o-Iodoxybenzoic Acid (IBX) as a Viable Reagent in the Manipulation of Nitrogen- and Sulfur-Containing Substrates:  Scope, Generality, and Mechanism of IBX-Mediated Amine Oxidations and Dithiane Deprotections

Abstract

o-Iodoxybenzoic acid (IBX), a highly versatile hypervalent iodine(V) reagent, was found to efficiently mediate the dehydrogenation of amines in addition to facilitating the oxidative cleavage of dithioacetals and dithioketals. Through the development of relevant IBX-based protocols, a plethora of useful synthetic intermediates, including imines, oximes, ketones, and aromatic N-heterocycles, were found to be readily accessible under notably mild conditions. Further investigation of these transformations led to the elucidation of valuable mechanistic details, resulting in the conclusion that they proceed via ionic rather than single electron transfer (SET) pathways.

Allene formation by gold catalyzed cross-coupling of masked carbenes and vinylidenes

“…6); 75% deuterium incorporation was observed for H a , leading us to conclude that H a and H b come from the alkynes 5 and the ␣-position of the nitrogen moiety of enamines 4, respectively. Note, that in this case imine 8b has been isolated (as mentioned above, imine 8a is partly degraded under the reaction conditions, whereas imine 8b is stable), and its spectroscopic data compared with those reported in the literature (41).…”

2‐Iodoxybenzoesäure – ein einfaches Oxidationsmittel mit einer Vielfalt an Anwendungsmöglichkeiten

“…[146] Beispielsweise reagieren cyclische Amine mit IBX direkt zu Imidazolen, Isochinolinen, Pyridinen oder Pyrrolen. [147] 1,4-Dihydropyridine aromatisieren in Gegenwart von IBX zu den entsprechenden Pyridinen. [148] 4.1.…”

Masked Ketenes as Dienophiles in the Diels–Alder Reaction

“…A two-step procedure was used to unmask the ketone, beginning with dithiane protection, followed by in situ reduction of the nitro group to yield amine 53. Finally, oxidation with 2-iodoxybenzoic acid (IBX) [70,71] revealed the ketone 54 in 86 % yield. From this intermediate, only four steps were required to complete the synthesis of the natural product.…”