Base-Mediated Cascade Rearrangements of Aryl-Substituted Diallyl Ethers

Abstract

Two base-mediated cascade rearrangement reactions of diallyl ethers were developed leading to selective [2,3]-Wittig-oxy-Cope and isomerization-Claisen rearrangements. Both diaryl and arylsilyl-substituted 1,3-substituted propenyl substrates were examined, and each exhibits unique reactivity and different reaction pathways. Detailed mechanistic and computational analysis was conducted, which demonstrated that the role of the base and solvent was key to the reactivity and selectivity observed. Crossover experiments also suggest that these reactions proceed with a certain degree of dissociation, and the mechanistic pathway is highly complex with multiple competing routes.

Crown Ether Base: Highly Active, Regioselective and Reusable Catalytic Systems for Double Bond Migration in Allylic Compounds

“…Additionally, there are also four papers reporting the usage of the 18‐Crown‐6/KOH system,, (two of which were published by us) devoted to the isomerization of N ‐allylimidazole, N ‐allylimines to appropriate 2‐aza‐1,3‐diene, allyl‐phenyl‐ ether, sulfide, and selenide to appropriate 1‐propenyl derivatives . Recently, t ‐BuOK or t ‐BuOK/18‐Crown‐6 were used for aryl‐substituted diallyl ethers isomerization‐Claisen or [2, 3]‐Wittig‐Anionic Oxy‐Cope rearrangements respectively . Moreover, CsF/18‐Crown‐6 system was used for the isomerization of N ‐allylimines .…”

O-Allylated Pudovik and Passerini Adducts as Versatile Scaffolds for Product Diversification

“…under otherwise identical conditions led to the desired α-ketoamide 7a in 65% yield. 8 These conditions were eventually applied to the allyloxy amides 6b-d affording the desired α-ketoamides 7b-d in 76-88% yield (Scheme 2).…”

“…13 C{1H} NMR (101 MHz, CDCl 3 ) δ 140.5, 137.5 (d, J = 5.9 Hz), 131. 8,125.6 (d,J = 7.4 Hz),124.7,124.3,122.8 (d Diethyl (1-hydroxy-1-phenyl)ethylphosphonate (2s). n-BuLi (as a 2.5 M solution in hexanes, 2.1 µL, 5.3 µmol) and diethyl phosphite (822 µL, 6.38 mmol, 1.2 equiv.)…”

Organocatalytic Name Reactions Enabled by NHCs

“…This creates a product—enol or ketone, depending on keto-enol tautomerization. Isomerization is faster in this type of reaction, and it can take place at a lower temperature [ 117 , 118 , 119 , 120 ].…”