Approach to cis-Phlegmarine Alkaloids via Stereodivergent Reduction: Total Synthesis of (+)-Serratezomine E and Putative Structure of (−)-Huperzine N

A unified strategy for the synthesis of the cisphlegmarine group of alkaloids is presented, leading to the first synthesis of serratezomine E (1) as well as the putative structure of huperzine N (2). A contrasteric hydrogenation method was developed based on the use of Wilkinson's catalyst, which allowed the facial selectivity of standard hydrogenation to be completely overturned. Calculations were performed to determine the mechanism, and structures for huperzines M and N are reassigned

Sugars in Space: A Quantum Chemical Study on the Barrierless Formation of Dihydroxyacetone in the Interstellar Medium

Among many theories on the life’s origins, regions between star systems in a galaxy is hypothesized to provide prebiotic material on Earth. Simple sugars, including glycolaldehyde, are confirmed to exist in interstellar medium (ISM) and can be intermediates in the formose reaction to form dihydroxyacetone or DHA. In the studied segment of the formose reaction, hydroxy carbene is sequentially added to formaldehyde, forming glycolaldehyde (hydroxyacetaldehyde) after the first addition and glycerone in the second. The proposed theoretical mechanism was validated through quantum chemical calculations. An exothermic and exergonic pathway favourable in ISM conditions was found, giving a possible explanation for glycerone formation. The products in question participates in biological processes like energy production, the phosphorylated form of glycerone, DHA-P, participates in glycolysis, and energy storage while glycerone is the source of the glycerine backbone in lipids. The studied reaction is a segment of the formose reaction and further polymerization can lead to pentose and hexose, which take part in the formation of RNA and DNA. Hence, this research explores the hypothesis of exogenous production and delivery of prebiotic material to Earth, building up to the conditions allowing the formation of rudimentary lifeforms.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Approach to cis-Phlegmarine Alkaloids via Stereodivergent Reduction: Total Synthesis of (+)-Serratezomine E and Putative Structure of (−)-Huperzine N

A unified strategy for the synthesis of the cisphlegmarine group of alkaloids is presented, leading to the first synthesis of serratezomine E (1) as well as the putative structure of huperzine N (2). A contrasteric hydrogenation method was developed based on the use of Wilkinson's catalyst, which allowed the facial selectivity of standard hydrogenation to be completely overturned. Calculations were performed to determine the mechanism, and structures for huperzines M and N are reassigned

Approach to cis-Phlegmarine Alkaloids via Stereodivergent Reduction: Total Synthesis of (+)-Serratezomine E and Putative Structure of (−)-Huperzine N

A unified strategy for the synthesis of the cisphlegmarine group of alkaloids is presented, leading to the first synthesis of serratezomine E (1) as well as the putative structure of huperzine N (2). A contrasteric hydrogenation method was developed based on the use of Wilkinson's catalyst, which allowed the facial selectivity of standard hydrogenation to be completely overturned. Calculations were performed to determine the mechanism, and structures for huperzines M and N are reassigned

N-Hydroxyphthalimide/benzoquinone-catalyzed chlorination of hydrocarbon C-H bond using N-chlorosuccinimide

The direct chlorination of C-H bonds has received considerable attention in recent years. In this work, a metal-free protocol for hydrocarbon C-H bond chlorination with commercially available N-chlorosuccinimide (NCS) catalyzed by N-hydroxyphthalimide (NHPI) with 2,3-dicyano-5,6-dichlorobenzoquinone (DDQ) functioning as an external radical initiator is presented. Aliphatic and benzylic substituents and also heteroaromatic ones were found to be well tolerated. Both the experiments and theoretical analysis indicate that the reaction goes through a process wherein NHPI functions as a catalyst rather than as an initiator. On the other hand, the hydrogen abstraction of the C-H bond conducted by a PINO species rather than the highly reactive N-centered radicals rationalizes the high chemoselectivity of the monochlorination obtained by this protocol as the latter is reactive towards the C(sp(3))-H bonds of the monochlorides. The present results could hold promise for further development of a nitroxy-radical system for the highly selective functionalization of the aliphatic and benzylic hydrocarbon C-H

Dimension Reduction in Conformational Analysis: A Two-Rotor Mathematical Model of Amino Acid Diamide Conformational Potential Energy Surface

The conformational potential energy surface (PES) of a molecule provides insights into the relative stability of the possible foldamers. However, the time and space complexity of electronic structure calculations, commonly used to generate PES, increases exponentially with an increasing number of atoms. The use of mathematical functions to model the topology of conformational PES is an alternative to more computer-intensive quantum chemical calculations, but the choice and complexity of functions used are crucial in achieving more accurate results. This paper presents a method to illustrate the topology of amino acid diamide PESs through a linear combination of a Fourier series and a mixture of Gaussian functions. Results yield a significantly small error, with an average RMSE of 4.9946 kJ路molThe accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author