UV-mediated decomposition of diazomalonates in benzene: Unexpected access to functionalized bicyclo[3.2.0]heptane skeleton

Article abstract of DOI:10.1016/j.tetlet.2017.06.070

Upon irradiation with 300-nm UV light, the photolysis of diazomalonates in benzene unexpectedly affords 2,6-dicarboxylate bicyclo[3.2.0]hepta-2,6-dienes in low yields. These products are proven to be derived from cyclohepta-1,3,5-triene intermediates presumably via a tandem 1,5-carboxylate migration/[2+2] cycloaddition sequence.

Full text of DOI:10.1016/j.tetlet.2017.06.070

Accepted Manuscript
UV-Mediated Decomposition of Diazomalonates in Benzene: Unexpected Ac-
cess to Functionalized Bicyclo[3.2.0]heptane Skeleton
Yi-Jung Chiang, Jia-Liang Zhu
PII:
S0040-4039(17)30809-2
DOI:
http://dx.doi.org/10.1016/j.tetlet.2017.06.070
TETL 49062
Reference:
Tetrahedron Letters
To appear in:
Received Date:
Revised Date:
Accepted Date:
30 May 2017
21 June 2017
23 June 2017
Please cite this article as: Chiang, Y-J., Zhu, J-L., UV-Mediated Decomposition of Diazomalonates in Benzene:
Unexpected Access to Functionalized Bicyclo[3.2.0]heptane Skeleton, Tetrahedron Letters (2017), doi: http://
dx.doi.org/10.1016/j.tetlet.2017.06.070
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers
we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and
review of the resulting proof before it is published in its final form. Please note that during the production process
errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Graphical Abstract
UV-Mediated Decomposition of
Diazomalonates in Benzene: Unexpected
Access to Functionalized
Leave this area blank for abstract info.
Bicyclo[3.2.0]heptane Skeleton
Yi-Jung Chiang and Jia-Liang Zhu*

1
Tetrahedron Letters
UV-Mediated Decomposition of Diazomalonates in Benzene: Unexpected Access to
Functionalized Bicyclo[3.2.0]heptane Skeleton
Yi-Jung Chiang and Jia-Liang Zhu
Department of Chemistry, National Dong Hwa University, No.1 Sec. 2 Da Hsueh Rd., Shuo-Feng, Hualien 97401, Taiwan, R.O.C.
ARTICLE INFO
ABSTRACT
Article history:
Received
Received in revised form
Accepted
Upon irradiation with 300-nm UV light, the photolysis of diazomalonates in benzene
unexpectedly affords 2,6-dicarboxylate bicyclo[3.2.0]hepta-2,6-dienes in low yields. These
products are proven to be derived from cyclohepta-1,3,5-triene intermediates presumably via a
tandem 1,5-carboxylate migration/[2 + 2] cycloaddition sequence.
Available online
2009 Elsevier Ltd. All rights reserved.
Keywords:
Diazomalonates
Benzene
UV-Mediated decomposition
Cycloheptatriene
Bicyclo[3.2.0]heptanes
Introduction
via a diradical intermediate.7 In addition, Ciganek previously
conducted a thermal and CuBr-catalyzed reaction of diethyl
The carbenes or carbenoids, derived from the decomposition
of diazomalonates, can participate in a variety of useful
transformations,1 such as cyclopropanation,2 C-Hbond activation3
and ylide formation.4 Among which, the reported
cyclopropanation reactions were mostly performed with
alkenes,2b-d and occasionally with alkynes2e or aromatic
compounds.2a In some cases, the resulting 1,1-dicarboxylate
cyclopropanes could undergo a spontaneous ring-opening to offer
the products that may be difficult to achieve by other
conventional methods.2a
diazomalonate (1b) in benzene, but only received tetraethyl
ethylenetetracraboxylate
resulting
from
the
carbene
dimerization.9 For the given substrates, these experimental results
suggest that the distribution of products can be profoundly
affected by the method selected for diazo decomposition.
In the course of exploring the carbene chemistry of
acceptor/acceptor (A/A)-substituted diazo copounds,5 we recently
had occasion to examine the decomposition of diazomolonates in
benzene. Before us, a few experiments on this subject had
already been carried out by several groups under different
reaction conditions.6,8,9 Jones and co-workers6 disclosed that a
decomposition of dimethyl diazomalonate (1a) in benzene could
be induced upon irradiation with sunlight, to deliver
equilibrating mixture of bicycle[4.1.0]hepta-2,4-diene
(norcaradiene) 2a and cycloheptatriene 3a via
a
Scheme 1. Previously reported decomposition of 1a in
benzene.
a
Originally we intended to find a reaction system favoring the
formation of 4a, and apply it to other A/A-type diazo substrates5
for preparing phenyl-substituted carbonyl derivatives. Regarding
the rather low yield obtained from the catalytic reaction,8 we
tentatively chose an UV-mediated photochemical treatment for
our study. Nevertheless, the attempt did not result in significant
improvement of 4a, but instead led to the discovery of a new
cyclization process allowing the construction of functionalized
bicyclo[3.2.0]heptane scaffold. Herein, we wish to report this
cyclopropanation/tautomerization sequence7 plus phenylmalonate
4a (Scheme 1), but without indicating the yields in their report.
In another approach, Livant’s group reported a rhodium-
catalyzed decomposition of 1a in refluxing benzene, affording
double cyclopropanation product 5 as the major component along
with 2a/3a and 4a.8 Although the formation of 4a in these cases
represented a formal insertion of the carbene species into the
aromatic C-H bond, it was demonstrated that this compound was
actually produced through the ring-opening of the norcaradiene
———
 Corresponding author. Tel.: +886-3-8633583; fax: +886-3-8633570; e-mail: jlzhu@gms.ndhu.edu.tw

2
Tetrahedron
interesting finding as well as the results obtained from other α-
70% yield. In such a manner, we were able to clarify the origin of
diazoacetates.
the products.
Result and Discussion
The photolysis was carried out by irradiating the solution of
1a10 in benzene with fluorescent lamps (λ = 300 nm) until all the
starting material had been consumed (TLC). Column
chromatography of the complex reaction mixture on silica gel led
to the isolation of two products. One product was the expected
compound 4a,11 while the other one, to our surprising, was
identified as 2,6-dicarboxylate bicyclo[3.2.0]hepta-2,6-diene 6a
by spectroscopic analyses (1H and 13C-NMR, DEPT 135, IR and
HRMS)12 (Scheme 2). Interestingly, the bicyclic product 6b,12
along with 4b,11 was also obtained from the reaction of 1b.10 The
Scheme 3. Rh(II)-Catalyzed decomposition of 1b in benzene
and conversion of mixture of 2b/3b into 6b.
2D-NOESY correlations of 6b shown in Scheme
2
Based on the aforementioned result, a plausible mechanism
for producing 6a/b is proposed in Scheme 4. The initial addition
of the carbenes derived from the photolysis of 1a/b to benzene
offers norcaradienes A, which can either undergo a ring-opening
leading to the formation of 4a/b,7 or interconvert
with cycloheptatrienes B. Once formed, intermediates B may
quickly participate in a photo-induced [4 + 2] cycloaddition17 to
afford tricyclic intermediates C. Subsequent dissociation of C
formally realize the 1,5-shift of a carboxylate group to give
intermediates D. Afterwards, isomerization of D via a 1,3-
hydrgen migration is considered to be possible because this can
introduce a conjugation on the shifted carboxylate group, to yield
the more stable isomers E. Finally, the [2 + 2] cyclization16b of E
furnishes products 6a and 6b.
unambiguously validated the assigned structures, in particular the
cis-stereochemistry between the H-1 and H-5 protons. Moreover,
1
the similar coupling patterns were observed in the H NMR
spectra of 6a and 6b. For example, their H-1 protons were both
displayed as a doublet of doublet signal with almost identical
coupling constants [6a: δ 3.85 (dd, J = 6.5, 3.2 Hz) ppm; 6b: 3.86
(dd, J = 6.6, 3.6 Hz)]. Since the mutual couplings between H-
3/H-7 and H-1 protons were not shown,12 we reason that the
3
splitting of the H-1 signals should be caused by a J coupling
with H-5 and an unusual long-range5J coupling13 with one of the
H-4 protons.
Scheme 2. Photochemical reactions of 1a/b with benzene
(including the NOESY correlations of 6b).
Although the original goal of promoting the formation of 2-
phenylmalonate was barely achieved, we were amazed by the
unexpected generation of 6a/b because this represents an
unprecedented cyclization process of diazomalonates. Besides,
the bicyclo[3.2.0]heptane structure of the resulting products is an
important motif that appears in a large number of biologically
active natural products14 and synthetically useful molecules.15
Consequently, many synthetic strategies for its construction have
been developed,16 including some photochemical reactions in
other systems.16a-d,16f,16i
We thought that 6a/b might be derived from norcaradienes or
cycloheptatrienes because no trace of such compounds were
detected in the crude mixtures of the reactions. To confirm this
assumption, we initially tried to obtain the putative intermediates
from 1b by using a reduced irradiation time (4 hrs). However, the
effort only led to the incomplete consumption of the starting
material and no desired compounds. We thus restored to a Rh(II)-
catalyzed reaction following the previously reported procedure.8
From which, a mixture of 2b and 3b was isolated in low yield, in
addition to lactone 7 (dr: 83:17) arising from the dimerization of
1b via a carbene CH insertion process (Scheme 3). Notably, the
dimerization was not reported for 1a under the same catalytic
conditions.8 When subjected to the irradiation in a benzene
solution, the mixture of 2b/3b was smoothly converted into 6b in
Scheme 4. Proposed rational for producing 6a/b.
To probe the scope of the process, we next examined the
reactivity of ethyl diazo(diethoxyphosphoryl)acetate (1c), a
substrate that can be readily prepared18 and has been widely
employed as a carbene precursor for transition metal-catalyzed
decomposition.19 Upon exposure to the UV light for 24 hrs, we
were pleased to find that the desired 2,6-disubstituted
bicyclo[3.2.0]hepta-2,6-diene 6c could be formed in 53% isolated
1
yield (Scheme 5). The H and 13C-NMR spectra of 6c were
shown to be more complicated than those of 6a/b due to the
couplings with the 31P nuclei. Therefore, several other NMR
1
techniques (1H-1H NOESY, H-13C COSY, 31P-NMR and DEPT

3
45, 90, 135) in combination with HRMS analysis were also
employed to unambiguously confirm the structure.20 With this
encouraging result in hand, we further synthesized a few
analogues 1d-g21 by varying alkyl or cycloalkyl group on the
carboxylate moiety. Irradiation of them in benzene caused the
formation of the corresponding bicyclic products 6d-g in 30-39%
yields.
column chromatography or preparative TLC turned out to be
difficult. Moreover, the absolute configurations at the ring-
junction positions were not determined because of overlapping
signals in the proton NMR spectrum. According to the
mechanism proposed in Scheme 4, we envision that
a
stereoselectivity can only be introduced during the final [2 + 2]
cycloaddition step with the aid of the facial differentiation
created by a chiral auxiliary. In this case, the bornyl group is
apparently not quite suitable for this purpose regarding the
distereomeric ratio of 6h. Currently, the search for more efficient
auxiliaries for stereocontrol and/or diastereomeric resolution is
under active investigation.
Scheme 6. Synthesis and photolysis of 1h.
Scheme 5. UV-Mediated photolysis of 1c-g in benzene.
In addition, the photolysis of ethyl α-cyano diazoacetate (1i)25
was also evaluated. Upon irradiation for 24 hrs in benzene, the
reaction only produced the mixed norcaradiene 2c26 and
cyanophenylacetate 4c27 in 12% and 44% yield, respectively
(Scheme 7). Several researchers previously described the
dominating existence of several cyano-substituted norcaradienes
in the equilibrium with their cycloheptatriene tautomers,28 and
the non-production of bicyclo[3.2.0]heptane derivative from 1i is
considered to be consistent with these reports.
It is worthy to note that the yields from 6c to 6g are uniformly
higher than those of 6a and 6b. While exact reason remains
unclear, we assume that this phenomenon can be explained by
the bulky steric profile of the diethoxyphosphoryl group. During
cycloheptatriene intermediacy, a larger steric repulsion between
the phosphoryl and carboxylate groups may compel the C=O
bond into a closer proximity with the triene unit, to therefore
facilitate the [4 + 2] cycloaddition process proposed in Scheme 4
(Figure 1). A supporting evidence for this hypothesis was
received from the reaction of commercially available ethyl
diazoacetate, giving ethyl cyclohepta-1,3,5-triene-7-carboxylate
(3c)22 as the only isolated product (17%) even after the prolonged
irradiation time (48 hrs) (see the Supporting Information). Within
a boat-shaped7 conformation, the failure for 3c to undergo the
ring contraction is probably due to unfavorable orientation of the
carboxylate group when the aforementioned steric hindrance
no longer exists. Another reason may relate to the destabilization
of norcaradienes, which is caused more by a phosphoryl group
than by an ester substituent (～ 1 kcal mol-1).23 This effect can
possibly result in an increased proportion of cycloheptatriene
tautomers for producing 6c-g.
Scheme 7. UV-Mediated photolysis of 1i in benzene.
Conclusion
We have discovered a novel photochemical process during the
investigation of the UV-promoted decomposition of
diazomalonates in benzene. From the simple starting materials, it
allows access to bicyclo[3.2.0]heptane framework bearing
suitable functionalities for further modifications. A detailed study
has revealed that the process may be applicable to other
diazoacetates depending on the α-substitutions of the substrates.
Albeit the yields of the products are moderate at best, the easy
availability of the diazo precursors10,18,21,24 combined with
potential utility of the products16 will stimulate a variety of
imaginative uses of this intriguing protocol as we suspect.
Figure 1. Proposed conformations for cycloheptatriene
intermediates and compound 3c.
We have also briefly explored the possibility for asymmetric
Acknowledgments
construction of bicyclo[3.2.0]heptane skeleton using
a
diazophosphoryl precursor containing a chiral carboxylate group.
As illustrated in Scheme 6, transesterification of triethyl
phosphonoacetate with (1S)-endo-(-)-borneol afforded the known
chiral ester 8,24 which was then subjected to diazo transfer by
treating with p-acetamidobenzenesulfonyl azide (p-ABSA) and
NaH to give the requisite substrate 1h in satisfactory yield. Even
with the bulky ester substituent, the desired photochemical
reaction of 1h could still proceed to yield product 6h as a 60:40
mixture of two diastereomers. However, separation of them by
We are grateful to the Ministry of Science and Technology of
Taiwan, R.O.C. for financial support (MOST 104-2113-M-259-
001); and Miss Ly-Mei Syu, Miss Mei-Yue Jian from the
Department of Chemistry of National Chung Hsing University
for HRMS and NMR analyses.
A. Supplementary data

4
Tetrahedron
18. For preparation and characterization of 1c, see: Hirayama, T.;
Okaniwa, M.; Imada, T.; Ohashi, A.; Ohori, M.; Iwai, K.; Mori,
K.; Kawamoto, T.; Yokota, A.; Tanaka, T.; Ishikawa, T. Biorg.
Med. Chem. 2013; 21: 5488-5502.
Experimental conditions, spectroscopic date for all new
compounds; NMR spectra for all prepared compounds in this
article.
19. For recent examples, see: (a) Sharma, S.; Han. S. H.; Ji, W.; Oh.
J.; Lee, S.-Y.; Oh, J. S.; Jung, Y. H.; Kim, I. S. Org. Lett. 2015; 17:
2852-2855; (b) Maura Marinozzi, M.; Pertusati, F.; Serpi, M.
Chem. Rev. 2016; 116: 13991-14055, and references cited therein.
References and notes
1.
2.
For reviews, see: (a) Peace, B. W.; Wulfman, D. S. Synthesis.
1973; 137-145; (b) Droste, J. J.; Audia, J. E.; Gevorgyan, V.;
Rubin M.; Chan, W. W.; Yu, W.-Y. In Handbook of Reagents for
Organic Synthesis: Reagents for Heteroarene Functionalization;
Charette, A. B., Ed.; John Wiley & Sons: UK, 2015, pp 296-305.
For examples, see: (a) Gibe, R.; Kerr, M. A. J. Org. Chem. 2002;
67: 6247-6249; (b) Doyle, M. P.; Hu, W. Arkivoc. 2003; 15-22; (c)
González-Bobes, F.; Fenster, M. D. B.; Kiau, S.; Kolla, L.;
Kolotuchin, S.; Soumeillant, M. Adv. Synth. Catal. 2008; 350:
813–816; (d) Nishimura, T.; Maeda, Y.; Hayashi, T. Angew.
Chem., Int. Ed. 2010; 49: 7324-7327; (e) Cui, X.; Xu, X.; Wojtas,
L.; Kim, M. M.; Zhang, X. P. J. Am. Chem. Soc. 2012; 134:
19981–19984.
20. 6c: IR (neat) 3100, 1716, 1604, 1164, 2023, 792, 756 cm-1 1H
;
NMR (400 MHz, CDCl3) δ 7.06 (s, 1 H, H-7), 6.55 (dt, JH-P = 11.4
Hz, J = 1.2 Hz, 1 H, H-3), 4.23-4.14 (m, 2 H, CO2CH2CH3), 4.11-
4.06 [m, 4 H, PO(OCH2CH3)2], 3.83-3.79 (m, 1 H, H-1), 3.69-3.65
(m, 1 H, H-5), 2.62-2.57 (m, 2 H, H-4), 1.32 [t, J = 7.04 Hz, 6 H,
PO(OCH2CH3)2], 1.27 (t, J = 7.2 Hz, 3 H, CO2CH2CH3) ppm; 31P
NMR (161 MHz, CDCl3) δ 16.0 ppm; 13C NMR (100 MHz,
CDCl3) δ 162.1 (C=O), 152.3 (C-7), 148.9 (d, JC-P = 15.9 Hz, C-
3), 141.12 (C-6), 133.0 (d, JC-P = 189.8 Hz, C-2), 61.9 [d, JC-P
5.6 Hz, PO(OCH2CH3)2], 61.8 [d, JC-P = 5.6 Hz, PO(OCH2CH3)2],
60.3 (CO2CH2CH3), 52.3 (d, JC-P = 12.9 Hz, C-1), 44.7 (d, JC-P
=
=
11.9 Hz, C-5), 32.9 (d, JC-P = 18.6 Hz, C-4), 16.4 [d, JC-P = 2.6 Hz,
PO(OCH2CH3)2], 16.3 [d, JC-P = 2.6 Hz, PO(OCH2CH3)2], 14.2
(CO2CH2CH3) ppm; HRMS-EI: m/z [M]+ calcd. for C14H21O5P:
300.1127; found: 300.1128.
3.
4.
For a recent example, see: Xia, Y.; Liu, Z.; Feng, S.; Zhang, Y.;
Wang, J. J. Am. Chem. Soc. 2015; 80: 223-236, and references
cited therein.
For a recent example, see: Liu, S.; Shao, X.; Zhang, P.; Lu, L.;
Shen, Q. Org. Lett. 2015; 17: 2752-2755, and references cited
therein.
21. For the preparation and characterization of 1d-f, see Ref. 5a.
22. For the characterization of 3c, see: Mackay, W. D.; Johnson, J. S.
Org. Lett. 2016; 18: 536-539.
23. Thomas, E. J. In "Alicyclic Chemistry"; McKervey, M. A., Ed.;
The Chemical Society, Burlington House: London, 1978; Vol. 6,
p. 205.
5.
6.
(a) Shie, J. Y.; Zhu, J. L. Tetrahedron. 2016; 72: 1590-1601; (b)
Zhu, J. L.; Wu, Y. P. Synlett. 2017; doi: 10.1055/s-0036-1588174.
Jones, M., Jr.; Ando, W.; Hendrick, M. E.; Kulczycki, A., Jr.;
Howley, P. M.; Hummel, K. F.; Malament, D. S. J. Am. Chem.
Soc. 1972; 94: 7469–7479.
24. For the preparation of 8, see: Zhu, J. L.; Chen. P.-E.; Huang, H.-
W. Tetrahedron Asymmetry. 2013; 24: 23-36.
25. For preparation and characterization of 1i, see: Wurz, R. P.; Lin,
W.; Charette, A. B. Tetrahedron Lett. 2003; 44: 8845-8848.
26. Compound 2c was formed as a single diastereomer and its
stereochemistry remains to be determined. For the previous
synthesis of 2c, see: Hui, K.-W.; Shechter, H. Tetrahedron Lett.
1982; 23: 5115-5118.
27. For the characterization of 4c, see: Semmes, J. G.; Bevans, S. L.;
Mullins, C. H.; Shaughnessy, K. H. Tetrahedron Lett. 2015; 56:
3447-3450.
7.
8.
9.
Jansen, H.; Slootweg, J. C.; Lammertsma, K. Beilstein J. Org.
Chem. 2011; 7: 1713-1721, and the references cited therein.
Yang, M.; Webb, T. R.; Livant, P. J. Org. Chem. 2001; 66: 4945-
4949.
Ciganek, E. J. Org. Chem. 1965; 30: 4366-4367.
10. For the preparation of 1a and 1b, see: de Nanteuil, F.; Waser, J.
Angew. Chem. Int. Ed. 2011; 50: 12075-12079.
11. For the characterization of 4a and 4b, see: Satumov, E. T.;
Medvedev, J. J.; Nilov, D. I.; Sandzhieva, M. A.; Boyarskaya, I.
A.; Nikolaev, V. A.; Vasilyev, A. V. Tetrahedron. 2016; 72: 4835-
4844.
28. (a) MaNamara, O. A.; Maguire, A. R. Tetrahedron. 2011; 67: 9-40;
(b) Hall, G. E.; Roberts, J. D. J. Am. Chem. Soc. 1971; 93: 2203-
2207.
12. 6a: IR (neat) 3059, 1720, 1622, 1234, 778, 751 cm-1; 1H NMR
(400 MHz, CDCl3) δ 7.12 (br s, 1 H, H-7), 6.69 (t, J = 1.2 Hz, 1 H,
H-3), 3.85 (dd, J = 6.5, 3.2 Hz, 1 H, H-1), 3.73 (s, 3 H, OCH3),
3.72 (s, 3 H, OCH3), 3.65 (ddd, J = 8.1, 3.2, 3.2 Hz, 1 H, H-5),
2.62-2.60 (m, 2 H, H-4) ppm; 13C NMR (100 MHz, CDCl3) δ
165.1 (C=O), 162.6 (C=O), 153.1 (CH), 145.0 (CH), 140.8 (C),
136.3 (C), 51.6 (CH3), 51.4 (CH3), 50.5 (CH), 43.8 (CH), 32.3
(CH2) ppm; HRMS-EI: m/z [M]+ calcd. for C11H12O4: 208.0736;
found: 208.0734. 6b: IR (neat) 3060, 1709, 1618, 1230, 749, 736
cm-1; 1H NMR (400 MHz, CDCl3) δ 7.13 (br s, 1 H, H-7), 6.69 (t,
J = 1.2 Hz, 1 H, H-3), 4.25-4.16 (m, 4 H, CH2O), 3.86 (dd, J =
6.6, 3.6 Hz, 1 H, H-1), 3.66 (ddd, J = 8.4, 3.6, 3.6 Hz, 1 H, H-5),
2.63-2.60 (m, 2 H, H-4), 1.29 (t, J = 7.12 Hz, 3 H, CH3), 1.28 (t , J
= 7.12, 3 H, CH3) ppm; 13C NMR (100 MHz, CDCl3) δ 164.7
(C=O), 162.2 (C=O), 152.8 (CH), 144.6 (CH), 141.2 (C), 136.7
(C), 60.4 (OCH2), 60.2 (OCH2), 50.4 (CH), 43.8 (CH), 32.2 (CH2),
14.3 (CH3), 14.3 (CH3) ppm; HRMS-EI: m/z [M]+ calcd. for
C13H16O4: 236.1049; found: 236.1044.
13. Guenther H, Jikeli G. Chem. Rev. 1977; 77: 599–637.
14. For a review, see: Miesch, M. Curr. Org. Syn. 2006; 3: 327-340.
15. Kean, Z. S.; Ramirez, A. L. B.; Yan, Y. Craig, S. L. J. Am. Chem.
Soc. 2012; 134: 12939-12942.
16. For examples, see: (a) Joy, A.; Scheffer, J. R.; Ramamurthy, V.
Org. Lett. 2000; 2: 119-121; (b) Tanaka, K.; Nagahiro, R.;
Urbanczyk-Lipkowska, Z. Org. Lett. 2001; 3: 1567-1569; (c)
Farcet, J.-B.; Himmelbauer, M.; Mulzer, J. Org. Lett. 2012; 14:
2195-2197; (d) Penkett, C. S.; Woolford, J. A. 2012; 14: 5704-
5707; (e) Zheng. J.; Huang. Y.; Li, Z. Org. Lett. 2013; 15: 5758-
5761; (f) Jana. A.; Mondal, S.; Ghosh, S. Org. Biomol. Chem.
2015; 13: 1846-1859; (g) Robertson, B. D.; Brooner, R. E. M.;
Widenhoefer, R. A. Chem. Eur. J. 2015; 21: 5714-5717. (h)
Poplate, S.; Tröster, A.; Zou, Y.-Q.; Bach, T. Chem. Rev. 2016;
116: 9748-9815, and the references cited therein; (i) Kim, N.;
Brooner, R. E. M.; Widenhoefer, R. A. Organometallic. 2017; 36:
673-678.
17. Terrian, D. L.; Mohammad, T. Morrison, H. J. Org. Chem. 1995;
60: 1981-1984.

5
29.

6
Tetrahedron
Highlights
• Bicyclo[3.2.0]heptane scaffold is formed by
irradiating diazomalonates in benzene.
• The products are proven to be derived from
cycloheptatriene intermediates.
• This UV-mediated process is also applicable to α-
diazo phosphorylacetates.