Iodo cyclofunctionalization of 2,4-dialkenyl-1,3-dicarbonyl compounds: Synthesis of substituted 3-(2-furylidene)-2-furanones

Article abstract of DOI:10.1002/jhet.5570390406

A facile method for the synthesis of substituted 3-(2-furylidene)-2-furanones has been developed using cyclofunctionalization reactions of 2,4-dialkenyl-1,3-dicarbonyl compounds and iodine as electrophile in the presence of Na₂CO₃, i

Full text of DOI:10.1002/jhet.5570390406

Jul-Aug 2002
Iodo Cyclofunctionalization of 2,4-Dialkenyl-1,3-Dicarbonyl
Compounds: Synthesis of Substituted 3-(2-furylidene)-2-furanones
Claudete J. Valduga* [a], Hélio A. Stefani [a],and Nicola Petragnani [b]
639
[a] Faculdade de Ciências Farmacêuticas, Universidade de São Paulo
[b] Instituto de Química, Universidade de São Paulo
Av. Prof. Lineu Prestes, 580 - CEP 05508-900 - São Paulo – Brasil
Received May 11, 2001
A facile method for the synthesis of substituted 3-(2-furylidene)-2-furanones has been developed using
cyclofunctionalization reactions of 2,4-dialkenyl-1,3-dicarbonyl compounds and iodine as electrophile in
the presence of Na CO , in refluxing chloroform. Compounds 4 are obtained in modest to good yields and
2
3
1
1
13
1
13
their structural identification was established by H NMR, H COSY, C NMR and H- C COSY. A mech-
anism has been proposed to rationalize the formation of the ylidene furanone.
J. Heterocyclic Chem., 39, 639 (2002).
Introduction.
Scheme 1
The word "cyclofunctionalization" was introduced by
Clive [1] in 1977 to describe a process where the addition
of an electrophile to an alkene bearing an internal nucle-
ophile results in a cyclization. This electrophile remains
connected to one of the carbons of the double bond
involved in the reaction allowing for further modifications
that will depend on the choice of the functionalization
-
agent. Functional groups like OR, COOH, COO , CONR ,
2
NHR, SR, etc., will participate as internal nucleophiles in
the process.
Based on the empirical Baldwin rules [2] governing ring
closure reactions Cardillo and Orena [3] have emphasized
that the 5-exo mode appears to be preferred in both the
tetrahedral or trigonal ring closure under kinetic control,
although several factors seem to promote the 5-exo or 6-
endo process. Thus, in the lactonization reaction under
kinetic control and in the absence of strong electronic fac-
tors, preference for formation of γ-lactones relative to δ-
lactones can be observed [4]. Likewise a large number of
examples are found in the literature focusing on the prefer-
ence of 5 over 4 rings in the lactonization reactions under
thermodynamic control as well as the 5-exo over the
With the aim of synthesizing diiodocyclofunctionalized
compounds, the monoiodocyclofunctionalized compounds
2a-e and 2g-i (with endocyclic double bond) and 3a, 3c
and 3f (with exocyclic double bond) were submitted to a
second cyclization with iodine in excess/Na CO in
2
3
refluxing chloroform. The diiodocyclization was per-
formed also in a "one pot" procedure by treating directly
the starting dicarbonyl compounds (1a-i) with excess
iodine. This "one pot" procedure is more suitable due to its
experimental simplicity.
6-endo mode cyclization process.
The monoiodo compounds with endocyclic double bond
2a-e and 2g-i) were expected to produce the seven mem-
Results and Discussion.
(
Following an initial publication [5] describing the
iodocyclization of 2,4-dialkenyl-1,3-dicarbonyl com-
pounds (1 equivalent I /Na CO in CHCl ) we now report
the reaction of other substrates under similar conditions. In
all cases tetrahydrofuran derivatives with no pyran ring
formation were obtained, confirming the preference for the
five over the six-membered rings [3]. Iodoethers with
endocyclic double bond are mainly formed with exception
of the reactions with compounds 1a, 1c and 1f. Compound
ber lactones (ε-lactones), such as 5a, fused to a dihydrofu-
ranic ring. These seven-membered lactones should be
obtained also by the "one pot" dicyclization procedure of
the starting dicarbonyl substrates.
Likewise, five-membered lactones (γ-lactones) con-
nected to a tetrahydrofuran ring by a C-C double bond
(such 4a) should be obtained by the iodocyclization of the
exo-cyclic compound 3a, 3c and 3f.
Contrary to our expectation the aforementioned five-mem-
bered lactones were the only products formed regardless of
the method used, as exemplified in scheme 2 (see Table 1).
These results confirm once more the preference toward the
formation of five-membered over seven-membered lactones.
2
2
3
3
1
a gave rise only to a minor amount of the exocyclic deriv-
ative 3a (10%), 1c produced 3c as the minor product (2.9:1
exo/endo), and 1f formed exclusively the exo derivative 3f
(Scheme 1 and Table 1).

6
40
C. J. Valduga, H. A. Stefani, and N. Petragnani
Vol. 39
Scheme 2
These results can be rationalized by considering that
supported by the previously mentioned preference for the five-
membered over the seven-membered lactones (Scheme 3).
The low yield observed in the case of α-cyclohexenyl
substituted compounds like 4b, 4d and 4i (19%, 10% and
31%) can be attributed to the lack of anti-periplanarity in
the iodine assisted opening of the furan ring (illustrative
example 2b→4b, figure 1).
under the employed conditions compounds 4 cannot be
generated from 2 via the reverse sequence 2→1→4.
Based on the fact that unsaturated ethers [6,7] and esters
[
8] are also susceptible to iodocyclization, it can be tenta-
tively assumed that formation of 4 from 2 involves the
intermediate iodonium salt 7, or more probably the π com-
plex 6 [9] which suffers the known lactonization step lead-
ing to the bicyclic compound 4.
According to an earlier report [10], the lactonization step
requires two equivalents of iodine on account of the for-
mation of the π complex 6 followed by reaction with the
second equivalent of iodine to generate the iodonium salt 7
-
and the I anion.
The conversion 3→2 by the iodine assisted antiperiplanar
opening of the furan ring can be presumably attributed to the
greater stability of the endocyclic olefins toward the exo-
cyclic copartners [11]. Otherwise, the formation of 4 from 2
and from 1 by the two- or one-step procedure respectively, is
Figure 1. Cleavage of the dihydrofuran ring.
An alternative pathway to 2 can involve a direct
cyclization of 1 by attack of the OH group on the other
Scheme 3

Jul-Aug 2002
Iodo Cyclofunctionalization of 2,4-Dialkenyl-1,3-Dicarbonyl Compounds
641
Table 1
Iodomono- and Iododicyclofunctionalized Products

642
C. J. Valduga, H. A. Stefani, and N. Petragnani
Vol. 39
Table 1 (continued)
Substrate
Iodomonocyclofuntionalized Product
Iododicyclcofuntionalized
Product Yield %)
(Yield %)
*
Reported on the ref. 5.
iodine-π-complexed alkene at the 4 –position. Then 2
can be equilibrated with 6 giving 4.
HPLC was performed on an HP 1100 instrument, with a β-
cyclodextrin/carbamate column at 10° C, eluting with a mixture of
methanol/water 22 % at 0.3 mL/minute (the diastereomeric ratio
was identified in the case of the compounds 4a and 4e). Gas chro-
matography was carried out in an HP 6890 with methylsilicon col-
umn (30mX0.32mm). Flash chromatography was performed with
Merck silica gel 60 (230-400 mesh ASTM). For thin-layer chro-
matography (TLC) analysis, Merck TLC plates (silica gel 60
GF254, 0.25 mm) were used. All solvents and reagents were puri-
fied by conventional methods. Infrared spectra were recorded on a
BOMEM-FTIR-MB 102 spectrometer using potassium bromide.
Scheme 4
The ring fusion in compounds 4b, 4d, 4e, 4f and 4i is
expected to be cis in accordance with literature data [12]. It
was confirmed in the case of compounds 4b and 4e by
NMR spectroscopy H, C, HETCOR and COSY and by
X-ray in the case of compound 4e [13].
General Procedure.
Iodomonocyclization.
Compounds 4c, 4f, 4g, 4h and 4i were prepared in accordance
with the previously described method [5].
1
13
Iododicyclization.
2
,4-Dialkenyl-1,3-dicarbonyl compounds (prepared by the
previously described method [5]), (1 mmol), were treated with
iodine (4 mmoles) and Na CO (2 mmoles) in dry CHCl (10
2
3
3
mL) at reflux. The reaction was stirred until the consumption of
substrate (GC and TLC monitoring). Et O was added and the
2
organic phase washed with aqueous sodium thiosulfate (10%),
brine, and dried over Mg SO . The solvent was evaporated under
2
4
vacuum and the crude reaction mixture was purified by flash
chromatography on silica gel eluting with CH Cl to give the
Figure 2
2
2
product as a pale yellow oil or solid.
Conclusion.
Ethyl 5-(3-Butenyl)-2-iodomethyl-2,3-dihydro-4-furancar-
boxylate (2c).
We describe in this paper a simple one or two step pro-
cedure to synthesize 3-(2-furanylidene)-2-furanone com-
pounds starting from the easily accessible 2,4-dialkenyl-
We are unable to purify this compound. MS: m/z 39, 55, 67, 79,
9
3, 107, 121, 135, 149, 177, 223(100), 251, 277, 305, 321, 350.
1,3-dicarbonyl compounds.
Chromatographic yield: 17%.
Ethyl (E)-2-(5-Iodomethyltetrhydro-2-furylidene)-4-hexenoate
EXPERIMENTAL
(3c).
1
Compound 3c was obtained in 49 % yield; H NMR: δ 1.26 (t,
General.
1H, COSY and HETCOR NMR spectra were recorded on a 300
MHz spectrometer using TMS as the internal standard and CDCl
J= 7.09 Hz, 3H), 1.61-1.63 (m, 3H), 1.84-1.90 (m, 1H), 2.25-2.36
(m, 1H), 2.97-3.08 (m, 3H), 3.22-3.37 (m, 3H), 4.17 (q, J= 7.09
Hz, 2H), 4.47 (ddd, J= 12.7, 8.6 and 4.9 Hz, 1H), 5.39-5.48 (m,
3
as solvent. 13C NMR spectra were recorded at 75 MHz on the same
2H). C NMR: δ 7.68, 14.61, 18.03, 29.31, 30.22, 31.14, 59.72,
13
instrument with the solvent peak (CDCl ) as the reference (In
81.89, 102.39, 125.05, 129.22, 168.79, 169.64. MS: m/z 39, 55,
3
braces multiple signs correspond to diastereomeric mixture).
GC/MS and elemental analysis (C, H) were performed at the
Microanalytical Laboratory of the Chemistry Institute - USP.
67, 79, 93, 107, 121, 135, 149, 159, 177, 195, 223 (100), 263,
+
277, 305, 321, 350 (M ). IR: 2976, 2930, 1694, 1635, 1443,
-1
1368, 1303, 1187, 1110, 1056, 967, 887, 609 cm .

Jul-Aug 2002
Iodo Cyclofunctionalization of 2,4-Dialkenyl-1,3-Dicarbonyl Compounds
643
Anal. Calcd. for C H IO : C, 44.59; H, 5.47. Found: C,
Compound 4a was obtained in 78% yield; mp 89-90 °C.
Diastereomeric ratio: 1:1. H NMR: δ 1.88-1.95 (m, 1H), 2.25-
1
3
19
3
1
4
4.22; H, 5.58.
Ethyl (E)-2-(7-Iodoperhydrobenzo[b]-2-furylidene)-4-hexenoate
3f).
Compound 3f was obtained in 65% yield; H NMR: δ 1.28 (t,
J= 7.05 Hz, 3H), 1.63 (dd, J= 3.3 and 1.15 Hz, 3H), 1.40-1.96 (m,
2
(
2
.42 (m, 1H), 2.51-2.65 (m, 1H), 2.85-3.09 (m, 2H), 3.16-3.37
1
3
m, 5H), 4.41-4.57 (m, 2H). C NMR: δ 6.75, 6.89, 9.09, 8.98,
(
9.23, 29.74, 29.59, 31.61, 31.67, 75.11, 75.07, 82.98, 83.09,
1
93.97, 168.91, 171.38. IR: 2930, 1741, 1674, 1432, 1302, 1255,
1186, 1008, 860, 750 cm-1. MS: m/z 53, 79, 91, 125, 135, 147,
6
4
H), 2.61 (dd, J= 13.08 and 6.4 Hz, 1H), 2.96 and 2.98 (s, 3H),
.15 (J= 7.05 Hz, 2H), 4.42 (q, J= 5.20 Hz, 1H), 4.57 (t, J= 5.20
162, 179, 253, 265, 289, 321, 307 (100), 434 (M+).
Anal. Calcd. for C H I O : C, 27.65; H, 2.79. Found: C,
1
0 12 2 3
1
3
Hz, 1H), 5.44-5.48 (m, 2H). C NMR: δ 14.46, 17.93, 21.33,
27.95; H, 2.80.
2
1
1
1
5.98, [29.01, 29.12], 32.40, 34.62, 37.09, 59.62, 85.79, 104.06,
7
-Iodo-3-(5-iodomethyltetrahydro-2-furylidene)perhydrobenzo-
[b]-2-furanone (4b).
24.88, 129.14, 168.68, 168.94. MS: m/z 39, 67, 77, 95, 123, 147,
+
89, 217 (100), 263, 291, 391 (M ). IR: 2935, 1726, 1708, 1643,
-1
1
446, 1294, 1181, 1107, 1042, 875, 708, 622 cm .
Compound 4b was obtained in 19% yield; H NMR: δ 1.52-
1.56 (m, 1H); 1.64-1.70 (m, 2H), 1.86-1.99 (m, 4H), 2.29-2.36
(m, 1H), 2.96-3.05 (m, 1H), 3.28-3.42 (m, 4H), 4.28-4.62 (m,
Anal. Calcd. for C H IO : C, 49.29; H, 5.94. Found: C,
1
6
23
3
4
9.40; H, 5.53.
1
3
3
[
3
1
1
H). C NMR: δ [6.57, 7.40], [20.77, 21.11], [25.82, 26.12],
Ethyl 2-(1-Iodoethyl)-5-(3-pentenyl)-2,3-dihydro-4-furancar-
boxylate (2g).
28.88, 29.12], [29.42, 29.49], 29.64, [31.40, 31.90], [35.99,
6.28], [81.26, 81.43], [82.52, 83.43], [99.78, 100.54], [168.44,
68.48], [171.59, 171.62]. IR: 2934, 2858, 1743, 1678, 1441,
1
Compound 2g was obtained in 62% yield; H NMR: δ 1.28 (t,
J= 7.0 Hz, 3H), 1.63 (d, J= 4.6 Hz, 3H), 1.90 (d, J= 6.8 Hz, 3H),
.20-2.28 (m, 2H), 2.51-2.65 (m, 1H), 2.69-2.78 (m, 2H), 3.00
-1
328, 1254, 1027, 915, 877,794, 738, 692, 628 cm . MS: m/z 55
2
(
+
(
100), 149, 165, 221, 331, 348, 475 (M ).
dd, J= 15.0 and 10.9 Hz, 1H), 3.40-3.54 (m, 1H), 4.17 (q, J= 7.0
Anal. Calcd. for C H I O : C, 29.49; H, 3.15. Found: C,
1
3 16 2 3
1
3
Hz, 2H), 4.33-4.42 (m, 1H), 5.43-5.54 (m, 2H). C NMR: δ
2
5
9.63; H, 3.18.
1
1
1
1
4.34, 17.85, 23.48, 27.88, 29.78, 30.55, 35.77, 59.53, 101.62,
-Iodomethyl-3-(5-iodomethyltetrahydro-2-furylidene)tetrahy-
dro-2-furanone (4c).
25.73, 129.74, 165.60, 170.05. MS: m/z 55 (100), 67, 95, 121,
+
89, 221, 237, 291, 365 (M ). IR: 2971, 2926, 1725, 1443, 1362,
-1
227, 1115, 1035, 875, 597 cm .
1
Compound 4c was obtained in 59% yield; H NMR: δ 1.81-
1.93 (m, 1H), 1.96 (d, J= 6.3 Hz, 3H), 2.31-2.45 (m, 1H), 2.62-
Anal. Calcd. for C H IO : C, 46.17; H, 5.81. Found: C,
1
4
21
3
4
6.22; H, 5.66.
2
(
2
[
1
8
2
.72 (m, 1H), 2.94-3.08 (m, 2H), 3.29-3.43 (m, 3H), 4.10-4.35
1
3
m, 2H), 4.56 (quint, J= 6,0 Hz, 1H). C NMR: δ [6.76, 6.96],
3.95, [29.28, 29.31], [29.83, 29.85], [30.80, 30.94], 31.82,
80.18, 80.23], [83.03, 83.17], 94.41, [168.70, 168.73], [171.16,
Ethyl 2-Iodomethyl-5-(3-pentenyl)-2,3-dihydro-4-furancarboxy-
late (2h).
1
Compound 2h was obtained in 50% yield; H NMR: δ 1.28 (t,
71.57]. IR: 2942, 1740, 1674, 1334, 1253, 1187, 1083, 1010,
J= 7.11 Hz, 3H), 1.63 (d, J= 4.86 Hz, 3H), 2.21-2.33 (m, 2H),
.55-2.73 (m, 3H), 3.03 (dd, J=10.48 and 6.43 Hz, 1H), 3.25-3.33
m, 2H), 4.17 (q, J= 7.12 Hz, 2H), 4.64-4.70 (m, 1H), 5.42-5.47
m, 2H). 13C NMR: δ 9.11, 14.81, 18.27, 27.97, 30.19, 36.47,
-1
57, 751 cm . MS: m/z 43, 55 (100), 69, 85, 113, 149, 181, 227,
2
(
(
5
4
3
1
+
67, 295, 321, 421, 448 (M ).
Anal. Calcd. for C H I O : C, 29.49; H, 3.15. Found: C,
11 14 2 3
2
9.27; H, 3.05.
9.96, 80.73, 101.95, 126.21, 130.08, 166.03, 170.52. MS: m/z
3 (100), 67, 81, 95, 113, 131, 149, 193, 223, 239, 253, 277, 293,
7-Iodo-3-(7-iodoperhydrobenzo[b]-2-furylidene)perhydrobenzo-
[b]-2-furanone (4d).
+
11, 321, 351 (M ). IR: 2976, 2933, 1709, 1643, 1445, 1375,
-1
243, 1171, 1055, 971, 764, 522 cm .
Anal. Calcd. for C H IO : C, 44.59; H, 5.47. Found: C,
1
Compound 4d was obtained in 10% yield; H NMR: δ 1.30-
1
3
19
3
2
(
.00 (m, 12H), 2.65-2.29 (m, 1H), 2.97-3.05 (m, 2H), 3.38-3.40
4
4.52; H, 5.30.
1
3
m, 1H), 4.26-4.66 (m, 4H). C NMR: δ [27.75, 27.89], [28.84,
Ethyl 7-Iodo-2-(3-pentenyl)-3a,4,5,6,7,7a-hexahydrobenzo[b]-3-
furancarboxylate (2i).
28.92], [34.61, 34.65], 35.82, [81.22, 81.45], [87.02, 87.21],
[102.41, 102.83], [168.00, 168.14], [171.55, 171.58]. IR: 2931,
2
860, 1739, 1674, 1449, 1253, 1157, 1011, 911, 742, 527, 508
1
Compound 2i was obtained in 54 % yield; H NMR: δ 1.28 (t,
-1
cm . MS: m/z 41 (100), 55, 79, 91, 121, 165, 187, 207, 241, 259,
J= 7.01 Hz, 3H), 1.63 (d, J= 5.3 Hz, 3H), 1.42-2.04 (m, 6H), 2.24
+
2
99, 387, 514 (M ).
(dd, J= 13.6 and 6.63 Hz, 2H), 2.54-5.63 (m, 1H), 2.67-2.75 (m,
Anal. Calcd. for C H I O : C, 37.38; H, 3.92. Found: C,
1
6 20 2 3
1
4
1
2
1
2
1
H), 3.18 (dd, J= 15.28 and 7.54 Hz, 1H), 4.13-4.22 (m, 2H),
3
7.56; H, 4.25.
.56 (dd, J= 10.6 and 4.53 Hz, 1H), 4.69 (dd, J= 7,36 and 4.9 Hz,
1
3
H), 5.30-5.53 (m, 2H). C NMR: δ 14.39, 17.88, 20.70, 27.01,
8.06, 28.74, 29.86, 32.25, 39.24, 59.43, 87.01, 109.36, 125.88,
29.64, 165.64, 170.93. MS: m/z 55, 79, 91, 121, 139, 171, 189,
5-Iodomethyl-3-(7-iodoperhydrobenzo[b]-2-furylidene)tetrahy-
dro-2-furanone (4e).
Compound 4e was obtained in 78% yield; mp 77-79 °C.
+
07, 217, 245, 263, 317, 345, 391(100) (M ). IR: 2938, 1697,
1
Diastereomeric ratio: 1:1:1. H NMR: δ 1.32-1.40 (m, 1H); 1.49-
-1
635, 1445, 1316, 1168, 1089, 972, 775, 620 cm .
Anal. Calcd. for C H IO : C, 49.24; H, 5.94. Found: C,
1
.56 (m, 1H), 1.65-1.68 (m, 1H), 1.72-1.78 (m, 1H), 1.95 (q, J= 5.3
Hz, 2H), 2.62-2.64 (m, 1H), 2.69-2.75 (m, 1H), 2.96-2.98 (m, 1H),
.04-3.10 (m, 2H), 3.25 (dd, J= 8.0 e 10.5 Hz, 1H), 3.39 (dd, J=
3.85 and 10.50 Hz, 1H), 4.45 (q, J= 5.1 Hz, 1H), 4.50-4.58 (m,
1
3
19
3
5
0.02; H, 5.82.
3
5
-Iodomethyl-3-(5-iodomethyltetrahydro-2-furylidene)tetrahy-
13
dro-2-furanone (4a).
1H), 4.69 (t, J= 5.1 Hz, 1H). C NMR: δ 9.17, 21.27, 25.99,

644
C. J. Valduga, H. A. Stefani, and N. Petragnani
Vol. 39
2
1
8
1
8.09, 31.88, 32.15, 34.48, 35.34, 75.39, 87.35, 95.88, 168.79,
7-Iodo-3-[5-(1-iodoethyl)tetrahydro-2-furylidene]perhy-
drobenzo[b]-2-furanone (4i).
71.67. IR: 2934, 2858, 1743, 1678, 1441, 1328, 1254, 1027, 915,
-1
77, 794, 738, 692, 628 cm . MS: m/z 43, 55, 67, 79, 95, 125, 139,
1
Compound 4i was obtained in 31% yield; H NMR: δ 1.43-
+
75, 221, 254, 303, 321, 347 (100), 375, 419, 448, 474 (M ).
2
.00 (m, 9H), 2.19-2.37 (m, 1H), 2.91-3.08 (m, 1H), 3.25-3.32
Anal. Calcd. for C H I O : C, 32.94; H, 3.40. Found: C,
1
3
16 2
3
13
(m, 2H), 4.14-4.62 (m, 3H). C NMR: δ 23.67, 29.64, 28.98,
3
5
3.23; H, 3.30.
2
9.64, 30.34, 34.91, 80.90, 82.30, 100.01, 168.83, 172.79. IR:
-1
-(1-Iodoethyl)-3-(7-iodoperhydrobenzo[b]-2-furylidene)-
2934, 1726, 1446, 1361, 1247, 1169, 1016, 701 cm . MS: m/z
tetrahydro-2-furanone (4f).
41, 67, 79, 91, 121, 139, 167, 187, 205, 233 (100), 265, 279, 337,
+
3
3
61, 445, 463, 489 (M ).
1
Compound 4f was obtained in 52% yield; H NMR: δ 1.30-
Anal. Calcd. for C H I O : C, 34.45; H, 3.72. Found: C,
1
4 18 2 3
1
.77 (m, 6H), 1.92-1.97 (m, 3H), 2.65-2.71 (m, 2H), 2.99-3.07
4.73; H, 3.58.
(
m, 3H), 4.16-2.26 (m, 1H), 4.42-4.54 (m, 1H), 4.68 (t, J= 4.45
13
Hz, 1H). C NMR: δ 21.07, 23.97, 25.80, 27.88, 30.94, 31.81,
Acknowledgement.
3
2
5
3
2.56, 34.28, 35.18, 75.58, 88.73, 95.54, 168.31, 171.64. IR:
937, 1728, 1449, 1275, 1175, 1008, 765, 606 cm . MS: m/z 32,
-1
We thank the FAPESP (97/04222-3; 94/0712-8; 98/10821-0)
and CNPq (520683/96-0) for financial support.
5, 79, 91, 121, 141, 187, 205, 233 (100), 265, 279, 313, 331,
+
59, 387, 405, 487 (M ).
Anal. Calcd. for C H I O : C, 34.45; H, 3.72. Found: C,
4.39; H, 3.81.
1
4
18 2
3
REFERENCES AND NOTES
3
5
-(1-Iodoethyl)-3-[5-(1-iodoethyl)tetrahydro-2-furylidene]-
*
Author to whom correspondence should be addressed: E-
mail: cvalduga@usp.br , Fax: (internat.) + 55 11 3815-4418.
1] D. L. J. Clive, G. Chitattu, N. Curtis, W. A. Kiel and C. K.,
Wong, J. Chem. Soc., Chem. Commun., 725, (1977).
tetrahydro-2-furanone (4g).
[
1
Compound 4g was obtained in 71% yield; H NMR: δ 1.83-
1
2
2
2
.97 (m, 5H), 2.30-2.47 (m, 1H), 2.64-2.70 (m, 1H), 2.94-3.07 (m,
[
[
2] J. E. Baldwin, J. Chem. Soc. Chem. Commun., 734 (1976).
3] G. Cardillo and M. Orena, Tetrahedron, 46, 3321 (1990)
and references cited therein.
[4] C. Galli, G. Illuminati, L Mandolini and P. Tamborra, J.
Am. Chem. Soc., 99, 2591 (1977).
[5] H. A. Stefani, N. Petragnani, C. J. Valduga and C. A.
Brandt, Tetrahedron Lett., 38, 4977 (1997); see also Corrigendum in
Tetrahedron Lett., 39, 7624 (1998).
6] S. D. Richnovsky and P. A. Bartlett, J. Am. Chem. Soc.,
03, 3963 (1981).
7] P. A. Bartlett and P. C. Ting, J. Org. Chem., 51, 2230
1986).
[8] V. Jagër and H. J. Günther, Tetrahedron Lett., 2543 (1977).
9] A. R. Chamberlin, R. L. Mulholland Jr, S. D. Kahn and
W.J. Hehre, J. Am. Chem. Soc., 109, 672 (1987) and references cited
therein.
10] L. F. P. Amaral and S. C. Melo, J. Org. Chem., 38, 800
1973).
11a] R. B. Turner and R. H. Garner, J. Am. Chem. Soc., 79, 253
1957); [11b] R. B. Turner and R. H. Garner, J. Am. Chem. Soc., 80,
13
H), 3.35-3.45 (m, 1H), 4.15-4.29 (m, 4H). C NMR: δ [23.91,
3.94], [24.30, 24.36], [28.65, 28.83], [29.20, 29.23], [29.46,
9.48, 29.52], [30.82, 31.76], [31.73, 31.76], [80.13, 80.16],
[88.06, 88.37], [94.10, 94.18], [168.91, 168.89], [171.55, 171,73].
IR: 3443, 2932, 1743, 1676, 1447, 1379, 1333, 1253, 1192, 1081,
-1
1012, 855, 779, 751, 700, 596, 516cm . MS: m/z 41, 67, 95, 113,
+
127, 161, 179, 207, 241, 254, 321, 335 (100), 462 (M ).
Anal. Calcd. for C H I O : C, 31.39; H, 3.49. Found: C,
[
1
2 16 2 3
1
3
1.63; H, 3.26.
[
3
-[5-(1-Iodoethyl)tetrahydro-2-furylidene]-5-iodomethyltetrahy-
(
dro-2-furanone (4h).
[
1
Compound 4h was obtained in 66% yield; H NMR: δ 1.91-1.94
m, 1H), 1.95 (d, J= 6.3 Hz, 3H), 2.37-2.42 (m, 1H), 2.60-2.67 (m,
(
1H), 2.95-3.09 (m, 2H), 3.22-3.29 (m, 1H), 3.36-3.42 (m, 2H),
[
13
4.22-4.56 (m, 3H). C NMR: δ [8.93, 9.13, 9.22, 9.28], [24.30],
(
(
[
[
28.75], [29.20, 29.25], [29.49, 29.48, 29.61], [31.62, 31.71],
75.22], [87.80, 87.86, 87.98, 88.05]; [93.74, 93.80], [169.11,
[
1
1
1
69.21, 169.25, 169.34], [171.51, 171.57]. IR: 3434, 2936, 1714,
447, 1265, 861, 777, 752, 696, 611, 520 cm . MS: m/z 67, 91,
25, 148, 176, 193, 253, 275, 303, 321 (100), 448 (M ).
1
424 (1958).
12a] J. Klein, J. Am. Chem. Soc., 81, 364 (1959); [11b] H. O.
House, R. G. Carlson and H. Babad, J. Org. Chem., 28, 3359 (1963).
[13] J. Zukerman-Schpector, H. A. Stefani, C. J. Valduga, C. A.
Brandt and I. Caracelli, Z. Kristallogr., 213, 733 (1998).
-1
[
+
Anal. Calcd. for C H I O : C, 29.49; H, 3.15. Found: C,
11 14 2 3
2
9.35; H, 3.01.