Mechanistic Study of Domino Processes Involving the Bidentate Lewis Acid Catalyzed Inverse Electron‐Demand Diels−Alder Reaction

Abstract

The detailed understanding of mechanisms is the basis to design new reactions. Herein, we studied the domino bidentate Lewis acid catalyzed inverse electron‐demand Diels−Alder (IEDDA) reaction developed in our laboratory computationally as well as by synthetic experiments, to characterize different pathways. A quinodimethane intermediate was identified as key structure, which is the basis for all subsequent transformations: Elimination to an aromatic naphthalene, rearrangement to a dihydroaminonaphthalene and a photo‐induced ring opening. These insights allow to optimize the reaction conditions, such as catalytic utilization of amine, as well as to advance new reactions in the future.

Orthogonal Catalysis for an Enantioselective Domino Inverse‐Electron Demand Diels−Alder/Substitution Reaction

“…Based on previous studies on the bidentate Lewis acid catalyzed IEDDA reactions of phthalazines [26] as well as organocatalysis [27] we propose an orthogonal, [28] bicyclic mechanism (Scheme 4 ). One cycle is centered around the bidentate complexation of phthalazine ( 1 ) to Me 2 ‐DBA 2 .…”

Bis[1]benzothieno[1,4]thiaborins as a Platform for BODIPY Singlet Oxygen Photosensitizers

“…[25][26][27][28] On the other hand, incorporation of an electron-deficient atom such as boron atom into a π-electron conjugated system results in a significant lowering of the LUMO level which leads to electron-deficient characteristics. [29][30][31][32][33][34][35][36][37][38] Fused triarylboranes are thus commonly used as dopants for electron-transporting materials, [39][40][41][42][43] anion-receptors, [44][45][46][47][48] Lewis acid catalysts, [49][50][51][52][53][54][55][56][57][58][59][60] and light-emitting materials. [61][62][63][64][65][66][67] From the known structures of boracyclic compounds, [44,68] boron-containing thiophene-fused systems are an especially fascinating class of functional materials thanks to their unique optical properties derived from the electron-accepting character of boron atom combined with electron-conduct...…”

Investigation of Alkyl–Aryl Interactions Using the Azobenzene Switch – The Influence of the Electronic Nature of Aromatic London Dispersion Donors

“…11,13,14 The effects of London dispersion are an extensively studied field, and there have been a number of comprehensive reviews in recent years, indicating the importance of noncovalent interactions. 14 15 Stabilizing interactions with aromatic scaffolds have also been extensively explored. 16 The N -arylimide balance, established by Shimizu, was used for observing the effect of face-to-face aryl, halogen–aryl, OH–aryl, n-aryl, as well as CH–aryl interactions.…”

“…However, alkyl–aryl interactions are also contributors. 6 7 14 21 To disbar the alkyl–alkyl interactions and put a focus on the aryl–alkyl interactions, nine different AB derivatives were designed, which are substituted in meta position with Me, t -Bu, and n -heptyl on one phenyl ring and with electron-donating ( p -OMe), electron-withdrawing ( p -NO 2 ), and unsubstituted ( p -H) phenyl rings in meta position on the opposite phenyl ring relative to the corresponding azo unit (Figure 1 ). For synthesizing the all- meta -substituted ABs of interest with two aryl substituents on one side and two meta -alkyl substituents on the other side ( 1 – 9 ), three different synthetic routes were implemented (Figure 1 , Scheme 2 ): route 1 was applied for Me-, t -Bu-, and n -heptyl-substituted ABs with unsubstituted phenyl rings ( 1 – 3 ), route 2 for Me-, t -Bu-, and n -heptyl-substituted ABs with OMe-substituted phenyl groups in meta position ( 4 – 6 ), and route 3 for ABs with bis- para -NO 2 -substituted phenyl rings in meta position ( 7 – 9 , Scheme 2 ).…”