Hypervalent Iodine(III)-Mediated Umpolung Dialkoxylation of N-Substituted Indoles

Abstract

Herein, we report dialkoxylation of N-substituted indoles through a hypervalent iodine-mediated umpolung strategy, affording trans-2,3-dimethoxyindolines with up to 95% yield. In addition, C5-selective bromination of 2,3-dialkoxyindoline via NBS-mediated rearomatization was achieved. DFT calculation of the sequence of electrophilic addition and nucleophilic substitution pathway of N-substituted indoles has also been investigated.

Synthesis of Hypervalent Iodine Diazo Compounds and Their Application in Organic Synthesis

“…[5,6] These reports reflected the application of hypervalent iodine compounds mainly as reagents and catalysts in organic synthesis. With the rapid development of this field, organic chemists try to find new organic reactions by using the common hypervalent iodine reagents, [7][8][9] and they are also committed to developing new high hypervalent iodine compounds for new multi-purpose applications. [10][11][12] Generally speaking, common hypervalent iodine reagents were generally classied into iodine(III) and iodine(V) compounds, including phenyliodine diacetate (PIDA), phenyliodine bis(trifloroacetate) (PIFA), PhICl 2 , [hydroxyl(tosyloxy)iodo]benzene (HTIB), Togni's reagent, PhIO 2 , 2-iodoxybenzoic acid (IBX), Dess-Martin periodinane (DMP), 2iodoxybenzenesulfonic acid (IBS), etc (Scheme 1).…”

“…These reports reflected the application of hypervalent iodine compounds mainly as reagents and catalysts in organic synthesis. With the rapid development of this field, organic chemists try to find new organic reactions by using the common hypervalent iodine reagents, [7–9] and they are also committed to developing new high hypervalent iodine compounds for new multi‐purpose applications [10–12] …”

Total Synthesis of the Proposed Structure of Indolyl 1,2-Propanediol Alkaloid, 1-(1H-Indol-3-yloxy)propan-2-ol

“…Zhang's group presented a direct approach to C3-acetoxylated biindolyls via palladium catalysis using AgOAc under oxygen atmosphere as oxidants [24]. In contrast to the vast majority of metal-catalyzed synthesis approaches for oxygenated indoles [25][26][27][28][29][30][31][32][33][34][35], metal-free approaches have emerged as powerful synthetic tools owing to their sustainable properties [36][37][38][39][40][41][42][43][44][45][46][47]. However, these reactions are limited to the construction of either C2-oxygenated or C3-oxygenated indole/indoline.…”

Catalytic, Dearomative 2,3-Difluorination of Indoles

“…[4][5][6] The intramolecular version of this strategy has been explored in a lot of elegant studies. Furthermore, numerous intermolecular variations that offer enhanced synthetic versatility have also been developed, including metal-mediated, 7-10 photochemical, [11][12][13][14] electrochemical, [15][16][17] as well as nucleophilic 18 or electrophilic [19][20][21][22] dearomatization reactions (Scheme 1C). These diverse approaches enable the transformation of a planar 2D structure into a saturated 3D scaffold, thereby altering the molecular spatial arrangement.…”