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References
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Figure 2. Effect of temperature and pressure on the yields in
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The result may be rationalized by supposing an early
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and the steric demand of the aromatic amine, the effect
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The results obtained for the Strecker reactions reported
remain in harmony with the correlation between pres-
sure and steric congestion described in our previous
papers for various reactions.10,13 We feel these results of
utmost importance as pressure activation of sterically
congested reactions is thus shown to be a powerful tool
to overcome steric hindrance. We are pursuing the
ramifications of this specific pressure effect by exploring
the limits of the method and its actual nature.
11. Experimental procedure. The weighed amine (0.9–1.0
mmol) and the internal standard (1,2,3-trimethoxyben-
zene) are placed in a flexible 1 mL PTFE tube. About 1
mmol ketone is added before introduction of TMSCN
(1.2 mmol). The volume is adjusted with the ketone or
toluene depending on run. Then, the ampoule is intro-
duced in the vessel and submitted to the desired pressure.
After release of pressure the volatile compounds are
1
removed in vacuo. The residue is analyzed by H NMR
and the yield determined from relative intensities of char-
acteristic protons versus methoxy protons of the internal
standard. For preparative purposes, the mixture recov-
ered from the run is washed with a 2N HCl solution, an
aqueous NaHCO3 solution and water successively. After
extraction with ethyl acetate, the residual solid is chro-
matographed on silicagel.
Acknowledgements
G. Jenner thanks The Kyoto University Foundation for
Cooperative Work for a stay in Japan in 2001. J. C.
Kim thanks the Korea Science and Engineering Foun-
dation for support during his participation in this pro-
12. (a) Isizawa, J.; Sakakibara, K.; Hirota, M. Bull. Chem.
Soc. Jpn. 1996, 69, 1003–10015; (b) Hansch, C.; Leo, A.;
Taft, R. W. Chem. Rev. 1991, 91, 165–195.
ject. This work was supported in part by
a
Grant-in-Aid for Scientific Research from the Ministry
of Education, Culture, Sports, Science and Technology
of Japan.
13. Jenner, G. Tetrahedron Lett. 2001, 42, 4807–4810.