Search

A new strategy has been established for the synthesis of polysubstituted morpholin‐2‐ones through Stevens rearrangements of tertiary amines via in situ activation with epoxides. A range of α‐amino acid‐derived tertiary allylic, propargylic, and benzylic amines reacted with epoxides in the presence of zinc halide catalysts to afford structurally diverse allyl‐, allenyl‐, and benzyl‐substituted morpholin‐2‐ones, respectively, in moderate‐to‐good yields with high regioselectivity. The process involves [2,3]‐ and [1,2]‐Stevens rearrangements of quaternary ammonium ylide intermediates and constitutes a very convenient method to prepare polysubstituted morpholin‐2‐ones through tandem formation of C−N, C−O, and C−C bonds. Moreover, replacing epoxides with aziridines permitted the synthesis of polysubstituted piperazin‐2‐ones. New Stevens rearrangement: Zinc‐halide‐catalyzed ring‐opening of epoxides with α‐amino acid‐derived tertiary allylic, propargylic, and benzylic amines followed by [2,3]‐ and [1,2]‐Stevens rearrangements of the resulting quaternary ammonium ylide intermediates has been established as a convenient method to access polysubstituted morpholin‐2‐ones through tandem formation of C−N, C−O, and C−C bonds (see scheme). [ABSTRACT FROM AUTHOR]

Capping ligands are indispensable for the preparation of metal‐halide‐perovskite (MHP) nanocrystals (NCs) with good stability; however, the long alkyl‐chain capping ligands in conventional MHP NCs will be unfavorable for CO2 adsorption and hinder the efficient carrier separation on the surface of MHP NCs, leading to inferior catalytic activity in artificial photosynthesis. Herein, CsPbBr3 nanocrystals with short‐chain glycine as ligand are constructed through a facile ligand‐exchange strategy. Owing to the reduced hindrance of glycine and the presence of the amine group in glycine, the photogenerated carrier separation and CO2 uptake capacity are noticeably improved without compromising the stability of the MHP NCs. The CsPbBr3 nanocrystals with glycine ligands exhibit a significantly increased yield of 27.7 μmol g−1 h−1 for photocatalytic CO2‐to‐CO conversion without any organic sacrificial reagents, which is over five times higher than that of control CsPbBr3 NCs with conventional long alkyl‐chain capping ligands. [ABSTRACT FROM AUTHOR]