Efficient electrocatalytic addition reactions of allyl phenyl sulfone to electron deficient alkenes

Article abstract of DOI:10.1016/j.tet.2005.01.125

The use of tetraalkylammonium salts as electrolytes has been found to allow the formation of electrogenerated bases of especially high reactivity. Such conditions allow allyl phenyl sulfone to undergo addition to a variety of electron deficient vinyl and propenyl compounds (sulfone, ketone, nitrile, and ester). The additions are catalyzed by electrogenerated bases derived from the reactant itself, rather than via an added pro-base. The nature of the substrate molecule is seen to affect which type of product is formed, leading to an interplay between addition to 1 mol of substrate or to 2 mol of substrate. Yields of 1:1 adducts range from 6 to 81%, while yields of 1:2 adducts range from 57 to 96%.

Full text of DOI:10.1016/j.tet.2005.01.125

Tetrahedron 61 (2005) 3515–3523
Efficient electrocatalytic addition reactions of allyl phenyl sulfone
to electron deficient alkenes
*
Greg A. N. Felton and Nathan L. Bauld
Department of Chemistry and Biochemistry, The University of Texas at Austin, Austin, TX 78712, USA
Received 5 November 2004; revised 26 January 2005; accepted 28 January 2005
Abstract—The use of tetraalkylammonium salts as electrolytes has been found to allow the formation of electrogenerated bases of especially
high reactivity. Such conditions allow allyl phenyl sulfone to undergo addition to a variety of electron deficient vinyl and propenyl
compounds (sulfone, ketone, nitrile, and ester). The additions are catalyzed by electrogenerated bases derived from the reactant itself, rather
than via an added pro-base. The nature of the substrate molecule is seen to affect which type of product is formed, leading to an interplay
between addition to 1 mol of substrate or to 2 mol of substrate. Yields of 1:1 adducts range from 6 to 81%, while yields of 1:2 adducts range
from 57 to 96%.
q 2005 Elsevier Ltd. All rights reserved.
1. Introduction
attached to electron withdrawing groups (sulfone, ketone,
nitrile, and ester).
The buildup of basicity around the cathode during an
electrolytic reduction has long been known. The use of such
electrogenerated bases (EGBs) in directed synthesis has
8
Our previously published work showcased EGB promoted
addition of allyl phenyl sulfone to its propenyl isomer, along
with its novel reactions with vinyl sulfones to furnish high
(90–94%) yields of highly polar molecules in which 1 mol
of allyl phenyl sulfone has added consecutively, selectively,
and in a linear addition mode to 2 mol of the vinyl sulfone.
1
been investigated over the last few decades. The appli-
cations of EGBs include the electro-activation of both C–H
and N–H bonds, with subsequent N–C and C–C bond
2
,3
formation. The typical approach has been to provide
usually in stoichiometric amount) an additive (called a pro-
(
4,5
base) which serves as a precursor to the active base. A
relatively novel aspect of the reactions presented here is
that, in contrast to most of the earlier applications of EGBs
to organic synthesis, one of the reactants (allyl phenyl
sulfone) also serves as the pro-base. This use of direct
reduction of organic acids is an attractive, simplified
approach, which can be utilized in two ways. An ex situ
route, often enforced due to competitive substrate
The current work initially expands this area to include other
vinyl sulfones, obtaining similarly high yields. Competitive
addition to two different vinyl sulfones is also examined,
allowing for incorporation of a mole each of two sulfones.
An attempt has also been made to probe the range of
electron-deficient substrates that will allow Michael
9
addition of the electrogenerated conjugate base of allyl
phenyl sulfone. The formation of 1:2 adducts (4) is seen to
be generally limited to vinyl compounds (Fig. 1). The
formation of 1:1 adducts (3) is mostly seen with propenyl
substrates. However, several vinyl compounds yield both
product types, the ratio between which is explored, and a
mechanism is advanced.
6
reduction. Alternatively, and rather rarely, an in situ
route, as is presented here. This approach sees a further layer
of experimental simplification, and has been utilized for
malonic acid derivatives, for example.
7
The reactive EGBs formed during reduction lead to
exceptionally efficient and highly electrocatalytic additions
of allyl phenyl sulfone (via its conjugate base) to a variety of
vinyl and propenyl compounds, in which these groups are
The coupling of simple alkyl groups at the a position of allyl
phenyl sulfone has previously been seen (in a two step
10
chemical synthesis). However, the present work repre-
sents a large increase in the range of moieties that will
couple at the reactive a position. Stoichiometric use of
strong bases has been used in related allylic sulfone
Keywords: Catalytic; Electrogenerated base; Carbanion addition; Allyl
vinyl sulfone.
*
Corresponding author. Tel.: C1 512 471 3017; fax: C1 512 471 8696;
e-mail: bauld@mail.utexas.edu
1
1
compounds to affect addition to a,b-unsaturated esters,
0040–4020/$ - see front matter q 2005 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2005.01.125

3516
G. A. N. Felton, N. L. Bauld / Tetrahedron 61 (2005) 3515–3523
Figure 1. Summary of the products formed from the addition of the carbanion of 1 to 1 or 2 mol of various vinyl/propenyl compounds containing electron
withdrawing groups (EWGs).
1
2
cyclic ketones and nitroalkenes. The conjugate base of the
allyl sulfone was produced in a non-electrochemical manner
in these latter cases. The environmentally benign nature of
this work’s electrochemical formation of the reactive
carbanion, inherent in the simplified workup and the
consumption of electricity as the sole reagent (in catalytic
amounts), further adds to the experimental appeal and
potential utility of these reactions.
occurs until the vinyl substrate is largely consumed,
1
followed by self-addition of the excess 1.
4
Attempts to increase the yield of the rather unique cyclic
dimer, 5f (Fig. 2) formed from the addition of 1 to divinyl
8
sulfone (2f) proved unsuccessful, with yields of ca. 40%.
Yields of the allyl phenyl sulfone self-adduct, 3a, were
8
similarly not improved beyond 81%. Further expansion to
other electron deficient alkenes generally gave a more
complicated picture. A mixture of 1:2 and 1:1 adducts were
seen, in some cases along with secondary reaction products.
2
. Results and discussion
2
.1. Addition to vinyl sulfones
A brief account of the facile addition of the conjugate base
of allyl phenyl sulfone (substrate 1), to several vinyl
8
sulfones has been reported from this laboratory. Conse-
quently, the expansion of this work to other vinyl sulfones
was a clear next step. Use of ethyl and methyl vinyl sulfone
(2d and 2e) as electron-deficient addends unsurprisingly
followed a similar pattern of forming high yields of the
Figure 2. The cyclic 1:1 product, 5f, formed from a,g-addition of allyl
phenyl sulfone (1) to divinyl sulfone (2f). An example of a mixed trimer,
4cd, formed from addition of 1 to 1 mol each of tolyl vinyl sulfone (2c) and
ethyl vinyl sulfone (2d).
trimer product, 4 (Table 1).
2
.2. Addition to mixtures of vinyl sulfones
Table 1. Yields and minimum catalytic factors for cross addition of allyl
phenyl sulfone to electron deficient alkenes, leading to exclusive trimer
formation
The trimers formed from addition of 1 to vinyl sulfones
form readily in near quantitative yields. The reactions also
utilize all of the vinyl sulfone substrate prior to formation of
3a, so that the reactivity of the allyl carbanion to each vinyl
sulfone substrate can be probed by competitive addition
with two substrates in the reaction. The excess of any one
substrate was kept insufficient (below 2) to allow complete
reaction with that substrate only. In this way, each reaction
yields three trimers, two based on the addition to 2 mol of
each substrate, along with a ‘mixed’ trimer containing 1 mol
of each substrate.
Substrate
Yield (%)
Minimum
catalytic factor
a
b
2
2
2
2
b: Phenyl vinyl sulfone
c: Tolyl vinyl sulfone
91
95
96
92
13
7.4
17
15
b
d: Ethyl vinyl sulfone
e: Methyl vinyl sulfone
a
The reactions were monitored for completion in a step-wise fashion, such
that the exact amount of charge used to give completion is not known (see
experimental data). Therefore, the catalytic factors may be greater than
that stated. Catalytic factor based upon total charge used and moles of
K1 13
limiting reagent 1. Catalytic factors are found using 96,485 8C mol
Previously published results.
.
b
8
The reactivities of the vinyl sulfones (based on product
ratios in Table 2) generally follow a pattern which is
consistent with the expected relative stabilities of the
a-sulfonyl carbanions which would be formed in the
nucleophilic addition steps, based upon the relative
inductive effects of the four substituents attached to the
sulfonyl group (phenyl, tolyl, ethyl, and methyl. Presumably
these effects are present in both addition steps (see Fig. 3).
These mixed reactions show a reactive rank of 2bO2cO
These trimers were all produced from reactions with a vinyl
sulfone excess of !2.10, over 1. Indeed when the reaction
is run using an excess of 1 at a 1.97:1 ratio (to 2b), only the
trimer (4b) and the allyl phenyl sulfone carbanion addition
8
to propenyl phenyl sulfone (2a) product (3a) are obtained.
These products are seen in a 1:1.45 ratio, respectively, in
accord with the proposal that exclusive trimer formation

G. A. N. Felton, N. L. Bauld / Tetrahedron 61 (2005) 3515–3523
3517
Table 2. Reactions of allyl phenyl sulfone, 1, with two vinyl sulfones to
yield ‘mixed’ trimers incorporating all three components
monoadduct can be suppressed by using a slightly higher
excess of 2g. Under these conditions the yield of the trimer,
a
4g, is increased to 57%.
Substrates
Starting ratio
where 1Z1
Products
Product ratio
Addition to a propenyl nitrile (2h, crotononitrile) is seen to
be less facile, with yields of the 1:1 product of ca. 25%. The
2
2
2
2
2
bC2d
cC2d
cC2d
bC2e
dC2e
1.52:1.48
1.50:1.52
1.01:1.20
1.51:1.65
1.62:1.60
4d:4bd:4b
4d:4cd:4c
4d:4cd:4c
4e:4be:4b
4e:4de:4d
1:3.22:3.42
1:2.80:2.30
1:1.54:0.77
1:2.73:2.69
1:2 adduct is not observed, and indeed the yield of the 1:1
adduct is not increased by using a greater excess of 2h, even
though the yield of the self adduct of 1 (3a) is diminished.
This is probably due to greater competition from oligomeri-
zation reactions engendered by the excess of 2h (Fig. 4).
b
1:2.03:1.15
A simple mixed trimer is shown in Figure 2.
a
Based upon NMR integration of vinyl protons.
Based upon LRMS, as vinyl proton NMR were coincident.
b
2dO2e, as judged by the relative amounts of the two 1:2
adducts (the first and third numbers in the product ratios).
2.4. Addition to vinyl/propenyl ketones
The addition to a series of vinyl/propenyl ketones leads to
reasonable yields of 1:1 adducts, approaching 50% in the
case of ethyl vinyl ketone (Table 4). Yields of 2:1 products
are relatively limited (and not seen for 2k). A secondary
reaction of the formed trimers, 4i and 4j, leads to an
additional product; 6. This product is formed via an
2
.3. Addition to vinyl/propenyl nitriles
The addition to a vinyl nitrile (2g, acrylonitrile) gave
reasonable yields of products consisting primarily of the
1
:2 adduct (Table 3). The competing formation of the
8
Figure 3. Portions of the reaction mechanism of addition of 1 to vinyl sulfones.
Table 3. Product yields for the addition of 1 to a vinyl and a propenyl nitrile
Substrate
Ratio 1:
substrate
% Yield of
1:1 product (3)
% Yield of
1:2 product (4)
% Yield of
other products
Minimum
catalytic factor
2g: Acrylonitrile
2g: Acrylonitrile
2h: Crotononitrile
2h: Crotononitrile
1:2.06
1:3.09
1:3.11
1:5.98
6
42
57
—
—
2a: 3
—
3a: 43
3a: 28
25
12
16
12
—
26
22
1
5
aldol-type cyclization. However, both products 4i and 6i
are formed in low yields even when the ratio of methyl vinyl
ketone (2i) is trebled, leaving the 1:1 dimer as the main
product. The near four-fold excess of ethyl vinyl ketone
does not lead to large yields of 4j or 6j, indicating a distinct
preference to form the dimer 3j. It appears that addition to a
second mole of ketone is less favored in the ethyl vinyl
ketone case. The rationale for this may be steric in nature, or
involve the slight differences in acidity of the substrates. An
additional curiosity was observed, that use of an old supply
of w90% tech grade methyl vinyl ketone lead to a 45%
yield of the 1:1 product (along with 7% of 2a), presumably
the impurities are acidic in nature, protonating the
Figure 4. View of 4g showing the atom labeling scheme. Displacement
ellipsoids are scaled to the 50% probability level.
Table 4. Product yields for the addition of 1 to a series of vinyl and a propenyl ketones
Substrate
Ratio 1:
substrate
% Yield of
1:1 product (3)
% Yield of
1:2 derived product
% Yield of
other products
Minimum
catalytic factor
a
2i: Methyl vinyl ketone
1:1.00
28
6i: 5
2a: 7
13
3
—
2a: 1
—
a: 6
a
2i: Methyl vinyl ketone
2j: Ethyl vinyl ketone
2j: Ethyl vinyl ketone
2k: Propenyl methyl ketone
1:3.05
1:2.01
1:3.84
1:2.52
18
27
47
26
6i: 12
11
6j: trace
6j: trace
—
6.7
7.9
4.2
3a: w4
a
Two isomers, see Section 4.10 for details.

3518
G. A. N. Felton, N. L. Bauld / Tetrahedron 61 (2005) 3515–3523
Scheme 1. Formation of 6 via aldol-type cyclization of 4.
Table 5. Product yields for the addition of 1 to a series of vinyl esters
Substrate
Ratio 1:
substrate
% Yield of
1:1 product (3)
% Yield of
1:2 product (4)
% Yield of
other products
Minimum
catalytic factor
2
l: Methyl acrylate
m: Ethyl acrylate
1:2.09
1:2.09
16
28
18
20
2a: 8
7l: 12
2a: 8
2.5
4.5
2
3
7
a: 3
m: 7
2
2
m: Ethyl acrylate
n: Phenyl acrylate
1:3.08
1.2.03
13
22
15
—
2a: 2
m: 13
2a: 24
2.0
1.5
7
intermediate after one addition. Introduction of small
amounts of water into pure 2i electrolyses, however, did
not re-create these results.
by the lowered catalytic factor, as some of the charge is used
by the ketone (Scheme 1).
2
.5. Addition to vinyl esters
Addition to the propenyl ketone studied, 2k, led to moderate
amounts of the 1:1 dimer, the presence of the propenyl
group clearly retarding trimer formation. Increases in the
excess of 2k actually reduced yields, at 6:1 no 3k was
formed. This is clearly due to the reactivity of the ketone
under these conditions, probably leading to a variety of
oligomerization reactions. This reactivity is also indicated
The coupling of the allyl phenyl sulfone carbanion to a
series of esters yielded both adduct types (1:1 and 1:2) along
with the formation of a third product derived from the 1:2
trimer. The catalytic factors seen in all three additions are
some of the lowest observed in this work, this taken with the
moderate yields, indicates reduction and possible reactivity
of the substrates themselves (say, via oligomerization).
Addition to methyl and ethyl acrylate generally proceeded
to reasonable total product yields around 50% (Table 5).
As noted, this yield is made up of three products, with 7
being formed from the cyclization of 4, and subsequent
condensation (loss of an alcohol).
An attempt was made to force the reaction all the way to this
cyclic product by increasing the excess (in this case, of ethyl
acrylate), and reducing for longer. While 2a formation is
reduced, and no 1 is recovered, there is still some formation
of the 1:1 adduct. The yield of the cyclic product is
somewhat increased, at the expense of total product yield.
This cyclic product is a keto–enol tautomer, with the enol
form predominant in ca. 3:1 excess (in d-chloroform), while
X-ray crystallography shows only the enol form (see Fig. 5).
The mechanism for formation of 7 is presented in Scheme 2.
The addition to phenyl acrylate, 2n, interestingly stops at the
1
:1 adduct stage. While this may in part be due to the steric
hindrance of the more bulky phenyl group, it may also be
appropriate to consider a possible additional electronic basis
Figure 5. View of 7l showing the atom labeling scheme. Displacement
ellipsoids are scaled to the 50% probability level.
Scheme 2. Formation of the keto–enol tautomer 7 via cyclization/condensation (loss of alcohol, MeOH or EtOH).

G. A. N. Felton, N. L. Bauld / Tetrahedron 61 (2005) 3515–3523
Table 6. Product yields for the addition of 1 to esters
3519
Substrate
Ratio 1: substrate
% Yield of 1:1 product (3)
% Yield of other products
Minimum catalytic factor
2o: Methyl crotonate
2p: Ethyl crotonate
2q: Diethyl maleate
1:2.00
1:2.09
1:1.02
6
6
11
3a: 57
3a: 46
2a: 20
11
8.0
4.0
3a: 16
2a: 4
0
2
q : Diethyl fumarate
1:1.03
22
2.1
relating to the resonance interaction of the phenyl group
with the attached ester oxygen. This interaction, which is
not present in an alkyl ester, competes with normal ester
resonance, making the oxygen atom bound to the phenyl
group less electron donating than in the case of an alkyl
ester. The net result is that the ester carbonyl group is more
electron-deficient than in the case of alkyl esters and better
able to stabilize the intermediate carbanion. This would not
only enhance the rate of the initial addition, but perhaps
retard the rate of the second addition.
phenyl sulfone to undergo addition, via its carbanion, to a
variety of electron deficient vinyl and propenyl compounds
(sulfone, ketone, nitrile, and ester). These Michael additions
are catalyzed by electrogenerated bases derived from the
reactant itself, rather than via an added pro-base. This work
clearly displays the variety of substrates to which addition
will occur, yet also highlights some important limitations in
terms of yields. While several cases approach moderate
50% yields, the products formed from addition to sulfonyl
compounds provide the most useful yields from this EGB
approach. Mechanisms are advanced to explain the relative
yields of dimeric and trimeric products, based upon the
nature of the substrate molecule. The mechanisms for the
formation of two secondary products from initial trimer
products are also discussed. Yields of 1:1 adducts range
from 6 to 81%, while yields of 1:2 adducts range from 57 to
96%. Electrocatalytic factors for the majority of reactions
If we consider 7 to form via the trimer, we see that while
equal amounts of 3m and 4m were formed in the
electrolysis, there is a slight excess of 4l formation over 3l
(
30%:16%, respectively). This observation, while small in
magnitude, falls in line with the previous discussion, by
considering ethyl acrylate a small step along the route from
methyl acrylate to the extreme case of phenyl acrylate.
K1
are in excess of 10, representing better than 0.1 F mol
processes.
2
.6. Addition to other esters
The carbanion addition to propenyl esters is rather
inefficient, leading to disappointing yields of the 1:1 cross
addition product of just 6% in each case (Table 6). It is clear
from the reasonable yields of 3a (ca. 50%) that the addition
of the carbanion is much more facile to the in situ formed 2a
than to the higher concentration propenyl ester.
4
. Experimental
4
.1. General electrolysis procedure
A typical experiment utilizes 100 mg of allyl phenyl
sulfone, 1, along with the described mole ratio of alkene.
Both alkene and 1 are dissolved in 22 mL of electrolyte
solution, giving a typical concentration of 1 of 0.025 M, and
added to the working electrode (WE) compartment of the
electrolysis cell. The electrolyte solution is 0.100 M
Et NBF , in dry acetonitrile. The acetonitrile is distilled
fresh for each electrolysis from a reservoir containing
phosphorus pentoxide. Electrolyte solution (6 mL) is added
to the counter electrode (CE) compartment.
The addition of the allyl phenyl sulfone carbanion to diethyl
0
maleate (2q) and diethyl fumarate (2q ) leads to formation
of the same 1:1 adduct (3q). The reaction picture here is
rather unclear, firstly it appears that additional reduction
time for the fumarate doubled the yield of 3q whilst
restricting 2a formation (presumably by consuming any that
is formed). However, continued reduction generally leads to
limited product yields, indicating that the 1:1 adduct may
4
4
1
6
itself be electroreductive under these conditions. Also,
increased excess of the maleate/fumarate does not improve
yields, a 3:1 excess giving only trace amounts of the 1:1
Electrolysis of 1 and substrate was carried out at K2.5 V in
each case with stirring under positive nitrogen flow at room
temperature. Electrolysis voltages were versus a ‘pseudo-
standard’ silver wire (encased in porous vycor glass)
reference electrode (RE). The RE used is seen to have a
calibration to SCE of approximately C0.1 V, when in 0.1 M
0
product. This suggests that 2q/2q are reducing under these
conditions, possibly leading to oligomerization. It may be
the more advanced oligomerization in the reaction with the
fumarate, inherent in greater reduction time, which
consumes any 3a that is formed. It seems unlikely that
any difference in the reactivity of the isomers would lead to
formation of 3a in one case and not the other, particularly as
the same 1:1 adduct is formed in both cases.
17
Et NBF acetonitrile solution. The CE and WE consisted of
4
4
reticulated vitreous carbon (25 mm!5 mm!5 mm), their
corresponding compartments separated by a course frit. The
RE was placed within 0.5 cm of the WE. The reaction was
stopped when thin-layer chromatography (TLC) indicated
that 1 had been consumed. The reactant solution (WE
compartment only) then underwent an aqueous workup with
sequential washings of dichloromethane (benzene when
noted). The organic phase was retained and dried with
Na SO . The dichloromethane was removed by rotary
3. Conclusion
The use of tetraalkylammonium salts as electrolytes has
been found to allow the formation of electrogenerated bases
of especially high reactivity. Such conditions allow allyl
2
4
evaporation, with the crude solution being purified by
preparative TLC (1 mm thick, elution with ethyl acetate/

3520
G. A. N. Felton, N. L. Bauld / Tetrahedron 61 (2005) 3515–3523
petroleum ether mixture, 1:1.5 ratio). Bands were identified,
collected by scraping, and extracted with dichloromethane.
Filtering removed the silica, with a rotary evaporator again
employed to remove the solvent, yielding the desired
products.
4.5.1. E-5,7-Bis(ethylsulfonyl)-3-phenylsulfonyl-2-hep-
tene (4d). H NMR (300 MHz, CDCl ): 1.43 (6H, t,
1
3
7.5Hz), 2.30 (2H, m), 2.52 (2H, m), 3.06 (6H, m), 3.33 (2H,
m), 5.17 (1H, d, JZ17.4 Hz), 5.47 (1H, d, JZ10.8 Hz), 5.75
(1H, dd, JZ10.8, 17.4 Hz), 7.57 (2H, t, JZ7.8 Hz), 7.70
1
3
(
1H, t, JZ7.5 Hz), 7.81 (2H, d, JZ8.4 Hz). C NMR
Notes. In the few cases when 1 was recovered, the yields of
products and the catalytic factors are corrected accordingly.
PTLC for 4d and 4e was not carried out, as NMR/LRMS
showed purity, and benzene separation excluded electrolyte.
Also these two compounds proved difficult to extract from
collected PTLC bands (recovering no 4d and small amounts
of 4e).
(300 MHz, CDCl ): 6.9 (2C), 21.6 (2C), 46.2 (2C), 48.2
3
(2C), 67.9, 122.9, 129.2 (2C), 131.0 (2C), 133.5, 134.0,
134.9. LRMS (CIC): 423, 281. HRMS (CIC): calcd;
423.0970, found; 423.0960.
4
.6. Electrolysis of 1 and methyl vinyl sulfone (2e)
Electrolysis of 90 mg (0.022 M) of 1 and 108 mg (0.046 M;
2.06:1 ratio relative to 1) of 2e was carried out for 3.1 8C.
Upon benzene extraction 178 mg (92%) of 4e was
recovered.
4
.2. Analysis
1
Room temperature H NMR spectra were recorded on a
1
3
Varian UnityC300 as solutions in CDCl3. C NMR and
COSY spectra were recorded on a Varian Unity Inova 500
spectrometer. Chemical shifts (d) are relative to tetra-
methylsilane, and coupling constants (J) are given in Hertz
4.6.1. E-5,7-Bis(methylsulfonyl)-3-phenylsulfonyl-2-hep-
tene (4e). H NMR (300 MHz, CDCl ): 2.30 (2H, m), 2.47
1
3
(2H, m), 2.99 (6H, s), 3.15 (2H, m), 3.45 (2H, m), 5.16 (1H,
(
Hz). Splitting patterns are designated as follows: s, singlet;
d, 17.4Hz), 5.46 (1H, d, JZ11.1 Hz), 5.76 (1H, dd, JZ11.1,
d, doublet; t, triplet; q, quartet; m, multiplet; dd, doublet of
doublets; br, broad. X-ray diffraction analyses were
conducted using a Nonius Kappa CCD diffractometer.
Low-resolution mass spectra (LRMS) were recorded on a
Finnigan MAT TSQ-70 mass spectrometer, with high-
resolution mass spectra (HRMS) recorded on a VGZAB-2E
mass spectrometer.
1
7
7.4 Hz), 7.57 (2H, t, JZ7.8 Hz), 7.70 (1H, t, JZ7.5 Hz),
13
.81 (2H, d, JZ8.1 Hz). C NMR (300 MHz, CDCl ): 22.1
3
(2C), 41.4 (2C), 49.1 (2C), 67.9, 123.0, 129.3 (2C), 131.0
(2C), 133.4, 134.0, 135.0. LRMS (CIC): 395, 180. HRMS
(CIC): calcd; 395.0657, found; 395.0662.
4
.7. Electrolysis of 1 with a mixture of two substrates
4
.3. Equipment/reagents
Electrolysis of 85 mg (0.021 M) of 1, 119 mg (0.032 M) of
b, and 83 mg (0.031 M) of 2d was carried out for 8.0 8C.
This amounted to a 1:1.52:1.48 ratio of 2a:2b:2d. NMR
analysis of the 368 mg of recovered crude gave a 4d:4bd:4b
ratio of 1:3.22:3.42 and a 2d:2b ratio of 17.4:1 (no 1).
2
A potentiostatic controller, the Electrosynthesis Company
ESC) model 415, was used to control the applied potential.
(
The charge used was tracked by a digital coulometer, ESC
model 640. The applied potential was confirmed using a
digital multimeter (Wavetek DM7), operating as a potentio-
meter. The electrode material was Duocel 80 PPI reticulated
vitreous carbon. Substrates and electrolyte were used as
purchased, from Alfa Aesar, Aldrich, and Lancaster
Electrolysis of 76 mg (0.019 M) of 1, 114 mg (0.028 M) of
c, and 76 mg (0.029 M) of 2d was carried out for 8.0 8C.
2
This amounted to a 1:1.50:1.52 ratio of 2a:2c:2d. NMR
analysis of the 349 mg of recovered crude gave a 4d:4cd:4c
ratio of 1:2.80:2.30, and a 2d:2c ratio of 11.7:1 (no 1).
(98–99% purity, except for 2k: 85 and 90%, which is
corrected for in ratio calculations).
Electrolysis of 68 mg (0.017 M) of 1, 69 mg (0.017 M) of
2c, and 54 mg (0.020 M) of 2d was carried out for 5.0 8C.
This amounted to a 1:1.01:1.20 ratio of 2a:2c:2d. Upon
benzene extraction, NMR analysis of the 206 mg of
recovered crude gave a 4d:4cd:4c ratio of 1.30:2.00:1,
with only 2d remaining of the three starting materials. PTLC
separation gave 32 mg (16%) of 4c and 62 mg (34%) of 4cd,
along with less than 2 mg of 4d (see Section 4.1, notes).
4
.4. Electrolysis of allyl phenyl sulfone (1) in isolation
and with phenyl vinyl sulfone (2b), tolyl vinyl sulfone
2c), and divinyl sulfone (2f)
(
Electrolysis of 188 mg (0.047 M) of 1 and 88 mg (0.024 M;
a 1:1.97 ratio relative to 1) of 2b was carried out for 3.5 8C.
NMR analysis of the 296 mg of recovered crude gave a
4b:3a ratio of 1:1.45. Other experimental and characteri-
zation details for these electrolyses have been previously
4.7.1. 1-Ethylsulfonyl,3-phenylsulfonyl,3-ethenyl,5-tolyl
sulfonyl-pentane (4cd). H NMR (300 MHz in CDCl ):
8
published, along with X-ray data for 4b and 5f. It should be
1
3
noted that further NOE NMR study of 3a has shown that the
methyl group is trans to the phenyl sulfonyl group (as
shown in Fig. 1).
1
(
.44 (3H, t. JZ7.5 Hz), 2.24 (2H, m), 2.41 (2H, m), 2.48
3H, s), 3.02 (5H, m), 3.32 (2H, m), 5.10 (1H, d. 17.7Hz),
5
7
.43 (1H, d. JZ10.8 Hz), 5.69 (1H, dd, JZ10.8, 17.4 Hz),
.40 (2H, d. JZ8.4 Hz), 7.55 (2H, t. JZ8.1 Hz), 7.69 (1H, t.
1
3
4
.5. Electrolysis of 1 and ethyl vinyl sulfone (2d)
JZ7.5 Hz), 7.77 (4H, m). C NMR (300 MHz, CDCl3):
.9, 21.6, 21.9, 22.9, 46.2, 48.1, 50.9, 67.8, 122.8, 128.3
6
Electrolysis of 99 mg (0.025 M) of 1 and 136 mg (0.051 M;
.08:1 ratio relative to 1) of 2d was carried out for 3.0 8C.
Upon benzene extraction, 221 mg (96%) of 4d was isolated.
(2C), 129.2 (2C), 130.5 (2C), 131.0 (2C), 133.4, 134.0,
134.8, 135.8, 145.6. LRMS (CIC): 485, 343. HRMS (CIC):
calcd; 485.1126, found; 485.1107.
2

G. A. N. Felton, N. L. Bauld / Tetrahedron 61 (2005) 3515–3523
3521
Electrolysis of 79 mg (0.020 M) of 1, 110 mg (0.030 M) of
b, and 76 mg (0.033 M) of 2e was carried out for 8.0 8C.
This amounted to a 1:1.51:1.65 ratio of 2a:2b:2e. NMR
1.00:1 ratio relative to 1) of 2i was carried out for 3.0 8C.
Upon extraction/PTLC 35.7 mg (28%) of 3i, 4.1 mg (3%) of
6i (hydroxyl syn to acetyl), 2.8 mg (2%) of 6i (hydroxyl anti
to acetyl) and 6.3 mg (7%) of 2a were isolated. 2.7 mg of 1
was recovered.
2
analysis of the 330 mg of recovered crude product gave a
4
e:4be:4b ratio of 1:2.73:2.69, and a 2e:2b ratio of 6.64:1
no 1).
(
Electrolysis of 86 mg (0.021 M) of 1 and 101 mg (0.065 M;
3.05:1 ratio relative to 1) of 2i was carried out for 4.0 8C.
Upon extraction/PTLC 21 mg (18%) of 3i, 11 mg (7%) of 6i
(hydroxyl syn to acetyl) and 7 mg (5%) of 6i (hydroxyl anti
to acetyl) were isolated.
Electrolysis of 88 mg (0.022 M) of 1, 93 mg (0.035 M) of
d, and 83 mg (0.036 M) of 2e was carried out for 8.0 8C.
2
This amounted to a 1:1.62:1.60 ratio of 2a:2d:2e. NMR
analysis of the 348 mg of recovered crude gave a 2d:2c ratio
of 1.36:1 (no 1), but could not distinguish between the three
possible trimers. LRMS analysis of the crude was used to
arrive at a 4e:4de:4d of 1:2.03:1.15.
1
Compound 3i. H NMR (300 MHz, CDCl ): 1.87 (3H, d,
3
JZ7.2 Hz), 2.10 (3H, s), 2.44 (2H, t, JZ7.2 Hz), 2.69 (2H,
t, JZ7.2 Hz), 7.03 (1H, q. JZ7.2 Hz), 7.53 (2H, m), 7.61
1
(1H, m), 7.84 (2H, m). C NMR (300 MHz, CDCl
2
3
4
.8. Electrolysis of 1 with acrylonitrile (2g)
3
): 14.3,
0.3, 30.1, 42.3, 128.2 (2C), 129.5 (2C), 133.5, 138.5,
Electrolysis of 95 mg (0.024 M) of 1 and 57 mg (0.049 M;
.06:1 ratio relative to 1) of 2g was carried out for 2.0 8C.
Upon extraction/PTLC 63 mg (42%) of 4g, 7 mg (6%) of
g, and 3 mg (3%) of 2a were isolated.
139.7, 140.9, 207.4. LRMS (CIC): 253, 168, 125. HRMS
(CIC): calcd; 253.0898, found; 253.0890. NOE NMR study
of 3i shows methyl group is trans to the phenyl sulfonyl
group (as shown in Fig. 1).
2
3
1
Compound 6i (hydroxyl syn to acetyl). H NMR (300 MHz,
Electrolysis of 80 mg (0.020 M) of 1 and 72 mg (0.062 M;
.09:1 ratio relative to 1) of 2g was carried out for 3.5 8C.
Upon extraction/PTLC 72 mg (57%) of 4g was isolated.
3
CDCl
d, JZ12 Hz), 2.22 (3H, s), 2.45 (3H, m), 3.74 (1H, d, JZ
.4 Hz), 5.24 (1H, d, JZ16.8 Hz), 5.64 (2H, m), 7.53 (2H, t,
JZ7.5 Hz), 7.65 (1H, t, JZ7.8 Hz), 7.80 (2H, d, JZ
3
): 1.14 (3H, s), 1.25 (1H, m), 1.64 (3H, m), 2.01 (1H,
2
1
Compound 3g. H NMR (300 MHz, CDCl ): 1.98 (3H, d,
3
1
3
JZ7.2 Hz), 2.59 (4H, s), 7.18 (1H, q. JZ7.2 Hz), 7.56 (2H,
t, JZ7.8 Hz), 7.65 (1H, t, JZ7.8 Hz), 7.86 (2H d, JZ
7.5 Hz). C NMR (500 MHz, CDCl ): 23.8, 27.1, 28.4,
3
31.1, 34.3, 52.3, 67.4, 68.7, 123.6, 128.5 (2C), 131.0 (2C),
132.8, 133.8, 134.8, 213.8. LRMS (CIC): 323, 305, 181,
163. HRMS (CIC): calcd; 323.1317, found; 323.1325.
Configuration of the hydroxyl group with regards to the
carbonyl group is inferred from the NMR shift of the
hydroxyl group proton.
1
.1 Hz). C NMR (300 MHz, CDCl ): partial only: 14.8,
3
8
3
22.5, 32.6, 105.9, 128.3 (2C), 129.7 (2C), 133.9, 141.3.
LRMS (CIC): 236, 125. HRMS (CIC): calcd; 236.0745,
found; 236.0747.
1
Compound 4g. H NMR (300 MHz, CDCl ): 2.18 (2H, m),
3
1
Compound 6i (hydroxyl anti to acetyl). H NMR (300 MHz,
2.36 (2H, m), 2.53 (2H, m), 2.73 (2H, m), 5.14 (1H, d, JZ
17.4 Hz), 5.53 (1H, d, JZ11.1 Hz), 5.74 (1H, dd, JZ11.1,
17.4 Hz), 7.60 (2H, t, JZ7.8 Hz), 7.75 (3H, m). X-ray
CDCl ): partial only: 1.22 (3H, s), 2.22 (3H, s), 2.84 (1H, s),
5.24 (1H, dd, JZ1.8, 16.2 Hz), 5.61 (2H, m), 7.52 (2H, m),
3
1
3
crystallography confirms structure (CCDC 254787).
7.63 (1H, m), 7.80 (2H, m). C NMR (500 MHz, CDCl
1.6, 25.7, 28.2, 31.2, 36.8, 54.3, 67.6, 72.1, 123.5, 128.5
(2C), 131.0 (2C), 133.2, 133.9, 134.7, 211.0. LRMS (CIC):
23, 241, 195, 124. HRMS (CIC): calcd; 323.1317, found;
3
):
2
4
.9. Electrolysis of 1 with crotononitrile (2h)
3
Electrolysis of 97 mg (0.024 M) of 1 and 111 mg (0.075 M;
.11:1 ratio relative to 1) of 2h was carried out for 3.3 8C.
Upon extraction/PTLC 34 mg (26%) of 3h and 42 mg
43%) of 3a were isolated.
323.1312.
3
4.11. Electrolysis of 1 with ethyl vinyl ketone (2j)
(
Electrolysis of 95 mg (0.024 M) of 1 and 88 mg (0.048 M;
2.01:1 ratio relative to 1) of 2j was carried out for 7.5 8C.
Upon extraction/PTLC 37 mg (27%) of 3j and 1 mg (1%) of
2a were isolated, along with a trace amount of 6j
(tentatively assigned).
Electrolysis of 89 mg (0.022 M) of 1 and 196 mg (0.133 M;
.98:1 ratio relative to 1) of 2h was carried out for 4.0 8C.
Upon extraction/PTLC 26.4 mg (22%) of 3h and 24.6 mg
5
(
28%) of 3a were isolated.
1
Compound 3h. H NMR (300 MHz, CDCl ): 1.22 (3H, d,
JZ6.9 Hz), 2.01 (3H, d, JZ7.5 Hz), 2.63 (2H, d, JZ
3
Electrolysis of 93 mg (0.023 M) of 1 and 165 mg (0.089 M;
3.84:1 ratio relative to 1) of 2j was carried out for 6.2 8C.
Upon extraction/PTLC 64 mg (47%) of 3j was isolated,
along with a trace amount of 6j (tentatively assigned).
7
7
1
1
.5 Hz) 3.16 (1H, m), 7.11 (1H, q. JZ7.5 Hz), 7.56 (2H, m),
13
.63 (1H, m), 7.86 (2H, m). C NMR (300 MHz, CDCl3):
5.0, 18.6, 23.5, 30.7, 118.2, 128.1 (2C), 129.6 (2C), 133.7,
40.4, 140.6, 143.0. LRMS (CIC): 250. HRMS (CIC):
1
Compound 3j. H NMR (300 MHz, CDCl ): 1.03 (3H, t, JZ
3
calcd; 250.0902, found; 250.0904.
.10. Electrolysis of 1 with methyl vinyl ketone (2i)
Electrolysis of 96 mg (0.024 M) of 1 and 37 mg (0.024 M;
7.2 Hz), 1.87 (3H, d, JZ7.2 Hz), 2.37 (2H, q, JZ7.2 Hz),
2
.45 (2H, t, JZ7.5 Hz), 2.69 (2H, t, JZ7.5 Hz), 7.02 (1H, q.
13
4
JZ7.2 Hz), 7.53 (2H, m), 7.61 (1H, m), 7.84 (2H m). C
NMR (300 MHz, CDCl ): 7.9, 14.3, 20.3, 36.1, 40.9, 128.2
3
(2C), 129.4 (2C), 133.5, 138.5, 139.7, 141.0, 210.1. LRMS

3522
G. A. N. Felton, N. L. Bauld / Tetrahedron 61 (2005) 3515–3523
(CIC): 267, 209, 191. HRMS (CIC): calcd; 267.1055,
found; 267.1062.
2 mg (3%) of 3a were isolated, along with 8.4 mg of
recovered 1.
1
Compound 6j. H NMR (300 MHz, CDCl ): partial only:
Electrolysis of 84 mg (0.021 M) of 1 and 142 mg (0.064 M;
3.08:1 ratio relative to 1) of 2m was carried out for 22.2 8C.
Upon extraction/PTLC 16.8 mg (13%) of 3m, 26.1 mg
(15%) of 4m, 19.8 mg (13%) of 7m, and 1.3 mg (2%) of 2a
were isolated.
3
3
.73 (1H, d, JZ2.4 Hz).
4
.12. Electrolysis of 1 with propenyl methyl ketone (2k)
Electrolysis of 100 mg (0.025 M) of 1 and 137 mg,
corrected to 116 mg (0.063 M; 2.52:1 ratio relative to 1)
of 2k was carried out for 12.6 8C. Upon extraction/PTLC
38 mg (26%) of 3k and 4 mg (4%) of impure 3a were
isolated.
1
Compound 3m. H NMR (300 MHz, CDCl
): 1.23 (3H, t,
3
JZ7.2 Hz), 1.89 (3H, d, JZ7.2 Hz), 2.49 (4H, m), 4.09
(2H, q, JZ7.2 Hz), 7.05 (1H, q. JZ7.2 Hz), 7.53 (2H, m),
1
7.63 (1H, m), 7.85 (2H, m). C NMR (500 MHz, CDCl
3
):
4.1, 14.2, 21.4, 32.9, 60.6, 128.1 (2C), 129.2 (2C), 133.2,
3
1
1
Compound 3k. H NMR (300 MHz, CDCl ): 1.01 (3H, d,
138.7, 139.6, 140.5, 172.2. LRMS (CIC): 283. HRMS
(CIC): calcd; 283.1004, found; 283.1004.
3
JZ6.9 Hz), 1.96 (6H, m), 2.68 (2H, m) 3.35 (1H, m), 6.98
(
m)). C NMR (500 MHz, CDCl ): 14.6, 19.0, 28.1, 30.0,
1H, q. JZ7.2 Hz), 7.51 (2H, m), 7.59 (1H, m), 7.83 (2H,
13
1
Compound 4m. H NMR (300 MHz, CDCl
): 1.26 (6H, t,
3
3
4
2
2
8.2, 127.9 (2C), 129.1 (2C), 133.1, 138.7, 140.9, 145.1,
06.3. LRMS (CIC): 267, 125. HRMS (CIC): calcd;
67.1055, found; 267.1051.
JZ7.2 Hz), 2.11 (2H, m), 2.33 (4H, m), 2.63 (2H, m), 4.14
(4H, q, JZ7.2 Hz), 5.09 (1H, d, JZ17.7 Hz), 5.38 (1H, d,
JZ10.8 Hz), 5.75 (1H, dd, JZ10.8, 17.7 Hz), 7.52 (2H, t,
1
3
JZ7.5 Hz), 7.65 (1H, m), 7.80 (2H, d, JZ7.2 Hz).
NMR (500 MHz, CDCl ): 14.2 (2C), 24.8 (2C), 28.7 (2C),
0.8 (2C), 68.9, 121.4, 128.6 (2C), 130.7 (2C), 133.9, 134.8,
C
4
.13. Electrolysis of 1 with methyl acrylate (2l)
3
6
Electrolysis of 85 mg (0.021 M) of 1 and 84 mg (0.044 M;
.09:1 ratio relative to 1) of 2l was carried out for 18.0 8C.
135.1, 172.6 (2C). LRMS (CIC): 383, 241. HRMS (CIC):
calcd; 383.1528, found; 383.1517.
2
Upon extraction/PTLC 22.5 mg (18%) of 3l, 27 mg (16%)
of 4l, 18.1 mg (12%) of 7l and 6.4 mg (8%) of 2a were
isolated.
1
Compound 7m. H NMR (300 MHz, CDCl
): 1.29
(3H-enol, 3H-keto, overlapping t), 2.14–2.51 (4H-enol,
3
6
H-keto, overlapping m), 2.60 (1H-enol, d, JZ16.2 Hz),
1
Compound 3l. H NMR (300 MHz, CDCl ): 1.89 (3H, d,
2.87 (1H-enol, d, JZ15.6 Hz), 4.22 (2H-keto, 2H-enol, m),
5.10 (1H, d, JZ17.4 Hz), 5.44 (1H, d, JZ10.8 Hz), 5.70
(1H, dd, JZ10.8, 17.4 Hz), 7.55 (2H, t, JZ7.8 Hz), 7.67
(1H, t, JZ7.5 Hz), 7.84 (2H, d, JZ7.2 Hz), 12.16 (1H-enol,
3
JZ6.9 Hz), 2.51 (4H, m), 3.65 (3H, s), 7.06 (1H, q. JZ
1
.2 Hz), 7.54 (2H, m), 7.62 (1H, m), 7.85 (2H, m). C NMR
3
7
(
300 MHz, CDCl ): 14.3, 21.7, 32.9, 52.0, 128.3 (2C), 129.5
3
1
3
(2C), 133.5, 139.0, 139.7, 140.5, 172.9. LRMS (CIC): 269.
HRMS (CIC): calcd; 269.0848, found; 269.0851.
s). C NMR (500 MHz, CDCl
60.7, 66.2, 94.3, 122.5, 128.5 (2C), 130.8 (2C), 131.9,
33.9, 135.0, 170.1, 171.7. LRMS (CIC): 337, 195. HRMS
(CIC): calcd; 337.1110, found; 337.1109.
3
): 14.2, 24.3, 25.1, 25.7,
1
1
Compound 4l. H NMR (300 MHz, CDCl ): 2.12 (2H, m),
3
2
1
1
.35 (4H, m), 2.65 (2H, m), 3.69 (6H, s), 5.09 (1H, d, JZ
7.4 Hz), 5.39 (1H, d, JZ10.8 Hz), 5.75 (1H, dd, 10.8, JZ
7.4 Hz), 7.53 (2H, t, JZ7.5 Hz), 7.66 (1H, m), 7.80 (2H,
4
.15. Electrolysis of 1 with phenyl acrylate (2n)
1
3
m). C NMR (300 MHz, CDCl ): 25.0 (2C), 28.7 (2C),
3
Electrolysis of 110 mg (0.027 M) of 1 and 182 mg
0.056 M; 2.03:1 ratio relative to 1) of 2n was carried out
5
1
2.2 (2C), 69.0, 121.7, 128.8 (2C), 130.9 (2C), 132.1, 132.6,
34.9, 173.2 (2C). LRMS (CIC): 355, 213. HRMS (CIC):
(
for 35.0 8C. Upon extraction/PTLC 40.2 mg (22%) of 3n
and 23.9 mg (24%) of 2a were isolated, along with 9 mg of
recovered 1.
calcd; 355.1215, found; 355.1219.
1
Compound 7l. H NMR (300 MHz, CDCl ): 1.92–2.02
3
(
1H-keto, m), 2.15–2.51 (4H-enol, 5H-keto, overlapping
m), 2.57 (1H-enol, d, JZ15.9 Hz), 2.86 (1H-enol, d, JZ
5.3 Hz), 3.67 (3H-keto, s), 3.76 (3H-enol, s), 5.10 (1H, d,
1
Compound 3n. H NMR (300 MHz, CDCl ): 1.94 (3H, d,
JZ7.2 Hz), 2.65 (2H, m), 2.78 (2H, m), 7.05 (2H, d, JZ
3
1
8
.4 Hz), 7.12 (1H, q. JZ6.9 Hz), 7.23 (1H, m), 7.38 (2H, t,
JZ17.4 Hz), 5.44 (1H, d, JZ10.8 Hz), 5.71 (1H, dd, 10.8,
JZ17.4 Hz), 7.55 (2H, t, JZ7.8 Hz), 7.67 (1H, t, JZ
7
(
3
13
JZ7.8 Hz), 7.55 (2H, m), 7.64 (1H, m), 7.90 (2H m). C
NMR (300 MHz, CDCl ): 14.5, 21.5, 32.7, 121.7 (2C),
3
.2 Hz), 7.84 (2H, d, JZ7.8 Hz), 12.08 (1H-enol, s). LRMS
CIC): 323, 181. HRMS (CIC): calcd; 323.0953, found;
23.0943. X-ray crystallography confirms enol structure
CCDC 254677).
1
1
26.1, 126.2, 128.3 (2C), 129.5 (2C), 129.7 (2C), 129.8,
39.4, 140.3, 171.2. LRMS (CIC): 365, 331, 183. HRMS
(CIC): calcd; 331.1004, found; 331.1012.
(
4
.14. Electrolysis of 1 with ethyl acrylate (2m)
4.16. Electrolysis of 1 with methyl crotonate (2o)
Electrolysis of 87 mg (0.022 M) of 1 and 100 mg (0.045 M;
.09:1 ratio relative to 1) of 2m was carried out for 9.2 8C.
Upon extraction/PTLC 34.4 mg (28%) of 3m, 33.6 mg
20%) of 4m, 10 mg (7%) of 7m, 6.6 mg (8%) of 2a and
Electrolysis of 80 mg (0.020 M) of 1 and 88 mg (0.040 M;
2.00:1 ratio relative to 1) of 2o was carried out for 4.0 8C.
Upon extraction/PTLC 8 mg (6%) of 3o and 46 mg (58%) of
3a were isolated.
2
(

G. A. N. Felton, N. L. Bauld / Tetrahedron 61 (2005) 3515–3523
3523
1
Compound 3o. H NMR (300 MHz, CDCl ): 1.10 (3H, d,
JZ7.2 Hz), 1.98 (3H, d, JZ6.9 Hz), 2.52 (2H, d, JZ
respectively. Copies of the data can be obtained, free of
charge, via www.ccdc.cam.ac.uk/data_request/cif or on
application to CCDC, 12 Union Road, Cambridge CB2
1EZ, UK (fax: C44(0) 1223 336033 or e-mail: deposit@
ccdc.cam.ac.uk).
3
7
7
.8 Hz) 3.29 (1H, q, 7.2), 3.54 (3H, s), 7.06 (1H, q. JZ
.2 Hz), 7.52 (2H, m), 7.60 (1H, m), 7.85 (2H, m). C NMR
13
(
500 MHz, CDCl ): 14.6, 18.9, 29.6, 39.1, 51.6, 128.0 (2C),
3
129.1 (2C), 133.0, 138.8, 140.7, 144.8, 172.0. LRMS (CIC):
283, 251, 141. HRMS (CIC): calcd; 283.1004, found;
283.0995.
Acknowledgements
4
.17. Electrolysis of 1 with ethyl crotonate (2p)
The authors acknowledge and thank the Robert A. Welch
Foundation (F-149) for support of this research.
Electrolysis of 87 mg (0.022 M) of 1 and 114 mg (0.045 M;
.09:1 ratio relative to 1) of 2p was carried out for 5.6 8C.
2
Upon extraction/PTLC 8 mg (6%) of 3p and 40 mg (46%)
of 3a were isolated.
1
Compound 3p. H NMR (300 MHz, CDCl ): 1.09 (3H, d,
References and notes
3
JZ7.2 Hz), 1.20 (3H, t, JZ7.2 Hz), 1.98 (3H, d, JZ
7
.2 Hz), 2.50 (2H, m) 3.29 (1H, m), 4.00 (2H, q, JZ7.2 Hz),
.05 (1H, q. JZ7.2 Hz), 7.52 (2H, m), 7.60 (1H, m), 7.86
1. Utley, J. H. P.; Nielsen, M. F. In Organic Electrochemistry;
Lund, H., Hammerich, O., Eds. 4th ed.; Marcel Dekker: New
York, 2001; Chapter 30.
7
1
2H, m). C NMR (500 MHz, CDCl ): 14.1, 14.6, 18.9,
3
(
3
29.6, 39.4, 60.5, 128.0 (2C), 129.1 (2C), 133.0, 138.7, 140.7,
144.9, 171.5. LRMS (CIC): 297, 251. HRMS (CIC): calcd;
297.1161, found; 297.1158.
2. Little, R. D.; Baizer, M. M. In The Chemistry of Enones; Patai,
S., Rapparort, Z., Eds.; Wiley: New York, 1989; pp 599–622.
3. Feroci, M.; Casadei, M. A.; Orsini, M.; Palombi, L.; Inesi, A.
J. Org. Chem. 2003, 68, 1548–1551.
4.18. Electrolysis of 1 with diethyl maleate (2q), and with
diethyl fumarate (2q )
4. Savall, A. J. In Rodd’s Chemistry of Carbon Compounds;
Sainsbury, M., Ed. 2nd ed.; Organic Electrochemistry;
Elsevier: Amsterdam, 2002; Vol. V, pp 215–217.
5. Casadei, M. A.; Cesa, S.; Rosi, L. Eur. J. Org. Chem. 2000, 13,
2445–2448.
0
Electrolysis of 87 mg (0.022 M) of 1 and 84 mg (0.022 M;
1
.02:1 ratio relative to 1) of 2q was carried out for 10.0 8C.
Upon extraction/PTLC 16 mg (11%) of 3q, 12 mg (16%) of
6. Niyazymbetova, M. E.; Evans, D. H. Tetrahedron 1993,
49(43), 9627–9687.
7. Palombi, L.; Feroci, M.; Orsini, M.; Inesi, A. Chem. Commun.
3
1
a, and 15.5 mg (20%) of 2a were isolated, along with
0.5 mg of recovered 1.
2
004, 16, 1846–1847.
Electrolysis of 99 mg (0.025 M) of 1 and 96 mg (0.025 M;
0
8. Felton, G. A. N.; Bauld, N. L. Tetrahedron Lett. 2004, 45(25),
4841–4845.
1
.03:1 ratio relative to 1) of 2q was carried out for 20.0 8C.
Upon extraction/PTLC 35 mg (22%) of 3q and 3.6 mg (4%)
of 2a were isolated, along with 18.4 mg of recovered 1.
9. Baizer, M. M.; Chruma, J. L.; White, D. A. Tetrahedron Lett.
1973, 14(52), 5209–5212.
1
0. Savoia, D.; Trombini, C.; Umani-Ronchi, A. J. Chem. Soc.
Perkin Trans. 1 1977, 2, 123–125.
1
Compound 3q. H NMR (300 MHz, CDCl ): 1.01 (3H, t,
3
JZ7.2 Hz), 1.23 (3H, t, JZ7.2 Hz), 1.90 (3H, d, JZ
11. Ghera, E.; Kleiman, V.; Hassner, A. J. Org. Chem. 1999,
64(1), 8–9.
7
.5 Hz), 2.45 (1H, dd, 4.5, JZ17.1 Hz), 3.05 (1H, dd, 10.2,
JZ17.1 Hz), 3.91 (2H, m), 4.09 (2H, m), 7.18 (1H, q. JZ
7
12. Hassner, A.; Ghera, E.; Yechezkel, T.; Kleiman, V.;
Balasubramanian, T.; Ostercamp, D. Pure Appl. Chem. 2000,
72(9), 1671–1683.
1
.2 Hz), 7.53 (2H, m), 7.62 (1H, m), 7.88 (2H, m). C NMR
3
(
300 MHz, CDCl ): 14.1, 14.3, 14.7, 34.8, 39.4, 61.2, 61.7,
3
1
1
28.6 (2C), 129.3 (2C), 133.6, 139.6, 139.7, 141.3, 170.6,
71.3. LRMS (CIC): 355. HRMS (CIC): calcd; 355.1215,
13. Hamman, C. H.; Hamnett, A.; Vielstich, W. Electrochemistry;
Wiley-VCH: Wienheim, 1998; pp 7–9.
found; 353.1222.
14. A 1a:1b ratio of 1:2 using the assumptions in the text, should
yield a 1.5:1 2a excess.
15. Felton, G. A. N.; Bauld, N. L. Tetrahedron 2004, 60(48),
4
.19. X-ray data
1
0999–11010.
Crystallographic data (excluding structure factors) for 4g
and the enol form of 7l have been deposited with the
Cambridge Crystallographic Data Centre as supplementary
publication numbers CCDC 254787 and CCDC 254677,
16. Nikishin, G. I.; Elinson, M. N.; Feducovich, S. K.; Ugrak, B. I.
Tetrahedron Lett. 1992, 33(22), 3223–3226.
17. Becker, J. Y.; Koch, T. A. Electrochim. Acta 1994, 39(13),
2067–2071.