Electrophilic diamination of alkenes by using FeCl(3)-PPh(3) complex as the catalyst.

Article abstract of DOI:10.1021/jo0200769

The FeCl(3)-PPh(3) complex was found to effectively catalyze the electrophilic diamination reaction of electron-deficient alkenes. Improvements on yields and stereoselectivity have been achieved for both alpha,beta-unsaturated carboxylic esters and ketones. Under the new catalytic system, alpha,beta-unsaturated carboxylic esters were found to be superior to their ketone counterparts, which is opposite to the previous (C(3)F(7)CO(2))(2)Rh](2)-catalyzed diamination. The reaction employs readily available N,N-dichloro-p-toluenesulfonamide (TsNCl(2)) and acetonitrile as the nitrogen sources and is very easy to perform at room temperature without the special protection of inert gases. The resulting diamino products belong to imidazolidine analogue and can further strengthen the importance of the new reaction. Modest to good yields (52-84%) and high regio- and stereoselectivity have been achieved for 10 examples.

Full text of DOI:10.1021/jo0200769

Electr op h ilic Dia m in a tion of Alk en es by Usin g F eCl3-P P h 3
Com p lex a s th e Ca ta lyst
Han-Xun Wei, Sun Hee Kim, and Guigen Li*
Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409-1061
qeggl@ttu.edu
Received J anuary 30, 2002
The FeCl3-PPh3 complex was found to effectively catalyze the electrophilic diamination reaction
of electron-deficient alkenes. Improvements on yields and stereoselectivity have been achieved for
both R,â-unsaturated carboxylic esters and ketones. Under the new catalytic system, R,â-unsaturated
carboxylic esters were found to be superior to their ketone counterparts, which is opposite to the
previous (C3F7CO2)2Rh}2-catalyzed diamination. The reaction employs readily available N,N-
dichloro-p-toluenesulfonamide (TsNCl2) and acetonitrile as the nitrogen sources and is very easy
to perform at room temperature without the special protection of inert gases. The resulting diamino
products belong to imidazolidine analogue and can further strengthen the importance of the new
reaction. Modest to good yields (52-84%) and high regio- and stereoselectivity have been achieved
for 10 examples.
The vicinal diamine functionality is extremely impor-
tant for organic synthesis, medicinal chemistry, and
pharmaceutical research.1,2 This functionality exists in
many biologically important compounds. Enantiomeri-
cally pure diamines have been utilized as chiral auxil-
iaries and chiral ligands for asymmetric synthesis.3,4 The
development of efficient synthetic approaches to this
functionality in regio- and stereoselective fashion repre-
sents a challenging topic, especially when the function-
alized olefins such as cinnamic esters and R,â-unsatur-
ated ketones are employed as the substrates. Recently,
we have discovered two new diamination reactions of
olefins which are electrophilic.5 The first reaction was
carried out in a tandem manner using N,N-dichloro-2-
nitrobenzenesulfonamide (2-NsNCl2) and acetonitrile as
the nitrogen sources without using any catalysts.5a The
diamination using alkyl cinnamates as substrates re-
sulted in anti alkyl NR-Ns, Nâ-Ac diaminophenylpropi-
onates. The latter diamination was achieved by using
N,N-dichloro-p-toluenesulfonamide (4-TsNCl2) and ac-
etonitrile as the nitrogen sources in the presence of the
catalytic complex of rhodium(II) heptafluorobutyrate and
triphenylphosphine.5b The reaction afforded imidazoline
products initially, which generated R,â-differentiated
vicinal diamines after acidic hydrolysis (Scheme 1).
We also attempted to reduce to practice an asymmetric
version of the latter diamination by using enantiomer-
cially pure Doyle-type Rhodium catalysts which are
commercially available.6,7 But so far, the success has been
limited. In fact, low enantiomeric excess (up to 30% ee)
and poor yield (<35%) were obtained. To increase the
chance of an asymmetric catalytic diamination reaction,
a search for other transition metal catalysts is being
conducted. In addition, some of the new transition
metal-ligand complexes have the advantage of conve-
nient handling since they are less hygroscopic. In this
paper, we disclose our results using the FeCl3-PPh3
complex to catalyze the electrophilic diamination reaction
of R,â-unsaturated carboxylic esters and R,â-unsaturated
ketones.
(1) (a) Ojima, I. In The Organic Chemistry of â-Lactams; Georg, G.
I., Ed.; VCH Publishers: New York, 1992; pp 197-255. (b) Ojima, I.
Acc. Chem. Res. 1995, 28, 383-389.
(2) (a) Lucet, D.; Le Gall, T.; Mioskowski, C. Angew. Chem., Int. Ed.
1998, 37, 2580-2627. (b) Vico, A.; Fernandez de la Pradilla, R. Recent
Res. Devel. Org. Chem. 2000, 4, 327-334.
(3) (a) Corey, E. J .; Lee, D.-H.; Sarshar, S. Tetrahedron Asymmetry
1995, 6, 3-6. (b) Chong, A. O.; Oshima, K.; Sharpless, K. B. J . Am.
Chem. Soc. 1977, 99, 3420-3426. (c) Reetz, M.; J aeger, R.; Drewlies,
R.; Hubel, M. M. Angew. Chem., Int. Ed. Engl. 1991, 30, 103-105. (d)
Hayashi, T.; Kishi, E.; Soloshonok, V. A.; Uozumi, Y. Tetrahedron Lett.
1996, 37, 4969-4972. (e) Solomon, M. E.; Lynch, C. L.; Rich, D. H.
Tetrahedron Lett. 1995, 36, 4955-4958.
(4) (a) Denmark, S. E.; Su, X.; Nishigaichi, Y.; Coe, D. M.; Wong,
K.-T.; Winter, S. B. D.; Choi, J . Y. J . Org. Chem. 1999, 64, 1958-
1967. (b) Han, H.; Yoon, J .; J anda, K. D. J . Org. Chem. 1998, 63, 2045-
2047. (e) Richardson, P. F.; Nelson, L. T. J .; Sharpless, K. B.
Tetrahedron Lett. 1995, 36, 9241-9244. (d) O’Brien, P.; Towers, T. D.
J . Org. Chem. 2002, 67, 304-307. (f) Alexakis, A.; Aujard, I.; Man-
geney, P. Synlett. 1998, 873-874. (g) Dghaym, R. D.; Dhawan, R.;
Arndtsen, B. A. Angew. Chem., Int. Ed., 2001, 40, 3228-3230.
(5) (a) Li, G.; Wei, H.-X.; Kim, S. H. Tetrahedron Lett. 2000, 41,
8699-8701. (b) Li, G. Wei, H.-X.; Kim, S. H.; Carducci, M. Angew.
Chem., Int. Ed. 2001, 40, 4277-4280.
Resu lts a n d Discu ssion
Similar to our previous electrophilic aminohalogena-
tion and diamination systems, the present reaction is also
very easy to perform.5,8-9 Essentially, it can be conducted
at room temperature in any stopped or capped vessel of
(6) (a) Doyle, M. P. Chem. Rev. 1986, 86, 919-939. (b) Doyle, M. P.
Aldrichimica Acta 1996, 29, 3-11.
(7) Davies, H. M. L. Aldrichimica Acta 1997, 30, 107-114.
(8) (a) Li, G.; Wei, H.-X.; Kim, S. H.; Neighbors, M. Org. Lett. 1999,
1, 395-397. (b) Li, G.; Wei, H.-X.; Kim, S. H. Org. Lett. 2000, 2, 2249-
2252.
10.1021/jo0200769 CCC: $22.00 © 2002 American Chemical Society
Published on Web 05/29/2002
J . Org. Chem. 2002, 67, 4777-4781
4777

Wei et al.
SCHEME 1
TABLE 1. Resu lts of F eCl3-P P h 3-Ca ta lyzed Cyclic Dia m in a tion of r,â-Un sa tu r a ted Keton es
a
b
Estimated by crude 1H NMR determination. >95% means no minor isomer was detected. The yields after purification via column
chromatography. c Previous results: 66% yield, 26:1 anti/syn stereoselectivity.
SCHEME 2
convenient size without the need of inert atmosphere
protection. In the previous Rh-catalyzed diamination,
N,N-dichloro-p-toluenesulfonamide (4-TsNCl2) was added
into the reaction mixture in two portions at different
times to optimize the yield. But in the present system,
4-TsNCl2 was added in one portion to make the procedure
simpler. In addition, as compared with the {(C3F7CO2)2-
Rh}2 catalyst, the ferric chloride catalyst is inexpensive
and is much easier to handle because it is less hygro-
scopic.
Since R,â-unsaturated ketones were proven to be
superior to their carboxylic ester counterparts as elec-
trophilic diamination substrates in our previous {(C3F7-
CO2)2Rh}2-catalyzed reaction,5b chalcone was thus chosen
as the first substrate for the initial study (Scheme 2, R1,
R2 ) Ph). It was found that the catalytic complex of
FeCl3-PPh3 worked much better than the rhodium(II)
heptafluorobutyrate and triphenylphosphine combina-
tion. The reaction was complete in 24 h instead of 44 h.
The chemical yield was also increased to 79% with the
complete control of anti/syn stereoselectivity as compared
to the previous results (66% and 26:1 anti/syn stereose-
lectivty) (Table 1). Similar improvements were also
observed for p-methoxychalcone and the terminal disub-
stituted substrates. Only in one case (entry 4 of Table 1)
was the yield slightly diminished to 52%, but the anti/
syn stereoselectivity was completely controlled.
Interestingly, it was later found that the R,â-unsatur-
ated esters were better substrates than R,â-unsaturated
ketones for this FeCl3/PPh3-catalyzed diamination (Scheme
3), which is in contrast to the previous reaction using
{(C3F7CO2)2Rh}2-PPh3 as the catalyst. Furthermore, the
improvements on both yields and anti/syn stereoselec-
tivty were observed for all five examples (6-10 of Table
2). For ethyl cinnamate substrate, the original chemical
yield of 49% was improved to 60%. Similar enhancement
was observed even for terminal disubstituted R,â-
(9) (a) Li, G.; Wei, H.-X.; Kim, S. H. Tetrathedron 2001, 57, 8407-
8411. (b) Wei, H.-X.; Kim, S. H.; Li, G. Tetrathedron 2001, 57, 3869-
3973.
4778 J . Org. Chem., Vol. 67, No. 14, 2002

Electrophilic Diamination of Alkenes
TABLE 2. Resu lts of F eCl3-P P h 3-Ca ta lyzed Cyclic Dia m in a tion of r,â-u n sa tu r a ted Ester s
a
b
Estimated by crude 1H NMR determination. >95% means no minor isomer was detected. The yields after purification via column
chromatography. c X-ray structure was obtained. Hydrolysis of 6: Into a 10 mL round-bottom flask equipped with a magnetic stir bar
was added 110 mg (0.25 mmol) of 6, 3 mL of THF and 0.5 mL of 6 N aqueous HCl. After being stirred at 70 °C for 30 min, the reaction
mixture was poured into 5 mL of cold water. The aqueous solution was extracted with EtOAc (3 × 5 mL), and the combined organic layers
were washed with brine (10 mL), dried by Na2SO3, and concentrated in vacuo to give the R,â-diamino carboxylic ester (111 mg, quant.)
which is nearly pure indicated by its crude NMR spectrum (see Supporting Information).
SCHEME 3
SCHEME 4
unsaturated carboxylic esters (entry 10 of Table 2) in
which the yield was increased to 77% from 69%. Only
one limitation has been encountered so far, i.e., the
reaction proceeded extremely slowly for those substrates
with a strong electron-withdrawing group (NO2) on the
aromatic rings at the olefin terminus.
In the case of the aminohalogenation side reaction, the
aziridinium intermediate is directly opened by chloride
to give the haloamine product whose structure has been
confirmed by comparison with a known sample. This
hypothesis is also supported by our initial diamination
reaction,5a although N,N-dichloro-p-nitrobenzenesulfona-
mide instead of N,N-dichloro-p-toluenesulfonamide was
employed as the nitrogen source. At the initial step of
this mechanism, the iron metal center of FeCl3 is
coordinated to the N-chlorine instead of the oxygen
moiety of N,N-dichloro-p-toluenesulfonamide. This in-
teraction weakens the N-Cl bond, which is necessary to
remove chlorine anion to form "Ts-Nδ+-Cl“ type of elec-
trophilic species for subsequent electrophilic addition.
The Fe-associated ”Cl-" near the carbonium reactive site
acts as the nucleophile to open the three-member ring of
the N-tosyl N-chloro aziridinium intermediate. The SN2
mechanism of this aziridinium ring opening is respon-
sible for the high anti stereoselectivty. The regioselec-
tivity can be explained by the fact that the â-position of
the aziridinium intermediate has more positive charge
than R-position because of the stabilization effect from
the â-phenyl ring.
Triphenylphosphine was found to play a critical role
for the current diamination. Triphenylphosphine appar-
ently inhibit the formation of vicinal haloamine side-
products which are generated from aminochlorination.
This reaction can proceed in competition with the main
diamination reaction. Both of these reactions proceed via
the formation of novel aziridinium intermediates as
described below. In fact, only a trace amount of diami-
nation products was detected if triphenylphosphine was
not utilized. Iron(III) chloride itself can catalyze ami-
nochlorination but gives incomplete conversion and a
poor yield (<30%). More diamine product was formed
when the amount of triphenylphosphine was increased,
and the turnover was observed when the ratio of PPh3
to FeCl3 reached 2:1. Similar to our previous catalytic
system, addition of 4 Å molecular sieves slightly improved
yields (∼5-10%). The use of other cosolvents, such as
toluene, benzene, CH2Cl2, CHCl3, EtNO2, and THF
together with acetonitrile failed to give any improvement.
Besides three known metals (zinc, copper, and rhod-
ium),5b,8-9 iron has become the fourth metal which can
effectively catalyze the formation of N-(p-tosyl),N-chlo-
roaziridinium intermediate as described in Scheme 4.5,8-9
J . Org. Chem, Vol. 67, No. 14, 2002 4779

Wei et al.
1: Isolated as a white solid (194 mg, 79% yield). Obtained
from the electronphilic addition reaction of chalcone (106 mg,
0.50 mmol) with N,N-dichloro-p-tolunesulfonamide (360 mg,
1.50 mmol) in the presence of triphenylphosphine (56.0 mg,
0.20 mmol) and iron(II) chloride (109 mg, 0.10 mmol). Mp 130-
131 °C. IR (deposit from CH2Cl2 solution on a NaCl plate):
1698 (CdO) cm-1. 1H NMR (300 MHZ, CDCl3) δ 7.80-7.74 (m,
4H), 7.64-7.61 (m, 1H), 7.49-7.44 (m, 2H), 7.32-7.23 (m, 6H),
6.90 (dd, J ) 1.40, 8.02 Hz, 2H), 5.56 (d, J ) 4.86 Hz, 1H),
5.01 (d, J ) 4.86 Hz, 1H), 2.45 (s, 3H); 13C NMR (75 MHz,
CDCl3) δ 193.3, 156.7, 145.7, 138.7, 134.4, 134.3, 133.5, 130.1,
129.0(2), 128.8, 128.7, 128.0, 126.6, 72.3, 71.9, 61.4, 21.7.
HRMS (MALDI-FTMS) m/z (M+ + 1) found 487.0644, calcd
for C24H20O3N2SCl2 487.0644.
The mechanism of this catalytic system is believed to
be similar to that of our previous rhodium-catalyzed
reaction,5b where the first step is to form the aziridinium
intermediate. This positively charged intermediate is
then attacked by MeCN to give nitrilium intermediate,
which belongs to the Ritter class of the nucleophilic
substitutions.10,11 The opening of the aziridinium ring by
acetonitrile occurring on the â-position is reponsible for
the complete regioselective control. Since the anti con-
figuration of methylcinnamate was retained in the prod-
uct, the coordination of MeCN to the iron center is
suggested to occur prior to the aziridinium ring opening.
For this coordination, the Lewis basic moieties could be
either N-chlorine or the sulfonyl oxygen of the Ts group.
At this moment, it is not clear how triphenylphosphine
plays the crucial role to inhibit the formation of halo-
amine products. It is possible that the secondary struc-
ture generated from the coordination of triphenylphos-
phine ligand to the iron center favors the formation of
the five-membered ring intermediate.
In summary, the FeCl3-PPh3 complex has been found
to be an effective catalyst for the regio- and stereoselec-
tive electrophilic diamination of R,â-unsaturated car-
boxylic esters and ketones. By using this catalyst,
improved chemical yields and stereoselectivity were
obtained for most cases which were examined. The
reaction is easier to handle due to the fact that the
catalyst is much less hygroscopic and N,N-dichloro-p-
toluenesulfonamide can be added in one portion. The
catalytic conditions for the conversion of the CHCl2 group
of the imidazoline into the CCl3 are being studied for
easier deprotection purposes.
2: Isolated as a white solid (189 mg, 73% yield). Obtained
from the electronphilic addition reaction of 4′-methyoxychal-
cone (120 mg, 0.50 mmol) with N,N-dichloro-p-tolunesulfona-
mide (360 mg, 1.50 mmol) in the presence of triphenylphos-
phine (56.0 mg, 0.20 mmol) and iron(II) chloride (109 mg, 0.10
mmol). Mp 58-59 °C. IR (deposit from CH2Cl2 solution on a
NaCl plate): 1688 (CdO), 1248 (C-O) cm-1 1H NMR (500
.
MHz, CDCl3) δ 7.78 (d, J ) 8.65 Hz, 2H), 7.74 (d, J ) 8.84 Hz,
2H), 7.22 (s, 1H), 6.92 (dd, J ) 2.00, 6.76 Hz, 4H), 5.53 (d, J
) 4 0.96 Hz, 1H), 5.01 (d, J ) 4.96 Hz, 1H), 3.88 (s, 3H), 2.45
(s, 3H); 13C NMR (75 MHz, CDCl3) δ 191.7, 164.5, 156.7, 145.6,
138.8, 134.5, 131.2, 130.0, 129.0, 128.6, 128.0, 126.6, 126.4,
114.2, 72.6, 71.5, 61.5, 55.6, 21.7. HRMS (MALDI-FTMS) m/z
(M+ + 1) found 517.0768, calcd for C25H22O4N2SCl2 517.0750.
3: Isolated as a colorless oil (156 mg, 60% yield). Obtained
from the electronphilic addition reaction of chalcone (106 mg,
0.50 mmol) with N,N-dichloro-p-tolunesulfonamide (360 mg,
1.50 mmol) in the presence of triphenylphosphine (56.0 mg,
0.20 mmol) and iron(II) chloride (109 mg, 0.10 mmol). IR
(deposit from CH2Cl2 solution on a NaCl plate): 1869 (CdO)
1
cm-1. H NMR (500 MHz, CDCl3) δ 7.77 (d, J ) 8.50 Hz, 2H),
7.69 (d, J ) 8.99 Hz, 2H), 7.44 (d, J ) 8.99 Hz, 2H), 7.33-
7.26 (m, 5H), 7.21 (s, 1H), 6.89 (d, J ) 8.50 Hz, 2H), 5.48 (d,
J ) 5.00 Hz, 1H), 5.00 (d, J ) 5.00 Hz, 1H), 2.46 (s, 3H); 13C
NMR (125 MHz, CDCl3) δ 192.4, 156.7, 145.9, 141.0, 138.5,
134.3, 131.8, 132.0, 132.1, 129.4, 129.1, 128.8, 127.9, 126.5,
72.3, 72.0, 61.4, 21.7.
Exp er im en ta l Section
Gen er a l P r oced u r e. All reactions were conducted without
inert gas protection. Acetonitrile was dried and freshly distilled
from calcium hydride under the nitrogen atmosphere. Other
commercial chemicals were used without purification, and
their stoichiometries were calculated based on the reported
purities from the manufacturers. Flash chromatography was
performed on silica gel 60 (230-400 mesh). 1H NMR (200 MHz)
and 13C NMR (125 MHz) were acquired in deuterated chloro-
form (CDCl3). High-resolution mass spectral analysis was
conducted by the mass spectroscopy laboratory of the Scripps
Research Institute.
Gen er a l P r oced u r e for Electr op h ilic Dia m in a tion . Into
a dry vial was added iron(II) chloride (109 mg, 0.10 mmol, 0.20
equiv), triphenylphosphine (56.0 mg, 0.20 mmol, 0.40 equiv),
and freshly distilled acetonitrile (3.0 mL). The mixture was
stirred at room temperature for 30 min before 4 Å molecular
sieves (200 mg, predried in the oven at 200 °C overnight) was
added. The resulting brownish yellow mixture was stirred for
10 min and was loaded with R,â-unsaturated carboxylic ester
or ketone (0.50 mmol) and N,N-dichloro-p-tolunesulfonamide
(360 mg, 1.50 mmol, 3.0 equiv). Shortly after N,N-dichloro-p-
tolunesulfonamide was added, the reaction became exothermic
with the color changed to bright yellow. The resulting bright
yellow slurry was stirred at room temperature for 24 h in the
capped vial without argon protection. The 4 Å molecular sieves
and other solid precipitates were filtered off and washed with
EtOAc (3 × 5 mL). The organic solution was directly concen-
trated without quenching and then purified via flash chroma-
tography with hexane and EtOAc as the eluent to give 1-p-
toluenesulfonyl-2-dichloromethyl-imidazoline.
4: Isolated as a colorless oil (110 mg, 52% yield). Obtained
from the electronphilic addition reaction of trans-4-phenyl-3-
buten-2-one (75.0 mg, 0.50 mmol) with N,N-dichloro-p-tolune-
sulfonamide (360 mg, 1.50 mmol) in the presence of triphen-
ylphosphine (56.0 mg, 0.20 mmol) and iron(II) chloride (109
mg, 0.10 mmol). IR (deposit from CH2Cl2 solution on a NaCl
1
plate): 1719 (CdO) cm-1. H NMR (300 MHz, CDCl3) δ 7.55
(d, J ) 8.41 Hz, 2H), 7.32 (s, 1H), 7.18-7.14 (m, 3H), 7.10-
7.08 (m, 2H), 6.69 (d, J ) 8.41 Hz, 2H), 5.14 (d, J ) 4.26 Hz,
1H), 4.28 (d, J ) 4.26 Hz, 1H), 2.40 (s, 3H), 2.39 (s, 3H); 13C
NMR (75 MHz, CDCl3) δ 206.0, 156.8, 146.0, 139.6, 132.6,
130.3, 128.6, 127.5, 127.4, 125.6, 75.5, 71.5, 61.8, 26.6, 21.6.
HRMS (MALDI-FTMS) m/z (M+ + 1) found 425.0500, calcd
for C19H18O3N2SCl2 425.0488.
5: Isolated as a colorless oil (142 mg, 84% yield). Obtained
from the electronphilic addition reaction of 4,4-dimethyl-3-
buten-2-one (50.0 mg, 0.50 mmol) with N,N-dichloro-p-tolune-
sulfonamide (360 mg, 1.50 mmol) in the presence of triphen-
ylphosphine (56.0 mg, 0.20 mmol) and iron(II) chloride (109
mg, 0.10 mmol). IR (deposit from CH2Cl2 solution on a NaCl
1
plate): 1715 (CdO) cm-1. H NMR (300 MHz, CDCl3) δ 7.75
(d, J ) 8.46 Hz, 2H), 7.41 (d, J ) 8.46 Hz, 2H), 7.21 (s, 1H),
3.99 (s, 1H), 2.47 (s, 3H), 2.23 (s, 3H), 1.21 (s, 3H), 0.89 (s,
3H); 13C NMR (75 MHz, CDCl3) δ 205.5, 153.5, 146.1, 133.2,
130.4, 127.6, 70.4, 61.7, 30.7, 27.8, 23.2, 21.7. HRMS (MALDI-
FTMS) m/z (M+ + 1) found 337.0484, calcd for C15H18O3N2-
SCl2 337.0488.
6: Isolated as a white solid (139 mg, 63% yield). Obtained
from the electronphilic addition reaction of trans-methyl
cinnamate (82.0 mg, 0.50 mmol) with N,N-dichloro-p-tolune-
sulfonamide (360 mg, 1.50 mmol) in the presence of triphen-
(10) Krimen, L. I.; Cota, D. J . Org. React. 1969, 17, 213-325.
(11) Chang, S.-J . Org. Proc. Res., Dev. 1999, 3, 232-234.
4780 J . Org. Chem., Vol. 67, No. 14, 2002

Electrophilic Diamination of Alkenes
ylphosphine (56.0 mg, 0.20 mmol) and iron(II) chloride (109
2-methylcinnamate (90.0 mg, 0.50 mmol) with N,N-dichloro-
p-tolunesulfonamide (360 mg, 1.50 mmol) in the presence of
triphenylphosphine (56.0 mg, 0.20 mmol) and iron(II) chloride
(109 mg, 0.10 mmol). IR (deposit from CH2Cl2 solution on a
mg, 0.10 mmol). Mp 126-127 °C. IR (deposit from CH2Cl2
1
solution on a NaCl plate): 1760 (CdO), 1291 (C-O) cm-1. H
NMR (300 MHz, CDCl3) δ 7.69 (d, J ) 8.41 Hz, 2H), 7.26-
7.18 (m, 6H), 6.88 (d, J ) 8.41 Hz, 2H), 5.21 (d, J ) 4.39 Hz,
1H), 4.56 (d, J ) 4.39 Hz, 1H), 3.81 (s, 3H), 2.42 (s, 3H); 13C
NMR (75 MHz, CDCl3) δ 169.7, 156.6, 145.7, 139.2, 133.8,
130.1, 128.8, 128.0, 127.7, 125.8, 72.0, 69.2, 61.4, 53.1, 21.6.
HRMS (MALDI-FTMS) m/z (M+ + 1) found 441.0446, calcd
for C19H18O4N2SCl2 441.0437.
NaCl plate): 1682 (CdO), 1252 (C-O) cm-1 1H NMR (300
.
MHz, CDCl3) δ 7.73-7.69 (dd, J ) 1.86, 6.60 Hz, 2H), 7.28-
7.22 (dd, J ) 1.86, 6.60 Hz, 2H), 7.22 (s, 1H), 7.12 (dd, J )
0.87, 4.87 Hz, 2H), 6.89-6.86 (m, 1H), 6.37 (d, J ) 7.60 Hz,
1H), 5.42 (d, J ) 4.23 Hz, 1H), 4.47 (d, J ) 4.23 Hz, 1H), 3.79
(s, 3H), 2.43 (s, 3H), 2.34 (s, 3H); 13C NMR (125 MHz, CDCl3)
δ 169.6, 156.6, 145.7, 137.0, 134.7, 134.1, 130.7, 130.1, 128.0,
127.7, 126.4, 125.5, 68.8, 68.7, 61.4, 53.1, 21.6, 19.4.
10: Isolated as a white solid (151 mg, 77% yield). Obtained
from the electrophilic addition reaction of methyl 3,3-dimethyl-
acrylate (59.0 mg, 0.50 mmol) with N,N-dichloro-p-tolune-
sulfonamide (360 mg, 1.50 mmol) in the presence of tri-
phenylphosphine (56.0 mg, 0.20 mmol) and iron(II) chloride
(109 mg, 0.10 mmol). Mp 134-136 °C. IR (deposit from CH2-
7: Isolated as a white solid (137 mg, 60% yield). Obtained
from the electronphilic addition reaction of trans-ethyl cin-
namate (90.0 mg, 0.50 mmol) with N,N-dichloro-p-tolune-
sulfonamide (360 mg, 1.50 mmol) in the presence of triphen-
ylphosphine (56.0 mg, 0.20 mmol) and iron(II) chloride (109
mg, 0.10 mmol). Mp 102-104 °C. IR (deposit from CH2Cl2
1
solution on a NaCl plate): 1755 (CdO), 1292 (C-O) cm-1. H
NMR (300 MHz, CDCl3) δ 7.70 (d, J ) 8.41 Hz, 2H), 7.26-
7.19 (m, 6H), 6.90 (d, J ) 8.41 Hz, 2H), 5.20 (d, J ) 4.28 Hz,
1H), 4.55 (d, J ) 4.28 Hz, 1H), 4.23 (q, J ) 7.13 Hz, 2H), 2.42
(s, 3H), 1.29 (t, J ) 7.13 Hz, 3H); 13C NMR (75 MHz, CDCl3)
δ 169.3, 156.6, 145.7, 139.3, 133.9, 130.0, 128.8, 128.0, 127.7,
125.8, 72.1, 69.3, 62.3, 61.5, 21.6, 14.0. HRMS (MALDI-
FTMS) m/z (M+ + 1) found 455.0587, calcd for C20H20O4N2-
SCl2 455.0594.
Cl2 solution on a NaCl plate): 1755 (CdO), 1292 (C-O) cm-1
.
1H NMR (300 MHz, CDCl3) δ 7.83 (dd, J ) 1.88, 6.65 Hz, 2H),
7.38 (dd, J ) 1.88, 6.65 Hz, 2H), 7.05 (s, 1H), 4.33 (s, 1H),
3.68 (s, 3H), 2.46 (s, 3H), 1.26 (s, 3H), 1.12 (s, 3H); 13C NMR
(75 MHz, CDCl3) δ 168. 5, 153.3, 145.6, 134.3, 130.0, 127.8,
70.9, 69.5, 61.4, 52.3, 29.3, 23.1, 21.7. HRMS (MALDI-FTMS)
m/z (M+ + 1) found 393.0437, calcd for C15H18O4N2SCl2
393.0449.
8: Isolated as a colorless solid (168 mg, 65% yield). Obtained
from the electronphilic addition reaction of trans-benzyl cin-
namate (120 mg, 0.50 mmol) with N,N-dichloro-p-tolune-
sulfonamide (360 mg, 1.50 mmol) in the presence of triphen-
ylphosphine (56.0 mg, 0.20 mmol) and iron(II) chloride (109
mg, 0.10 mmol). IR (deposit from CH2Cl2 solution on a NaCl
Ack n ow led gm en t. We gratefully acknowledge the
National Institutes of Health (GM-60261) and the
Robert A. Welch Foundation (D-1361) for the generous
support.
plate): 1760 (CdO), 1227 (C-O) cm-1 1H NMR (300 MHz,
.
CDCl3) δ 7.69 (d, J ) 8.46 Hz, 2H), 7.26 (d, J ) 8.46 Hz, 2H),
7.19 (s, 1H), 6.88 (d, J ) 6.74 Hz, 4H), 5.20 (d, J ) 4.29 Hz,
1H), 4.51 (d, J ) 4.29 Hz, 1H), 3.81 (s, 1H), 2.43 (s, 3H); 13C
NMR (125 MHz, CDCl3) δ 169.6, 157.0, 145.9, 135.3, 135.2,
133.8, 130.1, 127.7, 127.6, 115.9, 71.3, 69.2, 61.4, 53.2, 52.0,
21.6.
Su p p or t in g In for m a t ion Ava ila b le: 1H and 13C NMR
spectra of all pure products, the X-ray structure of 6, and the
1H NMR spectrum of the hydrolysis product of 6. This material
is available free of charge via the Internet at http://pubs.acs.org.
9: Isolated as a colorless solid (104 mg, 47% yield). Obtained
from the electronphilic addition reaction of trans-methyl
J O0200769
J . Org. Chem, Vol. 67, No. 14, 2002 4781