Chiral thiazolidines in the enantioselective ethylation of aldehydes: An experimental and computational study

Tavares, Nélia C.T.; Neves, César T.; Milne, Bruce F.; Murtinho, Dina; Pais, Alberto A. C. C.; Serra, M. Elisa Silva

doi:10.1016/j.jorganchem.2018.09.027

Cited by 2 publications

(1 citation statement)

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“…Asymmetric catalysis is another broadly studied branch in organic synthesis. Developing catalysts that are capable of transforming prochiral substrates into the desired enantiomer, with satisfactory enantiomeric excess and efficiency, is thus of great interest in organic synthesis, as well as industrial sectors that take the most advantage of chiral properties of molecules, such as cosmetics, care products, perfume or pharmaceutical industries [ 184 ].…”

Section: Cof Applicationsmentioning

confidence: 99%

Covalent Organic Frameworks: Synthesis, Properties and Applications—An Overview

et al. 2021

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Covalent Organic Frameworks (COFs) are an exciting new class of microporous polymers with unprecedented properties in organic material chemistry. They are generally built from rigid, geometrically defined organic building blocks resulting in robust, covalently bonded crystalline networks that extend in two or three dimensions. By strategically combining monomers with specific structures and properties, synthesized COF materials can be fine-tuned and controlled at the atomic level, with unparalleled precision on intrapore chemical environment; moreover, the unusually high pore accessibility allows for easy post-synthetic pore wall modification after the COF is synthesized. Overall, COFs combine high, permanent porosity and surface area with high thermal and chemical stability, crystallinity and customizability, making them ideal candidates for a myriad of promising new solutions in a vast number of scientific fields, with widely varying applications such as gas adsorption and storage, pollutant removal, degradation and separation, advanced filtration, heterogeneous catalysis, chemical sensing, biomedical applications, energy storage and production and a vast array of optoelectronic solutions. This review attempts to give a brief insight on COF history, the overall strategies and techniques for rational COF synthesis and post-synthetic functionalization, as well as a glance at the exponentially growing field of COF research, summarizing their main properties and introducing the numerous technological and industrial state of the art applications, with noteworthy examples found in the literature.

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Section: Cof Applicationsmentioning

confidence: 99%

Covalent Organic Frameworks: Synthesis, Properties and Applications—An Overview

et al. 2021

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Deciphering the mechanism behind efficient enantioselective ethylation with thiazolidine‐based amino alcohols

Tavares

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Costa

et al. 2021

Applied Organom Chemis

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Taking advantage of the opposite chirality of two privileged starting materials, l‐cysteine and d‐penicillamine, a wide range of thiazolidine‐based amino alcohols was synthesized. l‐Cysteine derivatives were more efficient chiral inductors than the d‐penicillamine ones, with ee up to 92% in the enantioselective ethylation of benzaldehyde. The scope of the best catalyst was evaluated using several aromatic, heteroaromatic, and aliphatic aldehydes, providing excellent (S)‐enantioselectivities. Given the opposite chirality of the l‐cysteine and d‐penicillamine thiazolidines, it was expected that the use of one or the other type of derivative as ligand would allow the formation of opposite configurations of the alkylated product. However, whereas the l‐cysteine thiazolidines predominantly gave the (S) form of the alkylated product, the d‐penicillamine ones led to both configurations. The significant difference in the stereochemical outcome of this reaction when catalyzed by the two types of ligands prompted us to investigate the reasons behind such results. Extensive quantum chemical calculations were performed in order to identify the transition state structures by which the enantioselective ethylation of benzaldehyde in the presence of these type of amino alcohols can proceed. An alternative path for the rate‐determining step was also explored and found decisive for the rationalization of the experimental outcomes. It was observed that the type of ligand dictates the accessible reaction paths for the formation of the chiral product, which ultimately determine the balance between the two possible configurations.

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Chiral thiazolidines in the enantioselective ethylation of aldehydes: An experimental and computational study

Cited by 2 publications

References 51 publications

Covalent Organic Frameworks: Synthesis, Properties and Applications—An Overview

Covalent Organic Frameworks: Synthesis, Properties and Applications—An Overview

Deciphering the mechanism behind efficient enantioselective ethylation with thiazolidine‐based amino alcohols

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