Aerobe Palladium(II)‐katalysierte 5‐endo‐trig‐Cyclisierung als ein Einstieg in die diastereoselektive C‐2‐Alkenylierung von Indolen mit tri‐ und tetrasubstituierten Doppelbindungen

Abstract

Der endo‐Trick: Ein endo‐Ringschluss auf das trigonale β‐Kohlenstoffatom eines an das Indolstickstoffatom angeknüpften α,β‐ungesättigten Akzeptors und eine nachgeschaltete Amidspaltung erlauben die diastereoselektive C‐2‐Alkenylierung von Indolen mit vollständig substituierten Doppelbindungen. Die Carboxygruppe dient als präparativ nützliche, vorübergehende Verknüpfungsstelle (siehe Schema).

Tuning the Stability of CaCO3 Crystals with Magnesium Ions for the Formation of Aragonite Thin Films on Organic Polymer Templates

“…mp 86–88 °C]; R f 0.5 (hexane/AcOEt: 8/2); IR (film): ν=3410, 3391, 3052, 3030, 2927, 1594, 1539, 1485, 1457, 1418, 1338, 1260, 1239, 1185, 1118, 1012, 955, 910 cm −1 ; 1 H NMR (400 MHz, CDCl 3 ): δ =8.15 (d, J =0.2 Hz, 1 H), 7.94 (dd, J =8.7, 3.9 Hz, 1 H), 7.66 (td, J =5.1, 2.5 Hz, 2 H), 7.46–7.39 (m, 3 H), 7.30–7.19 (m, 3 H); 13 C NMR (100 MHz, CDCl 3 ): δ =136.7, 135.6, 128.8, 127.5, 126.0, 125.8, 122.5, 121.8, 120.4, 119.9, 118.4, 111.4. These assignments matched with those previously published 50…”

Influence of Aromatic Residues on the Material Characteristics of Aβ Amyloid Protofibrils at the Atomic Scale

“…The Oestreich group has studied several important reactions that encompass CH activation, such as a Fujiwara–Moritani annulation of indoles78 or Pd‐catalyzed dehydrogenation of cyclohexene‐1‐carbonylindole amides 79. In a recent study, they utilized an intramolecular Pd‐catalyzed annulation of C‐3 substituted indoles, but followed this reaction by a subsequent amide cleavage and ester formation to furnish indoles bearing α,β‐unsaturated esters at the C‐2 position in moderate to good yields in most cases (Scheme ) 80…”

A Simple Heterogeneous Catalyst for Phosphite Addition on Carbonyl Groups

“…Although an alkene activation mechanism cannot be ruled out for this type of endo cyclizations,13a,26,27 mechanistic studies on alkenylation reactions of aromatic and heteroaromatic rings1b,15,16,28 support the prior palladation of the aromatic ring followed by cyclization onto the alkene. This last proposal is in agreement with the results obtained when the reaction was tested with different substitution patterns on the aromatic ring (Scheme ).…”

“…This arylpalladium would undergo a syn insertion to the activated alkene moiety in a 6‐ endo fashion, followed by β‐hydride elimination to afford the quinolone framework. Given the E ‐configuration of the starting alkenes, the subsequent syn β‐hydride elimination would require the prior epimerization of the α carbon through the formation of an OPd intermediate 25,26…”