Search for: All records

An experiment designed to teach principles of continuous flow technologies for photocatalysis is 10 described as a part of a two-week summer camp program for high school students. Students learned about green chemistry, photocatalysis, flow chemistry, and the role of 3–D printing for the design and production of custom millifluidic reactors. Students examined reactor designs which differed in terms of residence times and mixing capabilities. Such evaluation was based on the combination of blue and yellow dyes, followed by running a photocatalytic thiol-ene reaction on gram-scale. 

The aza Paternò–Büchi reaction is a [2+2]-cycloaddition reaction between imines and alkenes that produces azetidines, four-membered nitrogen-containing heterocycles. Currently, successful examples rely primarily on either intramolecular variants or cyclic imine equivalents. To unlock the full synthetic potential of aza Paternò–Büchi reactions, it is essential to extend the reaction to acyclic imine equivalents. Here, we report that matching of the frontier molecular orbital energies of alkenes with those of acyclic oximes enables visible light–mediated aza Paternò–Büchi reactions through triplet energy transfer catalysis. The utility of this reaction is further showcased in the synthesis ofepi-penaresidin B. Density functional theory computations reveal that a competition between the desired [2+2]-cycloaddition and alkene dimerization determines the success of the reaction. Frontier orbital energy matching between the reactive components lowers transition-state energy (ΔG^ǂ) values and ultimately promotes reactivity. 

Since the first reports of their isolation, the meroterpenoids cochlearol A and B have attracted interest from the synthetic community for their unique structural features. This review describes the attempted and successful total syntheses of these natural products and provides a summary of the strategies developed in the years since their isolation. 

Enantiodivergence is an important concept in asymmetric catalysis that enables access to both enantiomers of a product relying on the same chiral source as reagent. This strategy is particularly appealing as an alternate approach when only one enantiomer of the required chiral ligand is readily accessible but both enantiomers of the product are desired. Despite the potential significance, general catalytic methods to effectively reverse enantioselectivity by changing an achiral reaction parameter remain underdeveloped. Herein we report our studies focused on elucidating the origin of metal-controlled enantioselectivity reversal in Lewis acid-catalysed Michael additions. Rigorous experimental and computational investigations reveal that specific Lewis and Brønsted acid interactions between the substrate and ligand change depending on the ionic radius of the metal catalyst, and are key factors responsible for the observed enantiodivergence. This holds potential to further our understanding of and facilitate the design of future enantiodivergent transformations. 

The design of concise and efficient synthetic strategies to access naturally occurring, pharmaceutically active complex molecules is of utmost importance in current chemistry. It not only enables rapid access to these molecules and their analogues but also provides sufficient quantities for their biological evaluation. Identification of any symmetric or pseudosymmetric synthetic intermediates upon retrosynthetic bond disconnection of the target molecule holds the promise to significantly streamline the route towards the compound of interest. This review will highlight recent examples of successful natural product syntheses reported within the past five years that benefited from the recognition of symmetry elements during the retrosynthetic design.