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Aer stirring for 1 hour at room temperature, Grignard reagent 2a
(0.271 g, 1.5 mmol) and MgCl2 (0.009 g, 0.1 mmol) were added to
the resulting mixture. The mixture was stirred at room tempera-
ture for 30 min. The reaction mixture was extracted with
dichloromethane (2 Â 10 mL), and then washed with water (10
mL), followed by brine (10 mL). The organic layer was dried over
anhydrous sodium sulfate and concentrated under reduced pres-
sure. The resulting residue was then puried by ash column
chromatography on silica gel with EtOAc-hexane as eluent to
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In conclusion, a novel efficient one-pot synthesis of amides
from N-Alloc-, N-Boc-, and N-Cbz-protected amines was devel-
oped. In this study, in situ-generated isocyanates from the
reaction with 2-chloropyridine and triuoromethanesulfonyl
anhydride were employed to react with Grignard reagents,
providing the resulting amides with high yields. This synthetic
procedure was conducted under mild conditions, and forma-
tion of amides were achieved in a short time. Our results
suggest that this novel, direct, in situ-generated isocyanate-
mediated transformation of N-Alloc-, N-Boc-and N-Cbz-
protected amines into amides is facile and readily applicable
to synthesis of various amides.
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Conflicts of interest
There are no conicts to declare.
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Acknowledgements
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This research was supported by the National Research Foun-
dation of Korea (NRF) grant funded by the Korea government
(MSIT) (NRF-2021R1A2C1011204; H. K. K), and was also sup-
ported by the National Research Foundation of Korea (NRF-
2020R1I1A3071821; W. P. H.).
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15894 | RSC Adv., 2021, 11, 15890–15895
© 2021 The Author(s). Published by the Royal Society of Chemistry