode of the (3S,3′S)-AXT form with the protein in contrast to multiple (random) possibilities for albumin binding with the (3R,3′R)-AXT, and also a higher interaction energy of the latter enantiomer with the protein.

In this paper, we present the first example of using a catalytic amount of a nucleophilic seleno-organic catalyst in a tandem seleno-Michael/Michael reaction, leading to the formation of 2H/4H-chromenes. Chromenes represent a highly significant group of oxygen-containing heterocycles commonly found as structural scaffolds in a diverse range of fields such as medicinal chemistry, pharmaceutical agents, drug candidates, synthetic chemistry, and materials chemistry. Various preparation methods have been developed, utilizing different substrates in conjunction with metal catalysts, organocatalysts, Brønsted acids, bases, or Lewis acids. The synthetic utility of lithium selenolates has been demonstrated as efficient nucleophilic catalysts in the Rauhut-Currier cyclization of chalcone derivatives. This methodology allows for the synthesis of 2H- and 4H-chromenes depending on the substituents directly connected to the carbonyl group. The investigation focuses on the impact of various substituents in the aromatic fragment as well as conditions and selenolates. The scope of different starting materials was also considered.

This work reports the new method of Rauhut-Currier reaction (RC) with the use of lithium selenolates, which provided up to 80% yield in a non-asymmetric IRC reaction. Therefore, our paper involves the search for an efficient chiral additive in the asymmetric version. The influence of various reaction parameters, such as solvent, additives, temperature, and time, was examined. The results for the non-asymmetric version were significantly higher with the presence of water, but surprisingly different observations were obtained in the asymmetric version. Here, the chiral scandium complex with tertiary amine played an important role. The reaction carried out in the presence of chiral complexes gave the expected product with up to 60% yield and up to 70% ee.

The fluorescent 5-arylidene derivative of 1,3-dimethylbarbituric acid as a heterodiene reacted with vinyl thioether equipped with a taxol. The cycloadditions rate constants k₂ were estimated to be in the range from 0.9 × 10⁻² M⁻¹ s⁻¹ to 1.4 M⁻¹ s⁻¹.

Carbasugars are a wide group of carbohydrate mimetics in which the ring oxygen is replaced by a methylene group. The high importance of these compounds is related to their interesting biological and pharmacological properties which are the matter of current studies. In our work, a concise synthesis of carbasugars from naturally occurring D-pentoses is presented. The one-pot seleno-Michael reaction connected with intramolecular aldol reaction is a key step of the carbasugar core asymmetric synthesis. Further transformation of obtained carbasugar moiety led to different bioactive compounds. Tandem seleno-Michael reaction conjugated with oxidation/elimination step of in situ generated nucleophile was described a few years ago in the intermolecular variant. In our work, we present the first example of this reaction in an intramolecular way which leads to a previously inaccessible cyclic product of Morita–Baylis–Hillman reaction. Conducted experiments allowed us to obtain cyclic products with high yields and good diastereoisomeric excesses.