The chalcones derived from -alkynylacetophenones and aromatic aldehydes (yne-enones) when heated under reflux with iodine in acetic acid gave a range of benzo[]fluorenone derivatives in moderate to good yields. The transformation involves the formation of a vinyl indenone intermediate through regioselective alkyne hydration and intramolecular aldol condensation followed by electrocyclic ring closure and aromatization.
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http://dx.doi.org/10.1039/c9ra02376c | DOI Listing |
Chem Commun (Camb)
January 2025
College of Pharmaceutical Sciences, Ritsumeikan University, Kusatsu 525-8577, Shiga, Japan.
We have developed transition-metal-free synthetic methodologies for dibenzoxazepinones utilizing salicylamides as starting materials and employing two distinct types of successive hypervalent iodine-mediated arylocyclizations. This synthetic protocol encompasses selective phenol -arylation of salicylamides with diaryliodonium salts, followed by electrophilic aromatic amination utilizing chemically or electronically generated hypervalent iodine reagents in the second stage of the process.
View Article and Find Full Text PDFMolecules
December 2024
The Division of Chemical Biology and Medicinal Chemistry, College of Pharmacy, University of Texas at Austin, Austin, TX 78712, USA.
The hypervalent iodine-mediated formation of steroidal 5/5-spiroiminals and 5/5-spiroaminals from steroidal amines is presented. Under the influence of excess PhI(OAc) and iodine in acetonitrile at 0 °C, steroidal amines smoothly underwent cyclization to give a mixture of 5/5-spiroiminals and 5/5-spiroaminals. This reaction represents the first example of a C-H-activation-mediated formation of a spiroiminal.
View Article and Find Full Text PDFBeilstein J Org Chem
November 2024
University of Bristol, School of Chemistry, Bristol, BS8 1TS, UK.
Acc Chem Res
November 2024
Department of Chemistry, Seoul National University, Seoul 08826, Korea (South).
Chem Commun (Camb)
November 2024
Department of Chemistry and Biotechnology, Tallinn University of Technology, Akadeemia tee 15, Tallinn 12618, Estonia.
We report an iminium ion-promoted, asymmetric synthesis of cyclopropanes an electrocatalytic, iodine-mediated ring closure. The mild, controlled electrochemical generation of electrophilic iodine species in catalytic quantities prevents organocatalyst deactivation, while also eliminating the need for halogenating reagents, thus simplifying traditional synthetic approaches.
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