Iridium-Catalyzed Cage B(4)-Amidation Reaction of <i>o</i>-Carboranes with Dioxazolones: Selective Synthesis of Amidated <i>o</i>-Carboranes and Amidated and Methoxycarbonylated <i>nido</i>-Carboranes
Gi Uk Han, Yonghyeon Baek, Kyungsup Lee, Seohyun Shin, Hee Chan Noh, Phil Ho Lee
Abstract
Described is the Ir-catalyzed cage B(4)-amidation of o-carboranes with dioxazolones by carboxylic acid-assisted B(4)–H bond activation under extremely mild conditions, affording amidated o-carboranes and amidated and methoxycarbonylated nido-carboranes through sequential B(4)-amidation, O-methylation, and B(3)-deboronation in one pot. Carboxylic acid used as a directing group after the cage B(4)-amidation is efficiently trapped by trimethylsilyldiazomethane instead of undergoing decarboxylation. Mechanism studies demonstrated that the O-methylation through trapping of acid occurred first, followed by the B(3)-deboronation.
Topics & Concepts
ChemistryDecarboxylationIridiumCatalysisCarboxylic acidMedicinal chemistryStereochemistryOrganic chemistryCombinatorial chemistryBoron Compounds in ChemistryPharmacological Effects and Toxicity StudiesRadiopharmaceutical Chemistry and Applications