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1. The expanding world of biosynthetic pericyclases: cooperation of experiment and theory for discovery

   https://doi.org/10.1039/C8NP00075A  

   Jamieson, Cooper S.; Ohashi, Masao; Liu, Fang; Tang, Yi; Houk, K. N. (May 2019, Natural Product Reports)

   Covering: 2000 to 2018 Pericyclic reactions are a distinct class of reactions that have wide synthetic utility. Before the recent discoveries described in this review, enzyme-catalyzed pericyclic reactions were not widely known to be involved in biosynthesis. This situation is changing rapidly. We define the scope of pericyclic reactions, give a historical account of their discoveries as biosynthetic reactions, and provide evidence that there are many enzymes in nature that catalyze pericyclic reactions. These enzymes, the “pericyclases,” are the subject of this review. 

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2. Hydrogenation reactions of carbon on Earth: Linking methane, margarine, and life

   https://doi.org/10.2138/am-2020-6928CCBYNCND  

   McGlynn, Shawn E.; Glass, Jennifer B.; Johnson-Finn, Kristin; Klein, Frieder; Sanden, Sebastian A.; Schrenk, Matthew O.; Ueno, Yuichiro; Vitale-Brovarone, Alberto (May 2020, American Mineralogist)

   Abstract Hydrogenation reactions are a major route of electron and proton flow on Earth. Interfacing geology and organic chemistry, hydrogenations occupy pivotal points in the Earth’s global geochemical cycles. Some examples of hydrogenation reactions on Earth today include the production and consumption of methane in both abiotic and biotic reactions, the reduction of protons in hydrothermal settings, and the biological synthesis and degradation of fatty acids. Hydrogenation reactions were likely important for prebiotic chemistry on the early Earth, and today serve as one of the fundamental reaction classes that enable cellular life to construct biomolecules. An understanding and awareness of hydrogenation reactions is helpful for comprehending the larger web of molecular and material inter-conversions on our planet. In this brief review we detail some important hydrogenation and dehydrogenation reactions as they relate to geology, biology, industry, and atmospheric chemistry. Such reactions have implications ranging from the suite of reactions on early Earth to industrial applications like the production of hydrocarbon fuel. 

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3. Four Complications in Designing a Validated Survey to Gather Information on Student Reactions to Reflection Activities

   Mejia, K.; Turns, J.; Roldan, W. (January 2020, ASEE Conference Proceedings)

   Reflection and reflection activities are potentially valuable components of the instructional experiences educators design in order to support student learning. Published scholarship contains many allusions to students having reactions to reflection activities, but the nature of these reactions are rarely engaged in depth. In this work, we focus on four complications we have encountered while developing a survey to explore student reactions to reflection activities: complex reactions within a single student, complex patterns of reactions between students, students being differentially aware of their reactions to reflection, and students experiencing the reaction survey as a reflection activity itself. Additionally, we discuss potential implications of these complications for educators and researchers. 

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4. Predicting the stereoselectivity of chemical reactions by composite machine learning method

   https://doi.org/10.1038/s41598-024-62158-0  

   Chung, Jihoon; Li, Justin; Saimon, Amirul_Islam; Hong, Pengyu; Kong, Zhenyu (May 2024, Scientific Reports)

   Abstract Stereoselective reactions have played a vital role in the emergence of life, evolution, human biology, and medicine. However, for a long time, most industrial and academic efforts followed a trial-and-error approach for asymmetric synthesis in stereoselective reactions. In addition, most previous studies have been qualitatively focused on the influence of steric and electronic effects on stereoselective reactions. Therefore, quantitatively understanding the stereoselectivity of a given chemical reaction is extremely difficult. As proof of principle, this paper develops a novel composite machine learning method for quantitatively predicting the enantioselectivity representing the degree to which one enantiomer is preferentially produced from the reactions. Specifically, machine learning methods that are widely used in data analytics, including Random Forest, Support Vector Regression, and LASSO, are utilized. In addition, the Bayesian optimization and permutation importance tests are provided for an in-depth understanding of reactions and accurate prediction. Finally, the proposed composite method approximates the key features of the available reactions by using Gaussian mixture models, which provide suitable machine learning methods for new reactions. The case studies using the real stereoselective reactions show that the proposed method is effective and provides a solid foundation for further application to other chemical reactions. 

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5. Transition-Metal-Catalyzed Alkyl Heck-Type Reactions

   https://doi.org/10.1055/s-0037-1611659  

   Kurandina, Daria; Chuentragool, Padon; Gevorgyan, Vladimir (February 2019, Synthesis)

   The Heck reaction is one of the most reliable and useful strategies for the construction of C–C bonds in organic synthesis. However, in contrast to the well-established aryl Heck reaction, the analogous reaction employing alkyl electrophiles is much less developed. Significant progress in this area was recently achieved by merging radical-mediated and transition-metal-catalyzed approaches. This review summarizes the advances in alkyl Heck-type reactions from its discovery early in the 1970s up until the end of 2018. 1 Introduction 2 Pd-Catalyzed Heck-Type Reactions 2.1 Benzylic Electrophiles 2.2 α-Carbonyl Alkyl Halides 2.3 Fluoroalkyl Halides 2.4 α-Functionalized Alkyl Halides 2.5 Unactivated Alkyl Electrophiles 3 Ni-Catalyzed Heck-Type Reactions 3.1 Benzylic Electrophiles 3.2 α-Carbonyl Alkyl Halides 3.3 Unactivated Alkyl Halides 4 Co-Catalyzed Heck-Type Reactions 5 Cu-Catalyzed Heck-Type Reactions 6 Other Metals in Heck-Type Reactions 7 Conclusion 

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