Reactions of transition-metal η1-propargyl complexes with sulfur dioxide and sulfur trioxide: Transition-metal-carbon bond cleaving reactions of the cycloadducts which yield 1,2-oxathiole-2-oxides and -2,2-dioxides

Article abstract of DOI:10.1016/S0022-328X(99)00693-2

The preparation of several cyclopentadienyl iron dicarbonyl and triphenylphosphine manganese tetracarbonyl η¹-2-alkynyl complexes are reported. The [3+2] cycloaddition reactions of these complexes with sulfur dioxide and sulfur trioxide yielded transition-metal substituted 1,2-oxathiolene-2-oxides and 1,2-oxathiolene-2,2-dioxides, respectively. One of the η¹-propargyl complex SO₃ cycloadducts has been characterized by X-ray crystallography. The transition metal can subsequently be cleaved from the oxathiole-oxide and dioxide containing complexes to produce a variety of new sulfur containing heterocycles.

Full text of DOI:10.1016/S0022-328X(99)00693-2

www.elsevier.nl/locate/jorganchem
Journal of Organometallic Chemistry 598 (2000) 150–159
Reactions of transition-metal h1-propargyl complexes with sulfur
dioxide and sulfur trioxide: transition-metal–carbon bond cleaving
reactions of the cycloadducts which yield 1,2-oxathiole-2-oxides
and -2,2-dioxides
Allison L. Hurley, Mark E. Welker *,1, Cynthia S. Day 2
Department of Chemistry, Wake Forest Uni6ersity, PO Box 7486, Winston-Salem, NC 27109, USA
Received 24 September 1999; received in revised form 5 November 1999
Abstract
The preparation of several cyclopentadienyl iron dicarbonyl and triphenylphosphine manganese tetracarbonyl h1-2-alkynyl
complexes are reported. The [3+2] cycloaddition reactions of these complexes with sulfur dioxide and sulfur trioxide yielded
transition-metal substituted 1,2-oxathiolene-2-oxides and 1,2-oxathiolene-2,2-dioxides, respectively. One of the h1-propargyl
complex SO3 cycloadducts has been characterized by X-ray crystallography. The transition metal can subsequently be cleaved
from the oxathiole-oxide and dioxide containing complexes to produce a variety of new sulfur containing heterocycles. © 2000
Elsevier Science S.A. All rights reserved.
Keywords: Propargyl complexes; Alkynyl complexes; [3+2] Cycloaddition; Sulfur heterocycles
1. Introduction
ring sulfur heterocycles as synthetic targets because of
(1) their cancer chemopreventive effects since they func-
tion as glutathione S-transferase inducers [3]; and (2) a
recent report that 1,2-dithiolanes and 1,2-dithianes look
particularly promising as inhibitors of HIV type 1
replication [4]. This replication inhibition is apparently
a result of their ability to attack the conserved zinc
fingers (presumably via the sulfur of the heterocycle) of
retroviral nucleocapsid proteins causing zinc ejection
from the protein.
Cycloaddition reactions between transition-metal h1-
2-alkynyl (1) and h1-allyl complexes (1) and unsatu-
rated electrophilic reagents (2) have been studied in
detail for many years [1]. These [3+2] cycloaddition
reactions have been shown to yield transition-metal
substituted five-membered-ring heterocycles and carba-
cycles (3) [1].
In continuation of our efforts in this area, we report
here the preparation of cyclopentadienyl iron dicar-
bonyl- and (Ph3P)(CO)4 manganese-h1-alkynyl com-
plexes and their reactions with SO2 and SO3.
Demetallation reactions of these metal substituted cy-
cloadducts are also reported.
We have also now reported a number of examples of
these types of cycloaddition reactions [2]. We have been
particularly interested in developing this chemistry as a
new synthetic method for the preparation of unusual
sulfur heterocycles. We are interested in five membered
2. Experimental
* Corresponding author.
2.1. General
E-mail address: welker@wfu.edu (M.E. Welker)
1 Henry Dreyfus Teacher–Scholar Awardee (1994–1999).
2 Author to whom correspondence concerning X-ray crystallogra-
phy should be addressed.
All nuclear magnetic resonance (NMR) were ob-
tained using a Varian VXR-200 or Bruker AVANCE
0022-328X/00/$ - see front matter © 2000 Elsevier Science S.A. All rights reserved.
PII: S0022-328X(99)00693-2

A.L. Hurley et al. / Journal of Organometallic Chemistry 598 (2000) 150–159
151
300 FT NMR spectrometer. All absorptions are ex-
2.3. General procedure for the synthesis of substituted
phenyl propargyl alcohols (10–12) [8]
pressed in parts per million relative to residual un-
deuterated solvents. All infrared (IR) spectra were
obtained using a Perkin–Elmer 1620 FT-IR spec-
trophotometer. All elemental analyses were performed
by Atlantic Microlab Inc. of Norcross, GA. High reso-
lution mass spectral analyses (HRMS) were performed
by the Duke University Center for Mass Spectrometry.
Thin layer chromatography was carried out on 0.20
mm precoated polygram aluminum oxide plates or 0.25
mm precoated polygram SIL G/UV silica plates. Rou-
tine column chromatography was effected on alumina
absorption (150 mesh, neutral), purchased from Aldrich
or silica gel 60 purchased from VWR Scientific. Te-
trahydrofuran was distilled from sodium–benzophe-
none under a nitrogen atmosphere immediately prior to
use. Toluene and pentane were distilled from calcium
hydride prior to use. All reactions were carried out
under an atmosphere of dry nitrogen, unless otherwise
noted. Cyclopentadienyl iron dicarbonyl dimer, man-
ganese carbonyl dimer, and triphenyl phosphine were
purchased from Strem Chemicals and used as received.
Mn(CO)4[PPh3]CH2CꢀCR, (4 R=Me, 5 R=Ph) [5]
and CpFe(CO)2CH2CꢀCR (6, R=CH3) [6] and (7,
R=Ph) [6] were synthesized according to modified
literature procedures via addition of a THF solution of
the transition-metal anion to a THF solution of the
appropriate 2-alkynyl tosylate. Literature procedures
[5,6] typically use 2-alkynyl halides but the tosylates are
more convenient to work with since they are solids, and
have many times produced higher yields of propargyl
complex.
The appropriate iodobenzene was dissolved in tri-
ethylamine (10–50 ml) and propargyl alcohol was
added. The reaction mixture was deoxygenated thor-
oughly using nitrogen. Pd(PPh3)2Cl2 (0.01 mol%) and
CuI (0.02 mol%) were added and the resulting solution
was allowed to stir for 2 h at 25°C. H2O (20–40 ml)
and ethyl acetate (20–40 ml) were added. The aqueous
layer was extracted with ethyl acetate (2×20 ml). The
organic extracts were combined and dried with MgSO4.
The solvent was removed under reduced pressure. The
crude products were purified by recrystallization or
column chromatography on silica gel.
2.3.1. 3-(4-Methoxy)-phenyl-2-propyn-1-ol (10)
This compound has been prepared and characterized
previously by an alternate procedure [9]. 4-Iodoanisole
(5.00 g, 21.4 mmol), propargyl alcohol (1.25 ml, 21.4
mmol), Pd(PPh3)2Cl2 (0.150 g, 0.214 mmol) and CuI
(0.082 g, 0.428 mmol) were reacted using the above
procedure to yield a crude product which was purified
by column chromatography using silica gel (100% di-
ethyl ether). The resulting off-white solid (3.40 g, 21.0
mmol, 98%) proved identical by spectroscopic compari-
son to the previously reported material [9].
2.3.2. 3-(4-tert-Butyl)-phenyl-2-propyn-1-ol (11)
1-tert-Butyl-4-iodobenzene (1.00 g, 3.84 mmol),
propargyl alcohol (0.223 ml, 3.84 mmol), Pd(PPh3)2Cl2
(0.027 g, 0.038 mmol) and CuI (0.015 g, 0.077 mmol)
were reacted using the above procedure to yield a crude
product which was purified by column chromatography
using silica gel (100% diethyl ether). The resulting
product was a light yellow solid (0.615 g, 3.27 mmol,
2.2. 3-Cyclohex-(1%)-enyl-2-propyn-1-ol (9)
The boiling point and IR data for this compound but
no experimental procedure or other characterization
data have been reported previously [7]. 1-Ethynylcyclo-
hexene (8) (3.00 g, 28.6 mmol) was dissolved in diethyl
ether (125 ml) and cooled to −78°C. n-Butyllithium in
hexane (12.4 ml, 2.5 M in hexane, 31.1 mmol) was
added dropwise. The solution was allowed to stir at
−78°C for 1.5 h and then paraformaldehyde (1.70 g,
56.5 mmol) was added. The reaction mixture was al-
lowed to warm to 25°C overnight. The mixture was
poured into saturated aq. NH4Cl solution (125 ml) and
then extracted with diethyl ether (3×50 ml). The ether
extracts were dried with MgSO4 and the solvent was
removed under reduced pressure. The crude product
was purified by column chromatography on silica gel
using 1:1 diethyl ether–pentane to yield a light yellow
1
85%): m.p. 94–95°C. H-NMR (CDCl3): 7.33 (m, 4 H),
4.47 (s, 2 H), 1.90 (br s, 1 H), 1.29 (s, 9 H). Anal. Calc.
for C13H16O: C, 82.94; H, 8.57. Found: C, 82.18; H,
8.54. EI HRMS (m/z) Calc. for M+ (C13H16O),
188.1201, found 188.1203.
2.3.3. 3-(4-Nitro)-phenyl-2-propyn-1-ol (12)
This compound has been prepared in a much lower
yield and characterized previously by an alternate pro-
cedure [10]. 1-Iodo-4-nitrobenzene (5.00 g, 20.1 mmol),
propargyl alcohol (1.17 ml, 20.1 mmol), Pd(PPh3)2Cl2
(0.140 g, 0.200 mmol), and CuI (0.076 g, 0.400 mmol)
were reacted using the above procedure to yield a crude
product which was purified by recrystallization from
ethyl acetate and pentane. The tan solid (3.18 g, 17.9
mmol, 89%) proved identical by spectroscopic compari-
son to the previously reported material [10].
1
oil (3.17 g, 23.3 mmol, 82%). H-NMR (CDCl3): 6.09
(m, 1 H), 4.35 (s, 2 H), 2.07 (m, 4 H), 1.62–1.57 (m, 5
H). EI HRMS (m/z) Calc. for (M+) (C9H12O)
136.0888, found 136.0894.

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J=8.0 Hz, 2 H), 4.94 (s, 2 H), 2.40 (s, 3 H). Anal.
Calc. for C16H13NO5S: C, 57.99; H, 3.95. Found: C,
57.71; H, 4.06.
2.4. 1-Tosyl-3-cyclohexenyl-2-propyne (13)
3-Cyclohex-1%-enyl-2-propyn-1-ol (9) (3.04 g, 22.3
mmol), p-toluene sulfonyl chloride (4.04 g, 21.2 mmol)
and potassium hydroxide (6.26 g, 112 mmol) were
reacted in a manner analogous to our previously
reported procedure [2b] to yield the product (13)
(5.66 g, 19.5 mmol, 92%) as a light yellow oil. 1H-
NMR (CDCl3): 7.79 (d, J=8.1 Hz, 2 H), 7.31 (d,
J=8.1 Hz, 2 H), 5.97 (m, 1 H), 4.81 (s, 2 H), 2.42 (s,
3 H), 2.02 (m, 2 H), 1.92 (m, 2 H), 1.53 (m, 4 H). FAB
LRMS (m/z) Calc. for (MH+) (C16H19O3S): 291,
found 291.
2.8. Cyclopentadienyl(3-cyclohexenyl-2-
propynyl)dicarbonyliron (18)
The iron anion was generated from [CpFe(CO)2]2
(3.68 g, 10.4 mmol) and was added to a THF solution
of 13 (5.50 g, 18.9 mmol) using a procedure analogous
to one we have reported previously [2b]. The product
was obtained as a brown solid (18) (4.68 g, 15.8 mmol,
84%): m.p. 52–53°C. IR (NaCl): 2932, 2002, 1944
1
cm−1. H-NMR (C6D6): 6.10 (m, 1 H), 4.08 (s, 5 H),
2.25 (m, 2 H), 1.89 (m, 4 H), 1.41 (m, 4 H). 13C-NMR
(C6D6): 216.88, 130.55, 123.22, 98.51, 85.98, 53.61,
30.47, 25.88, 22.88, 22.08, −18.19. Anal. Calc. for
C16H16FeO2: C, 64.89; H, 5.45. Found: C, 64.18; H,
5.45.
2.5. 1-Tosyl-3-(4-methoxy)phenyl-2-propyne (14)
3-(4-Methoxy)phenyl-2-propyn-1-ol (10) (3.56 g, 22.0
mmol), p-toluene sulfonyl chloride (3.97 g, 20.9 mmol),
and potassium hydroxide (6.16 g, 110 mmol) were
reacted in a manner analogous to our previously re-
ported procedure [2b] to yield the product (14) (5.50 g,
17.4 mmol, 84%) as a white solid: m.p. 44–45°C.
1H-NMR (CDCl3): 7.83 (d, J=8.2 Hz, 2 H), 7.29 (d,
J=8.2 Hz, 2 H), 7.18 (d, J=8.7 Hz, 2 H), 6.78 (d,
J=8.7 Hz, 2 H), 4.91 (s, 2 H), 3.78 (s, 3 H), 2.38 (s, 3
H). FAB LRMS (m/z) Calc. for (MH+) (C17H17O4S):
317, found 317.
2.9. Cyclopentadienyl(3-(4-methoxy)phenyl-2-
propynyl)dicarbonyliron (19)
The iron anion was generated from [CpFe(CO)2]2
(3.26 g, 9.23 mmol) and was added to a THF solution
of 14 (5.31 g, 16.8 mmol) using a procedure analo-
gous to one we have reported previously [2b]. The
product obtained was a dark red solid (19) (3.87
g, 12.0 mmol, 72%): m.p. 60–61°C. IR (NaCl): 2003,
2.6. 1-Tosyl-3-(4-tert-butyl)phenyl-2-propyne (15)
1949, 1505, 1238, 827 cm−1
.
1H-NMR (C6D6):
3-(4-tert-Butyl)phenyl-2-propyn-1-ol (11) (0.550 g,
2.92 mmol), p-toluene sulfonyl chloride (0.529 g,
2.77 mmol) and potassium hydroxide (0.819 g, 14.6
mmol) were reacted in a manner analogous to our
previously reported procedure [2b] to yield the product
(15) (0.649 g, 1.90 mmol, 68%) as a white solid:
7.45 (d, J=8.0 Hz, 2 H), 6.66 (d, J=8.2 Hz, 2 H),
4.09 (s, 5 H), 3.21 (s, 3 H), 1.95 (s, 2 H). 13C-NMR
(C6D6): 216.88, 158.93, 132.63, 118.96, 114.30, 99.94,
85.99, 83.65, 54.70, −18.43. Anal. Calc. for
C17H14FeO3: C, 63.38; H, 4.38. Found: C, 63.18; H,
4.66.
1
m.p. 83–84°C. H-NMR (CDCl3): 7.83 (d, J=8.1 Hz,
2 H), 7.31–7.26 (m, 4 H), 7.16 (d, J=7.9 Hz, 2 H),
4.93 (s, 2 H), 2.37 (s, 3 H), 1.28 (s, 9 H). Anal. Calc.
for C20H22O3S: C, 70.15; H, 6.48. Found: C, 70.09; H,
6.59.
2.10. Cyclopentadienyl(3-(4-tert-butyl)phenyl-
2-propynyl)dicarbonyliron (20)
The iron anion was generated from [CpFe(CO)2]2
(0.355 g, 1.01 mmol) and was added to a THF solution
2.7. 1-Tosyl-3-(4-nitro)phenyl-2-propyne (16)
of 15 (0.626 g, 1.83 mmol) using
a procedure
analogous to one we have reported previously
[2b]. The product obtained was a dark red solid (20)
(0.615 g, 1.77 mmol, 97%): m.p. 58–59°C. IR (NaCl):
3-(4-Nitro)phenyl-2-propyn-1-ol (12) (3.18 g, 18.0
mmol), p-toluene sulfonyl chloride (3.25 g, 17.1 mmol),
and potassium hydroxide (5.04 g, 89.8 mmol) were
reacted in a manner analogous to our previously re-
ported procedure [2b], except that the reaction mixture
was allowed to stir overnight at 25°C to yield a yellow
solid (16) (3.32 g, 10.0 mmol, 59%): m.p. 103–104°C.
1H-NMR (CDCl3): 8.14 (d, J=8.5 Hz, 2 H), 7.84 (d,
J=8.0 Hz, 2 H), 7.40 (d, J=8.5 Hz, 2 H), 7.33 (d,
1
2961, 2009, 1951, 825 cm−1. H-NMR (C6D6): 7.53 (d,
J=8.4 Hz, 2 H), 7.16 (d, J=8.4 Hz, 2 H), 4.08 (s, 5
H), 1.93 (s, 2 H), 1.16 (s, 9 H). 13C-NMR (C6D6):
216.78, 149.50, 131.11, 125.54, 123.80, 101.06, 85.94,
53.95, 34.52, 31.22, −18.55. Anal. Calc. for
C20H20FeO2: C, 68.98; H, 5.79. Found: C, 69.22; H,
5.99.

A.L. Hurley et al. / Journal of Organometallic Chemistry 598 (2000) 150–159
153
2.11. General procedure for the synthesis of manganese
substituted 1,2-oxathiole-2-oxides [11]
2.13. Cyclopentadienyl(1-oxo-5-(4-methoxy)phenyl-
1,2-oxathiol-4-en-4-yl)dicarbonyliron (24)
The appropriate manganese propargyl complex (4 or
5) was dissolved in CH2Cl2 (10–15 ml), purged with
nitrogen and cooled to −78°C. Sulfur dioxide (10 ml)
was condensed at −78°C into the manganese complex
solution. The reaction mixture was allowed to warm to
25°C under nitrogen, to allow the evaporation of excess
sulfur dioxide. The solvent was removed by rotary
evaporation and the remaining solid was vacuum dried.
The crude products were purified by recrystallization
from CH2Cl2 and hexane.
The iron alkynyl complex (19) (1.50 g, 4.66 mmol)
was treated with SO2 using a procedure analogous to
one we have reported previously [2b]. The crude
product was purified by recrystallization from CH2Cl2–
pentane to yield a red–brown solid (24) (1.21 g, 3.13
mmol, 67%): m.p. (dec.) 105–106°C. IR (NaCl): 2024,
1
1966, 1494, 1242, 1099, 895 cm−1. H-NMR (CDCl3):
7.31 (d, J=8.1 Hz, 2 H), 6.94 (d, J=8.1 Hz, 2 H), 5.51
(d, J=14.7 Hz, 1 H), 5.13 (d, J=14.7 Hz, 1 H), 4.75
(s, 5 H), 3.83 (s, 3 H). 13C-NMR (CDCl3): 213.50,
213.30, 159.60, 152.89, 150.31, 131.64, 125.84, 114.02,
92.77, 85.50, 55.30. Anal. Calc. for C17H14FeO5S: C,
52.87; H, 3.65. Found: C, 52.69; H, 3.78.
2.11.1. Triphenylphosphine(4-(1-oxo-5-methyl-1,2-
oxathiol-4-enyl))tetracarbonylmanganese (21)
Complex 4 (1.00 g, 2.07 mmol) was treated with SO2
using the procedure outlined above to yield the product
(21) (0.691 g, 1.26 mmol, 61%) as a light yellow solid.
2.14. Cyclopentadienyl(1-oxo-5-(4-tert-butyl)phenyl-
1,2-oxathiol-4-en-4-yl)dicarbonyliron (25)
1
m.p. (dec.) 107–108°C (SO2 loss). H-NMR (CDCl3):
7.45–7.32 (m, 15 H), 5.11 (d, J=16 Hz, 1 H), 4.78 (d,
J=16 Hz, 1 H), 2.21 (s, 3 H). IR (CDCl3): 3155, 2987,
The iron alkynyl complex (20) (0.615 g, 1.77 mmol)
was treated with SO2 using a procedure analogous to
one we have reported previously [2b]. The crude
product was purified by recrystallization from CH2Cl2–
pentane to yield a yellow solid (25) (0.484 g, 1.17 mmol,
67%): m.p. 59–60°C. IR (NaCl): 2961, 2023, 1973,
2902, 2074 (s), 1989 (ssh), 1984 (s), 1979 (ssh) cm−1
.
Anal. Calc. for C26H22MnO7PS (M+H2O): C, 55.33;
H, 3.93. Found: C, 55.83; H, 3.81. FAB MS (m/z) Calc.
for C26H21MnO6PS (M+H+): 547. Found: 547.
1109, 897 cm−1 1H-NMR (CDCl3): 7.42 (d, J=8.3
.
2.11.2. Triphenylphosphine(4-(1-oxo-5-phenyl-1,2-
oxathiol-4-enyl))tetracarbonylmanganese (22)
Complex 5 (2.30 g, 4.23 mmol) was treated with SO2
using the procedure outlined above to yield the pro-
duct (22) (1.92 g, 3.16 mmol, 75%) as a light yellow
solid: m.p. (dec.) 100–101°C (SO2 loss). 1H-NMR
(CDCl3): 7.51–7.24 (m, 20 H), 5.21 (d, J=14 Hz, 1 H),
4.97 (d, J=14 Hz, 1 H). FAB HRMS (m/z) Calc.
for C31H23O6PSMn (M+H+): 609.0333. Found:
609.0317.
Hz, 2 H), 7.32 (d, J=8.0 Hz, 2 H), 5.52 (d, J=14.8
Hz, 1 H), 5.14 (d, J=14.8 Hz, 1 H), 4.73 (s, 5 H), 1.33
(s, 9 H). 13C-NMR (CDCl3): 213.41, 213.29, 152.34,
151.34, 150.59, 130.51, 130.02, 125.47, 92.88, 85.54,
34.70, 31.33. Anal. Calc. for C20H20FeO4S: C, 58.27; H,
4.89. Found: C, 58.54; H, 4.98.
2.15. General procedure for synthesis of
1,2-oxathiole-2-oxides (26–28) 6ia cuprate
demetallation
2.12. Cyclopentadienyl(1-oxo-5-cyclohexenyl-1,2-
oxathiol-4-en-4-yl)dicarbonyliron (23)
In a flame dried flask, CuI (three equivalents) was
suspended in freshly distilled THF (5–10 ml) and the
solution was purged thoroughly with nitrogen and
cooled to −10°C. Methyllithium (1.5 M in Et2O, six
equivalents) was added slowly. The resulting solution
was allowed to stir for 30 min at −10°C. In another
flame dried flask, the appropriate iron complex was
dissolved in THF (5–10 ml) and the solution was
purged thoroughly with nitrogen and cooled to
−10°C. The iron complex solution was added to the
cuprate solution using a double ended needle. The
reaction mixture was then allowed to stir at −10°C for
2 h. Saturated NH4Cl solution (10–20 ml) was then
added. The aqueous layer was extracted with diethyl
ether (2×15 ml). The organic extracts were combined
and dried with MgSO4. The solvent was removed by
rotary evaporation and the remaining oil or solid was
The iron alkynyl complex (18) (1.50 g, 5.07 mmol)
was treated with SO2 using a procedure analogous to
one we have reported previously [2b]. The crude
product was purified by recrystallization from CH2Cl2–
pentane to yield a yellow solid (23) (1.39 g, 3.86 mmol,
76%): m.p. (dec.) 104–105°C. IR (NaCl): 2925, 2107,
1966, 1101, 876 cm−1 1H-NMR (CDCl3): 5.80 (t,
.
J=1.1 Hz, 1 H), 5.35 (d, J=14.6 Hz, 1 H), 5.00 (d,
J=14.6 Hz, 1 H), 4.93 (s, 5 H), 2.16 (m, 4 H), 1.66
(m, 4 H). 13C-NMR (CDCl3): 213.63, 213.38, 153.11,
148.81, 131.33, 131.07, 92.60, 85.35, 29.82, 25.62, 22.60,
21.63. Anal. Calc. for C16H16FeO4S: C, 53.35; H,
4.48; Found: C, 52.67; H, 4.48. FAB HRMS (m/z)
Calc. for (M+H+) (C16H17O4FeS), 361.0197; found
361.0195.

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A.L. Hurley et al. / Journal of Organometallic Chemistry 598 (2000) 150–159
vacuum dried. The crude product was purified by
column chromatography using silica gel at 0°C (jack-
eted column cooled by recirculating ice water) with
diethyl ether–pentane (1:1).
2.16. Cyclopentadienyl(2,2-dioxo-5-phenyl-1,2-
oxathiol-4-en-4-yl)dicarbonyliron (30)
This compound was synthesized using two different
procedures. Method A: Freshly distilled THF (0.280
ml, 3.50 mmol) was added to a flame dried flask and
cooled to −78°C. SO3 (0.280 g, 0.140 ml, 3.50 mmol)
was added slowly to the cooled THF. This solution was
allowed to stir at −78°C for 5 min. Cyclopentadi-
enyl(3-phenyl-2-propynyl)dicarbonyliron (7) (1.00 g,
3.41 mmol) was dissolved in CH2Cl2 (15 ml) and the
resulting solution was added dropwise by an addition
funnel to the SO3–THF solution. The reaction mixture
was allowed to warm slowly to 25°C. Saturated
NaHCO3 solution (15 ml) was added. The aqueous
layer was extracted with CH2Cl2 (2×10 ml). The or-
ganic extracts were combined and dried with MgSO4.
The solvent was removed under reduced pressure. The
crude product was purified by recrystallization from
CH2Cl2–pentane to yield a yellow solid (0.917 g, 2.46
mmol, 72%) which was identical by spectroscopic com-
parison to previously reported material [12]. Method B:
Cyclopentadienyl(1-oxo-5-phenyl-1,2-oxathiol-4-en-4-
yl)dicarbonyliron (0.050 g, 0.140 mmol) (29) [2b] was
dissolved in CH2Cl2 (5 ml). The solution was purged
thoroughly with nitrogen and then cooled to 0°C. m-
Chloroperoxybenzoic acid (mCPBA) (60% pure, 0.040
g, 0.140 mmol) was dissolved in CH2Cl2 (5 ml) and
added dropwise to the iron complex solution. The
reaction mixture was allowed to warm to 25°C and stir
for 3 h. The solution was then cooled to −78°C and
filtered through a glass fritted funnel, which had been
cooled in a CH2Cl2–dry ice bath. Recrystallization of
the crude product from CH2Cl2–pentane afforded a
yellow solid (0.043 g, 0.115 mmol, 83%) which was
identical by spectroscopic comparison to previously
reported material [12].
2.15.1. 4-Methyl-5-cyclohexenyl-1,2-oxathiol-4-en-
1-yl oxide (26)
Iron complex 23 (0.100 g, 0.278 mmol) was reacted
with the cuprate formed from CuI (0.159 g,
0.833 mmol) and methyllithium (1.4 M in Et2O, 1.19
ml, 1.67 mmol), using the above procedure to produce
the crude product which was purified to yield a color-
less oil (26) (0.012 g, 0.061 mmol, 22%). IR (NaCl):
2924, 1123, 971, 694 cm−1 1H-NMR (CDCl3): 5.96
.
(m, 1 H), 5.46 (d, J=14.9 Hz, 1 H), 4.99 (d, J=14.9
Hz, 1 H), 2.17 (m, 4 H), 1.92 (s, 3 H), 1.65 (m, 4 H).
13C-NMR (CDCl3): 146.22, 137.20, 132.23, 127.01,
84.64, 28.55, 25.58, 22.39, 21.51, 11.23. Anal. Calc.
for C10H14O2S: C, 60.58; H, 7.12. Found: C, 60.84; H,
7.27.
2.15.2. 4-Methyl-5-(4-methoxy)phenyl-1,2-oxathiol-
4-en-1-yl oxide (27)
Iron complex 24 (0.200 g, 0.518 mmol) was reacted
with the cuprate formed from CuI (0.148 g, 0.777
mmol) and methyllithium (1.4 M in Et2O, 1.11 ml,
1.55 mmol), using the above procedure to produce
the crude product which was purified to yield an off-
white solid (27) (0.027 g, 0.120 mmol, 23%): m.p.
74–75°C. IR (NaCl): 1602, 1501, 1246, 1116 cm−1
.
1H-NMR (CDCl3): 7.36 (d, J=8.5 Hz, 2 H), 6.94 (d,
J=8.5 Hz, 2 H), 5.58 (d, J=15 Hz, 1 H), 5.14 (d,
J=15 Hz, 1 H), 3.82 (s, 3 H), 1.97 (s, 3 H). 13C-NMR
(CDCl3): 160.08, 143.43, 139.10, 130.20, 120.72, 114.44,
84.68, 55.34, 11.04. Anal. Calc. for C11H12O3S: C,
58.91; H, 5.39. Found: C, 59.71; H, 5.54. EI HRMS
(m/z) Calc. for M+ (C11H12O3S) 224.0507, found
224.0516.
2.17. 5-Phenyl-1,2-oxathiol-4-en-1-yl dioxide (31)
Iron complex 30 (0.100 g, 0.268 mmol) was dissolved
in CH2Cl2 (20 ml). The solution was purged thoroughly
with nitrogen and cooled to −78°C. A 70% solution of
HClO4 (0.138 ml, 1.61 mmol) was added. The reaction
mixture was allowed to stir at −78°C for 30 min. It
was then was warmed to 25°C and was allowed to stir
overnight. The solvent was removed under reduced
pressure and the remaining solid was vacuum dried.
The crude product was purified by chromatography on
a silica gel prep plate (1 mm) using 100% diethyl ether
to yield a tan solid (0.009 g, 0.046 mmol, 17%): m.p.
2.15.3. 4-Methyl-5-(4-tert-butyl)phenyl-1,2-oxathiol-
4-en-1-yl oxide (28)
Iron complex 25 (0.100 g, 0.243 mmol) was reacted
with the cuprate formed from CuI (0.139 g, 0.728
mmol) and methyllithium (1.4 M in Et2O, 1.04 ml, 1.46
mmol), using the above procedure to produce the crude
product which was purified to yield an off-white solid
(28) (0. 013 g, 0.052 mmol, 22.0%): m.p. 73–74°C. IR
1
(NaCl): 2954, 1123, 963, 694 cm−1. H-NMR (CDCl3):
7.43 (d, J=8.6 Hz, 2 H), 7.35 (d, J=8.3 Hz, 2 H), 5.60
(d, J=15.0 Hz, 1 H), 5.15 (d, J=15.1 Hz, 1 H), 1.99
(s, 3 H), 1.31 (s, 9 H). 13C-NMR (CDCl3): 152.15,
143.91, 139.62, 128.55, 125.93, 125.61, 84.76, 34.75,
31.19, 11.08. Anal. Calc. for C14H18O2S: C, 67.17; H,
7.25. Found: C, 66.77; H, 7.25.
132–133°C. IR (NaCl): 1327, 1167, 1029, 760 cm−1
.
1H-NMR (CDCl3): 7.67 (m, 2 H), 7.45 (m, 3 H), 6.92 (t,
J=2.3 Hz, 1 H), 5.12 (d, J=2.3 Hz, 2 H). 13C-NMR
(CDCl3): 138.17, 130.72, 129.33, 127.35, 126.72, 125.65,

A.L. Hurley et al. / Journal of Organometallic Chemistry 598 (2000) 150–159
155
69.96. Anal. Calc. for C9H8O3S: C, 55.09; H, 4.11;
Found: C, 55.46; H, 4.51.
to the cuprate solution using a double ended needle.
The reaction mixture was allowed to stir for 2 h at
−45°C. Saturated NH4Cl solution (20 ml) was added.
The aqueous layer was extracted with diethyl ether
(2×15 ml). The organic extracts were combined and
dried with MgSO4. The solvent was removed under
reduced pressure and the remaining solid was vacuum
dried. The crude product was purified by column chro-
matography using silica gel with 100% diethyl ether to
yield an off-white solid (0.026 g, 0.124 mmol, 31%):
m.p. 103–104°C. IR (NaCl): 1327, 1174, 978, 774, 753,
2.18. 4-Methyl-5-phenyl-1,2-oxathiol-4-en-1-yl dioxide
(32)
In a flame dried flask, CuCl (0.040 g, 0.402 mmol)
and anhydrous LiCl (0.034 g, 0.804 mmol) were sus-
pended in freshly distilled THF (5 ml). The solution
was purged thoroughly with nitrogen and then cooled
to −45°C. Methyllithium (1.4 M in Et2O, 0.574 ml,
0.804 mmol) was added slowly and the resulting solu-
tion was allowed to stir for 30 min at −45°C [13]. In
another flame dried flask, iron complex 30 (0.150 g,
0.402 mmol) was dissolved in THF (10 ml). The solu-
tion was purged thoroughly with nitrogen and cooled
to −45°C. The iron complex solution was then added
1
694, 622 cm−1. H-NMR (CDCl3): 7.45–7.50 (m, 5 H),
4.93 (s, 2 H), 2.02 (s, 3 H). 13C-NMR (CDCl3): 140.56,
131.40, 130.03, 129.14, 128.91, 125.76, 72.49, 13.01.
Anal. Calc. for C10H10O3S: C, 57.13; H, 4.79. Found:
C, 56.60; H, 4.83.
2.19. X-ray structure determination of cyclopenta-
dienyl(2,2-dioxo-5-phenyl-1,2-oxathiol-4-en-4-yl)-
dicarbonyliron (30)
Table 1
Crystal data and structure refinement for Fe(CO)2(C5H5)-
[SO3C3H2(C6H5)]
Single crystals of Fe(CO)2(C5H5)[SO3C3H2(C6H5)]
are, at 293 K, orthorhombic, space group P212121-D24
Empirical formula
Formula weight
Temperature (K)
C16H12FeO5S
372.17
293(2)
,
,
(no. 19) with a=6.746(2) A, b=13.300(2) A, c=
3
,
,
16.813(3) A, V=1508.4(5) A , and Z=4 {Dcalc.
=
1.639 g cm−3; v (Mo–Ka)=1.160 mm−1}. Cell
constants were obtained by least-squares analysis of 62
randomly selected reflections in the 2q range 6–25°. A
total of 1875 independent reflections having 2q(Mo–
Ka)B50.7° (the equivalent of 0.8 limiting Cu–Ka
sphere) were collected on a computer-controlled Bruker
P4 autodiffractometer using ꢀ scans and graphite-
monochromated Mo–Ka radiation. The structure was
solved using direct methods techniques with the Bruker
SHELXTL-PC (version 5.0) software package. The result-
ing structural parameters have been refined to conver-
gence (see Table 1) using counter-weighted full-matrix
least-squares techniques and a structural model which
incorporated anisotropic thermal parameters for all
nonhydrogen atoms and isotropic hydrogen atoms. The
hydrogen atoms were included in the structural model
as fixed atoms (using idealized sp3- or sp2-hybridized
,
Wavelength (A)
0.71073
Crystal system
Space group
Orthorhombic
P212121-D42 (no.
19)
Unit cell dimensions
,
a (A)
6.746(2)
13.300(2)
16.813(3)
1508.4(5)
4
,
b (A)
,
c (A)
V (A )
3
,
Z
Dcalc. (g cm−3
)
1.639
1.160, 0.688–1.000
Absorption coefficient (mm−1),
transmission range
F(000)
760
Crystal size (mm)
2q Range for data collection
Limiting indices
0.08×0.30×0.80
3.5–50.7
−15h58,
−165k51,
−15l520
2035
Reflections collected
Independent reflections
1875 [Rint=0.037]
Full-matrix
least-squares
1739/209
Refinement method on F2
,
geometry and CꢁH bond lengths of 0.97 and 0.93 A)
riding on their respective carbons with isotropic ther-
mal parameters fixed at values 1.2 times the equivalent
isotropic thermal parameter of their carbon atom.
As a check on the correctness of the enantiomorphic
description, the Flack parameter was varied during the
final cycle of refinement; its final value was −0.05(4).
Expected values are 0 (within three estimated SDs) for
correct and +1 for inverted absolute structure.
Data/parameters
Goodness-of-fit on F2
Final R indices
1.032
[1301 data, Fo\4|(Fo) data]
R1=0.053,
wR2=0.080
R1=0.077,
wR2=0.088
R1=0.094,
wR2=0.093
−0.05(4)
[1739 data, Fo2\0]
[all 1875 data]
Absolute structure parameter
Extinction coefficient
Largest difference peak and hole (e A
All calculations were performed using the SHELXTL
-
0.0023(6)
0.422 and −0.342
−3
PC (version 5.0) interactive software package (G.
Sheldrick, Bruker-AXS, Madison, WI).
,
)

156
A.L. Hurley et al. / Journal of Organometallic Chemistry 598 (2000) 150–159
3. Results and discussion
The alkynyl tosylates were then treated with the
cyclopentadienyl iron dicarbonyl anion (17) (Fp=
CpFe(CO)2) to yield the iron alkynyl complexes (18–
20) using a procedure analogous to one we have
reported previously [2b]. When tosylate (16) was treated
with the Fp anion, the tosylate (16) and [CpFe(CO)2]2
were recovered instead of the expected iron alkynyl
complex. We suspected that electron transfer occurred
between the iron anion (17) and the nitro group of the
tosylate, inhibiting the expected SN2 reaction. When the
reaction was carried out in dioxane, which has a lower
dielectric constant than THF, again the iron dimer and
tosylate (16) were recovered with no observation of the
desired product. Attempts to produce a nitrophenyl
alkynyl complex by nitrating phenyl complex (7) with
NO2BF4 were also unsuccessful.
3.1. Preparation of alkynyl complexes
Simple substituted propargyl complexes of the form
Mn(CO)4[PPh3]CH2CCR [5] and CpFe(CO)2CH2CCR
[6] where R=Me and Ph (4–7) were prepared by
modifications of literature procedures. These complexes
(4–7) were synthesized via addition of a THF solution
of the transition-metal anion to a THF solution of the
appropriate 2-alkynyl tosylate. Literature procedures
[5,6] typically use 2-alkynyl halides but the tosylates are
more convenient to work with since they are usually
solids and many times produce higher yields of the
propargyl complex [2b,e].
3.2. Cycloaddition reactions of alkynyl complexes with
sulfur dioxide and sulfur trioxide and subsequent
demetallation reactions of the cycloadducts
Only one cyclization of a manganese tetracarbonyl
triphenylphosphine alkynyl complex (4, 5 R=H) with
SO2 has been reported previously [11]. The alkynyl
complexes (4 and 5) underwent a [3+2] cycloaddition
with SO2 at −78°C to produce the air-stable man-
ganese substituted 1,2-oxathiole-2-oxides (21 and 22) in
good yield. We were hopeful that these new complexes
(21 and 22) would serve as precursors to a variety of
new 1,2-oxathiole-2-oxides via demetallation reactions.
Unfortunately, attempts at protonolysis (HCl, CH2Cl2,
HBF4, and Et2O; −78 to 25°C), oxidative carboxyla-
tion (Ce(IV), CO, EtOH:CH2Cl2) and halogenolysis (I2,
CH2Cl2, 25°C), which have worked for us in the past on
related iron complexes [2], resulted only in the decom-
position of these manganese complexes. Organocuprate
mediated demetallation conditions which have also
worked on iron complexes for us in the past [2], re-
sulted in the recovery of the unreacted complex 22 here.
New cyclohexenyl substituted propargyl complex (18)
and substituted phenyl propargyl complexes (19, 20)
were also easily prepared. 1-Ethynylcyclohexene (8) was
deprotonated with butyl lithium and then condensed
with paraformaldehyde to produce alcohol (9) (82%)
[7]. Substituted phenyl propargyl alcohols (10–12) were
prepared by Pd/Cu catalyzed cross coupling of the
appropriate aromatic iodide with propargyl alcohol [6].
The substituted propargyl alcohols were then converted
to tosylates (13–16) in high yield [2b,e]. The 4-nitro-
phenylpropynol (12) was the least nucleophilic, as ex-
pected, and required longer reaction times at higher
temperature to get a good conversion to the tosylate
(16).

A.L. Hurley et al. / Journal of Organometallic Chemistry 598 (2000) 150–159
157
Treatment of 23 with perchloric acid, for the purpose
of replacing the iron–ligand set with a proton, pro-
duced a complicated mixture of products, none of
which resembled the desired product. Reaction of iron
complex (24) with three equivalents of the highly THF
soluble methyl cuprate [13] generated from copper(I)
chloride, lithium chloride, and methyl lithium only
produced a 14% yield of 1,2-oxathiole-2-oxide (27).
Treatment of iron complex (24) with three equivalents
of the standard methyl cuprate generated from cop-
per(I) iodide and methyl lithium produced 27 in 23%
yield. Similarly, when iron complexes 23 and 25 were
treated with three equivalents of the same methyl
cuprate, 26 and 28 were both isolated in 22% yield.
Isolated yields of demetallated cycloadducts were prob-
ably diminished to some extent by competitive ring
opening reactions of 26–28 that these nucleophilic con-
ditions might induce [14].
Fig. 1. Perspective drawing of the solid state structure for
Fe(CO2)(C5H5)[SO3C3H2(C6H5)] (30). All nonhydrogen atoms are
represented by thermal vibrational ellipsoids drawn to encompass
50% of their electron density.
Table 2
Bond lengths in crystalline Fe(CO)2(C5H5)[SO3C3H2(C6H5)] a
b
Type b
Length (A)
,
,
Type
Length (A)
Fe1ꢁC1
Fe1ꢁC2
1.761(10)
1.741(8)
Fe1ꢁC6
Fe1ꢁC7
Fe1ꢁC8
Fe1ꢁC9
Fe1ꢁC10
Fe1ꢁCpg c
2.085(8)
2.086(8)
2.110(8)
2.100(8)
2.073(8)
1.719(–)
Fe1ꢁC4
1.963(7)
In the early 1970s, Wojcicki [12a,b] and Roustan
[12c] independently reported the [3+2] cycloaddition
of the iron complex (7) with the SO3–dioxane adduct to
produce 30 in 66% yield. We found that sulfur trioxide,
which had been precomplexed with THF, worked simi-
larly as expected. Metal substituted 1,2-oxathiole-2,2-
dioxide (30) can also be prepared by m-chloroperoxy-
benzoic acid (mCPBA) oxidation of the monoxide (29)
[2b]. In practice this later route was more convenient
for us because of the extreme moisture sensitivity of
sulfur trioxide.
S1ꢁO1
S1ꢁO3
S1ꢁO2
O2ꢁC3
1.423(6)
1.427(6)
1.575(5)
1.450(8)
S1ꢁC5
O4ꢁC1
O5ꢁC2
1.736(7)
1.117(9)
1.154(8)
C3ꢁC4
C5ꢁC11
1.484(10)
1.478(10)
C6ꢁC7
C6ꢁC10
C7ꢁC8
1.373(10)
1.407(11)
1.411(11)
1.394(11)
1.414(11)
1.355(13)
1.376(12)
1.382(10)
C4ꢁC5
1.356(9)
C8ꢁC9
C9ꢁC10
C13ꢁC14
C14ꢁC15
C15ꢁC16
C11ꢁC16
C11ꢁC12
C12ꢁC13
1.376(11)
1.394(10)
1.361(10)
a The numbers in parentheses are the estimated standard deviations
in the last significant digit.
b Atoms are labeled in agreement with Fig. 1.
c The symbol Cpg is used to represent the center of gravity for the
5-membered cyclopentadienyl ring; this value is therefore listed with-
out an estimated standard deviation.
The transition-metal mediated [3+2] cycloadditions
of the iron alkynyl complexes (18–20) with sulfur diox-
ide were performed under conditions analogous to prior
work [2b,6b]. All the alkynyl complexes (18–20) cy-
clized to produce iron substituted 1,2-oxathiole-2-ox-
ides (23–25) in good yield.
Iron sultone (30) was characterized by single crystal
X-ray crystallography. The molecular structure of com-
pound 30 is shown in Fig. 1. Table 1 contains crystal
data and structure refinement information. Tables 2
and 3 contain selected bond lengths and angles of 30.

158
A.L. Hurley et al. / Journal of Organometallic Chemistry 598 (2000) 150–159
The average FeꢁC(carbonyl) distance and the average
FeꢁCp centroid distance are both in agreement with
those previously observed in similar complexes [2e,13].
4. Summary
In summary, we have extended metal alkynyl–SO2
[3+2] cyclization reactions to produce new manganese
and iron substituted 1,2-oxathiole-2-oxides. The iron
substituted heterocycles can be demetallated but the
manganese complexes could not. We also report the
first crystal structure of a metal substituted 1,2-oxathi-
ole-2,2-dioxide and the first demetallation reactions of
this family of complexes. We will report on the biolog-
ical activity of these new heterocycles in due course.
,
The average FeꢁCvinyl bond length is 1.963 (4) A, which
is similar to values reported for other Fp complexes
containing a sulfur which is k to iron [2e,15]. The
average CꢂC bond distance in the sultone ring is
,
1.356(9) A, which is similar to the one we found
previously in a related iron substituted 1,2-oxathiole-2-
,
oxide (1.301(6) A) [2b].
Wojcicki had reported that sultone (30) was much
more stable to acid than related iron complexes [12b].
They report recovery of unreacted 30 from 1 h of
exposure to HCl saturated CH2Cl2 at 25°C, conditions
which would decompose the sultines reported here. We
found that when iron sultone (30) was treated with
perchloric acid, sultone (31) could be isolated in 17%
yield. Likewise, we found that the use of copper(I)
chloride and two equivalents of lithium chloride to
produce a more THF soluble dimethylcuprate [13] pro-
duced sultone (32) in 31% yield.
5. Supplementary material
Tables giving details of the X-ray structure determi-
nations, atomic coordinates and isotropic thermal
parameters, bond lengths and bond angles and an-
isotropic displacement parameters for 30 have been
deposited at the Cambridge Crystallographic Data Cen-
tre (CCDC no. 136602).
Acknowledgements
We thank the NIH NIGMS and the Camille and
Henry Dreyfus Foundation (Henry Dreyfus Teacher–
Scholar Award to M.E. Welker, 1994–1999) for their
support. Low resolution mass spectra were obtained on
an instrument purchased with the partial support of
NSF (CHE-9007366). The Duke University Center for
Mass Spectrometry performed high resolution mass
spectral analyses.
Table 3
Bond angles in crystalline Fe(CO)2(C5H5)[SO3C3H2(C6H5)] a
References
b
Type
Angle (°)
Type b
Angle (°)
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see: (a) M.E. Welker, Chem. Rev. 92 (1992) 97. (b) D.M.T.
Chan, in: B.M. Trost (Ed.), Comprehensive Organic Syntheses,
vol. 5, Pergamon, New York, 1991, p. 271. (c) A. Wojcicki,
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C2ꢁFe1ꢁC1
C1ꢁFe1ꢁC4
C4ꢁFe1ꢁC7
C2ꢁFe1ꢁC9
C1ꢁFe1ꢁC9
C4ꢁFe1ꢁC9
C2ꢁFe1ꢁC8
C1ꢁFe1ꢁC8
C4ꢁFe1ꢁC8
O1ꢁS1ꢁO3
O1ꢁS1ꢁO2
O3ꢁS1ꢁO2
C3ꢁO2ꢁS1
O5ꢁC2ꢁFe1
C4ꢁC5ꢁC11
C4ꢁC5ꢁS1
91.8(4)
91.5(3)
148.5(3)
131.0(4)
137.1(4)
87.2(3)
C2ꢁFe1ꢁC4
C2ꢁFe1ꢁC10
C1ꢁFe1ꢁC10
C4ꢁFe1ꢁC10
C2ꢁFe1ꢁC6
C1ꢁFe1ꢁC6
C4ꢁFe1ꢁC6
C2ꢁFe1ꢁC7
C1ꢁFe1ꢁC7
O1ꢁS1ꢁC5
94.6(4)
158.5(4)
99.9(4)
103.0(3)
122.6(4)
92.3(3)
142.4(3)
92.4(4)
119.0(3)
111.7(4)
113.7(3)
96.4(3)
178.9(8)
110.9(6)
110.2(6)
131.8(6)
117.9(5)
119.8(7)
96.6(4)
156.8(3)
109.3(3)
116.5(4)
108.2(4)
108.2(4)
111.3(4)
175.9(8)
131.4(7)
110.9(6)
117.7(6)
121.5(7)
O3ꢁS1ꢁC5
O2ꢁS1ꢁC5
O4ꢁC1ꢁFe1
O2ꢁC3ꢁC4
C5ꢁC4ꢁC3
C5ꢁC4ꢁFe1
C3ꢁC4ꢁFe1
C12ꢁC11ꢁC5
[3] T.W. Kensler, J.D. Groopman, T.R. Sutter, T.J. Curphey, B.D.
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C11ꢁC5ꢁS1
C16ꢁC11ꢁC5
a The numbers in parentheses are the estimated standard deviations
in the last significant digit.
b Atoms are labeled in agreement with Fig. 1.

A.L. Hurley et al. / Journal of Organometallic Chemistry 598 (2000) 150–159
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