Thermolysis of 4-diazotetrahydrofuran-3-ones: Total change of reaction course compared to photolysis

Article abstract of DOI:10.1002/ejoc.201400161

Thermolysis of 2,2,5,5-tetrasubstituted 4-diazodihydrofuran-3-ones in protic (BnOH) and aprotic (DMSO) media, in contrast to photolysis, gives rise to the formation of 2,2,4,5-substituted 3(2H)-furanones as a result of 1,2-alkyl (aryl) shift. The thermal

Full text of DOI:10.1002/ejoc.201400161

Job/Unit: O40161
/KAP1
Date: 02-04-14 16:39:15
Pages: 9
FULL PAPER
DOI: 10.1002/ejoc.201400161
Thermolysis of 4-Diazotetrahydrofuran-3-ones: Total Change of Reaction
Course Compared to Photolysis
Ludmila L. Rodina,[a] Jury J. Medvedev,[a] Olesia S. Galkina,[a] and Valerij A. Nikolaev*[a]
Keywords: Thermolysis / Photolysis / Rearrangement / Oxygen heterocycles / Diazo compounds / Carbenes / Reactive
intermediates
Thermolysis of 2,2,5,5-tetrasubstituted 4-diazodihydrofuran-
3-ones in protic (BnOH) and aprotic (DMSO) media, in con-
trast to photolysis, gives rise to the formation of 2,2,4,5-sub-
notably reduce the persistence of diazodihydrofuranones,
whereas aryl groups and electron-withdrawing substituents
increase their stability considerably. Thermolysis of substi-
stituted 3(2H)-furanones as a result of 1,2-alkyl (aryl) shift. tuted 4-diazodihydrofuran-3-ones in DMSO solution is a
The thermal stability of diazodihydrofuranones in these pro-
cesses is determined by the nature of the substituents at the
C-5 atom of the heterocyclic structure: alkyl and electron-
donating groups in the para-position of the aryl substituent
first-order reaction that furnishes higher yields of furanones
than thermolysis in BnOH. The reaction can serve as a pre-
parative method for the synthesis of tetrasubstituted-3(2H)-
furanones.
ferent. Thus, photolysis of the alkyl-substituted diazodi-
hydrofuran-3(2H)-ones produced the Wolff rearrangement
Introduction
Photochemical and thermal reactions of carbo- and products B (oxetanecarboxylic acids or their derivatives) al-
heterocyclic diazo ketones are widely used in organic syn- most quantitatively,[1e,5] whereas in the case of the 2- and/
thesis during the preparation of natural, biologically active or 5-aryl-substituted analogues, formation of hydrazones C
compounds, and in the other fields.[1] Most prominent is took place along with the Wolff rearrangement and other
their role in processes that involve the Wolff rearrangement photochemical reaction products (Scheme 1).[6]
and ring contractions as the central steps, which give access
In contrast, on thermolysis of similar diazodi-
to a variety of useful compounds, strained ring systems, and hydrofuran-3(2H)-ones, the reaction course changes com-
unusual structures that are difficult to access by other pletely. In this case, instead of the Wolff rearrangement or
means.[1–3]
reactions with retention of the “dinitrogen” of the di-
Frequently, thermolysis and photolysis of the cyclic diazo azogroup, a 1,2-shift of the alkyl or aryl group is observed,
ketones furnish the same Wolff rearrangement prod- with formation of the corresponding 3(2H)-furanones.
ucts[1a,1b,1d,2a,4] and, in this context, one would expect that
The main goal of the present study was to establish the
diazo ketones of the tetrahydrofuran series would react in common themes underlying the thermolysis of 2,2,5,5-tetra-
these processes in a similar manner. However, it turned out substituted 4-diazodihydrofuran-3(2H)-ones in protic and
that the direction of photochemical and thermal reactions aprotic media and to elucidate the synthetic potential of
of 4-diazodihydrofuran-3(2H)-ones A is fundamentally dif- such reactions.
Scheme 1. Main directions of photochemical reactions of 4-diazotetrahydrofuran-3(2H)-ones.
[a] Department of Chemistry, Saint-Petersburg State University,
To estimate scope and limitations of the processes, seven 4-
diazodihydrofuran-3(2H)-ones 1, 2a–c, and 3a–c with dif-
ferent general structures were selected. The selected sub-
strates varied in the nature of the substituents at the α-posi-
University prosp. 26, 198504 Saint-Petersburg, Russia
E-mail: vnikola@VN6646.spb.edu
http://chem.spbu.ru/org/989-rodina_nikolaev_group.html
Supporting information for this article is available on the
WWW under http://dx.doi.org/10.1002/ejoc.201400161.
Eur. J. Org. Chem. 0000, 0–0
© 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
1

Job/Unit: O40161
/KAP1
Date: 02-04-14 16:39:15
Pages: 9
L. L. Rodina, J. J. Medvedev, O. S. Galkina, V. A. Nikolaev
FULL PAPER
tion to the diazo group (alkyl or aryl for regioisomers 2 and from the reaction mixtures at regular intervals being ana-
1
3, respectively), as well as in the electronic effects of the lyzed by H NMR spectroscopy. Based on the analytical
para-substituents of the aryl groups (MeO, H or F) (Fig- data obtained, half-life times (τ1/2) of decomposition of di-
ure 1).
azo ketones 1–3 were calculated;[1a,7] the results are summa-
rized in Table 1 and the original kinetic data are given in
the Supporting Information.
Analysis of the kinetic data led to the following conclu-
sions: (1) the measured decrease of concentration of diazo
ketones 1–3 with time fits the first-order rate law; (2) diazo
ketones 3a–c, bearing aryl groups next to the diazocarbon
atom (Table 1, entries 5–7), are much more stable than their
regioisomers 2a–c and diazo ketone 1 (entries 1–4), with
alkyl (methyl) substituents adjacent to the diazo group. Par-
ticularly high thermal stability was observed in the case of
diazo ketone 3c, possessing a para-fluoro-substituted aryl
group on the C-5 atom of the heterocycle (τ1/2 at 160 °C of
5.8 h; entry 7).
As part of the analytical procedure, separation of the re-
action mixtures and identification of the reaction products
was accomplished. The structures of the reaction products
4–7 formed were established based on spectroscopic and an-
alytical information, as well as on comparison with litera-
ture data.[6b,8b]
The main products of thermal decomposition of diazo
ketones 1–3 were found to be 3(2H)-furanones 4–6. With
diazo ketones 1 and 2a–c, migration of one of the methyl
groups at C-5 takes place to produce 4,5-dimethyl-3(2H)-
furanones 4 and 5a–c, respectively, in yields of 67–82% (81–
87% based on reacted diazo ketone 1 or 2). Thermolysis of
the regioisomeric diazo ketones 3a–c led to 1,2-migration
of one of the aryl groups at C-5 of the heterocycle to give
4,5-diaryl-3(2H)-furanones 6a–c with yields of 33–98%
(75–99% based on reacted diazo ketone 3).
Figure 1. Starting diazo ketones 1, 2a–c, and 3a–c.
Because the direction of reactions of diazocarbonyl com-
pounds in protic and aprotic media are often quite dif-
ferent,[1] the thermal reactions of diazofuranones 1–3 were
studied in two solvents – benzyl alcohol (nucleophilic protic
solvent) and dimethyl sulfoxide (DMSO; dipolar aprotic
solvent).
Results and Discussion
Early investigations had shown that diazo ketones 1–3 of
the tetrahydrofuran series exhibit unusually high stability
for diazo compounds.[1a,7] Thus, heating a solution of diazo
ketone 3b in dioxane at reflux for many hours (ca. 100 °C,
Ͼ 20 h) does not cause notable decomposition, and ther-
molysis of diazo ketone 1 at 150–160 °C for 30 h (without
solvent) initiates only minor levels of decomposition with
the formation of the azine of 2,2,5,5-(tetramethyl)tetra-
hydrofuran-3,4-dione[8a] and 2,3-dihydro-2,2,4,5-tetrameth-
ylfuran-3-one 4[8b] (with yields of 6 and 4%, respectively,
1
based on H NMR spectroscopic analysis). In this context,
to elucidate the relative stability of diazo ketones 1–3 and to
select appropriate conditions for effective thermolysis, the
kinetics of their thermal decomposition was initially
studied.
After thermolysis of diazo ketones 2b and 3b, α-diketone
7b was isolated by using preparative TLC along with fur-
anones 5b and 6b. The formation of 7b was easily identified
by the pink color of the reaction mixture and by the appear-
Thermolysis of Diazo Ketones 1–3 in DMSO
ance of signals arising from the methyl groups of the diket-
1
Kinetics of the thermolysis of diazo ketones 1–3 was one 7b at δ = 1.41 ppm in the H NMR spectra (in CDCl3
studied in [D6]DMSO at 160Ϯ0.5 °C, with samples taken solution).
Table 1. Selected kinetic data obtained upon thermolysis of diazo ketones 1–3.
Entry
Diazo ketone R1
R2
t [h]
τ1/2 [h]
Content in reaction mixture [%][a]
4–6
2, 3[b]
1
2
3
4
5
6
7
1
Me
p-MeO-C6H4
Ph
p-FC6H4
Me
Me
Me
Me
Me
Me
Me
p-MeO-C6H4
Ph
p-FC6H4
2
4
4
3
5.3
4
6
0.1
0.7
0.5
0.8
1
2.3
5.8
4; 82
5a; 80 (87)
5b; 81
5c; 67 (81)
6a; 98 (99)
6b; 46 (78)
6c; 33 (75)
–
2a
2b
2c
3a
3b
3c
2a; 8
–
2a; 17
3a; ca. 1
3b; 41
3c; 56
[a] The yields of furanones 4–6 based on reacted diazo ketone are given in parentheses. [b] The content of the initial diazo ketones 2 and
3 in the reaction mixture.
2
www.eurjoc.org
© 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 0000, 0–0

Job/Unit: O40161
/KAP1
Date: 02-04-14 16:39:15
Pages: 9
Thermolysis of 4-Diazotetrahydrofuran-3-ones
Summing up the obtained kinetic data, the investigated structure of isomers 2a–c there is a weak interaction be-
4-diazodihydrofuran-3-ones 1–3 can be placed in the fol- tween the ortho-aryl protons and the oxygen atom of the
lowing order of increasing stability at 160 °C in DMSO carbonyl group,[10,11] which could result in an increased
solution (the associated values of τ1/2 are given in parenthe- contribution of the structure of the “diazo-anhydride” to
ses):
the resonance hybrid of diazo molecule 2, thus reducing the
stability of these diazo ketones.[1a]
1 (0.1 h) Ͻ 2a–c (0.5–0.8 h) Ͻ 3a (1 h) Ͻ 3b (2.3 h) Ͻ 3c (5.8 h)
Similar intramolecular interactions in the structure of the
It is evident from these data that diazo ketones 3a–c, regioisomeric diazo ketones 3 are not possible, and they
with α-aryl substituents on diazo group, are much more proved to be more thermally stable than regioisomers 2a–c.
stable than their 5,5-dimethyl-substituted analogues 2a–c.
The appearance in the reaction mixture of α-diketone 7b
In the former case, a negative inductive effect of the para- during thermolysis of diazo ketones 2b and 3b can be ex-
substituent on the aryl group is clearly defined: the greater plained by “oxidation” of intermediate α-oxocarbenes with
the –I effect of the substituent (for example with 3c), the DMSO according to Scheme 3. Thus, interaction of the sin-
more stable is the associated diazo ketone. At the same glet oxocarbenes E (generated upon thermolysis of diazo
time, incorporation of the aryl substituents in the α-position ketones 2 and 3) with the oxygen atom of DMSO leads to
to the C=O group in the case of diazo ketones 2a–c con- formation of intermediate sulfoxonium ylide F, and subse-
siderably reduces the stability of these diazo compounds.
quent fragmentation of the latter gives rise to α-diketone 7b
The effect of the nature of the para-substituent on the accompanied by elimination of Me2S.
aryl ring on the rate of thermal decomposition of diazo
ketones 3a–c, which is consistent with the sequence OMe
Ͼ H Ͼ F, can be explained as follows (Scheme 2). In line
with the known mechanism,[9] migration of substituents in
the course of 1,2-nucleophilic rearrangements takes place
through transition state D, which, to a large extent, governs
the activation energy of the decomposition process and,
Scheme 3. Postulated pathway for the formation of α-diketone 7b
upon thermolysis in DMSO.
thus, the stability of the diazo ketones under investigation.
Examples of “oxidation” of the diazo group and related
carbenes upon decomposition of diazo compounds in the
presence of oxygen donors are well-known in the chemistry
of carbenes.[12]
Scheme 2. Postulated pathway for 1,2-aryl migration on thermoly-
sis of 5,5-diarylsubstituted diazofuranones 3a–c.
It is evident that para-substituents with a +M effect (such
as a methoxy group) should reduce the energy of transition
state D and, consequently, should decrease the stability of
Thermolysis of Diazo Ketones 2a–c and 3a–c in BnOH
Thermolysis of diazo ketones 2a–c and 3a–c in BnOH
diazo ketone 3a. In contrast, the presence of an electron- solution was also carried out at 160Ϯ1 °C. On completion
withdrawing group (such as a para-fluoro substituent) leads of experiment, benzylic alcohol was removed in vacuo and
to an increase in the energy of transition state D and, ac- the composition of the reaction mixture was analyzed by
1
cordingly, an increase in the persistence of diazo ketone 3c. using H NMR spectroscopy. Generally, 3(2H)-furanones 5
These assumptions correlate well with the experimental and 6 were also identified as the main decomposition prod-
data, which show that the τ1/2 of diazo ketone 3c is 2.5 times ucts of diazo ketones 2 and 3 in BnOH solution, however,
higher than for 3b, and almost six times more than the half- the yields of these unsaturated ketones in this case were
life of diazo ketone 3a (Table 1).
usually lower than upon thermolysis in DMSO (Table 2).
To explain the pronounced difference in thermal stability Furthermore, along with furanones 5 and 6, in a few experi-
of the regioisomeric diazo ketones 2 and 3, it is suggested ments the formation of substantial amounts of dihydro-
that two α-alkyl (Me) groups with +I effect in the structure furan-3(2H)-ones 8b,c and 9b,c was observed, which were
of regioisomers 2 notably enhance a partial negative charge isolated from reaction mixtures. The maximum yield of the
on the adjacent diazo carbon atom, resulting in the expect- mono ketone (9c) was obtained upon thermolysis of the
ed[1a,9] decrease in the stability of diazo ketones 2. In the most stable diazo ketone 3c (31%; entry 7).
case of regioisomers 3, the two aryl substituents in the α-
The formation of mono ketones 8 and 9 during thermol-
position to the diazo group induce the opposite –I effect, ysis of diazo ketones 2 and 3 can be explained through the
and this, presumably, causes the considerable variation in double hydrogen abstraction from solvent by triplet oxo-
the thermal stability of diazo ketones 2 and 3 observed.
carbenes G, which appeared in the reaction mixture from
One more possibility that could explain the observed dif- the initially formed singlet oxocarbenes E as a consequence
ference in stability of regioisomers 2 and 3 is that in the of intersystem crossing (ISC) (Scheme 4). These results are
Eur. J. Org. Chem. 0000, 0–0
© 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
3

Job/Unit: O40161
/KAP1
Date: 02-04-14 16:39:15
Pages: 9
L. L. Rodina, J. J. Medvedev, O. S. Galkina, V. A. Nikolaev
FULL PAPER
Table 2. Thermolysis of diazodiketones 2 and 3 in BnOH solution.
Entry Diazo ketone
Ratio BnOH/DK t [h]
Composition of the reaction mixtures [%][a]
5, 6
8, 9
2, 3[b]
1
2
3
4
5
6
7
2a
2b
2c
3a
3b
3c
3c
5.5:1
5.5:1
5.5:1
5.5:1
13.5:1
5.5:1
13.5:1
3
4
4
6
20
6
19.5
5a; 42 (64)
5b; 37 (66)
5c; 25 (54)
6a; 12 (41)
6b; 94
6c; 17 (43)
6c; 24 (30)
–
2a; 35
2b; 44
2a; 54
3a; 71
–
3c; 60
3c; 20
8b; 8 (14)
8c; 4 (9)
–
9b; 6
9c; 10 (25)
9c; 31 (39)
[a] The yields of furanones 5, 6 and mono ketones 10, 11 based on reacted diazo ketone are given in parentheses. [b] The content of the
initial diazo ketones 2 and 3 in the reaction mixture.
in line with the commonly accepted mechanism of the re- mental procedure using thermal decomposition of the diazo
duction of diazocarbonyl compounds through triplet oxo- ketones 1–3 in DMSO can be applied for the synthesis of
carbene intermediates.[2a,2c,2d,13]
4,5-dialkyl- and 4,5-diaryl-3(2H)-furanones.
Discussion
Summarizing the results of these experiments, it is valid
to say that, in contrast to photolysis, on thermal decompo-
sition of diazo ketones 1–3 in protic and aprotic media the
basic reaction products are 3(2H)-furanones 4–6. The main
reason of the essential difference in the results of thermoly-
sis and photolysis is presumably laid in the following.
The short-lived excited states of diazo ketones 2 and 3
(1S1-DK) formed upon their UV irradiation mainly un-
dergo intramolecular processes such as the Wolff rearrange-
ment (Scheme 5), which, for cyclic diazo ketones, likely oc-
curs in a concerted mechanism.[14] However, during this
process some part of the electronically excited molecules of
diazo ketones 2 and 3 undergo ISC with the formation of
a triplet state (3T1-DK) from a singlet state (1S1-DK). The
triplet state of diazo ketone having a longer life, reacts in
an intermolecular manner with the tetrahydrofuran present
in the reaction mixture, giving rise to insertion of the ter-
Scheme 4. Formation of ketones 8 and 9 during thermolysis of di-
azo ketones 2 and 3.
From the data presented above it can be concluded that,
from a practical viewpoint, the temperature of thermolysis
of diazo ketones 1–3 must be no less than 160 °C and, of
the two solvents studied, DMSO is more convenient than
BnOH. To check in practice the synthetic utility of the ther-
mal reaction of diazo ketones 1–3 under these conditions,
preparative thermolysis using three diazo ketones 1, 2b and
3b were carried out followed by isolation of reaction prod-
ucts by silica gel chromatography (Table 3).
Table 3. Preparative thermolysis of diazo ketones 1, 2b, and 3b in
DMSO.
Entry Diazo ketone R1 R2
t [h] Yields [%][a]
4–6
7b
1
2
3
1
2b
3b
Me Me 2.5
4; 72
–
Ph Me
Me Ph
5
12
5b; 58 (60)[b] 19 (27)
6b; 58 (70)
3 (7)
[a] Isolated yield after chromatography. [b] Yields determined by
1H NMR spectroscopic analysis are given in parentheses.
As is seen from these data, the preparative yields of the
target unsaturated ketones 4–6 under these conditions are
Scheme 5. The proposed pathway for photochemical transforma-
in the range 58–72%, and therefore the suggested experi- tions of diazo ketones 2 and 3.
4
www.eurjoc.org
© 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 0000, 0–0

Job/Unit: O40161
/KAP1
Date: 02-04-14 16:39:15
Pages: 9
Thermolysis of 4-Diazotetrahydrofuran-3-ones
Starting Materials: Tetramethyl-substituted diazo ketone 1 was pre-
pared according to described protocols.[5] Diaryl-substituted diazo
ketones 2a–c and 3a–c were prepared from 2-methylbut-3-yn-2-ol
(Favorskij acetylene) and the corresponding p-OMe- and p-F-sub-
stituted benzophenones by analogy with diazo ketones 2b and
3b.[10]
minal nitrogen atom of the diazo group into the α-C–H
bond of tetrahydrofuran.[6]
In contrast to photolysis, thermal reactions of diazo
ketones 1–3 are realized at the “hot” vibrating levels of
the potential energy of the ground state (#S0-DK,
Scheme 6),[14f,15] which are much lower in energy than a sin-
4-Diazo-2,2-bis(4-methoxyphenyl)-5,5-dimethyldihydrofuran-
1
glet excited state S1 generated on photochemical irradia-
3(2H)-one (2a): Yellow solid; m.p. 131–132 °C. IR (CCl ): ν = 2088,
˜
4
tion of these diazo compounds. Probably, the energy of the
“hot” levels of #So is sufficient for the 1,2-alkyl (or aryl)
shift to furnish 3(2H)-furanones 4–6, but is not enough to
accomplish the Wolff rearrangement to give the corre-
sponding ketenes.
1692, 1608, 1551, 1510, 1351, 1296, 1251, 1218, 1176, 1040, 1006,
980 cm–1. 1H NMR (300 MHz, CDCl3): δ = 1.60 (s, 6 H, 2Me),
3.78 (s, 6 H, 2OMe), 6.84 (d, J = 9 Hz, 4 H), 7.37 (d, J = 9 Hz, 4
H) ppm. 13C NMR (75 MHz, CDCl3): δ = 28.9, 55.2, 78.1, 90.2,
113.5, 128.0, 134.0, 159.2, 193.3 ppm. HRMS (ESI): m/z calcd for
C20H20N2O4 [M + H]+ 353.1496; found 353.1498.
4-Diazo-5,5-bis(4-methoxyphenyl)-2,2-dimethyldihydrofuran-
3(2H)-one (3a): Yellow solid; m.p. 128–129 °C. IR (CCl ): ν = 2090,
˜
4
1694, 1551, 1511, 1347, 1253, 1223, 1175, 1040, 1004, 980 cm–1. 1H
NMR (300 MHz, CDCl3): δ = 1.34 (s, 6 H, 2Me), 3.81 (s, 6 H,
2MeO), 6.88 (d, J = 9 Hz, 4 H), 7.23 (d, J = 9 Hz, 4 H) ppm. 13C
NMR (75 MHz, CDCl3): δ = 25.3, 55.3, 83.9, 85.3, 113.8, 127.9,
136.0, 159.5, 197.3 ppm. HRMS (ESI): m/z calcd for C20H20N2O4
[M + H]+ 353.1496; found 353.1498.
Scheme 6. Complete scheme for the thermal reactions of diazo
ketones 1–3.
4-Diazo-2,2-bis(4-fluorophenyl)-5,5-dimethyldihydrofuran-3(2H)-one
(2c): Yellow solid; m.p. 115–116 °C. IR (CCl ): ν = 2091, 1694,
˜
4
Thermolysis of diazo ketones 1–3, unlike the concerted
1551, 1508, 1350, 1251, 1235, 1007, 980 cm–1. 1H NMR (300 MHz,
Wolff rearrangement upon photolysis, apparently takes
CDCl3): δ = 1.61 (s, 6 H, 2Me), 6.98–7.48 (8 H, 2Ar) ppm. 13C
1
place through the singlet oxocarbenes S, which, during the
2
NMR (75 MHz, CDCl3): δ = 28.9, 78.5, 89.3, 115.1 (d, JC,F
=
course of the reaction, are in part turned through ISC into
their triplet counterparts 3T (Scheme 6). Identification of α-
diketone 7b and mono ketones 8b,c and 9b,c in the thermal
reactions of diazo ketones 1–3 may be considered as the
arguments in favor of this assumption.
3
4
21.1 Hz), 128.3 (d, JC,F = 8.3 Hz), 137.4 (d, JC,F = 3 Hz), 162.4
(d, JC,F = 247.5 Hz), 192.2 ppm. HRMS (ESI): m/z calcd for
1
C18H14F2N2O2 [M + H]+ 329.1096; found 329.1098.
4-Diazo-5,5-bis(4-fluorophenyl)-2,2-dimethyldihydrofuran-3(2H)-one
(3c): Yellow solid; m.p. 113–114 °C. IR (CCl ): ν = 2092, 1699,
˜
4
1603, 1508, 1345, 1231, 1158, 1026, 1007 cm–1. 1H NMR
(300 MHz, CDCl3): δ = 1.34 (s, 6 H, 2Me), 7.04–7.31 (8 H,
2Ar) ppm. 13C NMR (75 MHz, CDCl3): δ = 25.2, 64.4, 83.4, 85.6,
115.6 (d, 2JC,F = 21.1 Hz), 128.3 (d, 3JC,F = 8.3 Hz), 139.4 (d, 4JC,F
Conclusions
Thermal decomposition of 2,2,5,5-tetrasubstituted 4-di-
azodihydrofuran-3(2H)-ones 1–3 in protic and aprotic me-
dia, in contrast to photolysis, gives rise to the formation of
1
= 3.0 Hz), 196.5, 162.6 (d, JC,F = 249.1 Hz) ppm. HRMS (ESI):
m/z calcd for C18H14F2N2O2 [M + H]+ 329.1096; found 329.1097.
Thermolysis of Diazo Ketones 1–3 in DMSO; General Procedure: A
solution of diazo ketone 1–3 (0.7 mmol) in [D6]DMSO (7 mL) was
placed in a small flask and heated at 160Ϯ0.5 °C. For rate of de-
composition determination, 5–10 samples of the reaction mixture
were taken from the flask and analyzed by 1H NMR spectroscopy;
at least three independent measurements were performed for each
sample. Based on the analytical data obtained, kinetic curves were
built and the half-life times (τ1/2) for the decomposition of diazo
ketones 1–3 were calculated. The rest of the reaction mixture from
the flask, after usual workup procedure (see below), was separated
by silica gel chromatography. The isolated compounds were iden-
tified by spectroscopic methods.
mainly 2,2,4,5-tetrasubstituted 3(2H)-furanones
Ϫ the
products of 1,2-alkyl or aryl shifts. Thermolysis of diazo-
dihydrofuran-3-ones in DMSO solution provides higher
yields of 3(2H)-furanones (58–72%), than reaction in
benzyl alcohol and can serve as a preparative method for
their synthesis.
Experimental Section
General Methods: 1H and 13C NMR spectra were recorded with
Bruker 300 MHz DPX or Bruker 400 MHz Avance instruments.
Chemical shifts of 1H and 13C NMR spectra are given in δ units
relative to tetramethylsilane (TMS). Coupling constants J are given
in Hz. HRMS experiments were performed with a “MaXis” GC–
MS spectrometer from Bruker Daltonik GmbH. IR spectra were
recorded with a Bruker TENSOR 37. CHN analysis was performed
with a Heraeus CHNO Rapid Analyser. Reactions were performed
in solvents dried and purified before use by common methods. All
reactions were monitored by thin-layer chromatography (TLC) car-
Thermolysis of Diazo ketone 1: Performed according to the general
procedure with 1 (33.6 mg, 0.2 mmol); samples were taken from the
reaction mixture after 15, 30, 50, 90, and 120 min. After complete
decomposition of diazo ketone 1 (2 h), furanone 4 was isolated as
the major reaction product.
2,2,4,5-Tetramethylfuran-3(2H)-one (4):[8b] Yield 23 mg (82%). 1H
NMR (300 MHz, CDCl3): δ = 1.34 (s, 6 H, 2Me),1.67 (s, 3 H, Me),
2.18 (s, 3 H, Me) ppm. 13C NMR (75 MHz, CDCl3): δ = 6.0, 15.8,
23.1, 88.7, 109.2, 188.5, 210.8 ppm.
ˇ
ried out on Silufol UV-254 (Kavalier, CSSR) plates. Preparative
TLC was performed on Silufol UV-254 plates. Silica gel L 40/
100 μm was used for column chromatography.
Thermolysis of Diazo Ketone 2a: Performed according to the gene-
ral procedure with 2a (70.4 mg, 0.2 mmol); samples were taken
Eur. J. Org. Chem. 0000, 0–0
© 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
5

Job/Unit: O40161
/KAP1
Date: 02-04-14 16:39:15
Pages: 9
L. L. Rodina, J. J. Medvedev, O. S. Galkina, V. A. Nikolaev
FULL PAPER
from the reaction mixture after 25, 50, 120, 165, 190, and 240 min.
After 4 h, the conversion of diazo ketone 2a amounted to 92%,
and furanone 5a was isolated as the major product.
from the reaction mixture after 25, 50, 75, 120, 145, 180, 210, and
240 min. The conversion of diazo ketone 3b after 5.25 h amounted
to 59%. Furanone 6b and diketone 7b were isolated as the major
reaction products.
2,2-Bis(4-methoxyphenyl)-4,5-dimethylfuran-3(2H)-one (5a): Yield
2,2-Dimethyl-4,5-diphenylfuran-3(2H)-one (6b):[6b] Yield 24 mg
(46%). 1H NMR (300 MHz, CDCl3): δ = 1.58 (s, 6 H, 2Me), 7.28–
7.68 (m, 10 H, ArH) ppm. 13C NMR (75 MHz, CDCl3): δ = 23.8,
87.4, 114.0, 127.9, 128.8, 129.0, 129.9, 130.4, 132.2, 178.4,
205.8 ppm.
52 mg (80%); colorless oil. IR (CCl ): ν = 1702, 1641, 1252, 1215,
˜
4
1178, 1040, 1006, 981 cm–1. 1H NMR (300 MHz, CDCl3): δ = 1.72
(s, 3 H, Me), 2.31 (s, 3 H, Me), 3.78 (s, 6 H, OMe), 6.85 (d, J =
9 Hz, 4 H), 7.34 (d, J = 9 Hz, 4 H) ppm. 13C NMR (75 MHz,
CDCl3): δ = 5.9, 15.1, 55.3, 91.1, 109.7, 113.7, 128.0, 130.9, 159.5,
184.0, 203.7 ppm. C20H20O4 (324.38): calcd. C 74.09, H 6.17; found
C 73.59, H 6.32.
2,2-Dimethyl-5,5-diphenylfuran-3,4(2H,5H)-dione (7b): Yield 7 mg
(12%).
Thermolysis of Diazo Ketone 2b: Performed according to the gene-
ral procedure with 2b (58.4mg, 0.2 mmol); samples were taken
from the reaction mixture after 25, 50, 80, 125, 160, 200, and
240 min. After 4 h, the starting diazo ketone 2b was completely
decomposed. Furanone 5b and diketone 7b were isolated as the
major reaction products.
Thermolysis of Diazo Ketone 3c: Performed according to the gene-
ral procedure with 3c (65.6 mg, 0.2 mmol); samples were taken
from the reaction mixture after 25, 50, 110, 135, 160, 180, 240, 285,
320, and 360 min. The conversion of diazo ketone 3c after 6 h was
44%, and furanone 6c was isolated as the main reaction product.
4,5-Bis(4-fluorophenyl)-2,2-dimethylfuran-3(2H)-one (6c): Yield
4,5-Dimethyl-2,2-diphenylfuran-3(2H)-one (5b):[6b] Yield 43 mg
(81.5%). 1H NMR (300 MHz, CDCl3): δ = 1.71 (s, 3 H, CH3), 2.31
(s, 3 H, CH3), 7.21–7.59 m (m, 10 H, ArH) ppm. 13C NMR
(75 MHz, CDCl3): δ = 6.3, 15.5, 91.3, 110.2, 126.9, 128.6, 128.8,
139.1, 183.9, 203.1 ppm.
20 mg (33%); white solid; m.p. 109–110 °C. IR (CCl ): ν = 1701,
˜
4
1551, 1418, 1384, 1241, 1160, 1160, 1051, 1007, 980 cm–1. 1H NMR
(300 MHz, CDCl3): δ = 1.55 (s, 6 H, 2Me), 7.03–7.30 (6 H), 7.63–
7.68 (dd, JH,H = 9, JH,F = 6 Hz, 2 H) ppm. 13C NMR (75 MHz,
2
CDCl3): δ = 23.3, 87.2, 112.5, 115.8 (d, JC,F = 21.9 Hz), 125.9 (d,
3
3JC,F = 18.9 Hz), 130.7 (d, 3JC,F = 9 Hz), 131.2 (d, JC,F = 8.3 Hz),
2,2-Dimethyl-5,5-diphenylfuran-3,4(2H,5H)-dione (7b): Yield 10 mg
1
1
(17.5%); pink oil. IR (CCl ): ν = 2984, 2930, 2856, 1807, 1769,
˜
4
162.3 (d, JC,F = 247.5 Hz), 164.7 (d, JC,F = 256.6 Hz), 177.0,
205.1, ppm. C18H14F2O2 (300.30): calcd. C 72.03, H 4.66; found C
72.06, H 4.68.
1666, 1492, 1508, 1380, 1263, 1160, 1043, 1013, 928 cm–1. 1H NMR
(300 MHz, CDCl3): δ = 1.41 (s, 6 H, 2 Me), 7.28–77.53 (10 H) ppm.
13C NMR (75 MHz, CDCl3): δ = 25.3, 80.3, 85.1, 126.8, 128.8,
129.1, 140.5, 199.8, 204.0 ppm. HRMS (ESI): m/z calcd. for
C18H16O3 [M + H]+ 281.1178; found 281.1138.
Thermolysis of Diazo Ketones 2–3 in Benzyl Alcohol; General Pro-
cedure: A solution of diazo ketone 2 or 3 (0.2 mmol) in BnOH
[0.1 mL (5.5 equiv.) or 0.3 mL (13.5 equiv.)] in a small flask was
heated at 160Ϯ1 °C. After competition of the reaction, benzyl
alcohol was distilled off in vacuo (10 Torr, 120 °C), the obtained
residue was dissolved in CDCl3 and analyzed by 1H NMR spec-
troscopy (tetrachloroethane as internal standard).
Thermolysis of Diazo Ketone 2c: Performed according to the gene-
ral procedure with 2c (65.6 mg, 0.2 mmol); samples were taken
from the reaction mixture after 40, 60, 90, 120, 150, and 180 min.
The conversion of diazo ketone 2c after 3 h was 83%. Furanone 5c
was isolated as the main reaction product.
Thermolysis of Diazo Ketone 2a Performed according to the general
procedure with 2a (70.4 mg, 0.2 mmol) for 3 h in benzyl alcohol
(0.1 mL). Conversion of the diazo ketone 2a by this time was 65%,
furanone 5a (42%) was identified as the main reaction product.
2,2-Bis(4-fluorophenyl)-4,5-dimethylfuran-3(2H)-one (5c): Yield
40 mg (67%); white solid; m.p. 70–71 °C. IR (CCl ): ν = 1708,
˜
4
1642, 1551, 1411, 1251, 1238, 1217, 1105, 1064, 1006, 980 cm–1. 1H
NMR (400 MHz, CDCl3): δ = 1.72 (s, 3 H, Me), 2.32 (s, 3 H, Me),
6.98–7.44 (8 H) ppm. 13C NMR (100 MHz, CDCl3): δ = 5.9, 15.1,
Thermolysis of Diazo Ketone 2b: Performed according to the gene-
ral procedure with 2b (58.4 mg, 0.2 mmol) for 4 h in benzyl alcohol
(0.1 mL). Conversion of the diazo ketone 2b by this time was 56%,
furanone 5b (37%) and mono ketone 8b (8%)[6b] were identified as
the main reaction products.
2
3
89.8, 109.8, 115.4 (d, JC,F = 21.0 Hz), 128.4 (d, JC,F = 8 Hz),
4
1
134.4 (d, JC,F = 3.0 Hz), 162.6 (d, JC,F = 246.0 Hz), 183.8,
202.5 ppm. C18H14F2O2 (300.30): calcd. C 72.03, H 4.66; found C
72.16, H 4.71.
Thermolysis of Diazo ketone 2c: Performed according to the general
procedure with 2c (65.6 mg, 0.2 mmol) for 4 h in benzyl alcohol
(0.1 mL). Conversion of the diazo ketone 2c by this time was 46%,
furanone 5c (25%) and mono ketone 8c (4%)[6b] were isolated from
the reaction mixture as the main reaction products.
Thermolysis of Diazo Ketone 3a: Performed according to the gene-
ral procedure with 3a (70.4 mg, 0.2 mmol); samples were taken
from the reaction mixture after 25, 60, 120, 180, 240, 270, 300, and
315 min. Conversion of diazo ketone after 5.25 h heating was 99%.
3(2H)-Furanone 6a was identified as the major product of the reac-
tion.
2,2-Bis(4-fluorophenyl)-5,5-dimethyldihydrofuran-3(2H)-one
(8c):
White solid; m.p. 80–81 °C. IR (CCl ): ν = 2978, 1757, 1605, 1506,
˜
4,5-Bis(4-methoxyphenyl)-2,2-dimethylfuran-3(2H)-one (6a): Yield
4
1234, 1158, 1052, 836 cm–1. 1H NMR (400 MHz, CDCl3): δ = 1.39
(s, 6 H, 2Me), 2.60 (s, 2 H, CH2), 6.97–7.51 (m, 8 H, 2Ar) ppm.
13C NMR (100 MHz, CDCl3): δ = 29.6, 49.2, 78.0, 85.9, 115.1 (d,
JC,F = 21.1 Hz), 127.83 (d, JC,F = 8.0 Hz), 138.0 (d, JC,F = 3.0 Hz),
162.2 (d, JC,F = 246.5 Hz), 213.2 ppm. HRMS (ESI): m/z calcd. for
C18H16O2F2 [M + H]+ 303.1191; found 303.1192.
64 mg (98%); white solid; m.p. 127–128 °C. IR (CCl ): ν = 1695,
˜
4
1386, 1256, 1218, 1179, 1007, 980 cm–1. 1H NMR (300 MHz,
CDCl3): δ = 1.55 (s, 6 H, 2CH3), 3.84 (s, 6 H, 2OCH3), 6.85 (d, J
= 9 Hz, 2 H), 6.92 (d, J = 9 Hz, 2 H), 7.25 (d, J = 9 Hz, 2 H), 7.64
(d, J = 9 Hz, 2 H) ppm. 13C NMR (75 MHz, CDCl3): δ = 55.2,
55.4, 86.5, 112.0, 113.7, 114.1, 122.4, 122.6, 130.1, 130.8, 158.9,
162.3, 177.4, 205.4 ppm. C20H20O4 (324.38): calcd. C 74.09, H 6.17;
found C 74.07, H 6.20.
Thermolysis of Diazo Ketone 3a: Performed according to the gene-
ral procedure with 3a (70.4 mg, 0.2 mmol) for 6 h in benzyl alcohol
(0.1 mL). Conversion of the diazo ketone 3a by this time was 29%,
furanone 6a (12%) was identified as the main reaction product.
Thermolysis of Diazo Ketone 3b: Performed according to the gene-
ral procedure with 3b (58.4mg, 0.2 mmol); samples were taken
6
www.eurjoc.org
© 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 0000, 0–0

Job/Unit: O40161
/KAP1
Date: 02-04-14 16:39:15
Pages: 9
Thermolysis of 4-Diazotetrahydrofuran-3-ones
Thermolysis of Diazo Ketone 3b: Performed according to the gene-
ral procedure with 3b (58.4 mg, 0.2 mmol) for 20 h in benzyl
alcohol (0.3 mL). Diazo ketone 3b completely decomposed by this
time, furanone 6b (94%) and mono ketone 9b (6%)[6b] were iden-
tified as the main products of the reaction.
[1]
[2]
[3]
a) M. Regitz, G. Maas, Diazo Compounds. Properties and Syn-
thesis Academic Press, New York, 1986, p. 65, p. 83; b) M. P.
Doyle, Modern Catalytic Methods for Organic Synthesis with
Diazo Compounds: From Cyclopropanes to Ylides, Wiley, 1998;
c) H. Zollinger, Diazo Chemistry II. Aliphatic, Inorganic and
Organometallic Compounds, Wiley-VCH, Weinheim, Germany,
1998; d) S. Patai, The Chemistry of Diazonium and Diazo
Groups, John Wiley, Chichester, UK, 1978, parts 1 and 2; e)
M. Regitz, I. K. Korobitsyna, L. L. Rodina, in: Methodicum
Chimicum, Thieme, Stuttgart, Germany, 1974, B.6, chapter 8.
For reviews on WR, see also: a) W. Kirmse, Eur. J. Org. Chem.
2002, 2193–2256; b) G. B. Gill, in: Comprehensive Organic Syn-
thesis (Eds.: B. M. Trost, I. Fleming); Pergamon Press, Oxford,
UK, 1991, vol. 3, p. 887; c) W. Ando, in: The Chemistry of
Diazonium and Diazo groups (Ed.: S. Patai), John Wiley, Chich-
ester, UK, 1978, part 1, p. 458; d) H. Meier, K. P. Zeller, Angew.
Chem. Int. Ed. Engl. 1975, 14, 32–43; Angew. Chem. 1975, 87,
52; e) L. L. Rodina, I. K. Korobitsyna, Russ. Chem. Rev. 1967,
36, 260–272; f) W. E. Bachman, W. S. Strove, Org. React. 1942,
1, 38–62.
a) T. P. Willumstad, O. Haze, X. Y. Mak, T. Y. Lam, Y. Wang,
R. L. Danheiser, J. Org. Chem. 2013, 78, 11450–11469; b)
K. B. S. Magar, Y. R. Lee, Org. Lett. 2013, 15, 4288–4291; c) P.
Neupane, X. Li, J. H. Jung, Y. R. Lee, S. H. Kim, Tetrahedron
2012, 68, 2496–2508; d) M. Presset, Y. Coquerel, J. Rodriguez,
Org. Lett. 2010, 12, 4212–4215; e) M. Presset, Y. Coquerel, J.
Rodriguez, J. Org. Chem. 2009, 74, 415–418; f) T. Kopke, M.
Pink, J. M. Zaleski, J. Am. Chem. Soc. 2008, 130, 15864–15871;
g) G. V. Karpov, V. V. Popik, J. Am. Chem. Soc. 2007, 129,
3792–3793; h) L. N. Mander, M. M. McLachlan, J. Am. Chem.
Soc. 2003, 125, 2400–2401; i) S. G. Sudrik, S. P. Chavan,
K. R. S. Chandrakumar, S. Pal, S. K. Date, S. P. Chavan, H. R.
Sonawane, J. Org. Chem. 2002, 67, 1574–1579.
To compare results of thermolysis and photolysis of diazo
ketones see, for example: diazoindanedione,[4a] diazodimed-
one,[4b–4d] carbo- and O-heterocyclic diazocyclohexane-
diones,[4d,4e] diazodibenzocycloheptanedione.[4f] a) M. P. Cava,
R. J. Spangler, J. Am. Chem. Soc. 1967, 89, 4550–4551; b) H.
Schwall, V. Schmidt, B. Eistert, Chem. Ber. 1969, 102, 1731–
1738; c) H. Vershambre, D. Vocelle, Can. J. Chem. 1969, 47,
1981–1988; d) I. K. Korobitsyna, V. A. Nikolaev, J. Org. Chem.
USSR 1976, 12, 1246–1255; V. A. Nikolaev, S. M. Korneev,
I. V. Terent’eva, I. K. Korobitsyna, J. Org. Chem. USSR 1992,
27, 1845–1858; e) B. Eistert, G. Heck, Justus Liebigs Ann.
Chem. 1965, 681, 138–146, and references cited therein; f) W.
Reid, R. Conte, Chem. Ber. 1972, 105, 799–804.
a) I. K. Korobitsyna, L. L. Rodina, V. G. Shuvalova, Zh. Org.
Khim. 1968, 4, 2016–2020; b) I. K. Korobitsyna, L. L. Rodina,
Zh. Org. Khim. 1965, 1, 932–938.
a) V. A. Nikolaev, O. S. Galkina, J. Sieler, L. L. Rodina, Tetra-
hedron Lett. 2010, 51, 2713–2716; b) L. L. Rodina, S. A. Mala-
shikhin, O. S. Galkina, V. A. Nikolaev, Helv. Chim. Acta 2009,
92, 1990–1998; c) L. L. Rodina, V. L. Mischenko, S. A. Mala-
shikhin, M. Platz, V. A. Nikolaev, Russ. J. Org. Chem. 2003,
39, 1530–1532.
Thermolysis of Diazo ketone 3c: Performed according to the general
procedure with 3c (65.6 mg, 0.2 mmol) for 6 h in benzyl alcohol
(0.1 mL). Conversion of diazo ketone 3c by this time was 40%,
furanone 6c (17%) and mono ketone 9c (10%)[6b] were identified
as the main reaction products.
Thermolysis of Diazo Ketone 3c: Performed according to the gene-
ral procedure with 3c (65.6 mg, 0.2 mmol) for 19.5 h in benzyl
alcohol (0.3 mL). Conversion of diazo ketone 3c by this time was
80%, and furanone 6c (24%) and mono ketone 9c (31%)[6b] were
isolated from reaction mixture.
5,5-Bis(4-fluorophenyl)-2,2-dimethyldihydrofuran-3(2H)-one
(9c):
White solid; m.p. 58–59 °C. IR (CCl ): ν = 2982, 2933, 1762, 1606,
˜
4
1508, 1236, 1159, 1095, 995, 837 cm–1. 1H NMR (400 MHz,
CDCl3): δ = 1.21 (s, 6 H, 2Me), 3.27 (s, 2 H, CH2), 6.98–7.37 (m,
8 H, 2Ar) ppm. 13C NMR (100 MHz, CDCl3): δ = 25.3, 48.2, 81.5,
82.0, 115.3 (d, 2JC,F = 21.3 Hz), 127.8 (d, 3JC,F = 8.0 Hz), 141.8 (d,
1
4JC,F = 4.0 Hz), 162.1 (d, JC,F = 246.5 Hz), 216.3 ppm. HRMS
(ESI): m/z calcd for C18H16O2F2 [M + H]+ 303.1191; found
303.1191.
Preparative Synthesis of 3(2H)-Furanones 4, 5b, and 6b; General
Procedure: A solution of diazo ketone (1, 2b, 3b) in DMSO was
heated at 160Ϯ1 °C until complete decomposition of the starting
diazo ketone was observed (reaction was monitored by TLC). Then
the reaction mixture was cooled, diluted with water, and extracted
with CH2Cl2. The organic layer was washed with water to remove
traces of DMSO and dried with anhydrous Na2SO4. The solvent
was distilled off and the residue was passed through a short
chromatography column with silica gel (petroleum/acetone, 10:1)
to give 3(2H)-furanones 4–6.
[4]
2,2,4,5-Tetramethylfuran-3(2H)-one (4): Prepared according to the
general procedure from diazo ketone 1 (241 mg, 1.4 mmol) in
DMSO (3 mL) at 160Ϯ1 °C during 2.5 h to give furanone 4
(145 mg, 72%).
4,5-Dimethyl-2,2-diphenylfuran-3(2H)-one (5b): Prepared according
to the general procedure from diazo ketone 2b (75 mg, 0.26 mmol)
in DMSO (4 mL) at 160Ϯ1 °C during 5 h to give furanone 5b
(40 mg, 58%). Diketone 7b (14 mg, 19%) was isolated as a by-prod-
uct.
[5]
[6]
2,2-Dimethyl-4,5-diphenylfuran-3(2H)-one (6b): Prepared according
to the general procedure from diazo ketone 3b (240 mg, 0.82 mmol)
in DMSO (7 mL) at 160Ϯ1 °C during 12 h to give 3(2H)-furanone
6b (125 mg, 58%). Diketone 7b (7 mg, 3%) was isolated as a by-
product.
[7]
[8]
a) M. Regitz, W. Bartz, Chem. Ber. 1970, 103, 1463–1476; M.
Regitz, W. Bartz, Chem. Ber. 1970, 103, 11477–1485; b) V. V.
Popik, V. A. Nikolaev, J. Chem. Soc. Perkin Trans. 2 1993,
1791–1793.
a) L. L. Rodina, F. Pragst, W. Jugelt, J. Prakt. Chem. 1974,
316, 286–292; b) T. Kawaguchi, S. Yasuta, Y. Inoue, Synthesis
1996, 1431–1432.
Supporting Information (see footnote on the first page of this arti-
cle): Kinetic data for decomposition of diazo ketones 1–3 in
1
DMSO, and copies of the H and 13C NMR spectra of new com-
pounds.
[9]
a) A. Nickon, Acc. Chem. Res. 1993, 26, 84; b) L. Seghers, H.
Shechter, Tetrahedron Lett. 1976, 23, 1943–1946.
Acknowledgments
[10]
[11]
S. A. Malashikhin, A. Linden, H. Heimgarthner, L. L. Rodina,
V. A. Nikolaev, Helv. Chim. Acta 2008, 91, 1662–1669.
G. R. Desiraju, T. Steiner, The Weak Hydrogen Bond: In Struc-
tural Chemistry and Biology, Oxford University Press, USA,
2001, p. 29.
Scientific research was performed using the resources of the “Cen-
ter for chemical analysis and materials research” and the “Center
for Magnetic Resonance” of Saint-Petersburg State University.
Eur. J. Org. Chem. 0000, 0–0
© 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
7

Job/Unit: O40161
/KAP1
Date: 02-04-14 16:39:15
Pages: 9
L. L. Rodina, J. J. Medvedev, O. S. Galkina, V. A. Nikolaev
FULL PAPER
[12] For the “oxidation” of diazo compounds and carbenes, see: a)
P. Fremont, N. Marion, S. P. Nolan, Coord. Chem. Rev. 2009,
253, 862–892; b) M. Ma, C. Li, L. Peng, F. Xie, X. Zhang, J.
Wang, Tetrahedron Lett. 2005, 46, 3927–3929; c) A. Saba,
Synth. Commun. 1994, 24, 695–699; d) H. Tomioka, N. Isikava,
K. Kamatsu, J. Am. Chem. Soc. 1992, 114, 8045–8053; e) H. L.
Casal, N. H. Werstiuk, J. C. Scaiano, J. Org. Chem. 1984, 49,
5214–5217; f) Y. Hata, M. Watanabe, S. Inoe, S. Oae, J. Am.
Chem. Soc. 1975, 97, 2553–2554; g) E. E. Schweizer, G. J.
O’Neill, J. Org. Chem. 1963, 28, 2460–2461.
[13] a) K. Hirai, T. Itoh, H. Tomioka, Chem. Rev. 2009, 109, 3275–
3332; b) H. Tomioka, Triplet Carbenes, in: Reactive Intermedi-
ate Chemistry (Eds.: R. A. Moss, M. S. Platz, M. Jones Jr.),
John Wiley & Sons, New York, 2004, p. 402; c) P. A. Blair, S.
Chang, H. Shechter, J. Org. Chem. 2004, 69, 7123–7133; d) K.
Hirai, K. Yasuda, H. Tomioka, Chem. Lett. 2000, 398–399.
[14]
a) G. Burdzinski, J. Kubicki, M. Sliwa, J. Rehault, Y. Zhang,
S. Vyas, H. L. Luk, C. M. Hadad, M. S. Platz, J. Org. Chem.
2013, 78, 2026–2032; b) D. Wolpert, M. Schade, T. Brixner, J.
Chem. Phys. 2008, 129, 094504/1–094504/10; c) V. A. Nikolaev,
V. V. Shevchenko, M. S. Platz, N. N. Khimich, Russ. J. Org.
Chem. 2006, 42, 815–827; d) V. Popik, Can. J. Chem. 2005, 83,
1382–1390; e) V. V. Shevchenko, N. N. Khimich, M. S. Platz,
V. A. Nikolaev, Tetrahedron Lett. 2005, 46, 435–438; f) A. Bog-
danova, V. V. Popik, J. Am. Chem. Soc. 2003, 125, 14153–
14162; g) V. A. Nikolaev, Yu. Frenkh, I. K. Korobitsyna, J.
Org. Chem. USSR 1978, 14, 1338–1346.
[15] M. J. S. Dewar, R. C. Dougherty, The PMO Theory of Organic
Chemistry, Plenum Press, New York, 1975, chapter 6.
Received: January 30, 2014
Published Online: ᭿
8
www.eurjoc.org
© 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 0000, 0–0

Job/Unit: O40161
/KAP1
Date: 02-04-14 16:39:15
Pages: 9
Thermolysis of 4-Diazotetrahydrofuran-3-ones
Thermolysis
L. L. Rodina, J. J. Medvedev,
O. S. Galkina, V. A. Nikolaev* ......... 1–9
Thermolysis of 4-Diazotetrahydrofuran-3-
ones: Total Change of Reaction Course
Compared to Photolysis
Thermolysis of substituted 4-diazodihydro-
furan-3-ones in aprotic media, in contrast
to photolysis, gives high yields of 2,2,4,5-
tetrasubstituted 3(2H)-furanones as the
products of 1,2-alkyl (aryl) shifts.
Keywords: Thermolysis / Photolysis / Re-
arrangement / Oxygen heterocycles / Diazo
compounds / Carbenes / Reactive inter-
mediates
Eur. J. Org. Chem. 0000, 0–0
© 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
9