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Bridged cyclobutanes and sulfur heterocycles are currently under intense investigation as building blocks for pharmaceutical drug design. Two formal cycloaddition modes involving bicyclobutanes (BCBs) and pyridinium 1,4‐zwitterionic thiolate derivatives were described to rapidly expand the chemical space of sulfur‐containing bridged cyclobutanes. By using Ni(ClO4)2 as the catalyst, an uncommon higher‐order (5+3) cycloaddition of BCBs with quinolinium 1,4‐zwitterionic thiolate was achieved with broad substrate scope under mild reaction conditions. Furthermore, the first Lewis acid‐catalyzed asymmetric polar (5+3) cycloaddition of BCB with pyridazinium 1,4‐zwitterionic thiolate was accomplished. In contrast, pyridinium 1,4‐zwitterionic thiolates undergo an Sc(OTf)3‐catalyzed formal (3+3) reaction with BCBs to generate thia‐norpinene products, which represent the initial instance of synthesizing 2‐thiabicyclo[3.1.1]heptanes (thia‐BCHeps) from BCBs. Moreover, we have successfully used this (3+3) protocol to rapidly prepare thia‐BCHeps‐substituted analogues of the bioactive molecule Pitofenone. Density functional theory (DFT) computations imply that kinetic factors govern the (5+3) cycloaddition reaction between BCB and quinolinium 1,4‐zwitterionic thiolate, whereas the (3+3) reaction involving pyridinium 1,4‐zwitterionic thiolates is under thermodynamic control. [ABSTRACT FROM AUTHOR]

Bridged cyclobutanes and sulfur heterocycles are currently under intense investigation as building blocks for pharmaceutical drug design. Two formal cycloaddition modes involving bicyclobutanes (BCBs) and pyridinium 1,4‐zwitterionic thiolate derivatives were described to rapidly expand the chemical space of sulfur‐containing bridged cyclobutanes. By using Ni(ClO4)2 as the catalyst, an uncommon higher‐order (5+3) cycloaddition of BCBs with quinolinium 1,4‐zwitterionic thiolate was achieved with broad substrate scope under mild reaction conditions. Furthermore, the first Lewis acid‐catalyzed asymmetric polar (5+3) cycloaddition of BCB with pyridazinium 1,4‐zwitterionic thiolate was accomplished. In contrast, pyridinium 1,4‐zwitterionic thiolates undergo an Sc(OTf)3‐catalyzed formal (3+3) reaction with BCBs to generate thia‐norpinene products, which represent the initial instance of synthesizing 2‐thiabicyclo[3.1.1]heptanes (thia‐BCHeps) from BCBs. Moreover, we have successfully used this (3+3) protocol to rapidly prepare thia‐BCHeps‐substituted analogues of the bioactive molecule Pitofenone. Density functional theory (DFT) computations imply that kinetic factors govern the (5+3) cycloaddition reaction between BCB and quinolinium 1,4‐zwitterionic thiolate, whereas the (3+3) reaction involving pyridinium 1,4‐zwitterionic thiolates is under thermodynamic control. [ABSTRACT FROM AUTHOR]

Bicyclo[2.1.1]hexanes (BCHs) are becoming ever more important in drug design and development as bridged scaffolds that provide underexplored chemical space, but are difficult to access. Here a silver‐catalyzed dearomative [2π+2σ] cycloaddition strategy for the synthesis of indoline fused BCHs from N‐unprotected indoles and bicyclobutane precursors is described. The strain‐release dearomative cycloaddition operates under mild conditions, tolerating a wide range of functional groups. It is capable of forming BCHs with up to four contiguous quaternary carbon centers, achieving yields of up to 99 %. In addition, a scale‐up experiment and the synthetic transformations of the cycloadducts further highlighted the synthetic utility. [ABSTRACT FROM AUTHOR]

Bicyclo[2.1.1]hexanes (BCHs) are becoming ever more important in drug design and development as bridged scaffolds that provide underexplored chemical space, but are difficult to access. Here a silver‐catalyzed dearomative [2π+2σ] cycloaddition strategy for the synthesis of indoline fused BCHs from N‐unprotected indoles and bicyclobutane precursors is described. The strain‐release dearomative cycloaddition operates under mild conditions, tolerating a wide range of functional groups. It is capable of forming BCHs with up to four contiguous quaternary carbon centers, achieving yields of up to 99 %. In addition, a scale‐up experiment and the synthetic transformations of the cycloadducts further highlighted the synthetic utility. [ABSTRACT FROM AUTHOR]

Cycloadditions. Bicyclo[n.1.1]alkanes show great promise in substituting planar aromatic rings, akin to the "butterfly effect". In their Research Article (e202408578), Jian‐Jun Feng et al. present a Lewis acid‐catalyzed cycloaddition of bicyclobutanes (butterfly conformation) with 2D pyridinium thiolate derivatives...By Yuanjiu Xiao; Feng Wu; Lei Tang; Xu Zhang; Mengran Wei; Guoqiang Wang and Jian‐Jun FengReported by Author; Author; Author; Author; Author; Author; Author [Extracted from the article]

Cycloadditions. Bicyclo[n.1.1]alkanes show great promise in substituting planar aromatic rings, akin to the "butterfly effect". In their Research Article (e202408578), Jian‐Jun Feng et al. present a Lewis acid‐catalyzed cycloaddition of bicyclobutanes (butterfly conformation) with 2D pyridinium thiolate derivatives...By Yuanjiu Xiao; Feng Wu; Lei Tang; Xu Zhang; Mengran Wei; Guoqiang Wang and Jian‐Jun FengReported by Author; Author; Author; Author; Author; Author; Author [Extracted from the article]

The exploration of the complex chemical diversity of bicyclo[n.1.1]alkanes and their use as benzene bioisosteres has garnered significant attention over the past two decades. Regiodivergent syntheses of thiabicyclo[4.1.1]octanes (S‐BCOs) and highly substituted bicyclo[2.1.1]hexanes (BCHs) using a Lewis acid‐catalyzed formal cycloaddition of bicyclobutanes (BCBs) and 3‐benzylideneindoline‐2‐thione derivatives have been established. The first hetero‐(4+3) cycloaddition of BCBs, catalyzed by Zn(OTf)2, was achieved with a broad substrate scope under mild conditions. In contrast, the less electrophilic BCB ester undergoes a Sc(OTf)3‐catalyzed [2π+2σ] reaction with 1,1,2‐trisubstituted alkenes, yielding BCHs with a spirocyclic quaternary carbon center. Control experiments and preliminary theoretical calculations suggest that the diastereoselective [2π+2σ] product formation may involve a concerted cycloaddition between a zwitterionic intermediate and E‐1,1,2‐trisubstituted alkenes. Additionally, the hetero‐(4+3) cycloaddition may involve a concerted nucleophilic ring‐opening mechanism. [ABSTRACT FROM AUTHOR]

The exploration of the complex chemical diversity of bicyclo[n.1.1]alkanes and their use as benzene bioisosteres has garnered significant attention over the past two decades. Regiodivergent syntheses of thiabicyclo[4.1.1]octanes (S‐BCOs) and highly substituted bicyclo[2.1.1]hexanes (BCHs) using a Lewis acid‐catalyzed formal cycloaddition of bicyclobutanes (BCBs) and 3‐benzylideneindoline‐2‐thione derivatives have been established. The first hetero‐(4+3) cycloaddition of BCBs, catalyzed by Zn(OTf)2, was achieved with a broad substrate scope under mild conditions. In contrast, the less electrophilic BCB ester undergoes a Sc(OTf)3‐catalyzed [2π+2σ] reaction with 1,1,2‐trisubstituted alkenes, yielding BCHs with a spirocyclic quaternary carbon center. Control experiments and preliminary theoretical calculations suggest that the diastereoselective [2π+2σ] product formation may involve a concerted cycloaddition between a zwitterionic intermediate and E‐1,1,2‐trisubstituted alkenes. Additionally, the hetero‐(4+3) cycloaddition may involve a concerted nucleophilic ring‐opening mechanism. [ABSTRACT FROM AUTHOR]

• Visible light-promoted C3-ethoxycarbonylmethylation of imidazopyridines and ethyl diazoacetate. • Application in facile accessing Zolpidem. • Simple to operate. • Abstarct. • A highly efficient and straightforward C3-ethoxycarbonylmethylation of imidazopyridines with ethyl diazoacetate via a visible light-promoted C - H bond functionalization was developed. Various C3-ethoxycarbonylmethylated imidazopyridines could be efficiently synthesized in moderate to good yields and the importance of the products has been illustrated by their convenient transformation into imidazopyridine-based drug molecules. The reaction can be extended to various diazo compounds and Zolpidem could be successfully synthesized in one step by reacting commercially available intermediate with diazo N,N-dimethylacetamide using this visible light-induced reaction. [ABSTRACT FROM AUTHOR]

A novel and efficient method for highly regioselective cyanomethylation of 8‐aminoquinoline amides at C5 position was developed. Such reactions proceed under transition metal‐free and base‐free conditions. This protocol features simple operation, high efficiency, good functional group tolerance and broad substrate scope. Moreover, the etherification or acetonation products were also obtained when acetonitrile was replaced by ethers or acetone, and a radical process was involved in the reaction. [ABSTRACT FROM AUTHOR]