Prenylated and reverse-prenylated indolines are privileged scaffolds in numerous naturally occurring indole alkaloids with a broad spectrum of important biological properties. Development of straightforward and stereoselective methods to enable the synthesis of structurally diverse prenylated and reverse-prenylated indoline derivatives is highly desirable and challenging. In this context, the most direct approaches to achieve this goal generally rely on transition-metal-catalyzed dearomative allylic alkylation of electron-rich indoles. However, the electron-deficient indoles are much less explored, probably due to their diminished nucleophilicity. Herein, a photoredox-catalyzed tandem Giese radical addition/Ireland–Claisen rearrangement is disclosed. Diastereoselective dearomative prenylation and reverse-prenylation of electron-deficient indoles proceed smoothly under mild conditions. An array of tertiary α-silylamines as radical precursors is readily incorporated in 2,3-disubstituted indolines with high functional compatibility and excellent diastereoselectivity (>20:1 d.r.). The corresponding transformations of the secondary α-silylamines provide the biologically important lactam-fused indolines in one-pot synthesis. Subsequently, a plausible photoredox pathway is proposed based on control experiments. The preliminary bioactivity study reveals a potential anticancer property of these structurally appealing indolines.
As an application of digital concepts, unattended convenience stores are widely disseminated and considered one of the trends of future business development. It is an important consideration for the development of unattended convenience stores to determine the potential of operation efficiency and improve inefficient units. This paper establishes a bi-level DEA model with multi-followers and uses weak disposability technology to deal with undesirable intermediate measures, aiming to accurately evaluate the performance of the whole bi-level system of unattended convenience stores and each participant. Thus, extended Kuhn-Tucker conditions are applied to solve the proposed model. It is found that the benefit efficiency of the lower subsystem always belongs to the maximum and minimum benefit efficiency of all followers, and the benefit efficiency of the system is between the upper and lower benefit efficiency. Using a case study of unattended convenience stores in the Chengdu area, the validity and practicability of the model in the evaluation of benefit efficiency are shown and more explicit management opinions are provided.
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