Synthetic utility of umpoled diaryl thioketone-lanthanoid intermediates: Desulfurization, cross coupling with electrophiles, and desulfurizative homocoupling

Full text of DOI:10.1021/jo951355h

372
J . Org. Chem. 1996, 61, 372-375
choosing the reaction conditions, various transformations
Syn th etic Utility of Um p oled Dia r yl
such as desulfurization, cross coupling with electrophiles,
and desulfurizative homocoupling via the expected di-
anion complexes are possible. We now report the forma-
tion and reactivity of lanthanoid-diaryl thioketone di-
anionic intermediates.10
Th iok eton e-La n th a n oid In ter m ed ia tes:
Desu lfu r iza tion , Cr oss Cou p lin g w ith
Electr op h iles, a n d Desu lfu r iza tive
Hom ocou p lin g
Yoshikazu Makioka,† Shin-ya Uebori,† Masumi Tsuno,†
Yuki Taniguchi,‡ Ken Takaki,† and Yuzo Fujiwara*,‡
Resu lts a n d Discu ssion
Department of Applied Chemistry,
Faculty of Engineering, Hiroshima University,
Kagamiyama, Higashi-Hiroshima 739, J apan, and
Department of Chemical Science and Technology,
Faculty of Engineering, Kyushu University,
Hakozaki, Higashi-ku, Fukuoka 812, J apan
Treatment of thiobenzophenone (1a ) with an equimolar
amount of ytterbium or samarium metal in benzene-
hexamethylphosphoramide (HMPA) (4:1) or tetrahydro-
furan (THF)-HMPA (2:1) afforded a red homogeneous
solution. Quenching the reaction with H2O gave diphen-
ylmethanethiol (2a ), diphenylmethane (3a ), tetraphen-
ylethene (4a ), and 1,1,2,2-tetraphenylethane (5a ). Table
1 summarizes the results of the reaction of 1a with
ytterbium metal under various conditions. The reaction
pathways are shown in Scheme 1. At room temperature,
little difference was observed between THF and benzene
solvent (entries 1 and 2). In THF, the yield of 2a was
improved by carrying out the reactions at lower temper-
ature, and 2a was selectively obtained in 94% yield at
-35 °C (entry 4). Reaction did not take place at -78 °C.
Higher temperatures caused a more complicated reaction,
and 2a -5a were all formed with low selectivity (entry
7). Under the refluxing conditions in benzene instead of
THF, olefin 4a was obtained in 64% yield (entry 8). The
desulfurized product 3a can be selectively obtained by
treatment of 1a with 2 equiv of ytterbium metal at room
temperature for 20 h (entries 5 and 6). Without HMPA,
1a and ytterbium were recovered quantitatively. Similar
results were obtained when samarium was used instead
of ytterbium, but none of the products were obtained from
1a and samarium(II) diiodide or magnesium. It has been
reported that reaction of 1a with metallic sodium gives
a mixture of thioketyl and dianionic intermediates,11 but
further reductive desulfurization does not occur. On the
other hand, dimeric olefin 4a is formed by desulfurizative
homocoupling of 1a with a d-block transition metal like
copper.12 Our results show that lanthanoid metals
possess both features of these two types of metals, which
can be controlled by changing the reaction temperature
or the metal proportion.
Formation of 2a and 3a suggests that the thiocarbonyl
carbon of 1a is umpoled by a two- or four-electron
transfer from ytterbium in the same manner whereby
carbonyl carbons of diaryl ketones become nucleophilic
by the reduction with lanthanoid metals.7 In fact,
treatment of the intermediates with deuterium oxide
under various conditions affords the deuteriated 2a and
3a (Scheme 2). It should be noted that deuterium
incorporation in 3a is over 100%. This is evidence
supporting that the unstable B shown in Scheme 1 is
formed in situ by the reaction of 1a with excess amounts
of ytterbium. When the reaction mixture was oxidized
with 5 equiv of benzil after the treatment of 1a with
ytterbium metal under the conditions to produce 3a
selectively as indicated in entry 6 of Table 1, 1a , ben-
zophenone, and 4a were formed in 23%, 19%, and 16%
Received J uly 25, 1995
In tr od u ction
Lanthanoid reagents have been extensively utilized in
organic synthesis because of their unique properties.1 For
example, the strong reducing ability of low-valent lan-
thanoids has provided a facile reduction of many func-
tional groups and a convenient method for reductive
carbon-carbon bond formation.2 Oxophilicity and high
coordination numbers of trivalent lanthanoids have
enabled them to act as new Lewis acids.3 However, these
properties have been less explored in organic sulfur
chemistry, since little is known about the reactivity of
the lanthanoid reagents toward sulfur functionality.4,5
Previously, we reported that the carbonyl carbons of
diaryl ketones were umpoled6 by the reaction with
ytterbium metal, and the thus formed ytterbium-ben-
zophenone dianionic complexes were successfully char-
acterized by X-ray analyses.7 The anionic carbonyl
carbons were nucleophilic and were coupled with various
electrophiles such as ketones, esters, and epoxides.8
Diaryl imines were also reduced by lanthanoid metals
in a similar manner, and R-amino acids were obtained
by treatment of the lanthanoid-diaryl imine intermedi-
ates with carbon dioxide.9 We have applied this meth-
odology to diaryl thioketones to study their reductive
reactions with lanthanoids, and we have found that, by
† Hiroshima University.
‡ Kyushu University.
(1) (a) Imamoto, T. Lanthanides in Organic Synthesis; Academic
Press: London, 1994; p 21. (b) Kagan, H. B.; Namy, J . L. In Handbook
on the Physics and Chemistry of Rare Earths; Gscheidner, K. A., J r.,
Eyring, J ., Eds.; North-Holland: Amsterdam, 1984; Vol. 6, p 525. (c)
Fujiwara, Y.; Takaki, K.; Taniguchi, Y. J . Alloys Compd. 1993, 192,
200.
(2) (a) Kagan, H. B.; Sasaki, M.; Collin, J . Pure Appl. Chem. 1988,
60, 1725. (b) Molander, G. A. Chem. Rev. 1992, 92, 29.
(3) (a) Kobayashi, S. Synlett 1994, 689. (b) Fujiwara, Y.; Takaki,
K.; Taniguchi, Y. Shokubai 1995, 37, 211.
(4) Some sulfur-containing organolanthanoid complexes have been
isolated: Mashima, K.; Nakayama, Y.; Fukumoto, H.; Kanehisa, N.;
Kai, Y.; Nakamura, A. J . Chem. Soc., Chem. Commun. 1994, 2523 and
references therein.
(5) (a) Taniguchi, Y.; Maruo, M.; Takaki, K.; Fujiwara, Y. Tetrahe-
dron Lett. 1994, 35, 7789. (b) Gretz, E.; Vetter, W. M.; Stecher, H. A.;
Sen, A. Isr. J . Chem. 1990, 30, 327.
(6) Hase, T. A. Umpoled synthons; Wiley: New York, 1987.
(7) (a) Hou, Z.; Yamazaki, H.; Fujiwara, Y.; Taniguchi, H. Organo-
metallics 1992, 11, 2711. (b) Hou, Z.; Yamazaki, H.; Kobayashi, K.;
Fujiwara, Y.; Taniguchi, H. J . Chem. Soc., Chem. Commun. 1992, 722.
(8) (a) Hou, Z.; Takamine, K.; Aoki, O.; Shiraishi, H.; Fujiwara, Y.;
Taniguchi, H. J . Chem. Soc., Chem. Commun. 1988, 688. (b) Hou, Z.;
Takamine, K.; Aoki, O.; Shiraishi, H.; Fujiwara, Y.; Taniguchi, H. J .
Org. Chem. 1988, 53, 6077.
(10) Makioka, Y.; Tsuno, M.; Uebori, S.; Taniguchi, Y.; Takaki, K.;
Fujiwara, Y. Chem. Lett. 1994, 611.
(11) Minoura, Y.; Tsuboi, S. J . Org. Chem. 1972, 37, 2064.
(12) (a) Baran, J .; Laszlo, P. Tetrahedron Lett. 1985, 42, 5135. (b)
Gattermann, L. Ber. Dtsch. Chem. Ges. 1895, 28, 2869. (c) Alper, H.;
Ripley, S.; Prince, T. L. J . Org. Chem. 1983, 48, 250.
(9) (a) Takaki, K.; Tsubaki, U.; Tanaka, S.; Beppu, F.; Fujiwara,
Y.; Chem. Lett. 1990, 203. (b) Takaki, K.; Tanaka, S.; Fujiwara, Y.
Chem. Lett. 1991, 493.
0022-3263/96/1961-0372$12.00/0 © 1996 American Chemical Society

Notes
J . Org. Chem., Vol. 61, No. 1, 1996 373
Ta ble 1. Rea ction of Th ioben zop h en on e (1a ) w ith
Ytter biu m Meta l
Ta ble 2. Syn th esis of Dia r ylm eth a n es 3 fr om 1 a n d
Ytter biu m Meta la
product and yield (%)b
products (% yieldb)
Yb
T
time
(h)
entry
thioketone 1
entry solventa (equiv) (°C)
2a
3a
4a
5a
1
2
3
4
5
6
1b
1c
1d
1a
1e
1f
2b (0)
2c (0)
2d (15)
2a (0)
3b (22)
3c (53)
3d (67)
3a (80)
4b (73)
4c (44)
4d (9)
4a (0)
5b (0)
5c (0)
5d (0)
5a (9)
1
2
3
4
5
6
7
8
benzene
THF
THF
THF
THF
benzene
THF
benzene
1
1
1
1
2
2
1
1
rt
rt
0
2
2
3
72
65
81
94
20
0
8
17
10
3
72
80
40
7
13
0
0
0
0
0
17
64
7
16
7
3
8
9
7
5
c
-35
4
-
-
c
rt
rt
20
20
2
a
Conditions: Yb (2 equiv), benzene-HMPA (4:1), rt, 20 h.
Isolated yields for entries 1 and 2 and GC yields for entries 3
reflux
reflux
32
12
b
2
and 4. c No reaction.
a
b
HMPA was contained as a cosolvent. GC yield based on 1a .
Ta ble 3. Syn th esis of Tetr a a r yleth en es 4 fr om 1 a n d
Ytter biu m Meta la
Sch em e 1
products (% yieldb)
entry
thioketone 1
1
2
3
4
5
6
1b
1c
1d
1a
1e
1f
2b (0)
2c (0)
2d (0)
2a (7)
3b (8)
3c (4)
3d (12)
3a (12)
4b (71)
4c (53)
4d (62)
4a (64)
5b (0)
5c (0)
5d (0)
5a (5)
c
c
-
-
a
Conditions: Yb (1 equiv), benzene-HMPA (4:1), reflux, 2 h.
b
Isolated yields for entries 1 and 2 and GC yields for entries 3
and 4. c Complex reactions occurred.
oxalic amides are formed by the reduction of isocyanates.
This peculiar reactivity of lanthanoids to carbon-sulfur
double bonds is due to their strong reducing ability and
thiophilicity.
Other diaryl thioketones could also be desulfurized by
lanthanoid metals to give diarylmethanes 3 and tet-
raarylethenes 4, depending on their substituents and
reaction conditions. Results of the reaction of diaryl
thioketones 1a -f with excess amounts of ytterbium
metal are listed in Table 2. Yields of diarylmethane 3
decrease as the substituents become more electron
donating (entries 1-4). In particular, 4b was predomi-
nantly obtained in 73% yield in spite of the treatment of
1b with 2 equiv of ytterbium (entry 1). Diaryl thioke-
tones 1e and 1f, having chloro and fluoro groups, did not
react with ytterbium and were recovered quantitatively.
Table 3 summarizes the results on the desulfurizative
homocoupling reaction of 1a -f under the refluxing condi-
tions. In all cases except 1e and 1f, 4a -d were formed
predominantly in good yields. The substituent effects
shown in Tables 2 and 3 are completely opposite to those
of copper-mediated desulfurizative homocoupling of dia-
ryl thioketones affording symmetrical olefins 4, in which
thiopinacol coupling and subsequent desulfurization were
proposed as a reaction mechanism. Interestingly, 4a and
3a were obtained in 66 and 30% yields, respectively, by
heating the ytterbium-thiobenzophenone dianionic in-
termediate A formed at -35 °C, while it was converted
to 2a , not to the thiopinacol, on quenching with H2O at
this temperature as described above. Thus, the present
desulfurizative homocoupling could be promoted by C-S
bond cleavage of intermediate A followed by dimerization
of the unstable diarylcarbene intermediate.14,15
Sch em e 2
yields, respectively, along with decreased amounts of 3a
(24%). A similar result was obtained by exposing the
same mixture to air. Thus, the desulfurization process,
leading to B via A, is electronically reversible, although
1a was not regenerated quantitatively.7a
With respect to the products and their selectivity, these
results are quite different from those of the reaction of
benzophenone with ytterbium metal as previously re-
ported.7a Only diphenylmethanol was obtained from
benzophenone quantitatively by the stoichiometric reac-
tion in THF-HMPA, while deoxygenative reductions of
the ketone to 3a using excess amounts of ytterbium
resulted in lower yield (13%). Furthermore, neither 4a
nor 5a is formed in the reaction of benzophenone with
ytterbium metal under similar conditions. This feature
was also observed in the reduction of heterocumulenes
with a lanthanoid reagent.13 Samarium(II) iodide de-
sulfurizes isothiocyanates to give isocyanides, whereas
Formation of deuteriated 2a suggests the possibility
of nucleophilic coupling of diaryl thioketones with many
kinds of substrates. In fact, adducts are obtained from
(13) Liu, Y.-S; Bei, Z.-H.; Zhou, Z.-H. Chem. Lett. 1992, 1143.
(14) Attempts to capture the carbene intermediate with various
olefinic compounds failed.
(15) The product 5a was formed by the reduction of 4a with low-
valent ytterbium species: Hou, Z.; Taniguchi, H.; Fujiwara, Y. Chem.
Lett. 1987, 305.

374 J . Org. Chem., Vol. 61, No. 1, 1996
Notes
Ta ble 4. Cou p lin g Rea ction of Th iok eton e 1 w ith
Va r iou s Electr op h iles
benzophenone ketyl and distilled under argon. Hexameth-
ylphosphoramide (Caution: HMPA is highly toxic and suspected
of being a carcinogen) was dried over CaH2 at 100 °C and
distilled under reduced pressure. Diaryl thioketones 1a -f were
prepared according to the reported method17 and purified by
bulb-to-bulb distillation or recrystallization from ether/n-hexane.
Gen er a l P r oced u r e for th e Rea ction of Th ioben zop h e-
n on e (1a ) w ith Ytter biu m Meta l. All reactions were carried
out under argon. Ytterbium (173 mg, 1.0 mmol) was placed in
a 10-mL round-bottomed flask equipped with a rubber septum
and a reflux condenser, if necessary. HMPA (1 mL) was added,
and then methyl iodide (2 µL) was added to activate the
products
entry thioketone 1 electrophile time (h)
(% yield)a
1
2
3
4
5
6
7
8
1a
1b
1a
1a
1b
1a
1b
1a
MeI
MeI
EtBr
Br(CH2)2Br
Br(CH2)2Br
Br(CH2)3Br
Br(CH2)3Br
(CH3)2CO
0.5
0.5
5
5
5
4
4
0.5
6a (82)
6b (39), 7 (40)
6c (84)
8a (74)
8b (50)
8c (66)
8d (51)
9 (72)
ytterbium. After
a few minutes of stirring, a solution of
a
thiobenzophenone (198 mg, 1.0 mmol) in benzene (4 mL) was
added via cannula under argon. The reaction mixture was
stirred for an appropriate time after the reaction started. The
reaction mixture was treated with 2 M HCl (5 mL) and extracted
with diethyl ether (3 × 30 mL). The organic layer was washed
with saturated aqueous NaCl solution and dried over anhydrous
magnesium sulfate. Yields of the products were determined by
GC using n-tetracosane as an internal standard. The products
were isolated by liquid chromatography (silica gel, n-hexane/
ethyl acetate, 100/1) after the solvent was evaporated in vacuo.
The same scale reaction was also carried out in THF (6 mL)-
HMPA (3 mL). Reactions with samarium and other alkali or
alkaline earth metals were performed in a similar manner. The
amounts of ytterbium, reaction temperatures, and yields of the
products 2-5a are shown in Table 1.
GC yield based on the diaryl thioketone 1.
1a ,b and various electrophiles (eq 1 and Table 4).
Dip h en ylm eth a n eth iol (2a ):18 colorless liquid; IR (neat)
2550, 1590 cm-1; MS m/ z 167 (Ph2CH+); 1H NMR (CDCl3) δ 2.26
(d, J ) 5.0 Hz, 1 H), 5.44 (d, J ) 5.0 Hz, 1 H), 7.19-7.42 (m, 10
H); 13C NMR (CDCl3) δ 47.8 (1 C), 127.2 (2 C), 127.8 (4 C), 128.5
(4 C), 143.4 (2 C).
Dip h en ylm eth a n e (3a ):19 colorless liquid; MS m/ z 168 (M+);
1H NMR (CDCl3) δ 3.98 (s, 2 H), 7.17-7.31 (m, 10 H); 13C NMR
(CDCl3) δ 41.9 (1 C), 126.0 (2 C), 128.4 (4 C), 128.9 (4 C), 141.1
(2 C).
Tetr a p h en yleth en e (4a ):20 colorless crystals; mp 224-225
°C (lit.20 mp 223-224 °C); IR (Nujol) 3040, 1590 cm-1; MS m/ z
332 (M+); 1H NMR (CDCl3) δ 7.06 (br-s, 20 H); 13C NMR (CDCl3)
δ 126.4 (8 C), 127.6 (4 C), 131.3 (8 C), 141.0 (2 C), 143.7 (4 C).
1,1,2,2-Tetr a p h en yleth a n e (5a ):21 colorless crystals; mp
208-209 °C (lit.21 mp 210 °C); IR (Nujol) 3085, 1598 cm-1; MS
Reaction of 1a with alkyl monohalides produced C- and
S-alkylated thiobenzophenone derivatives 6 in high yields
(entries 1 and 3).16 Thianes 8a ,b and thiolanes 8c,d , five-
and six-membered cyclic sulfides, were provided from
R,ω-dihaloalkanes (entries 4-7). These results also
support the existence of intermediate A. As shown in
entry 8, acetone reacted with dianionic thiobenzophenone
to afford the â-hydroxy thiol 9 in good yield.
In conclusion, reaction of diaryl thioketones with
lanthanoid metals (Yb, Sm) affords mainly three types
of compounds: (1) adducts 6-10 by the coupling reactions
of lanthanoid-diaryl thioketones dianionic intermediates
with electrophiles, (2) diarylmethanes by four-electron
reduction of diaryl thioketones 1, and (3) tetraarylethenes
by desulfurizative homocoupling of 1. It is worth noting
that each of these compounds can be selectively obtained
by choosing the reaction conditions. Further synthetic
applications of these reactions are now underway.
1
m/ z 334 (M+); H NMR (CDCl3) δ 4.69 (s, 2 H), 6.92-7.25 (m,
20 H); 13C NMR (CDCl3) δ 59.7 (2 C), 127.5 (4 C), 128.4 (8 C),
128.9 (8 C), 140.2 (4 C).
Tr ea tm en t of th e In ter m ed ia tes w ith D2O. The inter-
mediates were prepared as mentioned above under the condi-
tions shown in Scheme 2. To the solution of the intermediates,
was added 1.0 mL of D2O. Yields of the products were
determined by GC after the usual workup. Deuterium contents
were determined by 1H NMR spectra of the isolated products in
CCl4.
Oxidation of th e In ter m ediates. The intermediates formed
by the reaction of 1 (1 mmol) with ytterbium (2 mmol) were
oxidized by adding benzil (5 mmol) or exposing the reaction
mixture to air. Yields of the products were determined by GC
as above after the usual workup.
Rea ction of Dia r yl Th iok eton e 1 w ith Ytter biu m : Syn -
th esis of Dia r ylm eth a n es. Reactions were performed as
mentioned above, except 2 equiv (2 mmol) of ytterbium was used
and the reaction time was longer (20 h). Results are listed in
Table 2.
Bis(4-(dim eth ylam in o)ph en yl)m eth an e (3b):22 yellow crys-
tals; mp 88-89 °C (lit.22 mp 90 °C); 1H NMR (C6D6) δ 2.58 (s, 12
H), 3.97 (s, 2 H), 6.68 (d, J ) 8.6 Hz, 4 H), 7.22 (d, J ) 8.6 Hz,
4 H); 13C NMR (C6D6) δ 40.0 (4 C), 40.6 (1 C), 113.3 (4 C), 128.5
(2 C), 130.8 (4 C), 149.5 (2 C).
Exp er im en ta l Section
Gen er a l. 1H and 13C NMR spectra were recorded at 270
MHz, and chemical shifts are reported in ppm on the δ scale
relative to internal TMS. GC analyses were carried out on a 1
m × 3.2 mm i.d. column of 2% silicon OV-17 on 60-80 mesh
Uniport HP. Mass spectra were obtained at 70 eV. Melting
points are uncorrected.
Ma ter ia ls. Materials were commercially available unless
otherwise noted. Ytterbium and samarium (40 mesh) were
washed with anhydrous n-hexane and were dried in vacuo for 3
days. Benzene and tetrahydrofuran were dried with sodium
(17) Pedersen, B. S.; Scheibye, S.; Nilson, N. H.; Lawesson, S.-O.
Bull. Soc. Chim. Belg. 1978, 87, 223.
(18) Nishio, T. J . Chem. Soc., Perkin Trans. 1 1993, 1113.
(19) Onaka, M.; Higuchi, K.; Nanami, H.; Izumi, Y. Bull. Chem. Soc.
J pn. 1993, 66, 2638.
(20) Whitlock, H. W., J r. J . Am. Chem. Soc. 1962, 84, 2807.
(21) Talapatra, S. K.; Chakrabarti, S.; Mallik, A. K.; Talapatra, B.
Tetrahedron 1990, 46, 6047.
(16) Treatment of B with methyl iodide afforded the 2, 2-diphenyl-
propane in 14% yield together with 6a in 11%.
(22) Faydh, J . M.; Swan, G. A. J . Chem. Soc. C 1969, 1775.

Notes
J . Org. Chem., Vol. 61, No. 1, 1996 375
1
Bis(4-m eth oxyp h en yl)m eth a n e (3c):19 colorless needles;
(neat) 3050 cm-1; MS m/ z 226 (M+ - Et), 195 (M+ - SEt); H
1
mp 45-46 °C (lit.19 mp 49.0-50.0 °C); H NMR (CDCl3) δ 3.76
NMR (CDCl3) δ 0.80 (t, J ) 7.4 Hz, 3 H), 1.03 (t, J ) 7.4 Hz, 3
H), 2.08 (q, J ) 7.4 Hz, 2 H), 2.36 (q, J ) 7.4 Hz, 2 H), 7.00-
7.50 (m, 10 H); 13C NMR (CDCl3) δ 9.4 (1 C), 13.5 (1 C), 23.0 (1
C), 33.0 (1 C), 60.8 (1 C), 126.2 (4 C), 127.9 (4 C), 128.6 (2 C),
145.3 (2 C). Anal. Calcd for C17H20S: C, 79.63; H, 7.86.
Found: C, 79.53; H, 7.73.
(s, 6 H), 3.85 (s, 2 H), 6.81 (d, J ) 8.6 Hz, 4 H), 7.08 (d, J ) 8.6
Hz, 4 H); 13C NMR (CDCl3) δ 40.1 (1 C), 55.2 (2 C), 113.8 (4 C),
129.7 (4 C), 133.7 (2 C), 157.8 (2 C).
Bis(4-m eth ylp h en yl)m eth a n e (3d ):23 colorless oil; MS m/ z
196 (M+); 1H NMR (CDCl3) δ 2.30 (s, 6 H), 3.89 (s, 2 H), 7.07 (s,
8 H); 13C NMR (CDCl3) δ 21.0 (2 C), 41.0 (1 C), 128.7 (4 C), 129.1
(4 C), 135.4 (2 C), 138.3 (2 C).
Bis(4-m eth ylp h en yl)m eth yl m eth yl su lfid e (7): colorless
oil; IR (neat) 3020, 2920, 1432, 1310 cm-1; MS m/ z 195 (M+
-
SMe), 91 (p-tol+); 1H NMR (CDCl3) δ 1.97 (s, 3 H), 2.31 (s, 6 H),
4.99 (s, 1 H), 7.11 (d, J ) 8.1 Hz, 4 H), 7.29 (d, J ) 8.1 Hz, 4 H);
13C NMR (CDCl3) δ 15.9 (1 C), 21.0 (2 C), 55.5 (1 C), 128.1 (4 C),
129.2 (4 C), 136.7 (2 C), 138.4 (2 C). Anal. Calcd for C16H18S:
C, 79.29; H, 7.49. Found: C, 79.17; H, 7.49.
Bis(4-m eth ylp h en yl)m eth a n eth iol (2d ): colorless oil; IR
1
(neat) 2556, 1510 cm-1; MS m/ z 228 (M+); H NMR (CDCl3) δ
2.22 (d, J ) 4.8 Hz, 1 H), 2.31 (s, 6 H), 5.38 (d, J ) 4.8 Hz, 1 H),
7.10 (d, J ) 7.9 Hz, 4 H), 7.28 (d, J ) 7.9 Hz, 4 H); 13C NMR
(CDCl3) δ 21.0 (2 C), 47.3 (1 C), 127.6 (4 C), 129.2 (4 C), 136.8 (2
C), 140.7 (2 C). Anal. Calcd for C15H16S: C, 78.90; H, 7.06.
Found: C, 78.82; H, 7.04.
2,2-Dip h en ylth iola n e (8a ): white needles; mp 71-72 °C; IR
(Nujol) 3054 cm-1; 1H NMR (CDCl3) δ 2.02 (quin, J ) 6.6 Hz, 2
H), 2.66 (t, J ) 6.6 Hz, 2 H), 3.09 (t, J ) 6.6 Hz, 2 H), 7.14-7.45
(m, 10 H); 13C NMR (CDCl3) δ 28.5 (1 C), 32.9 (1 C), 44.1 (1 C),
67.8 (1 C), 126.3 (2 C), 127.5 (4 C), 128.0 (4 C), 146.9 (2 C). Anal.
Calcd for C16H16S: C, 79.95; H, 6.71. Found: C, 79.86; H, 6.53.
2,2-Bis(4-m eth ylp h en yl)th iola n e (8b): colorless crystals;
mp 48-49 °C; IR (Nujol) 3018, 1504 cm-1; MS m/ z 268 (M+);
1H NMR (CDCl3) δ 2.01 (quin, J ) 6.9 Hz, 2 H), 2.29 (s, 6 H),
2.62 (t, J ) 6.9 Hz, 2 H), 3.07 (t, J ) 6.9 Hz, 2 H), 7.06 (d, J )
8.1 Hz, 4 H), 7.31 (d, J ) 8.1 Hz, 4 H); 13C NMR (CDCl3) δ 20.9
(2 C), 28.5 (1 C), 32.9 (1 C), 44.2 (1 C), 67.4 (1 C), 127.3 (4 C),
128.7 (4 C), 135.8 (2 C), 144.1 (2 C). Anal. Calcd for C18H20S:
C, 80.54; H, 7.51. Found: C, 80.51; H, 7.51.
2,2-Dip h en ylth ia n e (8 C): white needles; mp 72-73 °C; IR
(Nujol) 1590 cm-1; MS m/ z 254 (M+); 1H NMR (CDCl3) δ 1.58-
1.65 (m, 2 H), 1.78-1.87 (m, 2 H), 2.64 (t, J ) 5.6 Hz, 2 H), 2.76
(t, J ) 5.8 Hz, 2 H), 7.16-7.50 (m, 10 H); 13C NMR (CDCl3) δ
22.5 (1 C), 26.7 (1 C), 28.9 (1 C), 38.7 (1 C), 54.9 (1 C), 126.5 (2
C), 128.0 (4 C), 128.3 (4 C), 145.2 (2 C). Anal. Calcd for
Rea ction of Dia r yl Th iok eton e 1 w ith Ytter biu m : Syn -
th esis of Tetr a a r yleth en es. The procedure was similar to the
general procedure for the reaction of thiobenzophenone 1a with
ytterbium except for carrying out the reaction at reflux temper-
ature for 2 h. Yields of 4a and 4b were determined by GC, as
above, but yields of 4c and 4d were reported as isolated. Results
are listed in Table 3.
Tetr a k is(4-(d im eth yla m in o)p h en yl)eth en e (4b): yellow
crystals; mp 282-283 °C dec; IR (Nujol) 1347 cm-1 1H NMR
;
(C6D6) δ 2.48 (s, 24 H), 6.52 (d, J ) 8.9 Hz, 8 H), 7.51 (d, J ) 8.9
Hz, 8 H); 13C NMR (C6D6) δ 40.0 (8 C), 112.2 (8 C), 133.2 (8 C),
134.6 (4 C), 138.1 (2 C), 148.8 (4 C). Anal. Calcd for C34H40N2:
C, 80.91; H, 7.99; N, 11.10. Found: C, 80.76; H, 7.94; N, 10.86.
Tetr a k is(4-m eth oxyp h en yl)eth en e (4 C):12b colorless crys-
1
tals; mp 182-183 °C (lit.12b mp 181-182 °C); H NMR (CDCl3)
δ 3.73 (d, 12 H), 6.33 (d, J ) 8.9 Hz, 8 H), 6.93 (d, J ) 8.9 Hz,
8 H); 13C NMR (CDCl3) δ 55.0 (4 C), 113.0 (8 C), 132.5 (8 C),
136.9 (4 C), 138.3 (2 C), 157.7 (4 C).
Tetr a k is(4-m eth ylp h en yl)eth en e (4d ):24 colorless crystals;
C
17H18S: C, 80.26; H, 7.13. Found: C, 79.80; H, 6.78.
1
mp 151-153 °C (lit.24 mp 151 °C); MS m/ z 388 (M+); H NMR
(CDCl3) δ 2.25 (s, 12 H), 6.87 (s, 16 H); 13C NMR (CDCl3) δ 21.2
(4 C), 128.3 (8 C), 131.2 (8 C), 135.6 (4 C), 139.8 (2 C), 141.3 (4
C).
2,2-Bis(4-m eth ylp h en yl)th ia n e (8d ): colorless crystals; mp
66-68 °C; IR (Nujol) 3021, 1508 cm-1; MS m/ z 282 (M+); 1H
NMR (CDCl3) δ 1.59 (m, 2 H), 1.80 (m, 2 H), 2.30 (s, 6 H), 2.61
(m, 2 H), 2.71 (m, 2 H), 7.10 (d, J ) 8.3 Hz, 4 H), 7.26 (d, J )
8.3 Hz, 4 H); 13C NMR (CDCl3) δ 20.9 (2 C), 22.6 (1 C), 26.7 (1
C), 28.9 (1 C), 38.7 (1 C), 54.5 (1 C), 127.8 (4 C), 129.0 (4 C),
136.0 (2 C), 142.4 (2 C). Anal. Calcd for C19H22S: C, 80.80; H,
7.85. Found: C, 80.94; H, 7.75.
Cou p lin g Rea ction s of Dia r yl Th iok eton es 1 w ith Alk yl
Ha lid es. After the treatment of ytterbium (1.0 mL) with 1 (1.0
mmol) in THF (6 mL) and HMPA (3 mL) at 0 °C for 3 h, an
alkyl halide (2.7 mmol) was added to the mixture. Stirring was
continued at 0 °C for an appropriate time as indicated in Table
4. The usual workup followed by liquid chromatography (silica
gel, n-hexane/ethyl acetate, 100/1) gave the alkylated products.
Yields of the products were determined by GC using n-undecane
as an internal standard.
1,1-Dip h en yleth yl m eth yl su lfid e (6a ): colorless oil; IR
(neat) 3056 cm-1; MS m/ z 228 (M+); 1H NMR (CDCl3) δ 1.83 (s,
3 H), 2.04 (s, 3 H), 7.20-7.50 (m, 10 H); 13C NMR (CDCl3) δ
13.2 (1 C), 29.6 (1 C), 55.4 (1 C), 126.5 (2 C), 127.9 (4 C), 128.0
(4 C), 145.9 (2 C). Anal. Calcd for C15H16S: C, 78.90; H, 7.06.
Found: C, 78.90; H, 7.03.
1,1-Bis(4-m eth ylp h en yl)eth yl m eth yl su lfid e (6b): color-
less oil; IR (neat) 3000, 2950, 1437, 1305 cm-1; MS m/ z 209 (M+
- Me), 91 (p-tol+); 1H NMR (CDCl3) δ 1.82 (s, 3 H), 2.01 (s, 3
H), 2.33 (s, 6 H), 7.10 (d, J ) 5.8 Hz, 4 H), 7.28 (d, J ) 5.8 Hz,
4 H); 13C NMR (CDCl3) δ 13.2 (1 C), 20.9 (2 C), 29.7 (1 C), 54.9
(1 C), 127.8 (4 C), 128.7 (4 C), 136.1 (2 C), 143.1 (2 C). Anal.
Calcd for C17H20S: C, 79.63; H, 7.86. Found: C, 79.52; H, 7.82.
1,1-Dip h en ylp r op yl eth yl su lfid e (6c): colorless oil; IR
Cou p lin g R ea ct ion of Th iob en zop h en on e (1a ) w it h
Aceton e. After the reaction of ytterbium (1.0 mmol) with 1a
(1.0 mmol) in THF (6 mL) and HMPA (3 mL) at 0 °C for 3 h,
acetone (0.2 mL, 2.7 mmol) was added. Stirring was continued
at 0 °C for 0.5 h. After the usual workup, 1,1-diphenyl-2-
hydroxy-2-methylpropanethiol (9) was isolated by liquid chro-
matography (silica gel, n-hexane/ethyl acetate, 100/1) as a
colorless oil: IR (neat) 3470, 2500 cm-1; MS m/ z 208 (Ph2-
CCMe2+), 59 (Me2COH+); 1H NMR (CDCl3) δ 1.38 (s, 6 H), 2.34
(s, 1 H), 2.93 (br s, 1 H), 7.00-8.00 (m, 10 H). Anal. Calcd for
C
16H18OS: C, 74.37; H, 7.02. Found: C, 74.34; H, 6.94.
Ack n ow led gm en t. The present work was supported
by a Grant-in-Aid for Scientific Research on Priority
Areas of Reactive Organometallics No. 05236106 from
The Ministry of Education, Science and Culture, J apan.
Y.M. gratefully acknowledges the Research Fellowships
of the J apan Society for the Promotion of Science for
Young Scientists.
(23) Bank, S.; Schepartz, A.; Giammatteo, P.; Zubieta, J . J . Org.
Chem. 1983, 48, 3458.
(24) Bethell, D.; Callister, J . D. J . Chem. Soc. 1963, 3810.
J O951355H