C O M M U N I C A T I O N S
National Center for Computer Applications for time allocation on
the IBM P Series 690 (CHE 030060).
Supporting Information Available: Experimental procedures and
computational studies for Scheme 2. This material is available free of
References
(1) (a)Moss, R. A. Acc. Chem. Res. 1989, 22, 15. (b) Merrer, D. C.; Moss,
R. A. In AdVances in Carbene Chemistry; Brinker, U. H., Ed.; Elsevier:
Amsterdam, 2001; Vol. 3, pp 53f.
(2) (a)Mitsch, R. A. J. Heterocycl. Chem. 1964, 1, 59. (b) Mitsch, R. A. J.
Am. Chem. Soc. 1965, 87, 758. (c) Bjork, C. W.; Craig, N. C.; Mitsch, R.
A.; Overend, J. J. Am. Chem. Soc. 1965, 87, 1186. (d) Mitsch, R. A. J.
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(3) (a)Moss, R. A.; Fedorynski, M.; Shieh, W.-C. J. Am. Chem. Soc. 1979,
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(4) (a)Moss, R. A.; Wlostowski, M.; Shen, S.; Krogh-Jespersen, K.; Matro,
A. J. Am. Chem. Soc. 1988, 110, 4443. (b) Du, X.-M.; Fan, H.; Goodman,
J. L.; Kesselmayer, M. A.; Krogh-Jespersen, K.; LaVilla, J. A.; Moss, R.
A.; Shen, S.; Sheridan, R. S. J. Am. Chem. Soc. 1990, 112, 1920.
(5) Graham, W. H. J. Am. Chem. Soc. 1965, 87, 4396.
(6) (a)Cox, D. P.; Moss, R. A. Terpinski, J. J. Am. Chem. Soc. 1983, 105,
6513. (b) Moss, R. A.; Terpinski, J.; Cox, D. P.; Denney, D. Z.; Krogh-
Jespersen, K. J. Am. Chem. Soc. 1985, 107, 2743.
(7) Wlostowska, J.; Moss, R. A.; Guo, W.; Chang, M. J. Chem. Commun.
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(8) Moss, R. A.; Fedorynski, M.; Terpinski, J.; Denney, D. Z. Tetrahedron
Lett. 1986, 27, 419.
(9) Regitz, M., Ed. Carbene, Carbenoide, Methoden der Organische Chemie
(Houben-Weyl); Thieme Verlag: Stuttgart, 1989; Vol. E19b.
(10) (a) Mitsch, R. A. J. Heterocycl. Chem. 1966, 3, 245. (b) Robertus, R. L.;
McBrady, J. J.; Gagnon, J. G. J. Org. Chem. 1967, 32, 1944. (c) Meyers,
M. D.; Frank, S. Inorg. Chem. 1966, 5, 1455.
(11) (a) Mitsch, R. A.; Neuvar, E. W.; Koshar, R. J.; Dybvig, D. H. J.
Heterocycl. Chem. 1965, 2, 371. For generation of ClCF by photoextrusion
from a cyclopropyl precursor, see (b) Tippmann, E. M.; Platz, M. S. J.
Phys. Chem. A 2003, 107, 8547.
Figure 1. Infrared spectra following reaction of diazirine 5 with TBAF.
Diazirinone (9) at 2150 cm-1 decreases as CO at 2115 and 2173 cm-1
increases. Including ∼2 min of preparation time, the lifetime of 9 in this
experiment is ∼5 min.
Formation of p-nitrofluorobenzene 8 from diazirine 5 and TBAF
(see above) requires that Cl- and a N2CO fragment be liberated.
Computational studies in which we attempted to optimize a
Meisenheimer complex formed by fluoride addition at the ipso
carbon of 5 (see Scheme 2) led to Cl-, 8, and diazirinone 9 (i.e.,
N2CO).15 The computations of Korkin et al. find 9 to be the most
stable of various N2CO isomers; for example, it is about 11 kcal/
mol more stable than its known linear isomer nitrosyl cyanide
(OdN-CN).22 The decomposition of 9 to CO + N2 is exothermic
by >90 kcal/mol,22,23 but requires an activation energy of 2424-
2722,23 kcal/mol, so that 9 should be observable, if metastable.
The (unscaled) computed22 IR CdO frequency for 9 is 2064 cm-1
(B3LYP) or 2079 cm-1 (MP 2), reasonable fits to our observed
2150 cm-1. A better fit is OdN-CN, with a reported CN absorption
at 2170 cm-1 (gas phase),25 although it is difficult to envision its
direct generation from diazirine 5 and F-. We prepared OdN-
CN from nitrosyl chloride26 and AgCN.27 Reaction of cold (-20
°C) OdN-CN in DCE with TBAF in the IR cell led to immediate
disappearance of OdN-CN at 2164 cm-1, coupled with the
appearance of CO (2116 and 2169 cm-1). OdN-CN is known28
to (gradually) afford CO and N2 (presumably via prior dissociation
to NO and CN radicals),28 but how fluoride catalyzes this conversion
is unclear.
Importantly, the reaction of OdN-CN with TBAF (immediate
decomposition) differs from that of the product from 5 and TBAF
(decomposition over 5-9 min). We conclude that the carrier of
the 2150 cm-1 IR band from the reaction of 5 and TBAF is
diazirinone 9, which decays to CO and N2 with a lifetime of 5-9
min at -20 to 25 °C (in the presence of TBAF). The formation of
9 in this reaction, and its properties, are in reasonable accord with
computational studies.15,22-24
In summary, the reaction of p-nitrophenoxychlorodiazirine 5 with
TBAF follows three channels: (1) ∼17% of p-nitrophenoxide/F-
exchange to chlorofluorodiazirine 3 and p-nitrophenol 7, (2) ∼28%
of Cl/F exchange to p-nitrophenoxyfluorodiazirine 6, and (3) ∼55%
of ipso fluoride attack, affording p-nitrofluorobenzene 8 and the
previously unknown diazirinone 9.29
(12) Zollinger, J. L.; Wright, C. D.; McBrady, J. J.; Dybvig, D. H.; Fleming,
F. A.; Kurhajec, G. A.; Mitsch, R. A.; Neuvar, E. W. J. Org. Chem. 1973,
38, 1065.
(13) Fede´, J.-M.; Jockush, S.; Lin, N.; Moss, R. A.; Turro, N. J. Org. Lett.
2003, 5, 5027.
(14) Olah, G. A.; Olah, J. A.; Overchuck, N. A. J. Org. Chem.. 1965, 30,
3373.
(15) Details appear in the Supporting Information. Note that the carbonyl-
chloride adduct of diazirinone is not a bound species.
(16) (a)Dailey, W. P., III. Tetrahedron Lett. 1987, 28, 5801. (b) Bainbridge,
K. E.; Dailey, W. P., III. Tetrahedron Lett. 1989, 30, 4901.
(17) Creary, X.; Sky, A. F. J. Am. Chem. Soc. 1990, 112, 368.
(18) (a)Oliver, J. P.; Rao, U. V.; Emerson, M. T. Tetrahedron Lett. 1964, 5,
3419. (b) Mu¨ller, C.; Stier, F.; Weyerstahl, P. Chem. Ber. 1977, 110, 124.
(19) Dehmlow, E. V.; Franke, K. Ann. Chem. 1979, 1456. See also ref 9, pp
1487f.
(20) Lemal and Wei cite 2117 and 2171 cm-1. Lemal, D. M.; Wei, Y. Org.
Lett. 2004, 6, 3837 .
(21) Repetitions of this experiment gave similar results. The maximum observed
lifetime of 9 was 9 min.
(22) Korkin, A. A.; Schleyer, P. v. R.; Boyd, R. J. Chem. Phys. Lett. 1994,
227, 312. The aromatic stabilization energy of 9 is only 722-923 kcal/
mol.
(23) For comparable computational results, see Berson, J. A.; Birney, D. M.;
Dailey, W. P.; Liebman, J. F. In Modern Models of Bonding and
Delocalization; Liebman, J. F., Greenberg, A., Eds.; VCH: Weinheim,
Germany, 1988; pp 391-441.
(24) For pertinent discussion and unsuccessful attempts to prepare 9, see:
Dailey, W. P. Report AL-TR-90-044, 1990; Chem. Abstr. 1992, 116,
87188.
(25) Bak, B.; Nicolaisen, F. M.; Nielsen, O. J. J. Mol. Struct. 1979, 51, 17.
(26) Kalbandkeri, R. G.; Padma, D. K.; Murthy, A. R. V. Z. Anorg. Allg. Chem.
1979, 450, 103.
(27) Horsewood, P.; Kirby, G. W. J. Chem. Soc., Perkin Trans. 1 1980, 1587.
(28) Gowenlock, B. G.; Radom, L. Aust. J. Chem. 1978, 31, 2349.
(29) An attempt to intercept 9 with diphenylisobenzofuran was unsuccessful.
For NNCO in the gas phase, see: de Petris, G.; Cacace, F.; Cippolini, R.;
Cartoni, A.; Rosi, M.; Troiani, A. Angew. Chem., Int. Ed. 2005, 44, 462.
Acknowledgment. We thank Prof. W. P. Dailey for helpful
correspondence, Prof. R. Warmuth for the loan of an IR cell and
helpful discussions, Dr. D. P. Cox for preliminary experiments,
the National Science Foundation for financial support, and the
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