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.
View Article and Find Full Text PDFHerein, we disclose a fascinating highly stereoselective P(NMe) mediated intramolecular deoxygenative umpolung cascade Michael addition-initiated cyclopropanation with a diverse substrate adaptability. This methodology creates a new horizon for expedient access to valuable 6,5,3-fused scaffolds having an all-carbon quaternary stereocenter via Kukhtin-Ramirez (K-R) adduct formation, with excellent diastereoselectivity and yields under metal-free ambient conditions. A few functional group transformations have also been performed successfully.
View Article and Find Full Text PDFHerein we report an efficient stereoselective umpolung 1,2-addition of EtZn onto α-diketones followed by intramolecular cascade Michael cyclization. This strategy effectively delivers a broad range of substituted 1-indanones in excellent yields in a chemo- and regioselective fashion. Additionally, we performed a variety of synthetic transformations on the 1-indanone products.
View Article and Find Full Text PDFAn enantioselective synthesis of Rauhut-Currier (RC) adducts from 3-aryl cyclohexenone with a tethered enone moiety at the ortho-position on the aryl group is accomplished. This method provides a wide range of valuable synthetic building blocks having a unique [6-5-6] all-carbon-fused tricyclic skeleton. A primary amine-containing thiourea, a bifunctional organocatalyst, was found to be an efficient catalyst for this transformation.
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