Organic Letters
Letter
amine still allows for the nucleophilic substitution to
chloroformate. This proposed mechanism is also supported
by the reference in conventional synthesis of isocyanate with
the HCl salt of amine and phosgene or phosgene oligomers at
high temperature.13,28 Finally, we demonstrated Cbz and Fmoc
protections of an amine with this one-pot procedure. Benzyl
alcohol and 9-fluorenemethanol, even though they have strong
absorption at the UV region (Figure S2), were photochemi-
cally converted to the chloroformates in CHCl3. However,
since their chloroformates underwent thermal decomposition
at relatively high temperature, excess amounts of cyclohexyl-
amine were added to the sample solution to afford the
corresponding carbamates in 76% and 40% yields, respectively.
The yield of the latter reaction is relatively low and highly
dependent on the conditions due to the low solubility of 9-
fluorenemethanol in CHCl3.
ACKNOWLEDGMENTS
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The present work was sponsored by a Grant-in-Aid for
Scientific Research (B) (No. 17H02740) from the Ministry of
Education, Science, Sports, and Culture, Japan, and by The
Canon Foundation.
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ASSOCIATED CONTENT
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sı
* Supporting Information
The Supporting Information is available free of charge at
Experimental procedures and copies of 1H and 13C
AUTHOR INFORMATION
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(20) (a) Kawakami, K.; Tsuda, A. Chem. - Asian J. 2012, 7, 2240.
(b) Zhang, A.; Kuwahara, Y.; Hotta, Y.; Tsuda, A. Asian J. Org. Chem.
2013, 2, 572.
Corresponding Author
Akihiko Tsuda − Department of Chemistry, Graduate School of
Science, Kobe University, Kobe 657-8501, Japan; Department of
Pharmaceutical Sciences, Inner Mongolia Medical University,
́
́
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Authors
Fengying Liang − Department of Chemistry, Graduate School of
Science, Kobe University, Kobe 657-8501, Japan; Department of
Pharmaceutical Sciences, Inner Mongolia Medical University,
Hohhot, Inner Mongolia 010110, China
Masaki Yanai − Department of Chemistry, Graduate School of
Science, Kobe University, Kobe 657-8501, Japan
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Yuto Suzuki − Department of Chemistry, Graduate School of
Science, Kobe University, Kobe 657-8501, Japan
Complete contact information is available at:
Notes
The authors declare no competing financial interest.
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Org. Lett. XXXX, XXX, XXX−XXX