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Dearomative construction of multiply‐fused 2D/3D frameworks, composed of aromatic two‐dimensional (2D) rings and saturated three‐dimensional (3D) rings, from readily available quinolines has greatly contributed to drug discovery. However, dearomative cycloadditions of quinolines in the presence of photocatalysts usually afford 5,6,7,8‐tetrahydroquinoline (THQ)‐based polycycles, and dearomative access to 1,2,3,4‐THQ‐based structures remains limited. Herein, we present a chemo‐, regio‐, diastereo‐, and enantioselective dearomative transformation of quinolines into 1,2,3,4‐THQ‐based 6–6–4‐membered rings without any catalyst, through a combination of nucleophilic addition and borate‐mediated [2+2] photocycloaddition. Detailed mechanistic studies revealed that the photoexcited borate complex, generated from quinoline, organolithium, and HB(pin), accelerates the cycloaddition and suppresses the rearomatization that usually occurs in conventional photocycloaddition. Based on our mechanistic analysis, we also developed further photoinduced cycloadditions affording other types of 2D/3D frameworks from isoquinoline and phenanthrene. [ABSTRACT FROM AUTHOR]

Dearomative construction of multiply‐fused 2D/3D frameworks, composed of aromatic two‐dimensional (2D) rings and saturated three‐dimensional (3D) rings, from readily available quinolines has greatly contributed to drug discovery. However, dearomative cycloadditions of quinolines in the presence of photocatalysts usually afford 5,6,7,8‐tetrahydroquinoline (THQ)‐based polycycles, and dearomative access to 1,2,3,4‐THQ‐based structures remains limited. Herein, we present a chemo‐, regio‐, diastereo‐, and enantioselective dearomative transformation of quinolines into 1,2,3,4‐THQ‐based 6–6–4‐membered rings without any catalyst, through a combination of nucleophilic addition and borate‐mediated [2+2] photocycloaddition. Detailed mechanistic studies revealed that the photoexcited borate complex, generated from quinoline, organolithium, and HB(pin), accelerates the cycloaddition and suppresses the rearomatization that usually occurs in conventional photocycloaddition. Based on our mechanistic analysis, we also developed further photoinduced cycloadditions affording other types of 2D/3D frameworks from isoquinoline and phenanthrene. [ABSTRACT FROM AUTHOR]

The article titled "Inside Cover: Dearomative Construction of 2D/3D Frameworks from Quinolines via Nucleophilic Addition/Borate-Mediated Photocycloaddition" discusses the process of transforming 2D quinolines into triply-fused 2D/3D rings through nucleophilic addition, borate complex formation, and photocycloaddition. The cover image illustrates this process. Mechanistic studies have shown that the borate complex accelerates the photocycloaddition and prevents rearomatization in the excited state. The research was conducted by Ken Tanaka, Yuki Nagashima, and their team. [Extracted from the article]

The article titled "Innentitelbild: Dearomative Construction of 2D/3D Frameworks from Quinolines via Nucleophilic Addition/Borate-Mediated Photocycloaddition" discusses the construction of 2D/3D frameworks from 2D aromatics, specifically quinolines. The cover image illustrates the transformation of quinolines into triply-fused 2D/3D rings through nucleophilic addition, borate complex formation, and photocycloaddition. Mechanistic studies revealed that the borate complex accelerates the photocycloaddition process and suppresses rearomatization in the excited state. The research was conducted by Ken Tanaka, Yuki Nagashima, and their team. [Extracted from the article]