Cage-confined photocatalysis for wide-scope unusually selective [2 + 2] cycloaddition through visible-light triplet sensitization

Abstract

Light-induced [2 + 2] cycloaddition is the most straightforward way to generate cyclobutanes, which are core structures of many natural products, drugs and bioactive compounds. Despite continuous advances in selective [2 + 2] cycloaddition research, general method for intermolecular photocatalysis of acyclic olefins with specific regio- and diastereoselectivity, for example, syn-head-to-head (syn-HH) cyclobutane derivatives, is still lack of development but highly desired. Herein, we report a cage-confined photocatalytic protocol to enable unusual intermolecular [2 + 2] cycloaddition for α,β-unsaturated carbonyl compounds. The syn-HH diastereomers are readily generated with diastereoselectivity up to 99%. The cage-catalyst is highly efficient and robust, covering a diverse substrate range with excellent substituent tolerance. The mimic-enzyme catalysis is proposed through a host-guest mediated procedure expedited by aqueous phase transition of reactant and product, where the supramolecular cage effect plays an important role to facilitate substrates inclusion and pre-orientation, offering a promising avenue for general and eco-friendly cycloaddition photocatalysis with special diastereoselectivity.

Artificial Metal–Peptide Assemblies: Bioinspired Assembly of Peptides and Metals through Space and across Length Scales

“…Metallo-supramolecular chemistry, pioneered by Fujita − and Stang, − has become a mature research field in the past two decades. The powerful strategy of metal-mediated self-assembly has enabled the construction of a large variety of structurally well-defined molecular architectures with uniquely functional nanospaces. ,, They have been put through studies in various applications such as host–guest recognition, − molecular adsorption and separation, − catalysis, − biological applications, − etc. However, because of the challenges in introducing guest-adaptive feature into these supramolecular coordination complexes, their abilities in biomolecular recognition are highly ineffective compared to natural systems.…”

Flexible Vertex Engineers the Controlled Assembly of Distorted Supramolecular Tetrahedral and Octahedral Cages

“…Over the past decades, designing and synthesizing unique supramolecular cages featuring intriguing polyhedral geometries and confined cavities have sparked great interest in supramolecular community [1][2][3][4][5][6]. In addition to their aesthetically pleasing structures, their unique physical and chemical properties resulting from specific shapes and functionalities endow them wide applications across various fields, ranging from biomedicine [7][8][9], catalysis [10][11][12][13][14], guest encapsulation [15][16][17], separation [18,19] to luminescent materials [20][21][22]. Recent progress allows the structures of supramolecular cages to be readily designed and synthesized using highly directional coordination bonds linking metal ions with specific coordination geometries with organic linkers of different symmetries, lengths, and steric bulk [1][2][3][4][5][6][23][24][25][26].…”

Solution [2 + 2] photopolymerization of biomass-derived nonrigid monomers enabled by energy transfer catalysis

“…32 Nevertheless, if the solution [2 + 2] photopolymerization of biscinnamates can be realized, several advantages can be expected: (1) solution polymerizations could avoid the need for a precise monomer preorganization, and thus expand the monomer scope and facilitate the synthesis of polymers with structural variation and diversity; (2) solution polymerizations may afford polymer products with different structures and properties, and hopefully with a better processability than that of solid-state polymerization products; [23][24][25] (3) further, solution polymerizations are normally more convenient to conduct in comparison to solid state polymerizations. Given the recent advancement on the photocatalytic intermolecular [2 + 2] cycloaddition, [33][34][35][36][37][38][39][40] we conceived visible light triplet energy transfer catalysis 41,42 could probably overcome the challenging issues like low efficiency in intersystem crossing, [19][20][21][22]31,32 thus bringing in the opportunity to establish a visible light-regulated [2 + 2] photopolymerization of non-rigid biscinnamate monomers in solution. Moreover, after several years of our exploration on photo-controlled polymerizations based on the excited state electron-transfer 43,44 and proton-transfer 45,46 mechanisms, we became interested in the application of energy-transfer catalysis to polymerization, an approach that has not been well appreciated in the development of photocatalytic polymerizations so far.…”