Organocatalytic Asymmetric Construction of Spirooxazines via Chemoselective Cascade Addition of -Substituted Hydroxylamine with Keto-bis-enone.

Spirooxazines represent a privileged heterocyclic scaffold having pronounced biological importance. Herein, we introduce a chiral bifunctional squaramide catalyzed highly chemoselective cascade reaction involving aza-Michael/1,2-addition/oxa-Michael addition of -substituted hydroxylamine with keto-bis-enones. This strategy enables the synthesis of highly enantioenriched oxa-spirooxazines with a broad substrate tolerance.

Nanostructured lipopeptide-based membranomimetics for stabilizing bacteriorhodopsin.

Nanostructured 7-9-residue cyclic and unstructured lipopeptide-based facial detergents have been engineered to stabilize the model integral membrane protein, bacteriorhodopsin. Formation of a cylindrical-type micelle assembly induced by facial amphipathic lipopeptides resembles a biological membrane more effectively than conventional micelles. The hydrophobic face of this cylindrical-type micelle provides extended stability to the membrane protein and the hydrophilic surface interacts with an aqueous environment.

Stereodivergent Synthesis of Spiroaminals via Chiral Bifunctional Hydrogen Bonding Organocatalysis.

Spiroaminals represent novel structural motifs prevalent in diverse natural products and biologically active molecules. Achieving their enantioselective synthesis is a highly desirable and challenging task in synthetic endeavors due to their intricate molecular frameworks. Herein, we accomplished the first stereodivergent construction of spiroaminals using chiral bifunctional organocatalyzed intramolecular 1,2-addition followed by an oxa-Michael addition cascade in a high atom and step economical pathway.

Enantioselective Synthesis of 1,3-Benzothiazine Derivatives: An Organocatalytic Chemoselective Approach.

Herein, a highly chemoselective 1,2-addition of thiols with 2-isothiocyanatochalcones followed by an enantioselective intramolecular thia-Michael addition cascade has been established to construct enantioenriched [1,3]-benzothiazine derivatives for the first time. The cinchona-derived squaramide catalyst provides good to excellent yield and enantioselectivity of the products with broad substrate adaptability. Furthermore, this strategy has been extended to the diphenylphosphine oxide nucleophile to access enantioenriched organophosphorus-substituted [1,3]-benzothazines.

Anger is red, sadness is blue: Emotion depictions in abstract visual art by artists and non-artists.

Through the manipulation of color and form, visual abstract art is often used to convey feelings and emotions. Here, we explored how colors and lines are used to express basic emotions and whether non-artists express emotions through art in similar ways as trained artists. Both artists and non-artists created abstract color drawings and line drawings depicting six emotions (i.