Angewandte
Chemie
procedure. The series of operations was repeated three times. The
reaction mixture was allowed to react under an atmospheric pressure
of argon at 808C for 2 h. After the reaction, GC and GC-MS analyses
were performed. The yields of products were estimated from the
areas under the peaks in the spectra by incorporating an internal
standard.
Received: August 29, 2003
Revised: November 28, 2003 [Z52741]
Keywords: alkanes · lactams · nitrosation · oximation ·
.
synthesis design
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S. Yu, L. Kunlan, Science 2001, 292, 1139 – 1141.
Scheme 6. A plausible reaction pathway for the reaction of 1a with 2,
catalyzed by NHPI.
According to this reaction pathway, nitrosation of 1a
under an NO atmosphere instead of under Ar should improve
the yield of 3a. However, it was found to be difficult to obtain
3a selectively by NHPI-catalyzed reaction of 1a with 2 under
NO. When 1a was allowed to react with 2 in the presence of
NHPI at 808C for 2 h under an NO atmosphere, the reaction
resulted in a complex mixture of several products. We have
previously shown that the reaction of an alkane in the
presence of the catalyst NHPI under an NO atmosphere
proceeds by the formation of an alkyl cation intermediate that
is produced when the alkyl radical generated from the alkane
is oxidized by excess amounts of NO.[11] We therefore suggest
that transformation of the cyclohexyl radical into the
cyclohexyl cation may occur as a side reaction in the
nitrosation of 1a with 2 in the presence of excess amounts
of NO. The cyclohexyl cation generated could be converted
into cyclohexyl acetate by trapping with AcOH, into cyclo-
hexene by b-proton elimination, and into several reaction
products of the resulting cyclohexene. As a consequence, the
reaction of 1a with 2 in an NO atmosphere would lead to a
complex mixture of products. We think that NO may be
generated slowly from 2 during nitrosation of 1a by treatment
with 2 under an Ar atmosphere and that this explains why 3a
was obtained in only moderate yield. Further investigations
aiming to optimize the reaction conditions are now in
progress.
[3] About 2.8 kg of ammonium sulfate is generated per kilogram of
cyclohexanone oxime produced: G. Bellussi, C. Perego, Cattech
2000, 4, 4 – 16 .
[4] D. D. Davis in Ullmann's Encyclopedia of Industrial Chemistry,
5th ed., Vol. A1 (Ed.: W. Gerhartz), Wiley, New York, 1985,
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clopedia of Industrial Chemistry, 4th ed., Vol. 1 (Ed.: J. I.
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cited therein.
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(Enichem Anic S.r.L.), EP 00564040, 1993 [Chem. Abstr. 1994,
120, 76939].
[6] R. Raja, G. Sankar, J. M. Thomas, J. Am. Chem. Soc. 2001, 123,
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2001, 113, 228 – 230; Angew. Chem. Int. Ed. 2001, 40, 222 – 224.
[10] The Merck Index, 13th ed. (Eds.: M. J. O'Neil, A. Smith, P. E.
Heckelman), MERCK & CO., Whitehouse Station, 2001, p. 26 6 ;
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7075 – 7078; M. Eikawa, S. Sakaguchi, Y. Ishii, J. Org. Chem.
1999, 64, 4676 – 4679.
In conclusion, we have developed a novel, clean proce-
dure for the nitrosation of 1a by treatment with 2 in the
presence of NHPI as a catalyst. This method has some
advantages over conventional methods, such as the halogen-
free, relatively mild reaction conditions, good product selec-
tivity (almost no organic byproducts), and high recovery of
the catalyst.
Experimental Section
Representative procedure: NHPI (0.1 mmol) was added to a solution
of 1a (1 mL, 8 mmol) and 2 (1 mmol) in AcOH (1 mL) in a Schlenk
tube. The tube was cooled to À788C to freeze the solvent, degassed
in vacuo, then filled with Ar gas. The frozen solvent was melted at
room temperature and refrozen to repeat the evacuation/Ar purge
Angew. Chem. Int. Ed. 2004, 43, 1120 –1123
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