The first examples of cycloadditions of 2-diazo-1,3-dicarbonyl compounds to aromatic thioketones

Article abstract of DOI:10.1016/j.tetlet.2012.04.036

Acyclic 2-diazo-1,3-dicarbonyl compounds react at 20-50 ° with aromatic thioketones and through a cascade process, involving the cycloaddition of a diazo group dipole with the CS bond, elimination of nitrogen from the arising thiadiazoline, and subsequent

Full text of DOI:10.1016/j.tetlet.2012.04.036

Tetrahedron Letters 53 (2012) 3095–3099
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Tetrahedron Letters
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The first examples of cycloadditions of 2-diazo-1,3-dicarbonyl compounds
to aromatic thioketones
Valerij A. Nikolaev a, , Alexey V. Ivanov a, Anton A. Shakhmin a, Joachim Sieler b, Ludmila L. Rodina a
⇑
a Saint-Petersburg State University, University prosp. 26, St.-Petersburg 198504, Russia
b Universität Leipzig, Institut für Anorganische Chemie, Johannisallee 29, D-04103 Leipzig, Germany
a r t i c l e i n f o
a b s t r a c t
Article history:
Acyclic 2-diazo-1,3-dicarbonyl compounds react at 20–50 °C with aromatic thioketones and through a
cascade process, involving the cycloaddition of a diazo group dipole with the C@S bond, elimination of
nitrogen from the arising thiadiazoline, and subsequent [1,5]-electrocyclization of the intermediate
C@S-ylide, the relevant oxathioles being formed in yields of up to 70%. Carbocyclic 2-diazo-1,3-diketones
at room temperature react with thiones much more slowly, but with increasing temperature they partly
decompose to produce, via Wolff rearrangement, 2-oxoketenes, which yield [4+2]-cycloaddition prod-
ucts, that is oxathiinones and/or oxoketene dimers.
Received 14 February 2012
Revised 24 March 2012
Accepted 5 April 2012
Available online 16 April 2012
Keywords:
2-Diazo-1,3-diazocarbonyl compounds
Thioketones
Ó 2012 Elsevier Ltd. All rights reserved.
Oxathioles
Thiadiazoline
Thiocarbonyl ylides
2-Oxoketenes
Pyrandiones
Cycloaddition
1,5-Electrocyclization
Cycloaddition of aliphatic diazo compounds with unsaturated
compounds is well-known and is widely used for the preparation
of a variety of nitrogenous and other heterocycles.1–5 The most
reactive dipoles in these processes are diazoalkanes and 2-diazok-
etones, while the cycloaddition of 2-diazo-1,3-dicarbonyl com-
pounds with ordinary dipolarophiles is considered to be far less
common.6,7 To the best of our knowledge, detailed studies of cyclo-
addition reactions of diazodicarbonyl compounds have not been
conducted, and the literature data on this matter is somewhat
contradictory.
In pioneering work by Huisgen and Reissig, it was established
that diazomalonic ester and dibenzoyldiazomethane react easily
with the carbon–carbon triple and double bonds of dialkylpropyne
and an enamine to produce the standard [3+2]-cycloaddition prod-
ucts, pyrazoles, and pyrazolines, respectively.8,9 At the same time,
attempts to carry out the analogous reaction of dibenzoyldiazome-
thane and diazodimedone with DMAD failed.7
active superdipolarophiles in these reactions, that is thiobenzophe-
none, and only after the addition of Rh(II)-catalyst to the reaction
mixture, were the adducts of Ph2C@S with Rh(II)-carbenoids
formed. At the same time, we established13 that diazoacetylace-
tone, the first member of the acyclic diazodiketone series, reacts
with thiobenzophenone even at room temperature giving rise to
an oxathiole. The latter is the typical product of the reaction of dia-
zoketones with the C@S-bond of thiocarbonyl compounds.14,15
The main goal of our research was to perform a comprehensive
study of a variety of reactions of 2-diazo-1,3-dicarbonyl com-
pounds with aromatic thioketones, to elucidate the key features
of these processes, and to establish their feasibility for the prepara-
tion of oxathioles and other heterocyclic compounds.
Typical representatives of 2-diazo-1,3-dicarbonyl compounds of
different types were used in this study. These included acyclic dia-
zodiketones 1a–c, diazoketoester 1d, and carbocyclic diazodike-
tones 1e–h. As dipolarophiles, three aromatic thioketones were
used, thiobenzophenone 2a, 4,4’-dimethoxythiobenzophenone
2b, and thiofluorenone 2c, which are known to possess consider-
ably different reactivity in cycloaddition processes (Fig. 1).10
The reactions were carried out in benzene or toluene solutions
at various temperatures (18–23, 50 or 80 °C) depending on the
reactivity of the diazodicarbonyl compound.
Similar inconsistency was observed upon investigation of the
reactions of 2-diazo-1,3-dicarbonyl compounds with aromatic thi-
oketones (‘superdipolarophiles’10). According to recent results,11,12
diazomalonic ester and diazodimedone under standard reaction
conditions, do not interact with the C@S-bond of one of the most
It was found that acyclic diazo compounds 1a–d, even at stan-
dard temperatures (18–23 °C), reacted with thiobenzophenone 2a
to produce oxathioles as the sole reaction products (Scheme 1).16
⇑
Corresponding author at present address: 8 Linija 35, Apt. 5, St.-Petersburg
199004, Russia. Tel.: +7 812 323 10 68; fax: +7 812 428 69 39.
E-mail address: vnikola@VN6646.spb.edu (V.A. Nikolaev).
0040-4039/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.tetlet.2012.04.036

3096
V. A. Nikolaev et al. / Tetrahedron Letters 53 (2012) 3095–3099
O
O
O
R1
N2
R2
O
Ar
Ar
R2
R1
S
N2
1a-d
1e-h
2a-c
t-Bu
R1
=
1a, R1, R2 = Me,
2a, Ar = Ph
1b, R1 = Me, R2 = Et,
1c, R1, R2 = Ph,
2b, Ar = 4-MeOC6H4
R2
t-Bu
2c, Ar---Ar = fluoren-
1d, R1 = Me, R2 = OMe
ylidene
1e
1f
1g (cis)
1h (trans)
Figure 1. Structures of the diazodicarbonyl compounds 1a–h and thioketones 2a–c used in this study.
In the case of unsymmetrically substituted diazodicarbonyl com-
pound 1b (R1 = Me, R2 = Et), two regioisomeric oxathioles 3 and
30 were formed (15% and 25% yields, respectively), while with
methyl diazoacetate 1d, possessing acetyl and methoxycarbonyl
substituents on the diazo group, the reaction occurred regioselec-
tively giving rise to only one isomer of oxathiole 3d (R2 = OMe,
70%).
At 50 °C the rate of the reaction of the acyclic diazodiketones
1a,b with thiobenzophenone 2a increased by approximately seven
times, but the only reaction products (from 1H NMR spectroscopy)
under these conditions were still oxathioles 3 and 30, and their
yields remained essentially the same (54–56%) (Scheme 1).
Di(4-methoxy)thiobenzophenone 2b reacted with acyclic dia-
zodiketones 1a,b similarly to thiobenzophenone 2a to produce
oxathioles 4a,b and 4b0, however the reactions proceeded very
slowly.17 By contrast, the reactions of diazodiketones 1a,b with
thiofluorenone 2c were completed in 20–24 h, but the yields of
the corresponding oxathioles 5a,b and 50b were low (22–44%),18
apparently due to participation of this highly reactive thioketone
in side processes.19
Carbocyclic diazodiketones 1e–h were found to be far less reac-
tive than their acyclic analogues 1a–d at 18–23 °C.20 Increasing the
temperature to 80 °C notably speeded up the process, but partial
decomposition of diazodiketones 1e–h was observed, along with
side processes that gave rise to the formation (along with oxathioles
3e–h) of oxathiinones 6f–h and pyrandiones 7e–h (Scheme 2).
In the case of sterically overcrowded, and thermally the least
stable carbocyclic diazodiketones 1g,h (see below), the main reac-
tion products proved to be oxathiinones 6g,h and pyrandiones
7g,h.
The structures of isolated compounds 3a–h, 30b, 6f-h, 7e–g were
verified by 1H, 13C NMR and IR spectroscopy, and mass spectrome-
try.22 The most reliable indicators of the 1,3-oxathiolic structure
were the signals of the C@C–O carbon atoms of the heterocycle in
the 13C NMR spectra, which for most of the isolated oxathioles 3,
30 (except for 3d) were in a relatively narrow region of the spectra
at 111–114 ppm. The oxathiole 3d prepared from diazoketoester
1d had this signal at 102.0 ppm. The signals of the corresponding
carbon atoms of the oxathiinone system in compounds 6f–h were
observed at lower field (at 117–120 ppm).22 This allows reliable
discrimination of the oxathiole 3 and oxathiinone 6 structures from
13C NMR spectroscopic data.
The regioisomeric structures 3b and 30b were easily identified
by the locations of the signals of the CH3CO and CH3 groups in
the 1H and 13C NMR spectra. Thus, the acetyl group of isomer 3b
appeared at 2.38 and 31.0 ppm in the 1H and 13C NMR spectra
which were very close in value to the signals of the similar group
in oxathiole 3a (2.38, 30.5 ppm) obtained from diazoacetylacetone
1a. In contrast, the proton and carbon signals of the CH3 group on
the C@C double bond of isomer 30b (2.25, 16.0 ppm) were rather
close to those positions of the signals of the similar group in the
structure of 3a (2.26, 15.7 ppm).
The structures of a few key reaction products, oxathiole 3d and
oxathiinone 6f, were established unambiguously by X-ray crystal
structure analysis (Figs. 2 and 3).23
Thus, the main products from the reactions of acyclic diazodicar-
bonyl compounds 1a–d with aromatic thiones 2a–c were oxathi-
oles. According to the commonly accepted mechanism,14,15 as
applied to 2-diazo-1,3-dicarbonyl compounds A, the formation of
oxathioles B under standard conditions (rt, absence of a catalyst)
R1
Ar
O
O
Et
1a-d
R2
C6H6
Me
O
O
+
S
S
-N2
Ar2C=S
+
Ar
Ar
Ar
3'b, 4'b, 5'b
3a-d, 4a,b, 5a,b
Diazo
Yields of reaction
products (%) a
R1, R2
Temp (oC)
Time
compound
1a
1b
1c
1d
1a
1b
Me, Me
Me, Et
Ph, Ph
Me, OMe
Me, Me
Me, Et
18-23
18-23
18-23
18-23
50
7 d
7 d
62 d
62 d
24 h
30 h
53 (3a)
40 (3b+3'b; 1/1.7)
61 (3c)
70 (3d only)
54 (3a)
50
56 (3b+3'b; 1/1.7)
a Yield of isolated compounds.
Scheme 1. Reactions of acyclic diazodicarbonyl compounds 1a–d with thioketones 2a–c.

V. A. Nikolaev et al. / Tetrahedron Letters 53 (2012) 3095–3099
3097
O
O
O
O
R1
R1
R2
R2
R1
R2
R1
R2
C6H6, 80 oC
-N2
S
1e-h
+
Ph2C=S
S
+
Ph
+
Ph
Ph
O
O
O
O
Ph
3e-h
7e-h
6f-h
Yields of reaction products (%) a
Diazo
Time
(h)
R1, R2
compound
3e-h
15 (28)
27 (53)
8
6f-h
7e-h
b
1e
1f
-(CH2)3-
-CH2C(Me2)CH2-
cis-CH(t-Bu)CH2CH(t-Bu)-
trans-CH(t-Bu)CH2CH(t-Bu)-
60
100
1
–
22 (42)
11 (26)
50 c
8 (19)
24
1g
(14) d
1h
3
11
19(71)
a Yields determined by 1H NMR spectroscopy are given in brackets.
b Not isolated from the reaction mixture.
c Unseparable (by chromatography) mixture of two diastereoisomers.21
d One diastereoisomer according to 1H NMR spectroscopy. 21
Scheme 2. Reactions of carbocyclic diazodiketones 1e–h with thiobenzophenone 2a. (See above-mentioned references for further information.)
Rh-carbenoid)
E with the sulfur atom of the thiocarbonyl
group.14,15 Subsequent intramolecular 1,5-electrocyclization of
the thiocarbonyl ylide D formed will afford the same oxathioles
B (Scheme 3).
To clarify the possibility of thermal decomposition of the diazo-
dicarbonyl compounds and the probability of the ‘carbenic’ path-
way under the reaction conditions studied, the thermal stability of
a series of 2-diazo-1,3-dicarbonyl compounds 1 was estimated.25
It turned out that all the diazodicarbonyl compounds 1a, c–e, g,
h studied were relatively stable in benzene at 18–20 °C, and
according to 1H NMR data, did not undergo notable decomposition
or other changes over a few months under these conditions [s1/2
(18–23 °C) >> 3 months]. On raising the temperature to 50 °C, dia-
zoacetoacetic ester 1d, diazocyclohexanedione 1e and diazodime-
done 1f also remain unchanged for months. The least stable at
elevated temperatures, as was to be expected from literature
data,26,27 were acyclic 1a–c and sterically crowded diazodiketones
1g,h, with lifetimes of 32–96 h and 0.7–2.3 h at 50 and 77 °C,
correspondingly.
Figure 2. ORTEP-generated24 structure of oxathiole 3d.23 The ellipsoids denote 50%
probability.
The data obtained enabled us to conclude that at standard tem-
peratures (18–23 °C) the formation of oxathioles D from diazodi-
carbonyl compounds
A and thioketones Ar2C@S occured via
cycloaddition of the diazo compounds with the C@S bond of the
thiones (Scheme 3), and not via the initial decomposition of diazo
compound A and the generation of the intermediate thiocarbonyl
ylides D via diacylcarbene E. At the same time, on the basis of
the experimental data in hand we cannot rule out completely the
possibility of the ‘carbenic’ pathway (Scheme 3) at elevated tem-
peratures (>50 °C).
The formation of oxathiinones 6f–h and pyrandiones 7e–h (in
addition to oxathioles 3e–h) in the reactions of carbocyclic diazo-
diketones 1e–h at 80 °C is evidently caused by partial decomposi-
tion and Wolff rearrangement of the diazodiketones 1e–h at
elevated temperature, which gives rise to the appearance of 2-oxo-
ketenes F in the reaction medium (Scheme 4).28,29
Ketene F reacts either with thioketone 2a or with the other
molecule of acylketene, and through Diels–Alder [4+2]-cycloaddi-
tion with the C@S bond of the thioketone or C@C bond of the ke-
tene molecule, oxathiinones 6f–h, and pyrandiones 7e–h are
formed.
Figure 3. ORTEP-generated24 structure of oxathiole 6f.23 The ellipsoids denote 50%
probability.
can be rationalized via the initial cycloaddition of the diazo group
dipole with the C@S bond of the thioketone giving rise to thiadiaz-
oline C, which is usually extremely unstable. This eliminates a mol-
ecule of N2, and following 1,5-electrocyclization ([1,5]-EC) of the
resulting thiocarbonyl ylide D, the oxathiole B is formed (Scheme 3).
At elevated temperatures or on Rh-catalyzed decomposition of
diazodicarbonyl compound A in the presence of the thioketone,
the generation of the C@S-ylide D is also possible via an alternative
pathway—owing to interaction of the assumed diacylcarbene (or
In summary, we have established for the first time that acyclic
and carbocyclic 2-diazo-1,3-dicarbonyl compounds 1a–h react at
18–23 °C with aromatic thioketones 2a–c via a cascade process,

3098
V. A. Nikolaev et al. / Tetrahedron Letters 53 (2012) 3095–3099
R1
N
R2
r.t.
O
O
+ Ar2C=S
R1
+
R2
R1
R2
S
R1
R2
_
Ar
-N2
N
[1,5]-EC
O
O
O
or
catalyst
O
Ar
O
O
S
Ar
S
C
Ar
+ Ar2C=S
N2
-N2
Ar
Ar
Diacylcarbene
or carbenoid
B
D
A
E
Scheme 3. Two pathways for the formation of oxathioles B from diazodicarbonyl compounds A.
O
R1
C
80 oC
-N2
+ 2a, 80 oC
+ 2a or F
1e-h
6f-h
7e-h
3e-h
+
R2
O
F
Scheme 4. Two directions for the transformations of carbocyclic diazodiketones 1e–h at 80 °C.
to react at a distinct temperature until complete conversion of the thione 2 as
indicated by the disappearance of thioketone colour and TLC. The solvent was
removed and the residue was recrystallized from an appropriate solvent or
separated by column chromatography.
involving the cycloaddition of the diazo group dipole with the C@S
bond, elimination of nitrogen from the intermediate thiadiazoline,
and ensuing [1,5]-electrocyclization of the resultant C@S-ylide, to
give oxathioles in yields of up to 70%.
17. The yields of oxathioles 4a,b and 40b from thioketone 2b and diazodiketones
1a,b over 28 days were only 4–5% (according to 1H NMR spectroscopy).
18. The yields of oxathioles 5a,b and 50b in the reaction of thiofluorenone 2c with
diazoacetylacetone 1a and diazopropionylacetone 1b were 22–44%, presumably
due to side reactions of thiofluorenone, i.e. dimerization, oxidation, and hydrolysis.
19. Scheibye, S.; Shabana, R.; Lawesson, S.-O.; Romming, C. Tetrahedron 1982, 38,
993.
The carbocyclic 2-diazo-1,3-diketones react more slowly than
their acyclic counterparts. Also, incorporation of an electron-
donating group at the para position of the aryl ring of the thioke-
tone diminishes considerably the efficiency of the addition of the
diazodicarbonyl compounds to the C@S bond of the thione.
On increasing the temperature, the rate of cycloaddition of the
diazodicarbonyl compound increases considerably, but with carbo-
cyclic 2-diazo-1,3-diketones, partial thermolysis, and Wolff rear-
rangement occurs resulting in the generation of 2-oxoketenes,
that leads via [4+2]-cycloaddition to the formation of oxathiinones
and/or oxoketene dimers.
20. After 3 months at 18–23 °C the reaction mixture of diazocyclohexanedione 1e
and thiobenzophenone 2a, according to 1H NMR data contained only 8–10% of
oxathiole 3e. In the reaction of diazodimedone 1f and sterically crowded
diazodiketones 1g,h with thioketone 2a over the same period of time, no
evidence of any reaction was observed.
21. Nikolaev, V. A.; Korneev, S. M.; Terent’eva, I. V.; Korobitsyna, I. K. J. Org. Chem.
USSR 1991, 27, 1845.
22. Characterisation data for representative examples of compounds 3 and 6. 4-
Acetyl-5-methyl-2,2-diphenyl-1,3-oxathiole (3a). Colourless crystals, mp 54–
56 °C (from MTBE). Rf 0.45 (PE/MTBE, 2:1). UV (in MeOH), kmax. (lge): 283
(3.14), 332 (3.26). IR (THF, 0.03 M), cmꢀ1 (Irel., %): 1679 (53), 1649 (30), 1592
(100), 1449 (42), 1362 (30), 1271 (35), 981 (24), 701 (57). 1H NMR (CDCl3,
300 MHz): d 7.54–7.46 (m, 4H, Ph), 7.39–7.28 (m, 6H, Ph), 2.38 (s, 3H, CH3CO),
2.26 (s, 3H, CH3C@C) ppm. 13C NMR (CDCl3, 75 MHz): d 191.3 (C@O), 157.1 (O–
C@C), 142.9, 128.5, 128.2, 126.4 (all CAr), 112.6 (C@C–O), 101.1 (CPh2), 30.5
(CH3C@O), 15.7 (CH3C@C) ppm. MS (ESI), m/z: 297 [M+H]+, 319 [M+Na]+, 335
[M+K]+. Anal. Calcd for C18H16O2S: C, 72.94; H, 5.44. Found: C, 72.81; H 5.41.
Methyl 5-methyl-2,2-diphenyl-1,3-oxathiole-4-carboxylate (3d). Colourless
crystals, mp 72–73 °C (from PE). Rf 0.42 (PE/MTBE, 3:1). UV (in MeOH), kmax
References and notes
1. (a) Huisgen, R. Angew. Chem. 1955, 67, 439–463; (b) Huisgen, R. In 1,3-Dipolar
Cycloaddition Chemistry; Padwa, A., Ed.; Wiley: New York, 1984; Vol. 1, pp 1–
176.
2. Korobizina, I.; Rodina, L. L. In Methodicum Chimicum; Georg Thieme: Stuttgart,
1974; Vol. 6, pp 260–307.
3. Regitz, M.; Heydt, H. In 1,3-Dipolar Cycloaddition Chemistry; Padwa, A., Ed.;
Wiley: New York, 1984; Vol. 1, pp 393–558.
nm (lge
): 246 (3.44), 272 (3.42), 278 (3.43), 311 (3.44). IR (THF, 0.03 M), cmꢀ1
(Irel., %): 1713 (100), 1629 (68), 1284 (57), 787 (13), 759 (35), 724 (49), 700
(44). 1H NMR (CDCl3, 300 MHz): d 7.52–7.44 (m, 4H, Ph), 7.38–7.29 (m, 6H, Ph),
3.72 (s, 3H, OCH3), 2.38 (s, 3H, CH3C@C) ppm. 13C NMR (CDCl3, 75 MHz): d
163.5 (CO), 158.4 (O–C@C), 142.9, 128.4, 128.1, 126.3 (all CAr), 101.8, 101.1
(C@C–O, CPh2), 51.7 (OCH3), 14.7 (CH3C@C) ppm. MS (ESI), m/z (Irel., %): 281.06
(38) [M–OCH3]+, 313.09 (100) [M+H]+, 330.11 (13) [M+18]+, 335.07 (19)
[M+Na]+, 351.04 (15) [M+K]+. Anal. Calcd for C18H16O3S: C, 69.21; H, 5.16.
4. Zollinger, H. Diazo Chemistry II; VCH: Weinheim, 1995. pp 191–240.
5. Maas, G. In Padwa, A., Ed.; The Chemistry of Heterocyclic Compounds; Wiley:
New York, 2002; Vol. 59, pp 539–622.
6. Huisgen, R.; Grashey, R.; Sauer, J. In Alkene Chemistry; Patai, S., Ed.; Wiley: New
York, 1964; pp 806–977.
7. (a) Korobitsyna, I. K.; Bulusheva, V. V.; Rodina, L. L. Chem. Heterocycl. Compd.
1978, 471; (b) Bulusheva, V. V. Ph.D. Dissertation; Leningrad University, 1975.
8. Huisgen, R.; Reissig, H.-U. Angew. Chem., Int. Ed. Engl. 1979, 18, 330.
9. Huisgen, R.; Reissig, H.-U. Angew. Chem., Int. Ed. Engl. 1981, 20, 694.
10. Huisgen, R.; Langhals, E. Tetrahedron Lett. 1989, 30, 5369.
11. Mloston´ , G.; Heimgartner, H. Helv. Chim. Acta 1996, 79, 1785.
Found:
C,
69.39;
H
5.34.
cis-5,7-Di-tert-butyl-2,2-diphenyl-6,7-
dihydrocyclopenta[e][1,3]oxathiin-4(5H)-one (6g). Yellowish crystals, mp 152–
153 °C (from PE). Rf 0.34 (PE/acetone, 1.5:1). 1H NMR (CDCl3, 300 MHz): d 7.68–
7.65 (m, 4H, Ph), 7.38–7.33 (m, 6H, Ph), 2.79–2.77 (m, 2H, CH2), 1.88 (m, 1H,
CH), 1.27 (m, 1H, CH), 0.99 (s, 9H, t-Bu), 0.67 (s, 9H, t-Bu) ppm. 13C NMR (CDCl3,
75 MHz): d 182.8 (C@O), 174.4 (C@C–O), 142.2, 140.5, 129.7, 129.6, 128.9,
128.8, 128.3, 126.6 (C Ar); 119.5 (C@C–O), 96.8 (CPh2), 54.8, 48.9 (2 C t-Bu),
35.5, 33.9 (2 CMe3), 28.2, 28.8 (CH3), 24.3 (CH2) ppm. MS, m/z, (Irel., %): 420 (6)
[M]+, 341 (11), 222 (43), 221 (23), 198 (51), 182 (98), 151 (31), 137 (51), 109
(49), 105 (100), 69 (77), 41 (>100), 39 (49).
´
12. Kelmendi, B.; Mloston, G.; Heimgartner, H. Heterocycles 2000, 52, 475.
13. Ivanov, A. V.; Rodina, L. L.; Nikolaev, V. A. Abstracts of Papers, Vth International
Symposium ‘Chemistry of Aliphatic Diazo Compounds’ (Diazo-2011), Saint-
Petersburg, Russia, Jun 6–8, 2011; p 64.
14. (a) Ibata, T.; Nakano, H. Chem. Express 1989, 4, 93; (b) Ibata, T.; Nakano, H. Bull.
Chem. Soc. Jpn. 1990, 63, 3096; (c) Nakano, H.; Ibata, T. Bull. Chem. Soc. Jpn.
1993, 66, 238; (d) Nakano, H.; Ibata, T. Bull. Chem. Soc. Jpn. 1995, 68, 1393.
23. Single crystals of compounds 3d and 6f suitable for X-ray diffraction were
selected from analytical samples. Crystallographic measurements were made
using an IPDS1 diffractometer [Fa. STOE, Darmstadt, graphite monochromated
´
15. (a) Mloston, G.; Heimgartner, H. In Padwa, A., Ed.; The Chemistry of
Heterocyclic Compounds; Wiley: New York, 2002; Vol. 59, pp 315–360; (b)
Mloston´ , G.; Heimgartner, H. Curr. Org. Chem. 2011, 15, 675.
16. General procedure for the reaction of diazo compounds 1 with thioketones 2: To a
stirred solution of freshly prepared thioketone 2 (2–4 mmol) in 2–5 ml of
benzene (or toluene), diazo compound 1 (5–10% excess) was added in one
portion. Argon was bubbled through the reaction mixture and it was allowed
MoKa radiation (k 0.71073 Å)]. The structures were solved by direct methods
using the program SIR200230 and were refined using anisotropic
approximation for the non-hydrogen atoms using SHELX-90.31 All hydrogen
atoms were calculated and refined in riding modus. CCDC 865469 for 3d and
CCDC 865470 for 6f contain the supplementary crystallographic data. These

V. A. Nikolaev et al. / Tetrahedron Letters 53 (2012) 3095–3099
3099
data can be obtained free of charge via www.ccdc.cam.ac.uk/data_request/cif
from the Cambridge Crystallographic Data Centre.
24. Johnson, C. K. ORTEP II, Report ORNL-5138; Oak Ridge National Laboratory: Oak
Ridge, TN, 1976.
27. Popik, V. V.; Nikolaev, V. A. J. Chem. Soc., Perkin Trans. 2 1993, 1971.
28. (a) Tidwell, T. T. Ketenes II; Wiley: Hoboken, 2006; (b) Wentrup, C.; Heilmayer,
W.; Collenz, G. Synthesis 1994, 1219.
29. (a) Stetter, H.; Kiehs, K. Chem. Ber. 1965, 98, 1181; (b) Verschambre, H.; Vocelle,
D. Can. J. Chem. 1969, 47, 1981; (c) Nikolaev, V. A.; Frenkh, Yu.; Korobitsyna, I.
K. J. Org. Chem. USSR 1978, 14, 1069.
25. A solution of diazo compound 1 in CCl4 was placed in tightly-closed thick-
walled glass flask or in
a sealed glass ampoule and kept at a certain
temperature over the required time. The kinetic measurements of the
thermal decomposition of diazo compounds were carried out using IR
spectroscopy.
30. Burla, M. C.; Camalli, M.; Carrozzini, B.; Cascarano, G. L.; Giacovazzo, C.;
Polidori, G.; Spagna, R. J. Appl. Crystallogr. 2003, 36, 1103.
31. Sheldrick, G. M. Acta Crystallogr., Sect. A 1990, 46, 467.
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Diazo Compounds. Properties and Synthesis; Academic Press: Orlando-Toronto,
1986.