C O M M U N I C A T I O N S
Table 2. Reaction Scopea b
,
a Reactions were carried out in the scale of 0.5 mmol of azides 3
using 20 mol % of Cu(OAc)2 and 1 equiv of K3PO4 in DMF (0.1 M)
at 80 °C under an O2 atmosphere. b Isolated yields were recoreded
above. c 1-Naphthonitrile and N-methyl-aniline were obtained in 21 and
19% yields, respectively. d 4-Methoxybenzonitrile and N-methylaniline were
obtained in 27 and 12% yields, respectively. e NaOMe (1 equiv) was used
as a base. f See Supporting Information for more detail. g N-Methylaniline
was obtained in 45% yield. h Pyrazinone 6 was also obtained in 18%
yield.
Acknowledgment. This work was supported by funding from
Nanyang Technological University and Singapore Ministry of
Education. We thank Dr. Yongxin Li (Division of Chemistry and
Biological Chemistry, School of Physical and Mathematical Sci-
ences, Nanyang Technological University) for assistance in X-ray
crystallographic analysis.
the corresponding anilines 8 and N-H amides 9 were isolated as
side products generated probably via aryl transmission followed
by hydrolysis of the resulting N-aryl imines. Interestingly,
treatment of p-tolylamide derivative 3w under the present
catalytic conditions afforded azaspirocyclohexadienol 10 and
demethylated azaspirodienone 4a in 42 and 6% yields respec-
tively, without formation of expected spirocyclohexa-2,4-dienone
4w (eq 3) (see Supporting Information for more detail).
Based on these results, a proposed mechanistic possibility was
outlined in Scheme 2. It commences with denitrogenative formation
of iminyl copper II followed by its oxidation with O2 to form
peroxycopper(III) III. The reaction of p-tolylamide 3w (eq 3)
suggests that the intramolecular imino-cupration of III might form
C-N and C-Cu bonds concurrently at the ipso and its para position
of the benzene ring respectively, affording IV.12 Subsequent
isomerization of IV to peroxydiene V followed by elimination of
[Cu(II)-OH] species VI3b would deliver azaspirodienones 4. In
the cases of eqs 1 and 2, transfer of the aryl group might proceed
via C-N bond cleavage of IV.
Supporting Information Available: Experimental Procedures and
characterization of all new compounds. This material is available free
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