Simple, onepot, and facile synthesis of angularly fused [6-7-5], [6-7-6], [6-7-7], and [6,7] ring systems using baylishillman acetates

Article abstract of DOI:10.1002/ejoc.200901483

A simple, convenient, and one-pot synthesis of angularly fused [6-7-5], [6-7-6], [6-7-7], and [6,7] carbocyclic ring systems from Baylis-Hillman acetates through a strategy involving alkylation, formation of a vinyl chloride, and intramolecular cyclization (Friedel-Crafts or Michael reaction) is described.

Full text of DOI:10.1002/ejoc.200901483

SHORT COMMUNICATION
DOI: 10.1002/ejoc.200901483
Simple, One-Pot, and Facile Synthesis of Angularly Fused [6-7-5], [6-7-6],
[6-7-7], and [6,7] Ring Systems Using Baylis–Hillman Acetates
Deevi Basavaiah,*[a] Kunche Aravindu,[a] Katta Santosh Kumar,[a] and
Kanumuri Ramesh Reddy[a]
Keywords: Carbocycles / Cyclization / Fused-ring systems / Michael addition
A simple, convenient, and one-pot synthesis of angularly
fused [6-7-5], [6-7-6], [6-7-7], and [6,7] carbocyclic ring sys-
tems from Baylis–Hillman acetates through a strategy involv-
ing alkylation, formation of a vinyl chloride, and intramolecu-
lar cyclization (Friedel–Crafts or Michael reaction) is de-
scribed.
Introduction
The angularly fused tricyclic carbocyclic framework con-
taining cycloheptane as the central ring has a special and
respectable place in the history of carbocyclic rings due to
the presence of this tricyclic framework in various natural
products and bioactive molecules.[1a–1f] For example, an
angularly fused [6-7-5] carbocyclic skeleton is the core
structure present in several natural products and bioactive
molecules such as sphaeroane,[1a] (_)-presphaerene,[1a]
frondosin C,[1b] and phorbol esters.[1c] An angularly fused
Figure 1. Representative biologically active molecules containing a
tricyclic carbocyclic framework with cycloheptane as the central
[6-7-6] tricyclic system is present in biologically active com- ring.
pounds such as allocolchicine[1d,1e] and colchinol derivative
ZD6126,[1e] whereas an angularly fused [6-7-7] tricyclic ring
system is an integral part of the well-known alkaloid colchi-
cine.[1f] Important bioactive compounds such as theaflav-
The Baylis–Hillman reaction has become a useful and
in[1g,1h] and TAK-779[1i,1j] contain the [6,7] bicyclic carbocy-
clic ring framework. Because of the remarkable medicinal
importance of these fused-ring frameworks (Figure 1) and
also because of unfavorable entropic factors[2] in synthesiz-
ing seven-membered rings, the development of efficient pro-
tocols for the synthesis of such fused-carbocyclic frame-
works having cycloheptane as the key central ring has been
and continues to be one of the most attractive and challeng-
ing areas in carbocyclic chemistry.[2c,3] In continuation of
our interest in the synthesis of heterocyclic/carbocyclic mo-
lecules,[4] we herein report a simple one-pot multistep proto-
col for the synthesis of [6-7-5], [6-7-6], and [6-7-7] tricyclic,
as well as [6,7] bicyclic, carbocyclic frameworks from
Baylis–Hillman acetates by following a strategy involving
alkylation, formation of a vinyl chloride, and intramolecu-
lar Friedel–Crafts (or Michael) reaction.
popular synthetic tool for obtaining diverse classes of
densely functionalized molecules (usually referred to as the
Baylis–Hillman adducts) through atom-economical car-
bon–carbon bond-forming reactions involving coupling of
the α-position of an activated alkene with an electrophile
under the influence of a catalyst/catalytic system.[5,6] Appli-
cations of Baylis–Hillman adducts in a variety of organic
transformations and also in the synthesis of natural prod-
ucts/bioactive compounds have been well documented over
the last several years.[5,7]
Results and Discussion
On the basis of our experience and active involvement in
various aspects of this fascinating reaction,[4] we envisioned
that Baylis–Hillman acetates would be excellent synthons
(or alkylators) for the one-pot, multistep synthesis of all
three ([6-7-5], [6-7-6], and [6-7-7]) tricyclic carbocyclic
frameworks. Accordingly, we planned a retrosynthetic strat-
egy involving alkylation of suitable cyclic 1,3-diones with
[a] School of Chemistry, University of Hyderabad
Hyderabad 500046, India
Fax: +91-40-23012460
E-mail: dbsc@uohyd.ernet.in
Supporting information for this article is available on the
WWW under http://dx.doi.org/10.1002/ejoc.200901483.
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D. Basavaiah, K. Aravindu, K. S. Kumar, K. R. Reddy
SHORT COMMUNICATION
Scheme 1. Retrosynthetic strategy for the synthesis of angularly fused [6-7-5], [6-7-6], and [6-7-7] ring systems.
appropriate Baylis–Hillman acetates followed by intramo- hyde with methyl acrylate) and 5,5-dimethyl-1,3-cyclohex-
lecular cyclization (by Friedel–Crafts or Michael reaction) anedione (dimedone; 2a) as reaction partners. Our attempts
after in situ generation of the carbocation according to the to obtain desired [6-7-6] tricyclic carbocyclic molecule 3 un-
reaction sequence described in Scheme 1.
der various conditions (Scheme 2 and Table 1) were not suc-
Accordingly, we have first selected methyl 3-acetoxy-2- cessful, as (E)-4-benzylidene-9,9-dimethyl-2-oxabicyclo-
methylene-3-phenylpropanoate (1a; acetate of Baylis–Hill- [4.4.0]dec-1(6)-ene-3,7-dione (4a)[8] was obtained as the
man (BH) alcohol, obtained from the reaction of benzalde- major product. On the basis of our earlier studies[4g,6k] it
Scheme 2. Attempted synthesis of [6-7-6] ring systems by reaction of BH acetate 1a with dimedone (2a). Conditions A: 2  TiCl4 in DCE,
reflux, 12 h, 38%. Conditions B: (i) (COCl)2, r.t., 5 h; (ii) 2  TiCl4, reflux, 16 h, 32%.
Table 1. Reaction optimization: Synthesis of angularly fused [6-7-6] ring systems by the reaction of 1b with 2a.[a]
Entry
Conditions
Product
Yield [%]
1
2
3
4
5
6
7
8
9
10
(i) Et3N, r.t., 12 h; (ii) TFAA, r.t., 6 h[b]
–
4b
–
–
–
–
–
–
–
24
–
–
–
–
–
–
15
72
(i) Et3N, r.t., 12 h; (ii) TFAA, reflux, 12 h
(i) Et3N, r.t., 12 h; (ii) MeSO3H, r.t., 6 h[b]
(i) Et3N, r.t., 12 h; (ii) MeSO3H, reflux, 12 h[c]
(i) Et3N, r.t., 12 h; (ii) triflic acid, r.t., 6 h[b]
(i) Et3N, r.t., 12 h; (ii) triflic acid, reflux, 12 h[c]
(i) Et3N, r.t., 12 h; (ii) POCl3, r.t., 6 h[b]
(i) Et3N, r.t., 12 h; (ii) POCl3, reflux, 10 h[c]
(i) Et3N, r.t., 12 h; (ii) 2  TiCl4, reflux,12 h
(i) Et3N, r.t., 12 h; (ii) (COCl)2, r.t., 5 h; (iii) 2  TiCl4, r.t., 4 h
5
5
[a] All reactions were carried out on 1-mmol scale of Baylis–Hillman acetate 1b with 1 mmol of dimedone (2a). [b] At room temperature,
almost all the alkylated product was intact as evidenced by TLC examination. [c] Reaction was not clean.
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Simple, One-Pot, and Facile Synthesis of Angularly Fused Ring Systems
occurred to us that the presence of an electron-donating yields (Table 2, Entries 2–11). We further confirmed the
group on the aromatic ring of the BH acetate would help structures of molecules 10 and 13 (Figures 2 and 3) by sin-
to facilitate the intramolecular cyclization (Friedel–Crafts gle-crystal X-ray analysis.[9]
or Michael reaction).
Table 2. Synthesis of angularly fused [6-7-6], [6-7-7], and [6-7-5]
Accordingly, we selected methyl 3-acetoxy-3-(3,5-dimeth-
oxyphenyl)-2-methylenepropanoate (1b) as the reaction
frameworks by the reaction of 1b–d with 2a–d.[a]
partner with dimedone (2a). We performed this reaction un-
der different conditions (Table 1) and realized that BH ace-
tate 1b provided the expected [6-7-6] tricyclic carbocyclic
framework (Table 1, Entry 10). Thus, treatment of 1b
(1 mmol) with 2a (1 mmol) in the presence of Et3N pro-
vided the alkylated product, which (after removal of excess
triethylamine) upon reaction with oxalyl chloride (5 mmol)
in situ afforded the corresponding vinyl chloride. Subse-
quent intramolecular cyclization (Friedel–Crafts or Michael
reaction) was performed by using TiCl4 (2 mmol, 2  in
DCE) in 1,2-dichloroethane (DCE) as the Lewis acid at
room temperature for 4 h (after removal of DCM and ox-
alyl chloride under reduced pressure) to provide the desired
[6-7-6] tricyclic carbocyclic molecule, i.e., {13,15-
dimethoxy-4,4-dimethyl-9-methoxycarbonyltricyclo-
[9.4.0.02,7]pentadeca-1(15),2(7),9,11,13-pentaen-6-one (5)}
in 72% isolated yield after usual workup followed by col-
umn chromatography (Table 2, Entry 1). The structure of
this molecule was further confirmed by single-crystal X-ray
data (Figure 2).[9]
Entry Acetate
R1
R2
Dione
Product[b] Yield [%]
1
2
3
4
5
6
7
8
1b
1c
1b
1c
1d
1b
1c
1d
1b
1c
1d
OMe
OMe
OMe
OMe
OEt
OMe
OMe
OEt
OMe
H
OMe
H
H
OMe
H
H
OMe
H
2a
2a
2b
2b
2b
2c
2c
5[d]
6
72
67
75
64
61
63
59
57
52
53
50
7
8
9
10[d]
11
12
13[d]
14
15
2c
9
10
11
OMe
OMe
OEt
2d[c]
2d[c]
2d[c]
H
[a] All reactions were carried out on 1-mmol scale of Baylis–Hill-
man acetates (1b–d) with 1 mmol of cyclic dione (2a–d) in the pres-
ence of Et3N (1 mL) at room temperature for 12–14 h followed by
treatment with (COCl)2 at room temperature for 5 h in DCM and
then reaction of the resulting vinyl chloride with 2  TiCl4 in DCE
at r.t. (or reflux) for 4–14 h. [b] All compounds were fully charac-
terized (see Supporting Information). [c] Reaction was carried out
at 80 °C in Et3N/DMF for 8 h. [d] Structures of these molecules
were further confirmed by single-crystal X-ray data (see Supporting
To examine the generality of this strategy, we subjected
acetates, 1b–d, of Baylis–Hillman alcohols (derived from the
reaction of 3,5-dimethoxy and 3-alkoxybenzaldehydes with
methyl acrylate) to the reaction with 5,5-dimethyl-1,3-cyclo-
hexanedione (2a), 1,3-cyclohexanedione (2b), 1,3-cyclo-
heptanedione (2c), and 1,3-cyclopentanedione (2d) as nu-
cleophiles, which gave the desired [6-7-6], [6-7-7], and [6-7-
5] tricyclic carbocyclic derivatives 5–15 in 50–75% isolated Information).[9]
Figure 2. ORTEP diagrams of compounds 5 and 10 (hydrogen atoms were omitted for clarity).
Eur. J. Org. Chem. 2010, 1843–1848
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D. Basavaiah, K. Aravindu, K. S. Kumar, K. R. Reddy
SHORT COMMUNICATION
Figure 3. ORTEP diagrams of compounds 13 and 16 (hydrogen atoms were omitted for clarity).
With a view to extend this strategy to acyclic diones we
employed 2,4-pentanedione (2e) as a nucleophile. Thus, re-
action of 2,4-pentanedione with Baylis–Hillman acetate 1b
followed by treatment of the resulting trisubstituted alkene–
esters with oxalyl chloride and then with TiCl4 provided
desired [6,7] bicyclic framework 16 in 50% isolated yield
(Scheme 3). The structure of molecule 16 was also con-
firmed by single-crystal X-ray analysis (Figure 3).[9] Simi-
larly, Baylis–Hillman acetate methyl 3-acetoxy-3-(3-meth-
oxyphenyl)-2-methylenepropanoate (1c) upon reaction with
2,4-pentanedione (2e) provided [6,7] bicyclic derivative 17
in 46% isolated yield.
Scheme 3. One-pot synthesis of the [6,7] bicyclic carbocyclic frame-
work by the reaction of 1b and 1c with 2e. Reagents and conditions:
(i) Et3N, reflux, 10 h; (ii) (COCl)2/DCM, r.t., 8 h; (iii) TiCl4/DCE,
r.t. or reflux, 1–8 h.
A plausible mechanism taking dimedone as a model case
(nucleophile) for the formation of angularly fused tricyclic lecular cyclization of the in situ generated vinyl chloride
carbocyclic frameworks is presented in Scheme 4. Intramo- might involve either a Friedel–Crafts or a Michael reaction.
Scheme 4. Plausible mechanism [taking dimedone as a model case (nucleophile)].
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Simple, One-Pot, and Facile Synthesis of Angularly Fused Ring Systems
wada, Y. Iizawa, M. Shiraishi, Y. Aramaki, K. Okonogi, Y.
Ogawa, K. Meguro, M. Fujino, Proc. Natl. Acad. Sci. USA
1999, 96, 5698–5703; j) M. Shiraishi, Y. Aramaki, M. Seto, H.
Imoto, Y. Nishikawa, N. Kanzaki, M. Okamoto, H. Sawada,
O. Nishimura, M. Baba, M. Fujino, J. Med. Chem. 2000, 43,
2049–2063.
a) L. Yet, Chem. Rev. 2000, 100, 2963–3007; b) G. A. Molander,
Acc. Chem. Res. 1998, 31, 603–609; c) M. A. Battiste, P. M.
Pelphrey, D. L. Wright, Chem. Eur. J. 2006, 12, 3438–3447.
Conclusions
In conclusion, we have developed a simple, facile, and
convenient synthesis of angularly fused [6-7-5], [6-7-6], and
[6-7-7] tricyclic and [6,7] bicyclic carbocyclic frameworks,
thus demonstrating the application of Baylis–Hillman ad-
ducts as a valuable source of a one-pot, multistep protocol
for the synthesis of important and useful structural frame-
works.
[2]
[3]
a) N. Nicolaus, S. Strauss, J.-M. Neudorfl, A. Prokop, H.-G.
Schmalz, Org. Lett. 2009, 11, 341–344; b) L. F. Silva Jr., R. S.
Vasconcelos, M. A. Nogueira, Org. Lett. 2008, 10, 1017–1020;
c) K. M. Brummond, D. Chen, M. M. Davis, J. Org. Chem.
2008, 73, 5064–5068; d) F.-D. Boyer, I. Hanna, Org. Lett. 2007,
9, 715–718; e) F.-D. Boyer, I. Hanna, Org. Lett. 2007, 9, 2293–
2295; f) X. Li, R. E. Kyne, T. V. Ovaska, Org. Lett. 2006, 8,
5153–5156; g) T. Graening, H.-G. Schmalz, Angew. Chem.
2004, 116, 3292–3318; Angew. Chem. Int. Ed. 2004, 43, 3230–
3256; h) T. Ikemoto, A. Nishiguchi, H. Mitsudera, M. Wakim-
asu, K. Tomimatsu, Tetrahedron 2001, 57, 1525–1529; i) T. V.
Ovaska, J. L. Roark, C. M. Shoemaker, J. Bordner, Tetrahedron
Lett. 1998, 39, 5705–5708; j) P. A. Wender, K. D. Rice, M. E.
Schnute, J. Am. Chem. Soc. 1997, 119, 7897–7898.
a) D. Basavaiah, B. Devendar, D. V. Lenin, T. Satyanarayana,
Synlett 2009, 411–416; b) D. Basavaiah, D. V. Lenin, B. Deven-
dar, Tetrahedron Lett. 2009, 50, 3538–3542; c) D. Basavaiah,
R. J. Reddy, Org. Biomol. Chem. 2008, 6, 1034–1039; d) D. Ba-
savaiah, S. Roy, Org. Lett. 2008, 10, 1819–1822; e) D. Basa-
vaiah, K. Aravindu, Org. Lett. 2007, 9, 2453–2456; f) D. Basa-
vaiah, K. R. Reddy, Org. Lett. 2007, 9, 57–60; g) D. Basavaiah,
T. Satyanarayana, Chem. Commun. 2004, 32–33; h) D. Basa-
vaiah, D. S. Sharada, A. Veerendhar, Tetrahedron Lett. 2004,
45, 3081–3083.
For leading reviews on the Baylis–Hillman reaction, see: a) V.
Declerck, J. Martinez, F. Lamaty, Chem. Rev. 2009, 109, 1–48;
b) V. Singh, S. Batra, Tetrahedron 2008, 64, 4511–4574; c) D.
Basavaiah, K. V. Rao, R. J. Reddy, Chem. Soc. Rev. 2007, 36,
1581–1588; d) G. Masson, C. Housseman, J. Zhu, Angew.
Chem. 2007, 119, 4698–4712; Angew. Chem. Int. Ed. 2007, 46,
4614–4628; e) D. Basavaiah, A. J. Rao, T. Satyanarayana,
Chem. Rev. 2003, 103, 811–891; f) E. Ciganek in Organic Reac-
tions (Ed.: L. A. Paquette), Wiley, New York, 1997, vol. 51, pp.
201–350; g) D. Basavaiah, P. D. Rao, R. S. Hyma, Tetrahedron
1996, 52, 8001–8062; h) S. E. Drewes, G. H. P. Roos, Tetrahe-
dron 1988, 44, 4653–4670.
a) G.-N. Ma, J.-J. Jiang, M. Shi, Y. Wei, Chem. Commun. 2009,
5496–5514; b) G. W. Amarante, H. M. S. Milagre, B. G. Vaz,
B. R. V. Ferreira, M. N. Eberlin, F. Coelho, J. Org. Chem. 2009,
74, 3031–3037; c) A. Trofimov, V. Gevorgyan, Org. Lett. 2009,
11, 253–255; d) I. Deb, P. Shanbhag, S. M. Mobin, I. N. N.
Namboothiri, Eur. J. Org. Chem. 2009, 4091–4101; e) M. E.
Krafft, T. F. N. Haxell, K. A. Seibert, K. A. Abboud, J. Am.
Chem. Soc. 2006, 128, 4174–4175; f) T. Turki, J. Villieras, H.
Amri, Tetrahedron Lett. 2005, 46, 3071–3072; g) T. G. Back,
D. A. Rankic, J. M. Sorbetti, J. E. Wulff, Org. Lett. 2005, 7,
2377–2379; h) V. Nair, K. G. Abhilash, Synthesis 2005, 1967–
1970; i) B. G. Jellerichs, J.-R. Kong, M. J. Krische, J. Am.
Chem. Soc. 2003, 125, 7758–7759; j) D. Basavaiah, B. Sreeniva-
salu, A. J. Rao, J. Org. Chem. 2003, 68, 5983–5991; k) D. Basa-
vaiah, M. Bakthadoss, G. Jayapal Reddy, Synthesis 2001, 919–
923; l) G. Li, J. Gao, H.-X. Wei, M. Enright, Org. Lett. 2000,
2, 617–620; m) K.-S. Yang, K. Chen, Org. Lett. 2000, 2, 729–
731; n) D. Basavaiah, V. V. L. Gowriswari, T. K. Bharathi, Tet-
rahedron Lett. 1987, 28, 4591–4592; o) H. Amri, J. Villieras,
Tetrahedron Lett. 1986, 27, 4307–4308.
Experimental Section
General Experimental Procedure: A mixture of methyl 3-acetoxy-3-
(3,5-dimethoxyphenyl)-2-methylenepropanoate (1b; 1 mmol, 0.294 g)
and 5,5-dimethyl-1,3-cyclohexanedione (2a; 1 mmol, 0.140 g) in tri-
ethylamine (1 mL) was stirred at room temperature for 12 h. Then,
the excess amount of triethylamine was removed under reduced
pressure, and the reaction mixture was diluted with dichlorometh-
ane (3 mL). Oxalyl chloride (5 mmol, 0.635 g, 0.42 mL) was then
added dropwise, and the mixture was stirred at room temperature
for 5 h. The excess amount of oxalyl chloride and dichloromethane
were evaporated, and the reaction mixture was diluted with DCE
(3 mL). A solution of TiCl4 (2 mmol, 1 mL, 2  in DCE) was then
added dropwise at 0 °C and stirring was continued at room tem-
perature for 4 h. The reaction mixture was diluted with water
(10 mL) and extracted with diethyl ether (3ϫ15 mL). The com-
bined organic layer was dried with anhydrous Na2SO4. The solvent
was evaporated, and the residue thus obtained was purified by silica
gel column chromatography (20% EtOAc in hexanes) to provide
compound 5 as a colorless solid in 72% (0.256 g) isolated yield.
[4]
[5]
Supporting Information (see footnote on the first page of this arti-
cle): All the experimental details, spectroscopic data, and the 1H
and 13C NMR spectra for all the compounds.
Acknowledgments
We thank the Department of Science and Technology (DST, New
Delhi) for funding this project. K.A., K.S.K., and K.R.R. thank
the Council of Scientific and Industrial Research (CSIR, New
Delhi) for their research fellowships. We thank the University
Grants Commission (UGC, New Delhi) for support and for provid-
ing some instrumental facilities. We thank the National Single-
Crystal X-ray facility funded by the Department of Science and
Technology (DST, New Delhi). We also thank Professor S. Pal,
School of Chemistry, University of Hyderabad, for helpful dis-
cussions regarding X-ray data analysis.
[6]
[1] a) J. Lee, J. Hong, J. Org. Chem. 2004, 69, 6433–6440; b) A. D.
Patil, A. J. Freyer, L. Killmer, P. Offen, B. Carte, A. J. Jurewicz,
R. K. Johnson, Tetrahedron 1997, 53, 5047–5060; c) G. Goel,
H. P. S. Makkar, G. Francis, K. Becker, Int. J. Toxicol. 2007,
26, 279–288; d) O. Boye, A. Brossi, H. J. C. Yeh, E. Hamel, B.
Wegrzynski, V. Toome, Can. J. Chem. 1992, 70, 1237–1249; e)
P. D. Davis, G. J. Dougherty, D. C. Blakey, S. M. Galbraith,
G. M. Tozer, A. L. Holder, M. A. Naylor, J. Nolan, M. R. L.
Stratford, D. J. Chaplin, S. A. Hill, Cancer Res. 2002, 62, 7247–
7253; f) A. Brossi, J. Med. Chem. 1990, 33, 2311–2319; g) T.
Tanaka, Y. Miyata, K. Tamaya, R. Kusano, Y. Matsuo, S. Tam-
aru, K. Tanaka, T. Matsui, M. Maeda, I. Kouno, J. Agric. Food
Chem. 2009, 57, 5816–5822; h) C. S. Yang, J. D. Lambert, J. Ju,
G. Lu, S. Sang, Toxicol. Appl. Pharmacol. 2007, 224, 265–273;
i) M. Baba, O. Nishimura, N. Kanzaki, M. Okamoto, H. Sa-
[7]
a) T. Gendrineau, N. Demoulin, L. Navarre, J.-P. Genet, S.
Darses, Chem. Eur. J. 2009, 15, 4710–4715; b) M. Bakthadoss,
G. Sivakumar, D. Kannan, Org. Lett. 2009, 11, 4466–4469; c)
L. D. S. Yadav, C. Awasthi, Tetrahedron Lett. 2009, 50, 3801–
3804; d) V. Singh, V. Singh, S. Batra, Eur. J. Org. Chem. 2008,
Eur. J. Org. Chem. 2010, 1843–1848
© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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D. Basavaiah, K. Aravindu, K. S. Kumar, K. R. Reddy
SHORT COMMUNICATION
5446–5460; e) Z. Shafiq, L. Liu, Z. Liu, D. Wang, Y.-J. Chen,
Org. Lett. 2007, 9, 2525–2528; f) P. Shanmugam, B. Vis-
wambharan, S. Madhavan, Org. Lett. 2007, 9, 4095–4098; g)
S. I. Lee, G.-S. Hwang, S. C. Shin, T. G. Lee, R. H. Jo, D. H.
Ryu, Org. Lett. 2007, 9, 5087–5089; h) S. Gowrisankar, K. Y.
Lee, C. G. Lee, J. N. Kim, Tetrahedron Lett. 2004, 45, 6141–
6146; i) G. W. Kabalka, B. Venkataiah, G. Dong, J. Org. Chem.
2004, 69, 5807–5809; j) D. Basavaiah, R. M. Reddy, Tetrahe-
dron Lett. 2001, 42, 3025–3027; k) D. Basavaiah, P. K. S.
Sarma, J. Chem. Soc., Chem. Commun. 1992, 955–957; l) M. L.
Bode, P. T. Kaye, J. Chem. Soc. Perkin Trans. 1 1990, 2612–
2613.
b) Su and co-workers reported the synthesis of 4-benzyl-9,9-
dimethyl-2-oxabicyclo[4.4.0]deca-1(6),4-diene-3,7-dione by fol-
lowing the procedure given below (W. Zhong, Y. Zhao, W. Su,
Tetrahedron 2008, 64, 5491–5496).
[9]
CCDC-750184 (for 5), -750185 (for 10), -750186 (for 13), and
-750187 (for 16) contain the supplementary crystallographic
data for this paper. These data can be obtained free of charge
from The Cambridge Crystallographic Data Centre via
www.ccdc.cam.ac.uk/data_request/cif.
[8] a) Kim and co-workers prepared (E)-4-benzylidene-9,9-di-
methyl-2-oxabicyclo[4.4.0]dec-1(6)-ene-3,7-dione according to
1
the equation given below. Its melting point and its H and 13C
NMR spectroscopic data are reported. Our data is in agree-
ment with that of the literature data (S. C. Kim, H. S. Lee, J. N.
Kim, Bull. Korean Chem. Soc. 2007, 28, 147–150).
Received: December 20, 2009
Published Online: March 1, 2010
1848
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© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2010, 1843–1848