Preparation and reactions of 3,4-bisstannyl-2(5H)furanones

Article abstract of DOI:10.1016/S0040-4020(02)00995-X

Bistributylstannyl-2(5H)-furanone 4a has been prepared from 3-(tetrahydropyran-2-yl)oxy but-2-ynoate and shown to exhibit good selectivity in its Stille reactions with a range of halogenated compounds, leading to 4-substituted-3-stannyl-2(5H)-furanones, in generally moderate yield. Under certain reaction conditions, doubly substituted products were also isolated from the reactions. The 3,4-bistrimethylstannyl furanone, 4b, corresponding to 4a was prepared, but decomposed during all attempts to execute Stille reactions upon it.

Full text of DOI:10.1016/S0040-4020(02)00995-X

Tetrahedron 58 (2002) 9117–9129
Preparation and reactions of 3,4-bisstannyl-2(5H)furanones
*
Neil B. Carter, Ross Mabon, Alexandre M. E. Richecœur and J. B. Sweeney
Department of Chemistry, University of Reading, Whiteknights, Reading RG6 6AD, UK
Received 27 July 2000; revised 18 July 2002; accepted 8 August 2002
Abstract—Bistributylstannyl-2(5H)-furanone 4a has been prepared from 3-(tetrahydropyran-2-yl)oxy but-2-ynoate and shown to exhibit
good selectivity in its Stille reactions with a range of halogenated compounds, leading to 4-substituted-3-stannyl-2(5H)-furanones, in
generally moderate yield. Under certain reaction conditions, doubly substituted products were also isolated from the reactions. The 3,4-
bistrimethylstannyl furanone, 4b, corresponding to 4a was prepared, but decomposed during all attempts to execute Stille reactions upon
it. q 2002 Elsevier Science Ltd. All rights reserved.
1. Introduction
2. Results and discussion
Many natural and bioactive compounds contain the 2(5H)-
furanone subunit;1 consequently, we have attempted to
develop methodology to allow synthesis of such compounds
via palladium-catalyzed cross-coupling of 3- and 4-
tributylstannyl 2(5H)-furanones 1 and 2 (Fig. 1) with aryl
iodides.2 Furthermore, 3,4-diaryl-2(5H)-furanones (such
as VIOXXe, 33) have been demonstrated to be orally-
active, potent and selective inhibitors of cyclooxygenase-2
(‘COX-2’) enzymes, thereby offering much promise as
therapeutic moieties.4 We here report in detail5 the first
preparation of 3,4-bistributyl- and 3,4-bistrimethylstannyl
2(5H)-furanone 4a and 4b, respectively, and describe how
compound 4a was shown to undergo regiospecific
palladium-catalyzed cross-coupling reactions (‘Stille
reactions’) with halides; we also describe here the details
of optimization studies aimed at improving the efficiency of
the latter reaction.
In our previous work, monostannylfuranones 1 and 2
displayed differing reactivities in Stille couplings with a
variety of aryl iodides: in all cases, stannane 1 reacted more
efficiently.2 We reasoned, therefore, that bisstannane 4a
might exhibit regioselectivity in its reactions with coupling
partners and, we predicted, that if selectivity was exhibited,
the C4–Sn bond would be more reactive than the
neighbouring C3–Sn bond. Thus, it was anticipated that
4a would react with 1 equiv. of a suitable coupling partner
to give a 4-substituted 3-tributylstannylfuranone 5, rather
than a 3-substituted 4-tributylstannylfuranone 6 (Scheme 1).
2.1. Synthesis of 3,4-bisstannyl-2(5H)furanone
Our first synthetic targets were (Z)-2,3-bistributylstannyl-
butenoates 7a and 7b, which we anticipated would give easy
access to 4a. Thus, butynoates 8a and 8b6 reacted with
Figure 1.
Keywords: furanones; Stille reactions; nucleophilic.
*
Corresponding author; e-mail: j.b.sweeney@reading.ac.uk
0040–4020/02/$ - see front matter q 2002 Elsevier Science Ltd. All rights reserved.
PII: S0040-4020(02)00995-X

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N. B. Carter et al. / Tetrahedron 58 (2002) 9117–9129
Scheme 1.
Scheme 2.
7
hexabutylditin in the presence of PdCl2(PPh3)2 to give
these enoates in 75 and 98% yield, respectively (Scheme 2).
Using an acid-mediated cyclization protocol, only 7b gave
lactone 4a as a colourless liquid, in 74% yield. Under a
range of reaction conditions, the TBS-protected 3-hydro-
xymethyl-2,3-bisstannylacrylate 7a underwent decompo-
sition to give products whose structure could not be
determined.
for 5a closely matched the values observed whereas that
predicted for 6a was quite different; chemical correlation
(via protodestannylation, to give 9a1) confirmed that the
product of Stille coupling was indeed 5a. Thus, our
prediction that the difference in reactivity of the C3–Sn
and C4–Sn bond could be exploited had been borne out in
practice.
The selectivity shown in the coupling reaction proved to be
general: a range of aryl iodides reacted under typical
conditions to give products of cross-coupling, albeit in
moderate yield (Table 1). Reaction with allyl and benzyl
bromide, benzoyl chloride and b-bromostyrene proceeded
with similar regiocontrol and yields. These reactions did not
produce any trace of product in which two couplings had
occurred (i.e. where both C3– and C4–Sn bonds had
reacted with the coupling partner) or any product in which
coupling had occurred selectively at position 3 of the
furanone. Protodestannylation confirmed the regioselectiv-
ity of the reactions (Table 1).
2.2. Cross-coupling reactions of 3,4-bistributylstannyl-
2(5H)furanone
Thus, we were poised to examine the selectivity, if any,
shown by 4a in its coupling reactions. We expected that 4a
would, upon reaction with iodobenzene in the presence of
Pd2dba3, triphenylarsine and Cu(I)I in THF, would give 3-
tributylstannyl-4-phenyl-2(5H)-furanone 5a, as the major
product of the reaction. It was gratifying to see that only one
compound was produced in the reaction, in 37% yield. But
how could we determine the structure of the product? Using
the data already available, and that we had already gleaned
from our earlier studies,1 we predicted the 13C NMR
resonances of 5a and 6a to be those shown in Diagram 1.
2.3. Optimization of the cross-coupling reaction
Having demonstrated the validity of our synthetic proposal,
we next turned our attention to a thorough examination of
As can be see from Scheme 3, the predicted 13C NMR data
Diagram 1.

N. B. Carter et al. / Tetrahedron 58 (2002) 9117–9129
9119
Scheme 3.
the reaction conditions of the initial cross-coupling process,
with a view to improving the yields of 4-substituted-3-
tributylstannylfuranones obtained. The reaction of iodoben-
zene with 4a was examined under a wide range of
conditions, as detailed in Table 2, but the overall effect
upon the efficiency of the selective coupling process was,
except in a few cases, slight. A number of facts can be
deduced from these investigations: firstly, use of an excess
of either iodobenzene (entry 9) or bisstannane (entry 10) did
not improve the yield of 5a; it is noteworthy, however, that
even under these conditions the doubly-coupled product was
not seen in the crude product. The optimum temperature for
the process seems to be in the range 50–708C. Furthermore,
the polarity of the reaction solvent exerts a strong effect
upon the yield and selectivity of the process. Thus, when
CH2Cl2 (entry 22), THF, DME (entry 20) or NMP (entry 21)
was employed, a single product, 5a, was usually obtained in
a maximum of 44% yield (entry 28); when DMF was used
(entries 16–18), the yield of 5a was lower (#29%) and the
selectivity of the reaction was altered, because the product
of double coupling, 3,4-diphenyl-2(5H)-furanone 10, was
also obtained (in 28–36% yield) (entries 16–18 and Table
3). A similar observation was made when methanol was
used as solvent (entry 19). A mixture of singly and doubly-
substituted furanones (27 and 39% yield, respectively) was
also obtained in THF solvent when Pd(dppb)2 was the
coupling catalyst (entry 7), although use of the lower
homologue, Pd(dppp)2, did not furnish any coupled
products. Intriguingly, reaction of 4a with excess iodoben-
zene under the conditions which gave doubly-coupled
material did not give 10 as a single product: the yields of 5a
and 10 remained the same, allowing for experimental error.
Other than these latter data, the choice of catalyst seems to
have little effect, with Pd2dba3, Pd(PPh3)4, PdCl2(PPh3)2
and PdCl2(PhCN)2 all providing roughly similar yields of
singly-coupled furanone upon reaction in THF; variation of
catalyst stoichiometry (entries 23–25) led to diminished
yields of singly-coupled product and no double-coupling
was observed. In our hands, Cu(I) did not catalyze coupling
(entry 37). The nature of the additives present in the reaction
has a pronounced effect upon the yield, but not the
selectivity of the reaction. Thus, Cu(I)I alone (entry 30) is
a more effective additive than AsPh3 alone (entry 29) and
the nature of the Cu(I) species seems unimportant (compare
entries 30–32 and 34). The use of phenyl triflate rather than
iodobenzene was unproductive (entry 36). Addition of
further catalyst after an initial reaction period (entry 14) did
not enhance the yield sufficiently for the process to be
deemed necessary, and slow addition of stannane to the
reaction mixture (entry 35) had only a slight (and
detrimental) effect upon the yield of the reaction.
Given the bulk of the tributylstannyl group, it might be
reasonable to suggest that there is a steric inhibition of the
Table 1. Regioselective Stille couplings of bistributylstannyl-2(5H)-furanone (4a)
R
Conditionsa
Product (yield (%))
Product (yield (%))
Ph
A
B
A
A
A
B
A
A
A
A
C
D
5a (37)
5b (40)
5c (49)
5d (27)
5e (40)
5f (47)
5g (51)
5h (22)
5i (9)
9a (85)
9b (80)
9c (95)
9d (91)
9e (88)
9f (82)
9g (89)
9h (88)
9i (86)
9j (73)
9k (90)
9l (92)
2-Naphthyl
2-MeC6H4
3-CF3C6H4
2-MeOC6H4
2-O2NCC6H4
2-MeO2CC6H4
2-Thienyl
Bn
CH2vCHCH2
PhCO
PhCHvCH
5j (23)
5k (33)
5l (35)b
a
A: R-I (1 equiv.), Pd2dba3 (2 mol%), AsPh3 (8 mol%), Cu(I)I (8 mol%), THF; Method B: PdCl2(PPh3)2 (2 mol%), AsPh3 (8 mol%), Cu(I)I (8 mol%), THF,
508C; Method C: PhCOCl, BnClPd(PPh3)2 (2 mol%), CO, DMF, 508C; Method D: PhCHvCHBr, Pd2dba3 (2 mol%), DMF, 508C.
Only E-isomer obtained.
b

9120
N. B. Carter et al. / Tetrahedron 58 (2002) 9117–9129
Table 2. Optimization of the reaction of 4a with iodobenzene (1 equiv.)
Entry
Catalyst (mol%)
Additives (mol%)
Reaction conditions
Yield (%) 5a
1
2
3
4
5
6
7a
Pd2dba3 (2)
Pd2dba3 (2)
Pd(PPh3)4 (2)
PdCl2(MeCN)2 (2)
PdCl2(PhCN)2 (2)
Pd(dppp)2 (2)
CuI (8), AsPh3 (8)
CuI (8), (2-furyl)3P (8)
CuI (8), AsPh3 (8)
CuI (8), AsPh3 (8)
CuI (8), AsPh3 (8)
CuI (8), AsPh3 (8)
CuI (8), AsPh3 (8)
CuI (8), AsPh3 (8)
CuI (8), AsPh3 (8)
CuI (8), AsPh3 (8)
None
THF, 508C, 18–24 h
THF, 508C, 18–24 h
THF, 508C, 18–24 h
THF, 508C, 18–24 h
THF, 508C, 18–24 h
THF, 508C, 18–24 h
THF, 508C, 18–24 h
THF, 508C, 18–24 h
THF, 508C, 18–24 h
THF, 508C, 18–24 h
THF, 508C, 18–24 h
THF, 508C, 18–24 h
THF, 508C, 18–24 h
THF, 508C, 36–48 h
THF, rt, 7 days
DMF, 508C, 18–24 h
DMF, 708C, 18–24 h
DMF, 908C, 18–24 h
MeOH, 508C, 18–24 h
1,2-DME, 508C, 18–24 h
NMP, 508C, 18–24 h
CH2Cl2, rt, 3 days
THF, 508C, 18–24 h
THF, 508C, 18–24 h
THF, 508C, 18–24 h
THF, 508C, 18–24 h
THF, 508C, 18–24 h
THF, 508C, 18–24 h
THF, 508C, 18–24 h
THF, 508C, 18–24 h
THF, 508C, 18–24 h
THF, 508C, 18–24 h
NMP, rt–508C, 36–48 h
THF, 508C, 18–24 h
THF, 508C, 8 h
35
31
24
32
33
No reaction
Pd(dppb)2 (2)
27
38
37
26
8
PdCl2(PPh3)2 (2)
PdCl2(PPh3)2 (2)
PdCl2(PPh3)2 (2)
PdCl2(PPh3)2 (1)
PdCl2(PPh3)2 (2)
PdCl2(PPh3)2 (2)
PdCl2(PPh3)2 (4)
PdCl2(PPh3)2 (4)
PdCl2(PPh3)2 (4)
PdCl2(PPh3)2 (4)
PdCl2(PPh3)2 (4)
PdCl2(PPh3)2 (4)
PdCl2(PPh3)2 (4)
PdCl2(PPh3)2 (4)
PdCl2(PPh3)2 (4)
PdCl2(PPh3)2 (5)
PdCl2(PPh3)2 (10)
PdCl2(PPh3)2 (15)
PdCl2(PPh3)2 (2)
PdCl2(PPh3)2 (2)
PdCl2(PPh3)2 (2)
PdCl2(PPh3)2 (2)
PdCl2(PPh3)2 (2)
PdCl2(PPh3)2 (2)
PdCl2(PPh3)2 (2)
PdCl2(PPh3)2 (2)
PdCl2(PPh3)2 (2)
PdCl2(PPh3)2 (2)
PdCl2(PPh3)2 (2)
CuI (10)
9b
10c
11
12
13
14d
15
16e
17f
18g
19h
20
21
22
23
24
25
26
27
28
29
30
31
32
33i
34
35k
36l
37
38
no reaction
No reaction
None
CuI (8), (2-furyl)3P (8)
CuI (8), AsPh3 (8)
CuI (8), AsPh3 (8)
CuI (8), AsPh3 (8)
CuI (8), AsPh3 (8)
CuI (8), AsPh3 (8)
CuI (8), AsPh3 (8)
CuI (8), AsPh3 (8)
CuI (8), AsPh3 (8)
CuI (8), PPh3 (8)
CuI (8), AsPh3 (8)
CuI (8), AsPh3 (8)
CuI (8), AsPh3 (8)
CuI (8), AsPh3 (20)
CuI (50), AsPh3 (8)
CuI (200), AsPh3 (8)
AsPh3 (8)
24
42
18
29
28
25
12
30
25
27
37
29
11
39
29
44
18
39
36
CuI (8)
CuCN (8), AsPh3 (8)
CuCl (8), AsPh3 (8)
CuO2CArj (130), AsPh3 (8)
CuO2CAr (8), AsPh3 (8)
CuI (8), AsPh3 (8)
LiCl (300), AsPh3 (8)
NaCl (300)
27
No reaction
41
27
No reaction
No reaction
No reaction
NMP, 358C, 18–24 h
NMP, 908C, 6 h
THF/DMF 1:1, 808C, 18–24 h
PdCl2(PPh3)2 (2)
LiCl (300)
a
Reaction afforded 3,4-bis-(phenyl)furan-2(5H)-one (9a), (39%).
Reaction performed with 2 equiv. of iodobenzene.
Reaction performed with 2 equiv. of stannane.
b
c
d
e
f
Reaction performed in 2 mol% catalyst for 18–24 h then, a further 2 mol% added for additional 18–24 h.
Reaction afforded 3,4-bis-(phenyl)furan-2(5H)-one (9a) (28%).
Reaction afforded 3,4-bis-(phenyl)furan-2(5H)-one (9a) (28%).
Reaction afforded 3,4-bis-(phenyl)furan-2(5H)-one (9a) (36%).
Reaction afforded 3,4-bis-(phenyl)furan-2(5H)-one (9a) (27%).
Reaction stirred for 18–24 h at ambient temperature, followed by 18–24 h at 508C.
Ar¼2-thienyl.
g
h
i
j
k
l
Stannane added by syringe pump over 8 h.
Reaction using phenyl triflate as coupling partner.
reaction, leading to the moderate yields obtained in the
selective coupling process. To address this point, we
prepared the bistrimethylstannylfuranone, 4b, using a
similar route to that detailed above. If a steric phenomenon
were at the heart of the problem, one might reasonably
expect a smaller tin substituent to ameliorate the difficulties.
Thus, butynoate 8b reacted this time with hexamethylditin
to give the bistrimethylstannylacrylate, 11, in excellent
yield (Scheme 4). When reacted under the conditions which
had previously been used for the synthesis of the higher
stannane, 11 was converted into two compounds, the desired
bisstannylfuranone, 4b, and (Z)-methyl-3-(tetrahydropyran-
2-yl)oxymethyl-3-bis(trimethylstannyl)propenoate 12, in an
overall yield of 55%, with 4b, the desired furanone, present
in five times excess in the product ratio (4b/12¼5:1).
These compounds, both low-melting solids, were separable
using flash chromatography and were stable indefinitely at
2208C; bisstannane 4b was however, unstable at tempera-
tures greater than ambient, unless kept under a ruthlessly-
purged, oxygen-free environment. Given this fragility, it
was perhaps not surprising that 4b reacted with iodobenzene
to give unidentifiable products under a broad range of
experimental rubrics; no trace of furanone product or
starting material was identified from either the crude
reaction mixture or samples analyzed by flash chromatog-
raphy. Thus, it would seem that, at present, we are unable to
examine the influence of steric compromise upon the yield
of the selective couplings of bisstannylfuranones.
It is clear from the data presented in Tables 1 and 2 that the

N. B. Carter et al. / Tetrahedron 58 (2002) 9117–9129
Table 3. Double-coupling reaction of bistributylstannyl-2(5H)-furanone (4a)
9121
Conditions
Yield 5a (%)
Yield 10 (%)
THF, 508Ca
DMF, 508Cb
DMF, 708Cb
DMF, 908Cb
MeOH, 508Cb
27
29
28
25
12
39
28
28
36
27
a
Pd(dppb)2 (2 mol%), iodobenzene (1 equiv.), CuI (8 mol%), AsPh3 (8 mol%).
PdCl2(PPh3)2 (2 mol%), iodobenzene (1 equiv.), CuI (8 mol%), AsPh3 (8 mol%).
b
C4–Sn bond reacts preferentially in palladium-catalyzed
cross-coupling reactions with substrates. We note that there
are two obvious controlling factors in these reactions, an
electronic factor and a steric one. One might rationalize
these observations by noting that the polarization of the
CvC bond of the stannylfuranone diminishes the strength
of the C4–Sn bond (Fig. 2), thereby enhancing the rate of
transmetallation and favouring coupling at C4, but we have
little data which provide a piercing mechanistic insight at
this time.
One piece of evidence which perhaps supports this assertion
is the observation that bisstannane 4a reacts with a single
equivalent of elemental iodine at the C3–Sn bond (Scheme
5), to give iodostannane 13, as shown by chemical
correlation via protodestannylation to iodofuranone 14
(prepared unambiguously from monostannylfuranone 2).
Thus, the C3–Sn bond is the more nucleophilic of the two.
When 2 equiv. of iodine were used in the reaction,
diiodofuranone, 15, was obtained in 76% yield
Scheme 4.
Scheme 5. Conditions: (i) I2 (2 equiv.), CH2Cl2, rt, 18 h; (ii) 50% TFA (aq), EtOH, rt, 48%.
Figure 2.

9122
N. B. Carter et al. / Tetrahedron 58 (2002) 9117–9129
4.1.1. 3,4-Bis(tributylstannyl)furan-2(5H)-one (4a). (Z)-
Methyl-3-(tetrahydropyran-2-yl)oxymethyl-2,3-bis(tributyl
stannyl)propenoate (7b) (20.0 g, 25.7 mmol) and Dowexw
50W-X4 ion exchange resin (20.0 g) were combined in dry
methanol (250 mL) and the solution was stirred at 508C for
3 h. The mixture was allowed to cool to ambient
temperature and the resin removed by filtration through
Celitew and washed with ether (100 mL). The reaction
mixture was concentrated in vacuo and purification by
column chromatography (Rf 0.32, ether/petrol, 1:9) afforded
furanone (4a) as a clear colourless liquid (12.6 g, 74%).
nmax 1735, 1539, 1464; dH (CDCl3) 0.80–1.50 (54H, m),
4.83 (2H, s, 119Sn/117Sn coupling J¼4.5 Hz); dC (CDCl3)
10.2, 10.4, 13.5, 13.6, 27.3, 29.1, 81.2, 144.4, 178.3, 183.7;
m/z (EI) Found (M2Bu)þ, 605.1589 (69%), C24H47O2Sn2
requires 605.1620, 560 (15), 291 (25), 235 (48), 177 (100).
Scheme 6. Conditions: I2 (2 equiv.), CH2Cl2, rt, 120 h.
(Scheme 6); it is noteworthy that the reaction now required
almost five times as long as did the conversion of 4a to 13,
again implying that the C3–Sn bond is the more
nucleophilic of the two. Detailed investigation of the
mechanistic nuances responsible for these observations are
underway in our laboratory.
3. Conclusions
4.1.2. (Z)-Methyl 4-tert-butyldimethylsilyloxy-2,3-bis
(tributylstannyl)but-2-enoate
(7a).
Hexabutylditin
We have prepared, for the first time, bisstannylfuranones 4a
and 4b and, in the case of 4a, shown that a selective Stille
coupling is possible. The C4–Sn bond is consistently
substituted in such processes, except when polar solvents or
chelating phosphine ligands are used in the reaction. In
contrast, the C3–Sn bond is shown to be the more
nucleophilic of the chalcogenic bonds by its selective
reaction with iodine. We are currently pursuing zealously
the underlying principles responsible for this unusual
selectivity.
(0.72 g, 1.17 mmol) and methyl 4-(tert-butyldimethylsilyl-
oxy)but-2-ynoate (8a) (0.25 g, 1.17 mmol) were combined
in dry deoxygenated THF (7.5 mL). Dichlorobis(triphenyl-
phosphine)palladium(II) (10 mg, 0.002 mmol) was added,
and the mixture stirred at room temperature for 18 h. A
further portion of catalyst (247 mg, 0.035 mmol) was then
added, and the mixture stirred for a further 24 h. The
reaction mixture was concentrated in vacuo and purification
by column chromatography (Rf 0.51, ether/petrol, 1:19)
furnished bisstannane (7a) as a clear colourless liquid
(0.95 g, 98%). nmax 1708, 1549, 1465; dH (CDCl3) 0.05 (6H,
s), 0.78–1.48 (54H, m), 0.84 (9H, br. s), 3.60 (3H, s), 4.23
(2H, s); dC (CDCl3) 11.5, 11.7, 13.6, 19.2, 25.4, 27.3, 27.6,
28.9, 29.2, 30.4, 98.0, 149.8, 161.1 172.8; m/z (EI) Found
(M2Bu)þ, 751.2762 (6%), C31H65O3SiSn2 requires
751.2747, 463 (14), 347 (17), 291 (42).
4. Experimental
4.1. General techniques
Throughout the text, the term ‘petrol’ refers to the fraction
of petroleum ether with the boiling range 40–608C and
‘ether’ refers to diethyl ether. Diethyl ether and THF were
distilled from sodium benzophenone ketyl, methanol from
magnesium methoxide.
4.1.3. (Z)-Methyl 4-[(tetrahydropyran-2-yl)oxy]-2,3-bis(-
tributylstannyl)but-2-enoate (7b). Hexabutylditin (20.5 g,
35.3 mmol) and methyl 4-[(tetrahydropyran-2-yl)oxy]but-
2-ynoate (8b)6 (7.0 g, 35.3 mmol) were combined in dry
deoxygenated THF (500 mL). Dichlorobis(triphenylphos-
phine)palladium (II) (247 mg, 0.035 mmol) was added, and
the mixture stirred at ambient temperature for 18 h. A
further portion of catalyst (247 mg, 0.035 mmol) was then
added, and the mixture stirred for a further 24 h. The
reaction mixture was concentrated in vacuo and the residue
placed under high vacuum (0.1 mm Hg) for 4 h to give a
brown oil. Purification by column chromatography (Rf 0.18,
ether/petrol, 1:9) gave bisstannane (7b) as a clear colourless
liquid (20.6 g, 75%). nmax 1707, 1547, 1463; dH (CDCl3)
0.89–1.39 (54H, m), 1.45–1.92 (6H, m), 3.49–3.50 (1H,
m), 3.67 (3H, s), 3.80–3.85 (1H, m), 4.03 (1H, d,
J¼12.5 Hz), 4.39 (1H, d, J¼12.5 Hz), 4.59–4.61 (1H, m);
dC (CDCl3) 11.6,11.9, 14.0, 19.8, 25.9, 27.7, 27.9, 28.3,
29.5, 29.7, 31.0, 50.9, 61.7, 72.5, 98.0, 149.8, 161.1, 172.8;
m/z (CI, NH3) Found (M2Bu)þ, 723.2414 (100%),
C30H59O4Sn2 requires 723.2457, 679 (15), 637 (15), 433
(45), 373 (45), 335 (50), 269 (80), 177 (10), 138 (25), 85
(100).
Melting points were recorded on a Kofler hot-stage
apparatus and are uncorrected. Infra-red spectra were
recorded on a Perkin–Elmer 881 or Paragon 1000
spectrophotometer. Mass spectra were recorded on a Fisons
Autospec spectrometer. NMR spectra were recorded on a
Bruker DPX-250, or Bruker AX-400 spectrometer. Unless
otherwise stated, deuterochloroform was used as solvent
and TMS was used as the internal standard. Chemical shifts
1
in H NMR spectra are expressed as ppm downfield from
TMS, and in 13C NMR, relative to the internal solvent
standard. Coupling constants (J) are quoted in Hz.
Reactions involving chemicals or intermediates sensitive to
air or moisture were conducted under a nitrogen or argon
atmosphere in oven or flame-dried apparatus. Column
chromatography was performed using Merck Kieselgel 60
or Fluka Kieselgel 60 silica gel. Analytical thin-layer
chromatography was performed using either precoated
Merck Kieselgel 60 F254 glass-backed plates, or precoated
Merck Kieselgel 60 F254 aluminium backed plates and were
visualised under U.V. at 254 nm and by staining with iodine
and/or an acidic ammonium molybdate dip.
4.1.4. Methyl 4-(tert-butyldimethylsilyloxy)but-2-ynoate
(8a). Methyl 4-hydroxybut-2-ynoate (0.5 g, 4.38 mmol),
tert-butyldimethylsilylchloride (0.73 g, 4.8 mmol), DMAP

N. B. Carter et al. / Tetrahedron 58 (2002) 9117–9129
9123
(54 mg, 0.438 mmol) and triethylamine (0.67 mL,
4.38 mmol) were combined in dichloromethane (10 mL)
under argon. The mixture was stirred at ambient temperature
for 18 h. The solvent was removed in vacuo and purification
by column chromatography (Rf 0.48, ether/petrol 1:9)
yielded butynoate (8a) as a clear colourless liquid (0.47 g,
79%). nmax 2240, 1720; dH (CDCl3) 0.13 (6H, s), 0.90 (9H, s),
3.77 (3H, s), 4.43 (2H, s); m/z (EI) Found (MNH4)þ,
246.1533 (10%), C11H24NO3Si requires 246.1526.
(18.4 mg, 0.08 equiv.) under an argon atmosphere. 3,4-
Bis(tributylstannyl)furan-2(5H)-one (4a) (500 mg,
0.755 mmol) was added in deoxygenated THF (5 mL) and
the mixture stirred at ambient temperature. Tris(dibenzyli-
deneacetone)dipalladium(0) (13.7 mg, 0.02 equiv.) was
added to give a purple solution which became lime green
in colour over 10 min. The reaction mixture was then heated
to 508C for 18–24 h, by which time the reaction was judged
complete by tlc. The reaction mixture was concentrated in
vacuo and the residue purified by column chromatography.
4.1.5. (Z)-Methyl-3-(tetrahydropyran-2-yl)oxymethyl-
2,3-bistrimethylstannyl propenoate (11). Hexamethyldi-
tin (1.0 g, 3.05 mmol) and methyl 4-[(tetrahydropyran-2-
yl)oxy]but-2-ynoate (8b) (0.66 g, 3.33 mmol) were com-
bined in dry deoxygenated THF (15 mL). Dichlorobis(tri-
phenylphosphine)palladium (II) (4.2 mg, 0.03 mmol) was
added, and the mixture stirred at ambient temperature for
24 h. The solvent was removed in vacuo and purification by
column chromatography (Rf 0.4, ether/petrol, 1:4) afforded
bisstannane 11 as a clear colourless liquid (1.5 g, 95%). nmax
2948, 1707, 1557, 1455; dH (CDCl3) 0.22 (9H, s), 0.27 (9H,
s), 1.52–1.83 (6H, m), 3.35–3.45 (1H, m), 3.70 (3H, s),
3.80–3.85 (1H, m), 4.06–4.12 (1H, m), 4.44–4.38 (1H, m),
4.52 (1H, t, J¼3.3 Hz); dC (CDCl3) 26.7, 26.4, 19.3, 25.3,
30.3, 50.9, 61.5, 72.0, 97.8, 149.5, 162.2, 171.9; m/z (EI)
Found (M2Me)þ, 511.0125 (23%), C15H29O4Sn2 requires
511.0120, 427 (7), 328 (7), 246 (87), 165 (100).
4.1.8. 4-Phenyl-3-tributylstannylfuran-2(5H)-one (5a).
Reaction of 3,4-bis(tributylstannyl)furan-2(5H)-one (4a)
(500 mg, 0.755 mmol) and iodobenzene (154 mg,
0.755 mmol) gave furanone (5a) after purification by
column chromatography (Rf 0.28, ether/petrol, 1:4) as a
clear colourless oil (127 mg, 37%). nmax 1734, 1620, 1590;
dH (CDCl3) 0.81–1.48 (27H, m), 5.08 (2H, t, J¼3.5 Hz),
7.33–7.36 (2H, m), 7.43–7.47 (3H, m); dC (CDCl3) 10.4,
13.6, 27.1, 28.9, 73.9, 126.8, 128.8, 129.8, 130.2, 133.9,
174.0, 178.8; m/z (CI, NH3) Found (M2Bu)þ, 393.0879
(24%), C18H25O2Sn requires 393.0877, 235 (34), 161 (100),
131 (45), 104 (27).
4.1.9. 4-(2-Methylphenyl)-3-tributylstannylfuran-2(5H)-
one (5c). Reaction of 3,4-bis(tributylstannyl)furan-2(5H)-
one (4a) (500 mg, 0.755 mmol) and 2-iodotoluene (165 mg,
0.755 mmol) gave furanone (5c) after purification by
column chromatography (Rf 0.38, ether/petrol, 1:4) as a
clear colourless oil (171 mg, 49%). nmax 1741, 1620, 1597;
dH (CDCl3) 0.74–1.44 (27H, m), 2.27 (3H, s), 4.92 (2H, t,
J¼3.5 Hz), 7.05–7.33 (4H, m); dC (CDCl3) 9.5, 13.5, 19.6,
27.1, 28.8, 75.2, 125.8, 127.7, 129.1, 130.3, 132.2, 134.1,
134.5, 176.1, 178.4; m/z (EI) Found (M2Bu)þ, 407.1041
(100%), C19H27O2Sn requires 407.1033, 292 (45), 129 (21).
4.1.6. 3,4-Bistrimethylstannylfuran-2(5H)-one (4b) and
(Z)-methyl-3-(tetrahydropyran-2-yl)oxymethyl-3-bis-
(trimethylstannyl)propenoate (12). (Z)-Methyl-3-(tetra-
hydropyran-2-yl)oxymethyl-2,3-bistrimethylstannylpropen-
oate (11) (690 mg, 1.307 mmol) and Dowexw 50W-X4 ion-
exchange resin (1.38 g) were combined in dry methanol
(10 mL) and stirred at 508C for 3 h. The resin was removed
by gravity filtration, washed with ether (25 mL) and the
solvent removed in vacuo. Purification by column chroma-
tography (Rf 0.28, ether/petrol, 1:4) yielded bisstannane
(4b) as a semi-solid (245 mg, 46%). nmax (CHBr3) 1726,
1536, 1441, 1330; dH (CDCl3) 0.30 (9H, s, coupling to 119Sn/
117Sn J¼22.0, 228.0 Hz), 0.32 (9H, s, coupling to 119Sn/117Sn
J¼22.0, 28.0 Hz), 4.90 (2H, s, coupling to 119Sn/117Sn
J¼5.0 Hz); dC (CDCl3) 27.6, 27.4, 80.5, 144.9, 178.9,
184.6; m/z (EI) Found (M2Me)þ, 394.9272 (72%),
C9H17O2Sn2 requires 394.9270, 351 (45), 165 (100); and
(Z)-Methyl-3-(tetrahydropyran-2-yl)-oxymethyl-3-trimethyl-
stannylpropenoate (12) (Rf 0.60, ether/petrol, 2:3) as a
colourless oil (42 mg, 9%). nmax (CHCl3) 2945, 1715,
1606; dH (CDCl3) 0.25 (9H, s, coupling to 119Sn/117Sn
J¼27.5 Hz), 1.50–1.80 (6H, m), 3.48–3.53 (1H, m), 3.70
(3H, s), 3.81–3.84 (1H, m), 4.56 (1H, dd, J¼2.7, 17.4 Hz),
4.70 (1H, m), 5.07 (1H, dd, J¼2.7, 17.4 Hz), 5.96 (1H, s,
coupling to 119Sn/117Sn J¼2.8 Hz); dC (CDCl3) 28.9, 18.4,
24.3, 29.4, 50.1, 60.9, 70.9, 97.6, 122.8, 163.8, 173.5; m/z
(CI, NH3) Found (M2Me)þ, 349.0472 (24%), C12H21O4Sn
requires 349.0462, 263 (55), 165 (27), 85 (100).
4.1.10. 4-(3-Trifluromethylphenyl)-3-tributylstannyl-
furan-2(5H)-one (5d). Reaction of 3,4-bis(tributylstannyl)-
furan-2(5H)-one (4a) (500 mg, 0.755 mmol) and 3-iodo-
trifluoromethylbenzene (205 mg, 0.755 mmol) gave fura-
none (5d) after purification by column chromatography (Rf
0.38, ether/petrol, 1:4) as a clear colourless oil (106 mg,
27%). nmax 1743, 1620, 1583; dH (CDCl3) 0.80–1.50 (27H,
m), 5.10 (2H, t, J¼3.5 Hz), 7.52–7.74 (4H, m); dC (CDCl3)
10.7, 13.8, 27.4, 29.1, 74.0, 124.2 (q, J¼3.5 Hz), 127.0 (q,
J¼3.7 Hz), 129.8, 130.3, 131.6 (q, J¼33 Hz), 132.6, 135.1,
172.4, 178.5; m/z (EI) Found (M2Bu)þ, 461.0748 (34%),
C19H24F3O2Sn requires 461.0750, 347 (19), 131 (100).
4.1.11. 4-(2-Methoxycarbonylphenyl)-3-tributylstannyl-
furan-2(5H)-one (5g). Reaction of 3,4-bis(tributylstannyl)-
furan-2(5H)-one (4a) (500 mg, 0.755 mmol) and methyl-2-
iodobenzoate (135 mg, 0.755 mmol) gave furanone (5g)
after purification by column chromatography (Rf 0.21,
ether/petrol, 1:3) as a clear colourless oil (195 mg, 51%).
nmax 1726, 1619, 1594; dH (CDCl3) 0.77–1.55 (27H, m),
3.86 (3H, s), 5.03 (2H, t, J¼3.5 Hz), 7.23 (1H, dd, J¼1.0,
7.5 Hz), 7.55 (1H, ddd, J¼1.5, 7.5, 7.4 Hz), 7.63 (1H, ddd,
J¼1.5, 7.5, 7.5 Hz), 8.10 (1H, dd, J¼1.0, 7.5 Hz); dC
(CDCl3) 9.4, 13.4, 27.0, 28.6, 52.0, 74.6, 128.6, 129.0,
130.2, 130.7, 132.2, 136.2, 165.9, 176.7, 178.3; m/z (EI)
Found (M2Bu)þ, 451.0953 (9%), C20H27O4Sn requires
451.0931, 313 (40), 253 (19), 211 (79), 186 (24), 131 (12).
4.1.7. Synthesis of 4-aryl-3-tributylstannylfuran-2(5H)-
ones. Two methods were generally employed:
Method A. To a stirred solution of aryl iodide (0.755 mmol,
1.0 equiv.) in dry deoxygenated THF (5 mL) was added
copper(I) iodide (11.4 mg, 0.08 equiv.) and triphenylarsine

9124
N. B. Carter et al. / Tetrahedron 58 (2002) 9117–9129
4.1.12. 4-(2-Thienyl)-3-tributylstannylfuran-2(5H)-one
(5h). Reaction of 3,4-bis(tributylstannyl)furan-2(5H)-one
(4a) (500 mg, 0.755 mmol) and 2-iodothiophene (158 mg,
0.755 mmol) gave furanone (5h) after purification by
column chromatogaphy (Rf 0.31, ether/petrol, 1:4) as a
clear colourless oil (75 mg, 22%). nmax 1736, 1610, 1580;
dH (CDCl3) 0.84–1.55 (27H, m), 5.08 (2H, t, J¼3.0 Hz),
7.15 (1H, dd, J¼3.5, 5.0 Hz), 7.23 (1H, dd, J¼1.0, 3.5 Hz),
7.52 (1H, dd, J¼1.0, 5.0 Hz); dC (CDCl3) 10.8, 13.6, 27.2,
29.0, 73.1, 127.5, 127.7, 128.1, 129.0, 135.7, 165.3, 178.7;
m/z (EI) Found (M2Bu)þ, 399.0439 (100%), C16H23O2SSn
requires 399.04407, 285 (56), 121 (10).
27.5, 29.2, 75.6, 125.5, 130.7, 130.8, 131.0, 133.3, 134.1,
147.6, 172.6, 178.2. m/z (CI, NH3) Found 438.0703 (M2n-
Bu)þ, 100, C18H24SnO4N requires 438.0727; 361 (65), 270
(45), 206 (40), 138 (25).
4.1.16. 3-Tributylstannyl-4-benzylfuran-2(5H)-one (5i).
Reaction of benzyl bromide (55 mg, 0.32 mmol, 38 mL),
PdCl2(PPh3)2 (2 mol%), triphenylarsine (8 mol%), cop-
per(I) iodide (8 mol%) and (4a), (0.21 g, 0.32 mmol) in
THF (4 mL) for 18–24 h at 508C, followed by purification
by flash chromatography on silica gel (Rf 0.54, ether/petrol
2:3), afforded (5i), (14 mg, 0.03 mmol, 9%). nmax 2961,
1741, 1611; dH (CDCl3), 0.87–1.68 (27H, m), 3.80 (2H, s),
4.58 (2H, s), 7.13–7.16 (2H, m), 7.28–7.38 (3H, m); dC
(CDCl3) 10.4, 12.2, 27.7, 29.6, 37.4, 74.5, 127.7, 128.8,
129.4, 129.8, 137.0, 176.3, 179.2. m/z (CI, NH3) Found
407.1041 (M2n-Bu)þ, 60, C19H27SnO2 requires 407.1033;
175 (100), 91 (35).
Method B. To a stirred solution of organohalide in dry
deoxygenated THF (typically 3–5 mL) under an argon
atmosphere, was added PdCl2(PPh3)2 (2 mol%), triphenyl-
arsine (8 mol%) and copper(I) iodide (8 mol%). After
10 min at ambient temperature, the mixture was heated to
508C and (4a), as a solution in THF (3–5 mL), was added by
syringe. After 18–24 h at 508C, the product mixture was
gravity filtered and the solvent removed in vacuo to produce
a yellow/brown oil. Purification by flash chromatography on
silica gel (ether/petrol 1:19 to 2:3), afforded (5b, 5e and 5f)
in varying yield as clear colourless oils.
4.1.17. 3-Tributylstannyl-4-(prop-2-enyl)furan-2(5H)-
one (5j). Reaction of allyl bromide (36 mg, 0.30 mmol,
26 mL), PdCl2(PPh3)2 (2 mol%), triphenylarsine (8 mol%),
copper(I) iodide (8 mol%) and (4a), (0.20 g, 0.30 mmol) in
THF (4 mL) for 18–24 h at 508C, followed by purification
by flash chromatography on silica gel (Rf 0.43, ether/petrol
2:3), afforded (5j), (29 mg, 0.07 mmol, 23%). nmax 2956,
1740, 1578; dH (CDCl3), 0.83–1.64 (27H, m), 3.21 (2H, d,
J¼6.5 Hz), 4.72 (2H, s), 5.11–5.20 (2H, m), 5.71–5.84
(1H, m); dC (CDCl3) 10.3, 14.1, 27.9, 29.4, 35.4, 74.5,
118.8, 129.5, 133.4, 175.8, 179.3. m/z (EI)þ Found
(M2Bu)þ, 357.0855 (100%), C15H25O2Sn requires
357.0877, 328 (15). 291 (70), 253 (55), 211 (17), 152
(15), 125 (45), 66 (32).
4.1.13. 3-Tributylstannyl-4-(1-naphthyl)furan-2(5H)-
one (5b). Reaction of 1-iodonaphthalene (0.15 g,
0.60 mmol, 88 mL), PdCl2(PPh3)2 (2 mol%), triphenyl-
arsine (8 mol%), copper(I) iodide (8 mol%) and (4a),
(0.40 g, 0.60 mmol) in THF (10 mL) for 18–24 h at 508C,
followed by purification by flash chromatography on silica
gel (Rf 0.48 ether/petrol, 2:3), afforded (5b), (0.12 g,
0.24 mmol, 40%). nmax 2956, 1740, 1589; dH (CDCl3),
0.65–1.34 (m, 27H), 5.10 (s), 7.30–7.94 (m, 7H); dC
(CDCl3) 10.0, 13.9, 27.5, 29.3, 76.5, 125.1, 125.3, 125.4,
127.0, 127.4, 129.0, 129.9, 131.1, 132.6, 133.9, 134.8,
174.8, 178.9; m/z (CI, NH3) Found 443.1028 (M2n-Bu)þ,
25, C22H27SnO2 requires 443.1033; 269 (15), 211 (100),
181 (10), 153 (20).
4.1.18. 4-Benzoyl-3-tributylstannylfuran-2(5H)-one (5k).
3,4-Bis(tributylstannyl)furan-2(5H)-one (4a) (500 mg,
0.755 mmol) and benzoyl chloride (106 mg, 0.755 mmol)
were combined under a carbon monoxide atmosphere with
benzylchlorobistriphenylphosphinepalladium(II) in chloro-
form (10 mL). The mixture was heated to 558C under an
atmospheric pressure of carbon monoxide for 18 h, by
which time the reaction mixture was black in colour. The
reaction mixture was concentrated in vacuo and purification
by column chromatography (Rf 0.28, ether/petrol 1:3)
yielded furanone (5k) as an orange oil (120 mg, 33%).
nmax 1751, 1700, 1663; dH (CDCl3) 0.81–1.40 (27H, m),
5.10 (2H, t, J¼4.0 Hz), 7.52–7.90 (5H, m); dC (CDCl3)
10.3, 13.6, 27.1, 28.8, 73.8, 129.1, 129.6, 129.8, 134.7,
135.8, 139.4, 170.4, 177.5, 193.2; m/z (EI) Found
(M2Bu)þ, 421.0837 (100%), C19H25O3Sn requires
421.0825, 307 (21), 329 (15), 149 (19), 105 (99).
4.1.14. 3-Tributylstannyl-4-(o-methoxyphenyl)furan-
2(5H)-one (5e). Reaction of o-iodomethoxybenzene
(28 mg, 0.12 mmol, 16 mL), PdCl2(PPh3)2 (2 mol%), tri-
phenylarsine (8 mol%), copper(I) iodide (8 mol%) and (4a),
(80 mg, 0.12 mmol) in THF (2 mL) for 18–24 h at 508C,
followed by purification by flash chromatography on silica
gel (Rf 0.40, ether/petrol 2:3), afforded (5e), (23 mg,
0.05 mmol, 40%). nmax 2956, 1736, 1592; dH (CDCl3) d
0.80–1.62 (27H, m), 3.83 (3H, s), 5.09 (1H, s), 6.93–7.41
(4H, m); dC (CDCl3) 10.3, 13.9, 27.5, 29.1, 55.6, 75.2,
111.1, 120.8, 123.6, 129.7, 131.4, 131.5, 156.8, 173.7,
179.1. m/z (CI, NH3) Found 423.0968 (M2n-Bu)þ, 20,
C19H27SnO3 requires 423.0982; 269 (10), 191 (100).
4.1.19. 4-(E)-(2-Phenylethenyl)-3-tributylstannylfuran-
2(5H)-one (5l). b-Bromostyrene (138 mg, 0.755 mmol)
and triphenylarsine (18.4 mg, 0.08 equiv.) were combined
in dry deoxygenated DMF (5 mL). 3,4-Bis(tributylstannyl)-
furan-2(5H)-one (4b) (500 mg, 0.755 mmol) was added in
deoxygenated DMF (5 mL). Tris(dibenzylideneacetone)-
dipalladium(II) (13.7 mg, 0.02 equiv.) was added to give a
purple solution which changed to lime green in colour over
10 min. The reaction mixture was stirred under an argon
atmosphere at 508C for 18 h. The reaction mixture was
concentrated in vacuo and purification by column
4.1.15. 3-Tributylstannyl-4-(o-nitrophenyl)furan-2(5H)-
one (5f). Reaction of o-iodonitrobenzene (75 mg,
0.30 mmol), PdCl2(PPh3)2 (2 mol%), triphenylarsine
(8 mol%), copper(I) iodide (8 mol%) and (4a), (0.20 g,
0.30 mmol) in THF (4 mL) for 18–24 h at 508C, followed
by purification by flash chromatography on silica gel (Rf
0.27, ether/petrol, 2:3), afforded (5f), (68 mg, 0.14 mmol,
47%). nmax 2956, 1740, 1594; dH (CDCl3), 0.76–1.65 (27H,
m), 5.02 (2H, s), 7.30–8.23 (4H, m); dC (CDCl3) 10.1, 13.9,

N. B. Carter et al. / Tetrahedron 58 (2002) 9117–9129
9125
chromatography (Rf 0.32, ether/petrol, 1:3) gave furanone
(5l) as a clear colourless oil (126 mg, 35%). nmax 1743,
1727, 1624; dH (CDCl3) 0.88–1.61 (27H, m), 5.08 (2H,
br.s), 6.80 (1H, d, J¼16.0 Hz), 7.06 (1H, d, J¼16.0 Hz),
7.34–7.47 (5H, m); dC (CDCl3) 10.3, 13.7, 27.3, 29.0, 71.8,
121.6, 127.2, 129.1, 129.6, 131.9, 135.5, 135.7, 169.8,
178.9; m/z (EI) Found (M2Bu)þ, 419.1029 (100%),
C20H27O2Sn requires 419.1033, 305 (44), 259 (11), 141
(90).
needles (20 mg, 91%) mp 127–1298C (petrol). nmax
(CHBr3) 1782, 1749, 1628; dH (CDCl3) 5.27 (2H, d,
J¼2.0 Hz), 6.49 (1H, t, J¼2.0 Hz) 7.63–7.79 (4H, m); dC
(CDCl3) 70.8, 114.9,123.1 (q, J¼3.7 Hz), 128.2 (q,
J¼3.7 Hz), 129.6, 130.0, 130.5, 131.8, 162.0, 173.0; m/z
(EI) Found (M)þ, 228.0398 (36%), C11H7F3O4 requires
228.0398, 199 (100), 171 (32), 170 (24), 151 (21).
4.2.5. 4-(2-Methoxyphenyl)-furan-2(5H)-one (9e).1 Reac-
tion of 4-(2-methoxyphenyl)-3-tributylstannylfuran-2(5H)-
one (5e) (40 mg, 0.083 mmol) and 50% TFA (aq) gave
furanone 9e after purification by column chromatography
(Rf 0.38, ether/petrol, 1:1) as colourless needles (14 mg,
88%) mp 85–868C (petrol). nmax 3089, 1736, 1681; dH
(CDCl3) 3.86 (3H, s), 5.20 (2H, d, J¼2.0 Hz), 6.49 (1H, t,
J¼2.0 Hz), 6.92 (2H, m), 7.33–7.39 (3H, m); dC (CDCl3)
55.9, 73.2, 112.1, 115.3, 119.2, 121.4, 128.8, 133.3, 158.8,
161.4, 175.1; m/z (CI, NH3) Found (MH)þ, 191.0701
(100%), C11H11O3 requires 191.0708, 181 (7), 162 (25).
4.2. Protodestannylation of stannylfuranones 5a–5l
General procedure. To a stirred solution of 4-aryl-3-
stannylfuran-2(5H)-one (50–100 mg) in methanol (5 mL)
was added a solution of 50% TFA (aq) (1.0 mL). The
mixture was stirred at room temperature for 18–24 h. The
solvent was removed in vacuo and purification by column
chromatography and recrystallisation from petrol yielded 4-
arylfuranones as colourless needles.
4.2.1. 4-Phenylfuran-2(5H)-one (9a).1 Reaction of 4-
phenyl-3-tributylstannylfuran-2(5H)-one (5a) (50 mg,
0.11 mmol) and 50% TFA (aq) gave furanone 9a after
purification by column chromatography (Rf 0.25, ether/
petrol, 1:1) as colourless needles (15 mg, 85%) mp 95–
968C (from petrol). nmax (CHBr3) 1783, 1746, 1624, 1596;
dH (CDCl3) 5.21 (2H, d, J¼2.0 Hz), 6.36 (1H, t, J¼2.0 Hz),
7.43–7.51 (5H, m); dC (CDCl3) 71.0, 113.1, 126.4, 129.3,
129.6, 131.8, 163.9, 173.8; m/z (EI) Found (M)þ, 164.0521
(62%), C10H8O2 requires 160.0524, 131 (100), 103 (80),
102 (70), 77 (40), 51 (27).
4.2.6. 4-(2-Nitrophenyl)-furan-2(5H)-one (9f).1 Reaction
of 4-(2-nitrophenyl)-3-tributylstannylfuran-2(5H)-one (5f)
(16 mg, 0.03 mmol) and 50% TFA (aq) gave furanone 9f
after purification by column chromatography (Rf 0.32,
ether) as colourless needles (5 mg, 82%) mp 181–1828C
(petrol). nmax (paraffin) 1751; dH (CD3OD) 5.10 (d, 2H,
J¼2.0 Hz), 6.18 (t, 1H, J¼2.0 Hz), 7.42–7.46 (m, 1H),
7.66–7.80 (m, 2H), 8.14–8.18 (m, 1H); dC (CD3OD) 74.4,
118.8, 126.0, 127.6, 131.5, 132.4, 134.9, 148.8, 166.0,
175.2; m/z (CI, NH3) Found (MH)þ, 206.0442 (100%),
C10H8NO4 requires 206.0453, 223 (70), 291 (100), 133 (10).
4.2.2. 4-(1-Napthyl)-furan-2(5H)-one (9b).1 Reaction of 4-
(1-napthyl)-3-tributylstannylfuran-2(5H)-one (5b) (60 mg,
0.12 mmol) and 50% TFA (aq) gave furanone 9b after
purification by column chromatography (Rf 0.42, ether/
petrol, 1:1) as colourless needles (20 mg, 80%) mp 98–
1008C (petrol). nmax 1736, 1685; dH (CDCl3) 5.20 (2H, d,
J¼2.0 Hz), 6.39 (1H, t, J¼2.0 Hz), 7.19–7.55 (4H, m),
7.85–8.07 (3H, m); dC (CDCl3) 73.6, 119.3, 124.6, 125.4,
125.9, 127.2, 128.1, 128.9, 129.5, 130.7, 131.6, 134.3,
164.3, 174.0; m/z (CI, NH3) Found (MH)þ, 211.0751
(100%), C14H11O2 requires 211.0759, 181 (7), 165 (20), 152
(15).
4.2.7. 4-(2-Methoxycarbonylphenyl)-furan-2(5H)-one
(9g).1 Reaction of 4-(2-methoxycarbonylphenyl)-3-tributyl-
stannylfuran-2(5H)-one (5g) (50 mg, 0.098 mmol) and 50%
TFA (aq) gave furanone 9g after purification by column
chromatography (Rf 0.19, ether/petrol, 1:1) as colourless
needles (19 mg, 89%) mp 94–958C (petrol). nmax (CHBr3)
1779, 1748, 1721 1624, 1597; dH (CDCl3) 3.89 (3H, s) 5.09
(2H, d, J¼2.0 Hz), 7.31 (1H, dd, J¼1.0, 7.5 Hz), 7.54 (1H,
ddd, J¼1.5, 7.5, 7.5 Hz), 7.62 (1H, ddd, J¼1.5, 7.5, 7.5 Hz),
8.03 (1H, dd, J¼1.0, 7.5 Hz); dC (CDCl3) 52.6, 73.5, 117.3,
129.1, 130.0, 130.9, 132.5, 132.6, 166.6, 167.4, 173.4; m/z
(EI) Found (M)þ, 218.0575 (16%), C12H10O4 requires
218.0579, 186 (100), 158 (48), 130 (29), 77 (17).
4.2.3. 4-(2-methylphenyl)-furan-2(5H)-one (9c).1 Reac-
tion of 4-(2-methylphenyl)-3-tributylstannylfuran-2(5H)-
one (5c) (50 mg, 0.108 mmol) and 50% TFA (aq) gave
furanone 9c after purification by column chromatography
(Rf 0.28, ether/petrol, 1:1) as colourless needles (17 mg,
95%) mp 66–678C (pentane). nmax (CHBr3) 1780, 1749,
1615, 1571; dH (CDCl3) 2.48 (3H, s), 5.19 (2H, d,
J¼2.0 Hz), 6.27 (1H, t, J¼2.0 Hz), 7.26–7.40 (4H, m); dC
(CDCl3) 22.0, 72.3, 117.2, 126.6, 127.3, 129.7, 130.7,
132.0, 137.3, 163.8, 174.0; m/z (EI) Found (M)þ, 174.0684
(86%), C11H10O2 requires 174.0680, 145 (100), 117 (44),
116 (52), 115 (85), 91 (17).
4.2.8. 4-(2-Thienyl)-furan-2(5H)-one (9h).1 Reaction of 4-
(2-thienyl)-3-tributylstannylfuran-2(5H)-one (5h) (50 mg,
0.110 mmol) and 50% TFA (aq) gave furanone 9h after
purification by column chromatography (Rf 0.32, ether/
petrol, 1:1) as colourless needles (16 mg, 88%) mp 96–
978C (petrol). nmax (CHBr3) 1778, 1744, 1616; dH (CDCl3)
5.18 (2H, d, J¼1.5 Hz), 6.17 (1H, br. s) 7.15 (1H, dd, J¼3.5,
5.0 Hz), 7.32 (1H, br. d, J¼3.5 Hz), 7.57 (1H, br. s,
J¼5.0 Hz); dC (CDCl3) 70.9,111.3, 128.4, 128.5, 130.5,
132.9, 157.1, 173.5; m/z (EI) Found (M)þ, 166.0083
(100%), C8H6O2S requires 166.0088, 137 (85), 108 (53),
65 (7), 44 (20).
4.2.4. 4-(3-Trifluromethylphenyl)-furan-2(5H)-one (9d).1
Reaction of 4-(3-trifluromethylphenyl)-3-tributylstannyl-
furan-2(5H)-one (5d) (50 mg, 0.096 mmol) and 50% TFA
(aq) gave furanone 9d after purification by column
chromatography (Rf 0.19, ether/petrol, 1:1) as colourless
4.2.9. 4-Benzylfuran-2(5H)-one (9i).1 Reaction of 4-
benzyl-3-tributylstannylfuran-2(5H)-one
(5i)
(60 mg,
0.173 mmol) and 50% TFA (aq) gave furanone 9i after
purification by column chromatography (Rf 0.33, ether/

9126
N. B. Carter et al. / Tetrahedron 58 (2002) 9117–9129
petrol, 1:1) as a clear colourless oil (26 mg, 86%). nmax
3031, 1717, 1685; dH (CDCl3) 3.67 (2H, s), 4.65 (2H, m),
5.75 (1H, m), 7.10–7.13 (2H, m), 7.22–7.33 (3H, m); dC
(CDCl3) 35.7, 73.1, 117.1, 127.9, 129.1, 129.5, 135.9,
169.4, 174.1; m/z (CI, NH3) Found (MH)þ, 175.0765
(100%), C11H11O2 requires 175.0759, 115 (10), 96 (45), 91
(15).
iodide (8 mol%) and (4a), (0.30 g, 0.45 mmol) in THF
(6 mL) for 18–24 h at 508C, followed by purification by
flash chromatography on silica gel afforded (5a), (71 mg,
0.16 mmol, 35%).
(2) Reaction of iodobenzene (92 mg, 0.45 mmol, 50 mL),
Pd2dba3 (2 mol%), tri-(2-furyl)phosphine (8 mol%), cop-
per(I) iodide (8 mol%) and (4a), (0.30 g, 0.45 mmol) in
THF (6 mL) for 18–24 h at 508C, followed by purification
by flash chromatography on silica gel afforded (5a), (65 mg,
0.14 mmol, 31%).
4.2.10. 4-(Allyl)-furan-2(5H)-one (9j). Reaction of 4-
(allyl)-3-tributylstannylfuran-2(5H)-one
(5j)
(60 mg,
0.145 mmol) and 50% TFA (aq) gave furanone 9j after
purification by column chromatography (Rf 0.32, ether/
petrol, 1:1) as a clear colourless oil (13 mg, 73%). nmax
2927, 1748, 1685, 1653; dH (CDCl3) 3.11 (2H, m), 4.69 (2H,
dt, J¼1.0, 2.0 Hz), 5.11–5.20 (2H, m), 5.70–5.84 (1H, m);
dC (CDCl3) 33.3, 73.2, 116.6, 119.7, 131.9, 168.8, 174.2;
m/z (CI, NH3) Found (MH)þ, 125.0604 (100%), C7H8O2
requires 125.0602, 95 (20), 83 (10), 67 (15), 39 (13).
(3) Reaction of iodobenzene (92 mg, 0.45 mmol, 50 mL),
Pd(PPh3)4 (2 mol%), triphenylarsine (8 mol%), copper(I)
iodide (8 mol%) and (4a), (0.30 g, 0.45 mmol) in THF
(6 mL) for 18–24 h at 508 C, followed by purification by
flash chromatography on silica gel afforded (5a), (48 mg,
0.11 mmol, 24%).
4.2.11. 4-Benzoylfuran-2(5H)-one (9k).8 Reaction of 4-
benzoyl-3-tributylstannylfuran-2(5H)-one (5k) (50 mg,
0.105 mmol) with 50% TFA (aq) gave furanone 9k after
purification by column chromatography (Rf 0.28, ether/
petrol, 1:3), as colourless needles (18 mg, 90%) mp 101–
1028C (petrol). nmax (CHBr3) 1782, 1750, 1652; dH (CDCl3)
5.13 (2H, t, J¼2.0 Hz) 6.43 (1H, t, J¼2.0 Hz) 7.47–7.84
(5H, m); dC (CDCl3) 72.3, 125.8, 129.7, 135.1, 136.3, 160.2,
172.8, 189.7; m/z (EI) Found (MH)þ, 189.0546 (100%),
C11H8O3 requires 188.0473, 105 (73), 77 (17), 59 (10).
(4) Reaction of iodobenzene (92 mg, 0.45 mmol, 50 mL),
PdCl2(MeCN)2 (2 mol%), triphenylarsine (8 mol%), cop-
per(I) iodide (8 mol%) and (4a), (0.30 g, 0.45 mmol) in
THF (6 mL) for 18–24 h at 508C, followed by purification
by flash chromatography on silica gel afforded (5a), (65 mg,
0.14 mmol, 32%).
(5) Reaction of iodobenzene (92 mg, 0.45 mmol, 50 mL),
PdCl2(PhCN)2 (2 mol%), triphenylarsine (8 mol%), cop-
per(I) iodide (8 mol%) and (4a), (0.30 g, 0.45 mmol) in
THF (6 mL) for 18–24 h at 508C, followed by purification
by flash chromatography on silica gel afforded (5a), (69 mg,
0.15 mmol, 33%).
4.2.12. 4-((E)-2-Phenylethenyl)-furan-2(5H)-one (9l).8 4-
((E)-2-Phenylethenyl)-3-tributylstannylfuran-2(5H)-one (5l)
(50 mg, 0.105 mmol) was dissolved in methanol (5 mL). A
solution of 50% TFA (aq) (1.0 mL) was added, and the
mixture stirred at room temperature overnight. The solvent
was removed in vacuo and column chromatography (Rf 0.28,
diethyl ether/petrol, 1:3) gave the furanone 9l as colourless
needles (18 mg, 92%) mp 118–1208C (from ether/petrol 1:1).
(7) Reaction of iodobenzene (92 mg, 0.45 mmol, 50 mL),
Pd(dppb)2 (2 mol%), triphenylarsine (8 mol%), copper(I)
iodide (8 mol%) and (4a), (0.30 g, 0.45 mmol) were heated
in THF (6 mL) for 18–24 h at 508C, followed by
purification by flash chromatography on silica gel afforded
(5a), (55 mg, 0.12 mmol, 27%) and (10), (42 mg,
0.18 mmol, 39%).
nmax (CHBr3) 1778, 1744, 1634, 1590; dH (CDCl3) 5.03 (2H,
d, J¼1.0 Hz) 5.96 (1H, br. s), 6.80 (1H, d, J¼16.5 Hz) 7.00
(1H, d, J¼16.5 Hz) 7.30–7.44 (5H, m); dC (CDCl3) 70.4,
115.6, 118.6, 127.4, 129.0, 130.0, 134.8, 137.2, 161.9, 173.9;
m/z (EI) Found (M)þ, 186.0682 (25%), C12H10O2 requires
186.0681, 141 (100), 128 (52), 102 (10), 77 (11), 51 (20).
(8) Reaction of iodobenzene (92 mg, 0.45 mmol, 50 mL),
PdCl2(PPh3)2 (2 mol%), triphenylarsine (8 mol%), cop-
per(I) iodide (8 mol%) and (4a), (0.30 g, 0.45 mmol) in
THF (6 mL) for 18–24 h at 508C, followed by purification
by flash chromatography on silica gel afforded (5a), (77 mg,
0.17 mmol, 38%).
4.3. Optimization studies: synthesis of 3-tributylstannyl-
4-phenylfuran-2(5H)-one (5a)
General method. To a stirred solution of iodobenzene in dry
deoxygenated THF, DMF, CH2Cl2, MeOH, 1,2-DME or
NMP (2–3 mL) were added certain additives. After 10 min
at ambient temperature, the mixture was heated to the
apposite temperature. Furanone (4a) was then added via
syringe, as a solution in the appropriate solvent. After the
allotted reaction time, the product mixture was filtered and
the solvent removed in vacuo to produce the crude product
as an oil. Purification by flash chromatography on silica gel
afforded (5a) in varying yields as a colourless oil. The
numbers at the beginning of each paragraph are those
associated with the entry in Table 2.
(9) Reaction of iodobenzene (184 mg, 0.90 mmol, 101 mL),
PdCl2(PPh3)2 (2 mol%), triphenylarsine (8 mol%), cop-
per(I) iodide (8 mol%) and (4a), (0.30 g, 0.45 mmol) in
THF (6 mL) for 18–24 h at 508C, followed by purification
by flash chromatography on silica gel afforded (5a), (75 mg,
0.17 mmol, 37%).
(10) Reaction of iodobenzene (47 mg, 0.23 mmol, 26 mL),
PdCl2(PPh3)2 (2 mol%), triphenylarsine (8 mol%), cop-
per(I) iodide (8 mol%) and (4a), (0.30 g, 0.45 mmol) in
THF (6 mL) for 18–24 h at 508C, followed by purification
by flash chromatography on silica gel afforded (5a), (53 mg,
0.12 mmol, 26%).
(1) Reaction of iodobenzene (92 mg, 0.45 mmol, 50 mL),
Pd2dba3 (2 mol%), triphenylarsine (8 mol%), copper(I)
(13) Reaction of iodobenzene (92 mg, 0.45 mmol, 50 mL),

N. B. Carter et al. / Tetrahedron 58 (2002) 9117–9129
9127
PdCl2(PPh3)2 (2 mol%), tri-(2-furyl)phosphine (8 mol%),
copper(I) iodide (8 mol%) and (4a), (0.30 g, 0.45 mmol) in
THF (6 mL) for 18–24 h at 508C, followed by purification
by flash chromatography on silica gel afforded (5a), (48 mg,
0.11 mmol, 24%).
(22) Reaction of iodobenzene (61 mg, 0.30 mmol, 34 mL),
PdCl2(PPh3)2 (2 mol%), triphenylarsine (8 mol%), cop-
per(I) iodide (8 mol%) and (4a), (0.20 g, 0.30 mmol) in
CH2Cl2 (4 mL) for 72 h at ambient temperature, followed
by purification by flash chromatography on silica gel
afforded (5a), (37 mg, 0.08 mmol, 27%).
(14) Reaction of iodobenzene (92 mg, 0.45 mmol, 50 mL),
PdCl2(PPh3)2 (2 mol%), triphenylarsine (8 mol%), cop-
per(I) iodide (8 mol%) and (4a), (0.30 g, 0.45 mmol) in
THF (6 mL) for 18–24 h at 508C. A second addition of
PdCl2(PPh3)2 (2 mol%) was made and the reaction mixture
stirred at 508C for a further 18–24 h, followed by
purification by flash chromatography on silica gel afforded
(5a), (85 mg, 0.19 mmol, 42%).
(23) Reaction of iodobenzene (61 mg, 0.30 mmol, 34 mL),
PdCl2(PPh3)2 (5 mol%), triphenylarsine (8 mol%), cop-
per(I) iodide (8 mol%) and (4a), (0.20 g, 0.30 mmol) were
heated in THF (4 mL) for 18–24 h at 508C, followed by
purification by flash chromatography on silica gel afforded
(5a), (50 mg, 0.11 mmol, 37%).
(24) Reaction of iodobenzene (61 mg, 0.30 mmol, 34 mL),
PdCl2(PPh3)2 (10 mol%), triphenylarsine (8 mol%), cop-
per(I) iodide (8 mol%) and (4a), (0.20 g, 0.30 mmol) in
THF (4 mL) for 18–24 h at 508C, followed by purification
by flash chromatography on silica gel afforded (5a), (39 mg,
0.09 mmol, 29%).
(15) Reaction of iodobenzene (92 mg, 0.45 mmol, 50 mL),
PdCl2(PPh3)2 (2 mol%), triphenylarsine (8 mol%), cop-
per(I) iodide (8 mol%) and (4a), (0.30 g, 0.45 mmol) in
THF (6 mL) for 1 week at ambient temperature, followed by
purification by flash chromatography on silica gel afforded
(5a), (36 mg, 0.08 mmol, 18%).
(25) Reaction of iodobenzene (61 mg, 0.30 mmol, 34 mL),
PdCl2(PPh3)2 (15 mol%), triphenylarsine (8 mol%), cop-
per(I) iodide (8 mol%) and (4a), (0.20 g, 0.30 mmol) in
THF (4 mL) for 18–24 h at 508C, followed by purification
by flash chromatography on silica gel afforded (5a), (15 mg,
0.03 mmol, 11%).
(16) Reaction of iodobenzene (92 mg, 0.45 mmol, 50 mL),
PdCl2(PPh3)2 (2 mol%), triphenylarsine (8 mol%), cop-
per(I) iodide (8 mol%) and (4a), (0.30 g, 0.45 mmol) in
DMF (6 mL) for 18–24 h at 508C, followed by purification
by flash chromatography on silica gel afforded (5a), (59 mg,
0.13 mmol, 29%) and (10), (30 mg, 0.13 mmol, 28%).
(26) Reaction of iodobenzene (61 mg, 0.30 mmol, 34 mL),
PdCl2(PPh3)2 (2 mol%), triphenylarsine (20 mol%), cop-
per(I) iodide (8 mol%) and (4a), (0.20 g, 0.30 mmol) in
THF (4 mL) for 18–24 h at 508C, followed by purification
by flash chromatography on silica gel afforded (5a), (53 mg,
0.12 mmol, 39%).
(17) Reaction of iodobenzene (92 mg, 0.45 mmol, 50 mL),
PdCl2(PPh3)2 (2 mol%), triphenylarsine (8 mol%), cop-
per(I) iodide (8 mol%) and (4a), (0.30 g, 0.45 mmol) in
DMF (6 mL) for 18–24 h at 708C, followed by purification
by flash chromatography on silica gel afforded (5a), (57 mg,
0.13 mmol, 28%) and (10), (30 mg, 0.13 mmol, 28%).
(27) Reaction of iodobenzene (61 mg, 0.30 mmol, 34 mL),
PdCl2(PPh3)2 (2 mol%), triphenylarsine (8 mol%), cop-
per(I) iodide (0.5 equiv.) and (4a), (0.20 g, 0.30 mmol) in
THF (4 mL) for 18–24 h at 508C, followed by purification
by flash chromatography on silica gel afforded (5a), (39 mg,
0.09 mmol, 29%).
(18) Reaction of iodobenzene (92 mg, 0.45 mmol, 50 mL),
PdCl2(PPh3)2 (2 mol%), triphenylarsine (8 mol%), cop-
per(I) iodide (8 mol%) and (4a), (0.30 g, 0.45 mmol) in
DMF (6 mL) for 18–24 h at 908C, followed by purification
by flash chromatography on silica gel afforded (5a), (51 mg,
0.11 mmol, 25%) and (10), (38 mg, 0.16 mmol, 36%).
(28) Reaction of iodobenzene (61 mg, 0.30 mmol, 34 mL),
PdCl2(PPh3)2 (2 mol%), triphenylarsine (8 mol%), cop-
per(I) iodide (2 equiv.) and (4a), (0.20 g, 0.30 mmol) in
THF (4 mL) for 18–24 h at 508C, followed by purification
by flash chromatography on silica gel afforded (5a), (59 mg,
0.13 mmol, 44%).
(19) Reaction of iodobenzene (92 mg, 0.45 mmol, 50 mL),
PdCl2(PPh3)2 (2 mol%), triphenylarsine (8 mol%), copper(I)
iodide (8 mol%) and (4a), (0.30 g, 0.45 mmol) in MeOH
(6 mL) for 18–24 h at 508C, followed by purification by flash
chromatography on silica gel afforded (5a), (24 mg,
0.05 mmol, 12%) and (10), (29 mg, 0.12 mmol, 27%).
(29) Reaction of iodobenzene (61 mg, 0.30 mmol, 34 mL),
PdCl2(PPh3)2 (2 mol%), triphenylarsine (8 mol%) and (4a),
(0.20 g, 0.30 mmol) in THF (4 mL) for 18–24 h at 508C,
followed by purification by flash chromatography on silica
gel afforded (5a), (24 mg, 0.05 mmol, 18%).
(20) Reaction of iodobenzene (61 mg, 0.30 mmol, 34 mL),
PdCl2(PPh3)2 (2 mol%), triphenylarsine (8 mol%), cop-
per(I) iodide (8 mol%) and (4a), (0.20 g, 0.30 mmol) in
1,2-DME (4 mL) for 18–24 h at 508C, followed by
purification by flash chromatography on silica gel afforded
(5a), (41 mg, 0.09 mmol, 30%).
(30) Reaction of iodobenzene (61 mg, 0.30 mmol, 34 mL),
PdCl2(PPh3)2 (2 mol%), copper(I) iodide (8 mol%) and
(4a), (0.20 g, 0.30 mmol) in THF (4 mL) for 18–24 h at
508C, followed by purification by flash chromatography on
silica gel afforded (5a), (53 mg, 0.12 mmol, 39%).
(21) Reaction of iodobenzene (92 mg, 0.45 mmol, 50 mL),
PdCl2(PPh3)2 (2 mol%), triphenylarsine (8 mol%), cop-
per(I) iodide (8 mol%) and (4a), (0.30 g, 0.45 mmol) in
NMP (6 mL) for 18–24 h at 508C, followed by purification
by flash chromatography on silica gel afforded (5a), (51 mg,
0.11 mmol, 25%).
(31) Reaction of iodobenzene (61 mg, 0.30 mmol, 34 mL),
PdCl2(PPh3)2 (2 mol%), triphenylarsine (8 mol%),

9128
N. B. Carter et al. / Tetrahedron 58 (2002) 9117–9129
copper(I) cyanide (8 mol%) and (4a), (0.20 g, 0.30 mmol)
in THF (4 mL) for 18–24 h at 508C, followed by
purification by flash chromatography on silica gel afforded
(5a), (48 mg, 0.11 mmol, 36%).
Method B. Iodine (136 mg, 0.54 mmol) and 3-tributylstan-
nyl-furan-2(5H)-one (4a) (200 mg, 0.54 mmol) were com-
bined in dichloromethane (10 mL) and cooled to 08C under
an argon atmosphere. The mixture was allowed to warm to
ambient temperature and stirred for 18 h. Solid KF (31 mg,
0.54 mmol) was added and the mixture stirred for 3 h. The
mixture was filtered through Celitew and the solvent
removed in vacuo. Purification by column chromatography
(Rf 0.26, ether/petrol, 1:1) in the absence of light furnished
the iodide 14 as a colourless needles (55 mg, 50%); the
physical data associated with this compound exactly
matched that of the material obtained using Method A.
(32) Reaction of iodobenzene (61 mg, 0.30 mmol, 34 mL),
PdCl2(PPh3)2 (2 mol%), triphenylarsine (8 mol%), cop-
per(I) chloride (8 mol%) and (4a), (0.20 g, 0.30 mmol) in
THF (4 mL) for 18–24 h at 508C, followed by purification
by flash chromatography on silica gel afforded (5a), (36 mg,
0.08 mmol, 27%).
(34) Reaction of iodobenzene (61 mg, 0.30 mmol, 34 mL),
PdCl2(PPh3)2 (2 mol%), triphenylarsine (8 mol%), cop-
per(I) thiophene-2-carboxylate (8 mol%) and (4a), (0.20 g,
0.30 mmol) in THF (4 mL) for 18–24 h at 508C, followed
by purification by flash chromatography on silica gel
afforded (5a), (55 mg, 0.12 mmol, 41%).
4.3.3. 3,4-Bisiodofuran-2(5H)-one (15). Iodine (767 mg,
3.0 mmol) and 3,4-bistributylstannylfuran-2(5H)-one (4a)
(1.0 g, 1.51 mmol) were combined in dichloromethane
(10 mL) and cooled to 08C under an argon atmosphere.
The mixture was allowed to warm to ambient temperature
and stirred for 120 h in the absence of light. Solid potassium
fluoride (174 mg, 3.0 mmol) was added and the mixture
stirred for 3 h. The mixture was filtered through Celitew and
the solvent removed in vacuo. Purification by column
chromatography (Rf 0.52, ether/petrol, 1:1) in the absence of
light gave furanone 15 as a clear colourless oil (0.38 g, 76%)
mp 140–1418C (ether). nmax (CHBr3) 1773, 1748, 1578; dH
(CDCl3) 4.77 (2H, s); dC (CDCl3) 80.3, 99.3, 128.6, 169.0;
m/z (EI) Found (M)þ, 335.8144 (74%), C4H2O2I2 requires
335.8144, 209 (100), 165 (30), 127 (37).
(35) To a solution of iodobenzene (61 mg, 0.30 mmol,
34 mL) in THF (2 mL) under an argon atmosphere, was
added PdCl2(PPh3)2 (2 mol%), triphenylarsine (8 mol%)
and copper(I) iodide (8 mol%). The mixture was heated to
508C and (4a), (0.20 g, 0.30 mmol) was added in THF
(2 ml) by syringe pump over 8 h. The reaction mixture was
stirred in total for 18–24 h at 508C, followed by purification
by flash chromatography on silica gel afforded (5a), (37 mg,
0.08 mmol, 27%).
4.3.1. 3-Iodo-4-tributylstannylfuran-2(5H)-one (13). Iod-
ine (383 mg, 1.51 mmol) and 3,4-bistributylstannylfuran-
2(5H)-one (4a) (1.0 g, 1.51 mmol) were combined in
dichloromethane (10 mL) and cooled to 08C under an
argon atmosphere. The flask was wrapped in aluminium
foil, the mixture allowed to warm to ambient temperature
and stirred for 18 h in the absence of light. Solid
potassium fluoride (87 mg, 1.51 mmol) was added and
the mixture stirred for 3 h. The mixture was filtered
through Celitew and the solvent removed in vacuo.
Purification by column chromatography (Rf 0.38, ether/
petrol, 1:4) in the absence of light yielded furanone 13 as
a clear colourless oil (0.65 g, 87%). nmax 2924, 2871,
2851, 1758, 1556, 1464; dH (CDCl3) 0.87–1.56 (27H, m),
4.86 (2H, s); dC (CDCl3) 10.1, 13.6, 27.2, 29.0, 80.7,
95.9, 170.6, 180.0; m/z (EI) Found (M2Bu)þ, 442.9537
(44%), C12H20O2SnI requires 442.9530, 386 (21), 329
(30), 247 (18), 177 (13), 121 (19).
Acknowledgements
We thank the University of Bristol (part-funding to AMER),
the EPSRC (quota awards to R. M. and N. B. C.) the
Nuffield Foundation and ZENECA (award from Strategic
Research Fund to J. B. S.) for financial support. As ever, we
are indebted to the long-standing advice and guidance
provided by Mr Glen Buchman.
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