A new route to dihydrodithiins by a catalytic reaction of vinylthiiranes with W(CO)5(NCMe)

Full text of DOI:10.1021/ja973880z

1922
J. Am. Chem. Soc. 1998, 120, 1922-1923
Table 1. Results of Catalytic Transformations of Vinylthiiranes to
Dihydrodithiins by Compound 1
A New Route to Dihydrodithiins by a Catalytic
Reaction of Vinylthiiranes with W(CO)5(NCMe)
reagent
product
yield (%)a
TONb(24 h)
TOFc
Richard D. Adams,* J. W. Long, IV, and Joseph L. Perrin
2
3
4
5
6
7
8
9
10
8
82
84
86
212
141
149
146
53
15
29
24
19
2
Department of Chemistry and Biochemistry
UniVersity of South Carolina
80
34d
Columbia, South Carolina 29208
a Yields based on eq 2 at 24 h. b Number of moles product per mole
of catalyst (1 ) W(CO)5NCMe). c Number of moles product per mole
catalyst per hour (based on the amount of product formed after 4 h).
d 85% yield after 72 h.
ReceiVed NoVember 12, 1997
Dihydrodithiins A and B are a family of naturally occurring
compounds that have been found to exhibit a range of antiviral,
antifungal, and antibiotic properties.1
In recent investigations, we have found that simple thiiranes
can be converted into cyclic polydisulfides catalytically in the
presence of the catalyst W(CO)5, eq 1.2
(1)
Figure 1. An ORTEP diagram of W(CO)5(SSCH2CHdCHCH2), 11,
showing 40% probability thermal ellipsoids. Selected interatomic distances
(Å) and angles (deg): W-S(1) ) 2.549(2), S(1)-S(2) ) 2.062(2), S(1)-
C(1) ) 1.820(7), S(2)-C(4) ) 1.811(7), C(1)-C(2) ) 1.487(9), C(2)-
C(3) ) 1.323(8), C(3)-C(4) ) 1.49(1); W-S(1)-S(2) ) 105.32(8).
We have now found that vinylthiiranes3-5 are readily and
catalytically converted into a 1/1 mixture of the 3,6-dihydro-1,2-
dithiins A and the corresponding butadiene under unusually mild
conditions in the presence of W(CO)5(NCMe),6 1, eq 2.7 Using
the parent SCH2CH(CHdCH2), 2 (R1 ) R2 ) H), the 3,6-dihydro-
1,2-dithiin 7, was obtained in 82% yield at a turnover frequency
of 15/h at 25 °C.
In the absence of catalyst or in the presence of W(CO)6, only
traces of the dithiin products (<1%) were formed under the same
conditions. Table 1 provides the yields, turnover numbers, and
turnover frequencies for the various vinylthiiranes that have been
studied. On the basis of the turnover frequencies for product
formation, the addition of methyl substituents to the vinyl group
clearly increases the rate of reaction. On the other hand,
placement of a methyl group on the thiirane ring drastically
reduces the rate of reaction as shown by the reaction of thiirane
6.
(2)
(1) (a) Block, E. Angew. Chem., Int. Ed. Engl. 1992, 31, 1135. (b) Steliou,
K.; Folkins, P. L.; Harpp, D. N. AdV. Sulfur Chem. 1994, 1, 97. (c) Steliou,
K.; Gareau, Y.; Milot, G.; Salama, P. Phosphorus, Sulfur, Silicon 1989, 43,
209.
Small amounts of a tungsten complex, W(CO)5(SSCH2-
(2) (a) Adams, R. D.; Queisser, J. A.; Yamamoto, J. H. Organometallics
1997, 16, 1430. (b) Adams, R. D.; Queisser, J. A.; Yamamoto, J. H. J. Am.
Chem. Soc. 1996, 118, 10674.
CHdCHCH2), 11, were obtained from the reaction of 2 after
removal of the volatiles and purification of the residue by TLC
on silica gel.8 Compound 11 was characterized by single-crystal
X-ray diffraction analysis,9 and an ORTEP diagram of its
molecular structure is shown in Figure 1. The molecule contains
a W(CO)5 grouping with a 3,6-dihydro-1,2-dithiin ligand coor-
dinated to the tungsten atom through one of its two sulfur atoms,
W-S(1) ) 2.549(2) Å and S(1)-S(2) ) 2.062(2) Å.
(3) Vinyl epoxide was obtained from Eastman Chemical Co. Substituted
vinylthiiranes were prepared by conversion of the appropriate R,â-unsaturated
aldehydes to the corresponding vinyl epoxides by known procedures.4 All
vinyl epoxides were converted to the corresponding vinylthiiranes by treatment
with KSCN.5
(4) Trost, B. M.; Melvin, L. S., Jr. Sulfur Ylides. Emerging Synthetic
Intermediates; Academic Press: New York, 1975.
(5) Snyder, H. R.; Stewart, J. M.; Ziegler, J. B. J. Am. Chem. Soc. 1947,
69, 2672.
(6) Ross, B. F.; Grasselli, J. G.; Ritchey, W. M.; Kaesz, H. D. Inorg. Chem.
1963, 2, 1023.
(8) Only small quantities of 11 were obtained from the catalytic reactions
(e.g., 2.5 mg) due to the small amounts of 1 (5.0 mg) initially used. Compound
11 was obtained in 48% yield from the reaction of 50.0 mg of 1 (0.137 mmol)
with 0.17 mL of 2 (2.74 mmol) in 5 mL of methylene chloride at 25 °C for
24 h. The product was isolated by TLC on silica gel using a hexane/methylene
chloride 3/1 solvent mixture to yield 29.1 mg of 11. Spectral data for 11: IR
νCO (cm-1 in hexane) 2078 (w), 1986 (w), 1949 (vs), 1939 (m); 1H NMR (δ
in CDCl3) 6.08 (m, 1H), 6.00 (m, 1H), 3.62 (m, 2H), 3.43 (m, 2H); 13C NMR
(δ in C6D6) 199.42 (1C), 196.67 (4C), 124.89 (1C), 124.26 (1C), 41.23 (1C),
30.48 (1C). Anal. Calcd for C9H6O5S2W: C, 24.45, H, 1.37. Found: C, 24.12;
H, 1.47.
(7) A typical reaction is as follows: A 5.0 mg amount of 1 was placed
into an NMR tube with 0.5 mL of the selected vinylthiirane5 and 0.5 mL of
CD2Cl2. C6Me6 (10.0 mg) was added to serve as a quantitative reference. The
solution was shaken and maintained at room temperature for 24 h. During
this time there was a progressive transformation to a 1/1 mixture of the dithiin
and the corresponding diene. For 3,6-dihydrodithiin, 2: 1H NMR (δ in CDCl3)
5.97 (t, 3J ) 2.1 Hz, 2H), 3.26 (d, 3J ) 2.2 Hz, 4H); 13C NMR (δ in CDCl3)
125.50 (2C), 28.23 (2C). The mass spectrum shows the parent ion at 118
m/e, as well as additional ions with weights of 103, 85, and 64 m+/e.
S0002-7863(97)03880-8 CCC: $15.00 © 1998 American Chemical Society
Published on Web 02/14/1998

Communications to the Editor
J. Am. Chem. Soc., Vol. 120, No. 8, 1998 1923
Scheme 1 Catalytic Cycle for the Transformation of
Vinylthiirane (2) to 3,6-Dihydro-1,2-dithiin (7)
ment of the labile NCMe ligand from 1. The addition of an
equivalent of vinylthiirane to the CH2 terminus of the vinyl group
in a could lead to formation of a zwitterionic intermediate (b)
with opening of the ring of the coordinated thiirane and a shift
of the unsaturation to the position between the two CH groups.
Elimination of butadiene from the positively charged sulfur atom
in b, followed by neutralization of the charges on the two sulfur
atoms with formation of a S-S single bond, would yield the
product 11. Substitution of the dihydrodithiin ligand in 11 by
another equivalent of vinylthiirane results in regeneration of
intermediate a and closes the catalytic cycle.
The reactions of vinylthiirane with strong Lewis acids and
Lewis bases (e.g., ZnEt2, LiBu; BF3‚OEt2‚H2O, TiCl4) have been
reported to yield mixtures of 1,3 and 1,5 polymers by opening of
the thiirane rings.11 3,6-Dihydrodithiins have been synthesized
by the reaction of butadienes with suitable sources of S2.12 The
conversion of vinylthiiranes into 3,6-dihydro-1,2-dithiins and the
corresponding desulfurized butadiene by W(CO)5 appears to be
a most efficient and convenient method for the preparation of a
range of dihydro-1,2-dithiins and further illustrates the value of
this metal carbonyl in promoting transformations of strained ring
thioethers into new sulfur containing compounds.13
Acknowledgment. These studies were supported by the Division of
Chemical Sciences of the Office of Basic Energy Sciences of the U.S.
Department of Energy. Support for an upgrade of the NMR facilities at
the University of South Carolina was provided by an NSF ARI grant,
Grant No. CHE-9601723. We thank Eastman Chemical Co. for a sample
of vinyl epoxide that was used to prepare our vinylthiirane.
The catalytic activity of 11 for reaction 2 is the same as that
of 1 which suggests that 11 is a species in the catalytic cycle
(Scheme 1). It has been shown that 1 reacts with certain thiiranes
to form stable complexes with W(CO)5 by coordination of the
sulfur atom.2,10 Although we have not observed a vinylthiiraneW-
(CO)5 complex, we believe that the first step in these reactions is
the formation of a (thiirane)W(CO)5 intermediate (a) by displace-
Supporting Information Available: Details of the synthesis and
characterizations of the products and tables of final atomic positional
parameters, intramolecular bond distances and angles, and anisotropic
thermal parameters (11 pages). See any current masthead page for ordering
information and Web access instructions.
JA973880Z
(9) Crystal data for 11: space group ) Pbca, a ) 15.688(2) Å, b ) 17.534-
(3) Å, c ) 9.305(1) Å, Z ) 8, 1638 reflections, R ) 0.022, Rw ) 0.023.
Diffraction data were collected on a Rigaku AFC6S diffractometer using Mo
KR radiation. The structure was solved by direct methods using the Texsan
structure solving program library obtained from the Molecular Structure Corp.,
The Woodlands, TX.
(11) Lautenschlaeger, F.; Schnecko, H. J. Polym. Sci. 1979, 8, 2579.
(12) (a) Harpp, D. N.; MacDonald, J. G. J. Org. Chem. 1988, 53, 3812.
(b) Tardif, S. L.; Rys, A. Z.; Abrams, C. B.; Abu-Yousef, I. A.; Leste-Lasserre,
P. B. F.; Schultz, E. K. V.; Harpp, D. N. Tetrahedron 1997, 53, 12225. (c)
Rys, A. Z.; Harpp, D. N. Tetrahedron Lett. 1997, 38, 4931.
(13) (a) Adams, R. D.; Falloon, S. B.; Perrin, J.; Queisser, J. A.; Yamamoto,
J. H. Chem. Ber. 1996, 129, 313. (b) Adams, R. D.; Queisser, J. A.; Yamamoto,
Organometallics 1996, 15, 2489.
(10) Abel, E.; Cooley, N. A.; Kite, K.; Orrell, K. G.; Sik, V.; Hursthouse,
M. B.; Dawes, H. M. Polyhedron 1989, 8, 887.