The Rh(III)-catalyzed
regioselective C–H amidation of N-methoxy-1H-indole-1-carboxamides by 1,4,2-dioxazol-5-ones
was studied. N-Methoxy amide, the directing group
(DG) of interest, undergoes four different transformations through
DG-retained, -coupled, -eliminated, or -migrated processes under moderately
varied reaction conditions. Solvents, additives, and temperature play
important roles in these selective transformations; a trace addition
of water favors the functional group (FG)-assisted DG elimination;
extra addition of KHSO4 greatly enhances the formation of the DG-coupled product;
high-temperature and proper FG together can shift the position of
DG through intermolecular Friedel–Crafts-like acylation. The
catalytic mechanisms underlying these reactions were further investigated
through density functional theory calculations and experimental studies
including the characterization of amido-inserted rhodacycle. An overall
catalytic pathway was proposed to illustrate the reactions involved
in the regioselective amidation of N-methoxy-1H-indole-1-carboxamide.
The promising application of deuterium-labeled
compounds, such
as the drug deutetrabenazine, warrants efficient, selective, and direct
deuteration of organic entities. Here, we present a highly effective
regioselective direct C–H deuteration of indole in D2O using Cp*Co(CO)I2, [Cp*RhCl2]2, or their combination as a catalyst. This transition-metal-catalyzed
system made available mono(C2)-, di(C2/C7)-, tri(C2/C3/C7)-, and even
C4-deuterated products from diverse indole substrates, equipped with
the removable N1-directing group. The selective H/D exchanges on the
rest of the sites of the indoles were also realized by shifting the
directing group. Furthermore, an example of this approach was demonstrated
to acquire deuteromelatonin from the drug melatonin.
The popularization of mobile communication devices and location technology has spurred the increasing demand for location-based services (LBSs). While enjoying the convenience provided by LBS, users may be confronted with the risk of privacy leakage. It is very crucial to devise a secure scheme to protect the location privacy of users. In this paper, we propose an anonymous entropy-based location privacy protection scheme in mobile social networks (MSN), which includes two algorithms K-DDCA in a densely populated region and K-SDCA in a sparsely populated region to tackle the problem of location privacy leakage. The K-DDCA algorithm employs anonymous entropy method to select user groups and construct anonymous regions which can guarantee the area of the anonymous region formed be moderate and the diversity of the request content. The K-SDCA algorithm generates a set of similar dummy locations which can resist the attack of adversaries with background information. Particularly, we present the anonymous entropy method based on the location distance and request contents. The effectiveness of our scheme is validated through extensive simulations, which show that our scheme can achieve enhanced privacy preservation and better efficiency.
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