Photolysis of open-chain 1,2-diazidoalkenes: generation of 2-azido-2H-azirines, formyl cyanide, and formyl isocyanide

Article abstract of DOI:10.1016/j.tet.2008.04.037

Solutions of several open-chain 1,2-diazidoethenes were photolyzed to yield 2-azido-2H-azirines, which were identified by NMR spectroscopy at low temperature. On prolonged irradiation or warm-up of the NMR solutions, these heterocycles lost a second molecule of nitrogen to be cleaved into two fragments of cyano compounds. In the case of (Z)-2,3-diazidocinnamaldehyde, the formation of formyl cyanide was detected by IR spectroscopy when the photolysis was performed in argon matrix. The latter substance was rearranged to formyl isocyanide on irradiation. This new species was characterized by comparison of its experimental and calculated (B3LYP/6-311+G^**) IR spectrum.

Full text of DOI:10.1016/j.tet.2008.04.037

Tetrahedron 64 (2008) 5645–5648
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Photolysis of open-chain 1,2-diazidoalkenes: generation of 2-azido-2H-azirines,
formyl cyanide, and formyl isocyanideq
,
a
a
b,
*
Klaus Banert a , Joseph Rodolph Fotsing , Manfred Hagedorn , Hans Peter Reisenauer
,
*
Gu¨nther Maier b
a Institute of Chemistry, Chemnitz University of Technology, Strasse der Nationen 62, 09111 Chemnitz, Germany
b Institute of Organic Chemistry, Justus-Liebig-University Giessen, Heinrich-Buff-Ring 58, 35392 Giessen, Germany
a r t i c l e i n f o
a b s t r a c t
Article history:
Solutions of several open-chain 1,2-diazidoethenes were photolyzed to yield 2-azido-2H-azirines, which
were identified by NMR spectroscopy at low temperature. On prolonged irradiation or warm-up of the
NMR solutions, these heterocycles lost a second molecule of nitrogen to be cleaved into two fragments of
cyano compounds. In the case of (Z)-2,3-diazidocinnamaldehyde, the formation of formyl cyanide was
detected by IR spectroscopy when the photolysis was performed in argon matrix. The latter substance
was rearranged to formyl isocyanide on irradiation. This new species was characterized by comparison of
its experimental and calculated (B3LYP/6-311þG**) IR spectrum.
Received 7 February 2008
Received in revised form 7 April 2008
Accepted 10 April 2008
Available online 12 April 2008
Dedicated to Professor Ernst-Ulrich
Wu¨rthwein on the occasion of his 60th
birthday
Ó 2008 Elsevier Ltd. All rights reserved.
Keywords:
Azides
Azirines
Formyl isocyanide
Matrix isolation
Nitriles
Photochemistry
1. Introduction
5 were published recently.14 In this paper, we report that the pho-
tolyses of such substances indeed furnish proof of intermediate 2-
It is well known that cyclic 1,2-diazidoethenes of type 1 or 1,2-
diazidobenzenes undergo thermal2–9 and photochemical2,3,10 deg-
radations to form the corresponding dicyano derivatives 4 (Scheme
1). Inordertorationalizethiscleavageprocess, several intermediates
were postulated.5–8 By photolysis of 1,2-diazidobenzene in an inert
matrix at low temperature, ortho-phenylene-bisnitrene was gener-
ated.10 However, beyond the case of 1,2-diazidobenzenes, 2-azido-
2H-azirines 2 and 3 are the most plausible intermediates for the
transformation of 1 to yield 4.11 Nevertheless, direct proof of such
intermediates had not yet been obtained. Most probably, 2 and 3
could not be observed spectroscopically due to their anti-Bredt
structures.12,13 It emerges that open-chain 1,2-diazidoethenes 5 may
lead to spectroscopically observable 2-azido-2H-azirines (Table 1).
Fortunately, the syntheses of the first representatives of compounds
azido-2H-azirines 6 and 7 in the transformation of 5 into cyano
compounds 8 and 9.
N3
N
X
N3
N3
X
Y
X
X
C
C
N
N
N
+
Y
Y
Y
N3
1
3
4
2
Scheme 1.
2. Results and discussion
2.1. Photolysis of 1,2-diazidoethenes in solution
When solutions of the diazides (E)/(Z)-5a, (E)/(Z)-5b, or (E)/(Z)-
5c in deuterated chloroform were irradiated at low temperature, 1H
NMR monitoring indicated the formation of the corresponding in-
termediates 6 and 7 with maximum total yields of 54–67% (Table 1).
These heterocyclic compounds were easily assigned by comparing
q
See Ref. 1.
* Corresponding authors. Fax: þ49 371 531 21229 (K.B.); fax: þ49 641 99 34309
(H.P.R.).
E-mail addresses: klaus.banert@chemie.tu-chemnitz.de (K. Banert), hans.p.
reisenauer@org.chemie.uni-giessen.de (H.P. Reisenauer).
0040-4020/$ – see front matter Ó 2008 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2008.04.037

5646
K. Banert et al. / Tetrahedron 64 (2008) 5645–5648
Table 1
2.2. Photolysis of (Z)-2,3-diazidocinnamaldehyde in argon
matrix
Photolysis of open-chain 1,2-diazidoethenes 5a
N3
R1
N
N3
R2
N
N3
R2
N3
R1
hν
hν
R1 CN
R2 CN
+
R1
+
When (Z)-5d was irradiated in argon matrix at 366 nm, the
R2
or 20 °C
CDCl3
–50 °C
precursor was consumed after 1 min and a 2-azido-2H-azirine was
formed (Scheme 2). However, the new IR absorptions at 2134, 1727,
1456, 1296, 1260, 830, 764, and 680 cmꢁ1 did not allow to distin-
guish between 6d and 7d or a mixture of both in the desired un-
ambiguous manner (Fig. 1).
7
5
8
6
9
Starting
material
R1
R2
Maximum
yield
of 6 (%)
Maximum
yield of 7
(%)
Yield
of 8 (%)
Yield
of 9 (%)
Further photolysis at 313 nm transformed the intermediate
heterocycles 6d and/or 7d completely into benzonitrile (8d) and
known19 formyl cyanide (9d) within 10 min (Fig. 1). The latter
species was identified by its IR absorptions at 2907, 2225, 1708,
1383, and 905 cmꢁ1 (Table 2, negative bands in the difference
spectrum shown in the center of Fig. 2).20 This result demands that
during low temperature irradiation of 5d in solution besides
(E)/(Z)-5a
(E)/(Z)-5bc
(E)/(Z)-5c
(Z)-5d
CH2S(O)Ph
CH2SO2Ph
CH2SO2Ph
Ph
H
H
Me
CHO
CHO
28b
26
28
0
39b
34
26
43
>80
>99
>99
37
>80
>99
>99
0
(Z)-5e
4-Cl–C6H4
0
33
30
0
a
Irradiation was conducted by using a high-pressure mercury lamp and moni-
tored by NMR spectroscopy at ꢁ40 to ꢁ50 ꢀC. All yields (%) were based on precursors
5 and calculated by utilizing an internal 1H NMR standard.
b
Mixture of two diastereomers.
Using the single isomers of (E)-5b and (Z)-5b or performing the photolysis of (E)/
c
(Z)-5b in CD2Cl2 at ꢁ80 ꢀC gave nearly the same results.
7d
their 1H and 13C NMR data with those of known 2H-azirines.15 For
example, the isomers 6c and 7c are unequivocally distinguishable
because the 1H NMR signals of alkyl groups in the 3-position of 2H-
azirines are shifted downfield whereas the corresponding signals of
alkyl groups in the 2-position resonate at relative high field.
On prolonged irradiation or warm-up of the NMR solutions to
20 ꢀC, good to excellent yields of the nitriles 8a, 8b (¼8c), 9a (¼9b),
and 9c were obtained.16 Thermal cleavage of 6c to give 8c and 9c
was significantly slower than the analogous reaction of isomeric 7c.
This can be explained by the known17 fact that 2H-azirines are
stabilized by donor substituents in 3-position and destabilized by
electron-withdrawing substituents in the same position. In the
latter case, the electron deficiency at C-3 is increased, and thus the
small-ring heterocycle should be more reactive and rich in energy
when compared to the other 2H-azirines. While methyl is obvi-
ously a donor, the sulfonylmethyl group has to be classified most
probably as a weak acceptor. This is in agreement with B3LYP/6-
311þG** computations, which indicated that 6b is lower in energy
by 3.2 kcal/mol in comparison to 7b. Experimental results sup-
ported these calculations because the NMR signals of 6c but not
those of 7c were detected when a solution of (E)/(Z)-5c was stored
at 20 ꢀC.
6d
8d
8d
8d
8d
8d
9d
9d
8d
800
9d
2400 2000 1800 1600 1400 1200 1000
Wavenumber cm-1
600
Figure 1. Top: calculated (B3LYP/6-311þG ) IR spectrum of azirine 7d. Middle: cal-
culated IR spectrum of azirine 6d. Bottom: difference-FTIR spectrum from the photo-
cleavage of azirines 6d and/or 7d (obtained by subtraction of the spectra after and
before irradiation with 313 nm for 10 min, positive signals resulting mainly from the
azirines).
**
Table 2
Computed (B3LYP/6-311þG**, harmonic approximation) and experimental (argon
matrix, 10 K) IR absorptions of formyl cyanide 9d
Sym.
Mode
Computationa
Experimentb
In the case of the diazides (Z)-5d and (Z)-5e, the aldehyde group
acts as a strong acceptor. Thus, B3LYP/6-311þG** computations
show that 6d is 13.9 kcal/mol higher in energy than 7d. Therefore,
after irradiation at low temperature, only 7d and 7e but not highly
unstable 6d or 6e were identified by NMR spectroscopy. The dis-
tinction between 6d,e and 7d,e succeeded unequivocally with the
help of the 1H and 13C NMR data of the formed heterocycles. The
aromatic nitriles 8d and 8e were the only final products verified by
the same method because formyl cyanide (9d¼9e) cannot be
characterized by NMR.18 Therefore, the photolysis of (Z)-5d was
investigated using matrix isolation techniques.
a0
a0
a0
a0
a00
a0
a0
a00
a0
CH str.
CN str.
CO str.
OCH def.
CH wag.
CC str.
OCC def.
NCC def.
NCC def.
2986.4 (37.5)
2332.0 (30.6)
1782.1 (170.6)
1406.3 (8.0)
1002.3 (0.1)
919.6 (104.2)
625.3 (1.0)
2906.9 (vw)
2225.2 (w)
1708.4 (s)
1382.7 (vw)
d
904.9 (s)
d
301.1 (1.4)
227.2 (14.3)
d
d
a
Band positions in cmꢁ1, intensities (km molꢁ1) in parentheses.
b
Band positions in cmꢁ1, intensities (vw: very weak, w: weak, s: strong, vs: very
strong) in parentheses.
hν
= 366 nm
argon matrix
15 K
hν
= 313 nm
N3
Ph
N3
6d and / or 7d
NC
CHO
– PhCN
CHO
9d
5d
hν
hν
> 310 nm
hν
=
=
295–420 nm
295–420 nm
hν
hν
H
N
C
C
O
H
NC + CO
12
CN
CHO
=
=
13
10
11
295–420 nm
295–420 nm
Scheme 2.

K. Banert et al. / Tetrahedron 64 (2008) 5645–5648
5647
products of this fragmentation, prolonged irradiation led to un-
known formyl isocyanide, which was identified unequivocally by
its IR spectrum measured in argon matrix.
4. Experimental
4.1. General
4.1.1. NMR studies and photolyses in solution
Caution should be exercised during handling of neat azides 5,
which may be explosive. 1H NMR spectra were recorded at
300 MHz and 13C NMR spectra at 75 MHz. Chemical shifts (
d) are
reported in parts per million (ppm) downfield from TMS. Coupling
constants (J) are given in hertz (Hz) and spin multiplicities are in-
dicated by the following symbols: s (singlet), d (doublet), t (triplet),
q (quartet), m (multiplet). The photolyses of the solutions of the
azides 5 were performed with a 150-W Hg high-pressure lamp
(polychromatic) TQ 150 from Heraeus GmbH. Quartz or glass
equipment was used for cooling the lamp with the help of an
ethanol cryostat (Lauda GmbH). Solutions of the substrates (60–
80 mg/mL) in normal NMR sample tubes were cooled in the same
way to ꢁ50 ꢀC or to ꢁ80 ꢀC while being irradiated. In order to get
good yields of the 2H-azirines by preventing unwanted photo-
chemical reactions, solutions in CDCl3 or CD2Cl2, which perhaps
function as UV filter, were utilized. In some cases, these solutions
were flushed with argon in an ultrasonic bath prior to irradiation to
exclude oxygen. Dioxane, silicone grease, or TMS was used as an
internal standard to determine the yields based on 1H NMR data.
Monitoring the photolyses by 1H NMR spectroscopy means that
spectra were recorded at low temperature, e.g., ꢁ40 to ꢁ50 ꢀC, after
a definite time of irradiation. In most cases, the starting material 5
was consumed after an irradiation time of 10–20 min.
Figure 2. Top: computed (B3LYP/6-311þG**) IR spectrum of formyl isocyanide (10).
Middle: difference-FTIR spectrum from the photoisomerization of formyl cyanide (9d)
into formyl isocyanide (10) (obtained by subtraction of the spectra before and after
irradiation with
l>310 nm for 19 h; crossed-out signals belong to matrix-isolated
traces of atmospheric CO2 and H2O). Bottom: computed IR spectrum of formyl cyanide
(9d).
benzonitrile (8d) also formyl cyanide (9d) must have been formed
but escaped detection by secondary reactions.
Prolonged irradiation with l>310 nm led to a mixture of 9d and
a new substance, which turned out to be unknown21 formyl iso-
cyanide (10). This assignment was based on IR absorptions at 2952,
2093, 1742, 1375, 938, and 619 cmꢁ1 (Fig. 2, Table 3), which corre-
late very convincingly with those from B3LYP/6-311þG** compu-
tation. Relative energies of relevant minima and transition states on
the C2HNO energy hypersurface can be taken from the literature.21
The intensity of the signals of 9d and 10 decreased and new
absorptions at 3503, 2030, and 585 cmꢁ1 resulting exclusively from
hydrogen isocyanide (12)22 and a band for carbon monoxide (11)
4.1.2. Photolyses in matrix
The cryostat used for the matrix isolation studies was an APD
Cryogenics HC-2 closed-cycle refrigerator system fitted with KBr
windows for IR measurements. IR spectra were recorded with
a Bruker IFS 55 FTIR spectrometer (4500–300 cmꢁ1, resolution
0.7 cmꢁ1) and UV/vis spectra with an Agilent HP 8453 Diode-Array
spectrometer. Matrix isolation of diazide 5d was achieved by slowly
subliming the substance from a glass tube at ca. 30 ꢀC onto the 10 K
cold matrix window and condensing a high excess of argon at the
same time. For irradiations either a mercury low-pressure spiral
lamp (Gra¨ntzel) with an interference filter (254 nm) or a mercury
high-pressure lamp (HBO 200, Osram) with a monochromator
(Bausch & Lomb) was used.
appeared when photolysis was continued with
l
¼295–420 nm.
Because no hydrogen cyanide (9a) was generated in this final step,
formation of intermediate formyl and cyano radicals is unlikely. A
possible option for the splitting of 10 into 11 and 12 may be a back
reaction 10/9d, followed by a 1,3-hydrogen shift 9d/13, and
decay of short-lived cumulene 1321 to yield 11 and 12.
Table 3
Computed (B3LYP/6-311þG**, harmonic approximation) and experimental (argon
matrix, 10 K) IR absorptions of formyl isocyanide 10
4.2. 2-Azido-2-phenylsulfinylmethyl-2H-azirine (6a) (mixture
of diastereomers)
Sym.
Mode
Computationa
Experimentb
a0
a0
a0
a0
a00
a0
a0
a00
a0
CH str.
NC str.
CO str.
OCH def.
CH wag.
CN str.
OCN def.
NCN def.
NCN def.
3040.2 (29.7)
2156.9 (400.7)
1805.7 (321.1)
1400.6 (8.4)
1020.1 (0.2)
958.6 (199.2)
632.3 (11.5)
202.2 (0.5)
2951.9 (vw)
2093.1 (vs)
1742.4 (s)
1374.9 (vw)
d
1H NMR (CDCl3, ꢁ40 ꢀC):
d
¼2.57 (d, 2J¼ca.13.5 Hz,1H, CH2), 2.97
(d, 2J¼ca. 13.8 Hz, 1H, CH2), 3.41 (d, 2J¼ca. 13.5 Hz, 2H, CH2), 7.50–
7.73 (m, 2ꢂ5H),10.45 (s, 1H, H-3), 10.60 (s,1H, H-3). 1H NMR (CDCl3,
937.9 (s)
618.8 (w)
d
19 ꢀC):
d
¼2.62 (d, 2J¼13.5 Hz,1H, CH2), 2.99 (d, 2J¼13.8 Hz,1H, CH2),
3.43 (d, 2J¼13.5 Hz,1H, CH2), 3.45 (d, 2J¼13.8 Hz,1H, CH2), 7.50–7.73
175.3 (4.3)
d
(m, 2ꢂ5H), 10.38 (s, 1H, H-3), 10.50 (s, 1H, H-3). 13C NMR (CDCl3,
ꢁ40 ꢀC):
¼45.95 (s, C-2), 46.52 (s, C-2), 61.01 (t, CH2), 63.78 (t,
d
a
Band positions in cmꢁ1, intensities (km molꢁ1) in parentheses.
b
Band positions in cmꢁ1, intensities (vw: very weak, w: weak, s: strong, vs: very
CH2), 123.40 (d, 2C), 123.64 (d, 2C), 129.43 (d, 2C), 129.50 (d, 2C),
132.08 (d, C–p-Ph), 132.14 (d, C–p-Ph), 140.89 (s, C–i-Ph), 141.67 (s,
C–i-Ph), 170.67 (d, C-3), 171.44 (d, C-3).
strong) in parentheses.
3. Conclusion
4.3. 2-Azido-3-phenylsulfinylmethyl-2H-azirine (7a) (mixture
In summary, we have demonstrated for the first time that
2-azido-2H-azirines are intermediates in the photochemical or
thermal transformation of vicinal vinyl diazides to yield cyano
compounds. In the case of formyl cyanide being one of the final
of diastereomers)
1H NMR (CDCl3, ꢁ40 ꢀC):
¼3.61 (s, 1H, H-2), 3.75 (s, 1H, H-2),
d
4.23 (d, 2J¼14.7 Hz, 2H), 4.44 (d, 2J¼14.7 Hz, 2H), 7.50–7.73 (m,

5648
K. Banert et al. / Tetrahedron 64 (2008) 5645–5648
2ꢂ5H). 1H NMR (CDCl3, 19 ꢀC):
d
¼3.59 (s, 1H, H-2), 3.67 (s, 1H, H-2),
4.9. 2-Azido-3-(4-chlorophenyl)-2-formyl-2H-azirine (7e)
4.24 (d, 2J¼14.7 Hz, 1H, CH2), 4.25 (d, 2J¼14.7 Hz, 1H, CH2), 4.38 (d,
2J¼14.7 Hz, 1H, CH2), 4.39 (d, 2J¼14.7 Hz, 1H, CH2), 7.50–7.73 (m,
1H NMR (CDCl3, ꢁ50 ꢀC):
d
¼7.63 (AA0BB0, 2H), 7.88 (AA0BB0, 2H),
2ꢂ5H). 13C NMR (CDCl3, ꢁ40 ꢀC):
d¼46.24 (d, C-2), 46.56 (d, C-2),
8.88 (s, 1H, CH]O). C NMR (CDCl3, ꢁ50 ꢀC):
d
¼59.25 (s, C-2),
13
52.45 (t, CH2), 53.56 (t, CH2), 123.67 (d, 2C),123.74 (d, 2C),129.43 (d,
2C), 129.50 (d, 2C), 131.61 (d, C–p-Ph), 131.70 (d, C–p-Ph), 140.38 (s,
C–i-Ph), 140.68 (s, C–i-Ph), 168.87 (s, C-3), 169.07 (s, C-3).
118.71 (s, C-10), 130.21 (d), 131.87 (d), 141.86 (s, C-40), 161.21 (s, C-3),
193.65 (d, CH]O).
Acknowledgements
4.4. 2-Azido-2-phenylsulfonylmethyl-2H-azirine (6b)
Joseph Rodolph Fotsing gratefully thanks the German Academic
Exchange Service (DAAD) for a generous fellowship.
1H NMR (CD2Cl2, ꢁ50 ꢀC):
d
¼3.07 (d, 2J¼14.8 Hz, 1H, H2C), 3.94
(d, 2J¼14.8 Hz, 1H, H2C), 7.72 (m, 3H), 8.00 (m, 2H, H–o-Ph), 10.41 (s,
References and notes
1H, H-3). 13C NMR (CD2Cl2, ꢁ50 ꢀC):
¼44.93 (s, C-2), 61.30 (t, H2C),
d
127.64 (d, 2C), 129.24 (d, 2C), 134.38 (d, C–p-Ph), 137.25 (s, C–i-Ph),
1. Part 23 of the series ‘Reactions of unsaturated azides’. For part 22, see Banert, K.;
168.56 (d, C-3).
Wutke, J.; Ru
¨ffer, T.; Lang, H. Synthesis, in press.
2. Banert, K. Angew. Chem. 1987, 99, 932–934; Angew. Chem., Int. Ed. Engl. 1987, 26,
879–885.
3. Banert, K. Chem. Ber. 1989, 122, 123–128.
4.5. 2-Azido-3-phenylsulfonylmethyl-2H-azirine (7b)
4. Pearce, D. S.; Lee, M.-S.; Moore, H. W. J. Org. Chem. 1974, 39, 1362–1368.
5. Pearce, D. S.; Locke, M. J.; Moore, H. W. J. Am. Chem. Soc. 1975, 97, 6181–6186.
6. VanAllan, J. A.; Priest, W. J.; Marshall, A. S.; Reynolds, G. A. J. Org. Chem. 1968, 33,
1100–1102.
1H NMR (CD2Cl2, ꢁ50 ꢀC):
d
¼3.84 (s, 1H, H-2), 4.70 (s, 2H, H2C),
13
7.72 (m, 3H), 8.00 (m, 2H, H–o-Ph). C NMR (CD2Cl2, ꢁ50 ꢀC):
7. Hall, J. H. J. Am. Chem. Soc. 1965, 87, 1147–1148.
d
¼46.23 (d, C-2), 53.36 (t, H2C), 128.04 (d, 2C), 129.30 (d, 2C), 134.82
8. Hall, J. H.; Patterson, E. J. Am. Chem. Soc. 1967, 89, 5856–5861.
9. Smolinsky, G.; Pryde, C. A. J. Org. Chem. 1968, 33, 2411–2416.
10. Nicolaides, A.; Nakayama, T.; Yamazaki, K.; Tomioka, H.; Koseki, S.; Stracener, L.
L.; McMahon, R. J. J. Am. Chem. Soc. 1999, 121, 10563–10572.
(d, C–p-Ph), 136.42 (s, C–i-Ph), 167.70 (s, C-3).
11. Monocyclic 2-azido-2H-azirines were produced by another method, see:
Gallagher, T. C.; Storr, R. C. Tetrahedron Lett. 1981, 22, 2905–2908.
12. For the ring strain in 2H-azirines, see: Wu¨rthwein, E.-U.; Hergenro¨ther, T.;
Quast, H. Eur. J. Org. Chem. 2002, 1750–1755.
13. For other 2,3-bridged 2H-azirines, see: Banert, K.; Meier, B. Angew. Chem., Int.
Ed. 2006, 45, 4015–4019; Angew. Chem. 2006, 118, 4120–4123.
14. Fotsing, J. R.; Hagedorn, M.; Banert, K. Tetrahedron 2005, 61, 8904–8909.
15. Review: Nair, V. The Chemistry of Heterocyclic Compounds, Small-Ring Hetero-
cycles; Hassner, A., Ed.; Wiley: New York, NY, 1983; Vol. 42, Part 1, pp 215–332.
16. All nitriles 8 and 9 are commercially available or known in literature in the case
of 9a: Kanemasa, S.; Matsuda, H.; Kamimura, A.; Kakinami, T. Tetrahedron 2000,
56, 1057–1064.
4.6. 2-Azido-3-methyl-2-phenylsulfonylmethyl-2H-azirine
(6c)
1H NMR (CDCl3, ꢁ40 ꢀC):
d
¼2.65 (s, 3H, Me), 2.92 (d, 2J¼14.7 Hz,
1H, H2C), 3.97 (d, 2J¼14.7 Hz, 1H, H2C), 7.60–7.80 (m, 3H), 7.91–8.03
(m, 2H, H–o-Ph). 13C NMR (CDCl3, ꢁ40 ꢀC):
¼13.88 (q, Me), 47.88
d
(s, C-2), 62.65 (t, H2C), 127.89 (d, 2C), 129.47 (d, 2C), 135.57 (d, C–p-
Ph), 137.89 (s, C–i-Ph), 173.36 (s, C-3).
17. Review: Gilchrist, T. L. Aldrichimica Acta 2001, 34, 51–55.
18. For unsuccessful attempts even at very low temperature, see: Valle´e, Y.; Ripoll,
J.-L.; Lacombe, S.; Pfister-Guillouzo, G. J. Chem. Res., Miniprint 1990, 401–412.
19. (a) Judge, R. H.; Moule, D. C.; Biernacki, A.; Benkel, M.; Ross, J. M.; Rustenburg, J.
J. Mol. Spectrosc. 1986, 116, 364–370; (b) Clouthier, D. J.; Moule, D. C. J. Am. Chem.
Soc. 1987, 109, 6259–6261; (c) Bogey, M.; Destombes, J. L.; Valle´e, Y.; Ripoll, J. L.
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4.7. 2-Azido-2-methyl-3-phenylsulfonylmethyl-2H-azirine
(7c)
1H NMR (CDCl3, ꢁ40 ꢀC):
¼1.58 (s, 3H, Me), 4.69 (s, 2H, H2C),
d
7.60–7.80 (m, 3H), 7.91–8.03 (m, 2H, H–o-Ph). 13C NMR (CDCl3,
ꢁ40 ꢀC):
¼20.20 (q, Me), 45.67 (s, C-2), 53.12 (t, H2C), 128.17 (d,
d
2C), 129.56 (d, 2C), 135.06 (d, C–p-Ph), 136.63 (s, C–i-Ph), 173.50 (s,
C-3).
4.8. 2-Azido-2-formyl-3-phenyl-2H-azirine (7d)
1H NMR (CDCl3, ꢁ50 ꢀC):
¼7.60–7.70 (m, 2H), 7.73–7.82 (m,
d
1H), 7.89–7.97 (m, 2H), 8.88 (s, 1H, CH]O). 13C NMR (CDCl3,
ꢁ50 ꢀC):
d
¼59.19 (s, C-2), 120.14 (s, C-10), 129.70 (d), 130.76 (d),
135.48 (d, C-40), 161.89 (s, C-3), 193.88 (d, CH]O). The 13C NMR data
and especially the d
values of C-10 and C-40 indicate clearly that the
phenyl group of 7d is bound to C-3 of the 2H-azirine ring, see for
comparison Ref. 23.