Oxidative ipso-Rearrangement Performed by a Hypervalent Iodine Reagent and Its Application

Abstract

An oxidative ipso-rearrangement mediated by a hypervalent iodine reagent that enables rapid generation of a functionalized dienone system containing a quaternary carbon center connected to several sp(2) centers has been developed. The process occurs through transfer of an aryl group from a silyl segment present on the lateral chain. As an illustration of the potential of this transformation, a total synthesis of sceletenone, a small alkaloid, is described.

Metal‐Free Enantioselective Oxidative Arylation of Alkenes: Hypervalent‐Iodine‐Promoted Oxidative C−C Bond Formation

“…Thus,t he enantioselective competitive reaction indicates the higher reactivity of the silyl ether substrate compared to the hydroxy substrate under the reaction conditions.Itisremarkable that the TBS group does not act as ap rotecting group, however, it preferentially promotes the oxycyclization. [16] Thefact that the reactivity is dependent on the kind of oxy group can be explained by the reaction mechanism illustrated in Scheme 2. [17] Thehypervalent iodine reagent is activated by aLewis acid, [18] and then electrophilically adds to the olefin to yield 4.T he lactate-based hypervalent iodine reagent differentiates between the enantiotopic faces of the olefin.…”

“…[15] In fact, 1aa was recovered in the reaction of 1ab alone (entry 1). [16] Thefact that the reactivity is dependent on the kind of oxy group can be explained by the reaction mechanism illustrated in Scheme 2. Even in the presence of 1aa (entries 2and 3), the ee value of 2a is nearly the same as in the case of the TBS substrate alone (entry 1).…”

Rearrangements Induced by Hypervalent Iodine

“…When treated with (diacetoxyiodo)benzene, phenols such as 113 are transformed into dienones 116 as shown in Scheme 31 [27]. During this process, the phenoxenium ion 114 is produced.…”

“…The process may be extended to N-sulfonyl anilines, as illustrated by the conversion of the substrate 117 into the bicyclic enone 119 as shown in Scheme 32 [27].…”

Approach for the Direct Synthesis of β‐Dichlorosubstituted Acetanilides Using Iodine Trichloride (ICl3) as the Oxidant and Catalyst

“…Nowadays, hypervalent iodine reagents, as oxidants, have received much attention due to their low toxicity, mild reactivity, ready availability, high stability, easy handling, etc. [9][10][11][12][13][14][15][16][17][18][19][20] Herein, the ICl 3 in this work was used not as the oxidant but also as the catalyst (Eq. 2).…”