Palladium-catalyzed azathiolation of carbon monoxide

Article abstract of DOI:10.1021/jo9823137

A novel palladium-catalyzed azathiolation of carbon monoxide using sulfenamide (RSNR'₂) (1) is described to provide thiocarbamate 2 in good yields. The mechanistic proposal includes the following: (1) insertion of CO into Pd-S bond of Pd(SR)₂(PPh₃)(n) 4 to provide Pd[C(O)SR](SR)(PPh₃)(n) 5 and (2) σ-bond metathesis between S-N and Pd-C(O) bonds to afford 2 with the regeneration of 4.

Full text of DOI:10.1021/jo9823137

J . Org. Chem. 1999, 64, 7305-7308
7305
P a lla d iu m -Ca ta lyzed Aza th iola tion of Ca r bon Mon oxid e
Hitoshi Kuniyasu,* Hiroshi Hiraike, Masaki Morita, Aoi Tanaka, Kunihiko Sugoh, and
Hideo Kurosawa*
Department of Applied Chemistry, Faculty of Engineering, Osaka University, Suita,
Osaka 565-0871, J apan
Received November 24, 1998
A novel palladium-catalyzed azathiolation of carbon monoxide using sulfenamide (RSNR′2) (1) is
described to provide thiocarbamate 2 in good yields. The mechanistic proposal includes the
following: (1) insertion of CO into Pd-S bond of Pd(SR)2(PPh3)n 4 to provide Pd[C(O)SR](SR)-
(PPh3)n 5 and (2) σ-bond metathesis between S-N and Pd-C(O) bonds to afford 2 with the
regeneration of 4.
Ta ble 1. Effects of Ca ta lyst a n d Solven t on th e Rea ction
of 1a w ith COa
In tr od u ction
A variety of transition-metal-catalyzed reactions of
Y-G (Y ) S, Se) bond compounds with unsaturated
compounds such as acetylenes and CO have been devel-
oped lately, in which the polarity of Y-G is Yδ--Gδ+ (G
) H,1,2 Si,3 Ge,3 B,4 and P5) or neutral (G ) S,6 Se6). These
have served as a useful strategy in organic synthesis and
stimulated further study to uncover the hidden reactivity
of chalcogenates on metals.7 Herein described is a novel
metal-catalyzed azathiolation of carbon monoxide using
sulfenamide (RSNR′2) (1) whose unique Sδ+-Nδ- bond
character is a stereoelectronic component of the reac-
tion.8,9
run
catalyst
solvent
yieldb (%)
1
2
3
4
5
6
7
Pd(PPh3)4
Pd2(dba)3
Rh(PPh3)3Cl
Pd(PPh3)4
Pd(PPh3)4
Pd(PPh3)4
Pd(PPh3)4
pyridine
pyridine
pyridine
none
90c
29
67c
3
6
11
48
C6H6
C6H6
d
e
C6H6
a
b
1a (1 mmol), CO (20 kg/cm2), and solvent (0.5 mL). NMR
yield. c Isolated yield. With 0.05 mmol of pyridine. e With 1 mmol
d
of pyridine.
cm2) was catalyzed by 5 mol % of Pd(PPh3)4 in pyridine
(0.5 mL) at 80 °C for 10 h to provide N-diethyl phenyl-
thiocarbamate 2a in 90% yield (eq 1, run 1 of Table 1).
Resu lts a n d Discu ssion
We have found that the reaction of S-phenyl-N-dieth-
ylsulfenamide PhSNEt2 (1a ) (1 mmol) with CO (20 kg/
(1) (a) Dzhemilev, U. M.; Kunakova, R. V.; Gaisin, R. L. Izv. Akad.
Nauk SSSR, Ser. Khim. 1981, 11, 2655. (b) Kuniyasu, H.; Ogawa, A.;
Sato, K.; Ryu, I.; Kambe, N.; Sonoda, N. J . Am. Chem. Soc. 1992, 114,
5902. (c) Ba¨ckvall, J . E.; Ericsson, A. J . Org. Chem. 1994, 59, 5850.
(d) Ogawa, A.; Takeba, M.; Kawakami, J .; Ryu, I.; Kambe, N.; Sonoda,
N. J . Am. Chem. Soc. 1995, 117, 7564. (e) Ogawa, A.; Kawakami, J .;
Sonoda, N.; Hirao, T. J . Org. Chem. 1996, 61, 4161. (f) Xiao, W. J .;
Alper, H. J . Org. Chem. 1997, 62, 3422. (g) Ogawa, A.; Kawakami, J .;
Mihara, M.; Ikeda, T.; Sonoda, N.; Hirao, T. J . Am. Chem. Soc. 1997,
119, 12380. (h) Xiao, W. J .; Vasapollo, G.; Alper, H. J . Org. Chem. 1998,
63, 2609. (i) Ogawa, A.; Kawabe, K.; Kawakami, J .; Mihara, M.; Hirao,
T.; Sonoda, N. Organometallics 1998, 17, 3111. (j) Xiao, W. J .;
Vasapollo, G.; Alper, H. J . Org. Chem. 1999, 64, 2080. (k) Ogawa, A.;
Ikeda, T.; Kimura, K.; Hirao, T. J . Am. Chem. Soc. 1999, 121, 5108.
(2) (a) Kuniyasu, H.; Ogawa, A.; Sato, K.; Ryu, I.; Sonoda, N.
Tetrahedron Lett. 1992, 33, 5525. (b) Ogawa, A.; Kudo, A.; Hirao, T.
Tetrahedron Lett. 1998, 39, 5213.
(3) (a) Ogawa, A.; Kuniyasu, H.; Takeba, M.; Ikeda, T.; Sonoda, N.;
Hirao, T. J . Organomet. Chem. 1998, 564, 1. (b) Han, L.; Tanaka, M.
J . Am. Chem. Soc. 1998, 120, 8249.
(4) Ishiyama, T.; Nishijima, K.; Miyaura, N.; Suzuki, A. J . Am.
Chem. Soc. 1993, 115, 7219.
(5) Han, L.; Choi, N.; Tanaka, M. J . Am. Chem. Soc. 1996, 118, 7000.
(6) (a) Dzhemilev, U. M.; Kunakova, R. V.; Baibulatova, N. Z.;
Mustafina, E. M.; Galkin, E. G.; Tolstikov, G. A. Izv. Akad. Nauk SSSR,
Ser. Khim. 1989, 3, 747. (b) Kuniyasu, H.; Ogawa, A.; Miyazaki, S.;
Ryu, I.; Kambe, N.; Sonoda, N. J . Am. Chem. Soc. 1991, 113, 9796. (c)
Ogawa, A.; Kuniyasu, H.; Sonoda, N.; Hirao, T. J . Org. Chem. 1997,
62, 8361. (d) Gareau, Y.; Orellana, A. Synlett. 1997, 803. (e) Kondo,
T.; Uenoyama, S.; Fujita, K.; Mitudo, T. J . A. Chem. Soc. 1999, 121,
482.
The formation of 3% of Et2NH and 1.4% of [Et2NC(O)]2
was also confirmed by the 1H NMR spectrum of the crude
reaction mixture. The reaction was also catalyzed by Pd2-
(dba)3 (29%) and Rh(PPh3)3Cl (67%) in pyridine (runs 2
and 3). Reactions performed in benzene, CH3CN, DMSO,
HMPA, Et3N, and N-methylmorpholine or without sol-
vent only ended in producing a poor yield of 2a (runs 4
and 5 as examples). Pyridine was indispensable as a
solvent for completion of the reaction under the condi-
tions employed (runs 6 and 7). Among the catalysts
examined, Pt(PPh3)4, Ni(PPh3)2Cl2, Ru3(CO)12, Re2(CO)10,
and W(CO)6 were hardly active even in pyridine.
The result of the reactions of some sulfenamides with
CO was summarized in Table 2. The reaction using
p-tolSNEt2 (1b) was not completed in 10 h (run 1), but
was after 20 h to afford 86% of 2b (run 2). On the other
hand, p-ClC6H4SNEt2 (1c), p-FC6H4SNEt2 (1d ), and
m-MeOC6H4SNEt2 (1e) reacted faster than 1a to give
good yields of 2 (5 h for 2c (85%) and 2d (84%); 3 h for
2e (81%), runs 3-5). Replacement of ArS by benzyl-S-
(1f) and BuS- (1g) retarded carbonylation; more severe
reaction conditions (100 °C, 20 h) were required to
provide 26% and 43% of thiocarbamate, respectively
(runs 6 and 7). The reactions using ArSNMe2 proceeded
faster than that of ArSNEt2, and were completed within
(7) (a) Mann, G.; Baran˜ano, D.; Hartwig, J . F.; Rheingold, A. L.;
Guzei, I. A. J . Am. Chem. Soc. 1998, 120, 9205. (b) Baran˜ano, D.;
Hartwig, J . F. J . Am. Chem. Soc. 1995, 117, 2937.
(8) For a review of sulfenamides, see: Craine, L.; Raban, M. Chem.
Rev. 1989, 89, 689.
(9) Electronegativity (Pauling): S, 2.5; Se, 2.4; H, 2.1; Si, 1.8; Ge,
1.8; B, 2.0; P, 2.1; N, 3.0.
10.1021/jo9823137 CCC: $18.00 © 1999 American Chemical Society
Published on Web 09/11/1999

7306 J . Org. Chem., Vol. 64, No. 20, 1999
Kuniyasu et al.
Sch em e 2. P r op osed P r op a ga tion of
Ta ble 2. P a lla d iu m -Ca ta lyzed Aza th iola tion of COa
P d -Ca ta lyzed Aza th iola tion of CO
lyzed reaction of 1a with CO showed the formation of
[Pd(SPh)2(PPh3)]2 4a 12 in 56% yield after 3 h and 59%
yield after 10 h. (2) 4a was actually active as a catalyst
under the carbonylation of 1a to form 2a in 30% (5 mol
% of Pd, 80 °C, 10 h) or even 84% yield if 15 mol % of
PPh3 was added. (3) No formation of imine, which can
be generated from Pd-NR′2, was confirmed under the
reactions performed in Tables 1 and 2.13 (4) No reaction
was observed in the stoichiometric reaction of 1a with
Pd(PPh3)4 even at 80 °C for 12 h.
An alternative propagation shown in Scheme 2 involves
an insertion of CO into the Pd-S bond of 4 to provide
Pd[C(O)SR](SR) 514 followed by reaction with 1 to give 2
with regeneration of 4 (Scheme 2). According to this
mechanism, the RS group in 4 and the R′2N group of 1
are incorporated into newly forming 2. Indeed, when [Pd-
(Stol-p)2(PPh3)]2 4b was used as a catalyst in the reaction
of PhSNEt2 1a with CO, 83% of p-tolS of 4b was
converted into 2b at the beginning stage of the reaction
(eq 2). (Note that the carbonylation of 1b was slower than
that of 1a .) Although we were not able to confirm the
a
1 (1 mmol), CO (20 kg/cm2), and Pd(PPh3)4 (0.05 mmol) in
pyridine (0.5 mL) at 80 °C. Reaction times were roughly optimized.
Isolated yield. c NMR yield. 29% of 1b was recovered. e 100 °C.
b
d
f Et(H)NC(O)N(H)Et (3) (85%) and (PhS)2 (84%) were obtained.
g
30% of 3 was obtained.
Sch em e 1. An Un lik ely P a th of P d -Ca ta lyzed
Aza th iola tion of CO
formation of 5 even by the reaction of 4 with CO,15 the
reactivity of 5 with 1 in Scheme 2 was examined as
follows. When 1 equiv of PhSC(O)SPh 6 was added into
the pyridine solution of Pd(PPh3)4 in the presence of 5
equiv of 1h at -30 °C over 10 min, the formation of 80%
of 4a was confirmed by 31P NMR and 18% of 2h was
isolated by preparative TLC (eq 3).16 This fact clearly
3 h (compare run 1 in Table 1 with run 8, and run 3 with
run 9). When the reaction of PhSN(H)Et (1j) with CO
was carried out, 85% of Et(H)NC(O)N(H)Et 3 and 84%
of (PhS)2 were obtained after 1 h (run 10). No formation
of PhSC(O)N(H)Et (2j) was confirmed, even if the reac-
tion was stopped after 15 min (30% of 3) (run 11),
indicating that 2j formed in situ was very susceptible to
the nucleophilic substitution by 1j to afford 3 and (PhS)2.
While PhSN(allyl)2 (1k ) reacted with CO to furnish 83%
of 2k after 20 h (run 12), the reactions employing more
hindered PhSN(Pr-i)2 (1l) or PhSN(H)Ph (1m ) did not
take place even at 100 °C (runs 13 and 14).
With regard to the reaction mechanism of the present
Pd-catalyzed azathiolation of CO, a path involving oxida-
tive addition of 1 to Pd(0), insertion of CO into Pd-N
bond,10,11 and subsequent reductive elimination can be
envisioned (Scheme 1). However, this path is unlikely
judging from the following observations. (1) The 31P NMR
spectrum of crude reaction mixture of Pd(PPh3)4-cata-
indicated that some of short-lived Pd[C(O)SPh](SPh)-
(PPh3)n 5a generated by the oxidative addition of 6 to
Pd(0) was actually intercepted by 1h before deinsertion
of CO from 5a took place. A proposed transition state 7
in the reaction of 5 with 1 was shown in Scheme 3, in
which RS-NR′2 simultaneously interacted with both Pd
and electrophilic RSC(O) to provide the driving force of
(10) Alper et al. have reported the Co-catalyzed carbonylation of
thiazolidines, in which insertion of CO into the Co-N bond has been
proposed. See: Khumtaveeporn, K.; Alper, H. J . Am. Chem. Soc. 1994,
116, 5662.
(11) (a) Rahim, M.; Bushweller, C. H.; Ahmed, K. Organometallics
1994, 13, 4952. (b) Calet, S.; Urso, F.; Alper, H. J . Am. Chem. Soc.
1989, 111, 931. (c) Piotti, M. E.; Alper, H. J . Am. Chem. Soc. 1996,
118, 111. (d) Bryndza, H. E.; Fultz, W. C.; Tam, W. Organometallics
1985, 4, 939.
(12) Undetermined peaks suspected as more highly polymeric
complexes were also observed. (a) Rauchfuss, T. B.; Shu, J . S.; Rounhill,
D. M. Inorg. Chem. 1976, 15, 2096. (b) Schott, H.; Wilke, G. Angew.
Chem., Int. Ed. Engl. 1969, 8, 877. (c) Woodward, P.; Dahl, L. F.; Abel,
E. W.; Crosse, B. C. J . Am. Chem. Soc. 1965, 87, 5251.
(13) (a) Hartwig, J . F. Synlett 1996, 329. (a) Bryndza, H. E.; Tam,
W. Chem. Rev. 1988, 88, 1163. (b) Fryruk, M. D.; Montgomery, C. D.
Coord. Chem. Rev. 1989, 95, 1.

Palladium-Catalyzed Azathiolation of Carbon Monoxide
J . Org. Chem., Vol. 64, No. 20, 1999 7307
was purified by PTLC using Et2O/hexane (3/7) as an eluent.
A 188 mg (90%) of S-phenyl N-diethyl thiocarbamate 2a was
isolated as a clear colorless oil. Reactions listed in Table 2 were
carried out similarly. The reaction times in Table 2 were
roughly optimized (1, 2, 3, 5, 10, or 20 h). The NMR yields in
Tables 1 and 2 were determined from the crude reaction
mixture based on the relative ratio of 1, 2, Et2NH. The
substrates, catalysts, solvent, and yields of 2 were listed in
Tables 1 and 2.
Sch em e 3. P r op osed Tr a n sition Sta te
2a : colorless oil; 188 mg, 90%; registry no. of 2a (provided
by the author): 51861-23-5.
p-tol-SC(O)NEt2 (2b) (r u n 2 in Ta ble 2): colorless oil; 191
mg, 86%; 1H NMR (270 MHz, CDCl3) δ 1.22 (br, 6 H), 2.35 (s,
3 H), 3.42 (q, J ) 7.3 Hz, 4 H), 7.18 (d, J ) 7.8 Hz, 2 H) 7.38
(d, J ) 7.8 Hz, 2 H); 13C NMR (68 MHz, CDCl3) δ 13.69, 21.26,
42.45, 125.19, 129.65, 135.69, 139.16, 166.04; IR (NaCl) 2975,
1667, 1404, 1248, 1219, 1115, 1094, 808 cm-1; mass spectrum
(EI) m/e 223 (M+, 5). Anal. Calcd for C12H17NOS: C, 64.54; H,
7.67; N, 6.27; S, 14.36. Found: C, 64.48; H, 7.62, N, 6.46; S,
14.11.
the reaction.17 This process, facilitated by the electron-
withdrawing substituent in RSC(O) and suppressed by
the bulky group in R′2N, would determine the whole
reaction rate of Pd-catalyzed carbonylation of 1.
In conclusion, this paper reported a novel azathiolation
of carbon monoxide, demonstrating the efficiency of the
S-N bond compound as a substrate in transition-metal-
catalyzed reactions. Further study to develop a new
transformation using sulfenamide is currently underway.
p-Cl-C6H4SC(O)NEt2 (2c) (r u n 3 in Ta ble 2): colorless oil;
206 mg, 85%; registry no. of 2c (provided by the author):
51861-26-8.
p-F -C6H4SC(O)NEt2 (2d ) (r u n 4 in Ta ble 2): colorless oil;
191 mg, 84%; 1H NMR (270 MHz, CDCl3) δ 1.24 (br, 6 H), 3.41
(q, J ) 7.0 Hz, 4 H), 7.06 (t, J ) 7.8 Hz, J H-F ) 7.8 Hz, 2 H),
7.47 (dd, J ) 7.8 Hz, J H-F ) 5.4 Hz); 13C NMR (68 MHz, CDCl3)
δ 13.45 (br), 42.27, 42.37, 115.88 (d, J C-F ) 22.8 Hz), 124.06
(d, J C-F ) 2.7 Hz), 137.45 (d, J C-F ) 8.1 Hz), 161.42, 165.25
(d, J C-F ) 18.8 Hz); IR (NaCl) 2977, 1665, 1590, 1491, 1248,
1219, 1117, 831 cm-1; mass spectrum (EI) m/e 227 (M+, 5).
Anal. Calcd for C11H14FNOS: C, 6.21; H, 6.16; N, 6.16.
Found: C, 6.19; H, 6.19, N, 6.35.
Exp er im en ta l Section
Gen er a l Meth od s. 1H, 13C, and 31P NMR spectra in CDCl3
and benzene-d6 solution were recorded with a J EOL J NM-
GSX-270 (270 MHz) spectrometer. The chemical shifts in the
1H and 13C NMR spectra were recorded relative to Me4Si (or
C6H6 δ 7.16) and CDCl3 (δ 77.0), respectively. 31P NMR spectra
were recorded using 85% H3PO4 as an external standard. IR
spectra were recorded with
a Perkin-Elmer model 1600
spectrometer. Combustion analyses were performed in the
Instrumental Analysis Center of the Faculty of Engineering,
Osaka University. The synthesis and purification of substrates,
catalysts, and solvents are described in the Supporting Infor-
mation. Preparative TLC was carried out using Wakogel B-5F
silica gel.
m -MeOC6H4SC(O)NEt 2 (2e) (r u n 5 in Ta ble 2): colorless
oil; 195 mg, 81%; 1H NMR (270 MHz, CDCl3) δ 1.21 (br, 6 H),
3.42 (q, J ) 7.0 Hz, 4 H), 3.80 (s, 3 H), 6.92 (dd, J ) 5.9 Hz,
2.4 Hz, 1 H), 7.06-7.11 (m, 2 H), 7.29 (t, J ) 8.1 Hz, 1 H); 13
C
NMR (68 MHz, CDCl3) δ 13.29 (br), 42.23, 55.16, 55.24, 115.22,
120.57, 127.94, 129.45, 129.57, 159.46, 165.45; IR (NaCl) 2975,
1655, 1591, 1478, 1465, 1248, 1115, 853 cm-1; mass spectrum
(EI) m/e 239 (M+, 13). Anal. Calcd for C12H17NO2S: C, 60.22;
H, 7.16; N, 5.85; S, 13.40. Found: C, 60.29; H, 7.28; N, 5.86;
S, 13.37.
P a lla d iu m -Ca ta lyzed Aza th iola tion of Ca r bon Mon -
oxid e: Gen er a l P r oced u r e (Eq 1, Ta ble 1). P r ep a r a tion
of P h SC(O)NEt2 (2a ). Into a 50-mL stainless steel autoclave
were added S-phenyl-N-diethylsulfenamide 1a (181 mg, 1.0
mmol), Pd(PPh3)4 (58 mg, 0.05 mmol), and pyridine (0.5 mL).
Then the mixture was heated at 80 °C for 10 h under 20 kg/
P h SCH2C(O)NEt2 (2f) (r u n 6 in Ta ble 2): white solid; mp
30 °C; 57 mg, 26%; registry no. of 2f (provided by the author):
30085-50-8.
Bu SC(O)NEt2 (2g) (r u n 7 in Ta ble 2): colorless oil; 81
mg, 43%; registry no. of 2g (provided by the author): 91852-
97-0.
P h SC(O)NMe2 (2h ) (r u n 8 in Ta ble 2): colorless solid, mp
30 °C; 163 mg, 90%; registry no. of 2h (provided by the
author): 7304-68-9.
p-ClC6H4SC(O)NMe2 (2i) (r u n 9 in Ta ble 2): colorless
solid; mp 78 °C; 179 mg, 83%; registry no. of 2i (provided by
the author): 7304-69-0.
cm2 of carbon monoxide with magnetic stirring. The H NMR
1
spectrum of the crude homogeneous reaction mixture taken
in benzene-d6 showed the formation of 2a , 3% of Et2NH, and
1.4% of Et2NC(O)C(O)NEt2. The yield was determined from
the relative ratio of 2a , Et2NH, and [Et2NC(O)]2. The 31P NMR
spectrum showed the formation of [Pd(SPh)2(PPh3)]2 4a in 59%
yield (calculated based on all signals observed). The signals
of Et2NH, [Et2NC(O)]2, and 3a were assigned by the compari-
son with those of authentic samples. Then ca. 50 mL of hexane/
Et2O (1/1) was added into the crude reaction mixture, the
brown precipitate was removed through Celite, the residual
filtrate was concentrated in vacuo, and the residual mixture
P d -Ca ta lyzed Rea ction of P h SN(H)Et (1j) w ith CO
(Ru n s 10 a n d 11 in Ta ble 2). A 91 mg (84%) of (PhS)2 and
a 49 mg (85%) of Et(H)NC(O)N(H)Et (3) were isolated by
preparative TLC (80 °C, 1 h). When the reaction was carried
out at 80 °C for 15 min, the formation of 30% (relative to
(14) The definitive evidences of insertion of CO into the M-S bond
have been very rare. (a) Antebi, S.; Alper, H. Organometallics 1986,
5, 596. (b) Antebi, S.; Alper, H. Tetrahedron Lett. 1985, 26, 2609. (c)
Shim, S. C.; Antebi, S.; Alper, H. Tetrahedron Lett. 1985, 26, 1935. (d)
Takahashi, H.; Ohe, K.; Uemura, S.; Sugita, N. J . Organomet. Chem.
1987, 334, C43. (e) Wang, M. D.; Calet, S.; Alper, H. J . Org. Chem.
1989, 54, 20. (f) Kim, Y. J .; Osakada, K.; Sugita, K.; Yamamoto, T.;
Yamamoto, A. Organometallics 1988, 7, 2182. (g) Liu, H.; Tan, A. L.;
Mok, K. F.; Hor, T. S. A. J . Chem. Soc., Dalton Trans. 1996, 4023. (h)
Luh, T. Y.; Ni, Z. J . Synthesis 1990, 89. (i) Matsunaga, P. T.; Hillhouse,
G. L. Angew. Chem., Int. Engl. 1994, 33, 1748. (j) Khumtaveeporn, K.;
Alper, H. J . Org. Chem. 1994, 59, 1414. See also ref 1g and 6b.
(15) We have recently reported that the insertions of isocyanide into
Pd-S bond of 4 was reversible and its equilibrium leaned to the
deinsertion direction; see: Kuniyasu, H.; Sugoh, K.; Moon, S.; Kuro-
sawa, H. J . Am. Chem. Soc. 1997, 119, 4669.
1
unreacted 1j) of 3 was confirmed by the H NMR spectrum of
the crude reaction; however, no formation of PhSC(O)N(H)Et
(2j) was observed: mass spectrum of 3 (CI) m/e 171 (M + 1+,
100).
P h SC(O)N(a llyl)2 (2k ) (r u n 12 in Ta ble 2): colorless oil;
1
194 mg, 83%; H NMR (270 MHz, CDCl3) δ 4.01 (d, J ) 5.9
Hz, 4 H), 5.24 (br, 4 H), 5.81 (br, 2 H), 7.38 (m, 3 H), 7.51 (m,
2 H); 13C NMR (68 MHz, CDCl3) δ 39.45, 117.97, 128.43,
128.88, 129.13, 132.34, 135.19, 166.82; IR (NaCl) 1668, 1441,
1393, 1206, 980, 927, 750, 689 cm-1; mass spectrum (EI) m/e
233 (M+, 5). Anal. Calcd for C13H15NOS: C, 66.92; H, 6.48; N,
6.00; S, 13.74. Found: C, 66.81; H, 6.48; N, 6.09; S, 13.53.
Attem p ted P d -Ca ta lyzed Rea ction of P h SN(P r -i)2 (1l)
or P h SN(H)P h (1m ) w ith CO (Ru n s 13 a n d 14). The
reaction of 1l with CO (20 kg/cm2) in the presence of 5 mol %
(16) The reaction of 1h with 6 providing 2h without Pd(PPh3)4 was
very sluggish (2% after 12 h at rt).
(17) A bond metathesis between S-B and Pd-C bonds has been
recently reported; see: Cui, Q.; Musaev, D. G.; Morokuma, K. Orga-
nometallics 1998, 17, 1383.

7308 J . Org. Chem., Vol. 64, No. 20, 1999
Kuniyasu et al.
of Pd(PPh3)4 at 100 °C for 20 h did not provide any thiocar-
bamate. Only the formation of 28% of (i-Pr)2NH was confirmed.
The reaction using 1m under the same reaction conditions
gave 75% of PhNH2 and 80% of (PhS)2.
°C, and 6 (25 mg, 0.1 mL) dissolved in 3 mL of pyridine (3
mL) was added over 10 min. The 31P NMR spectrum of the
crude reaction mixture taken in benzene-d6 after stirring for
1 h showed the formation of 80% of 4a . Then ca. 50 mL of
hexane was added, the precipitation was removed through
Celite, and the filtrate was concentrated in vacuo. The residual
reaction mixture was subjected to preparative TLC to afford
3.3 mg (18% based on 6) of 2h .
Attem p ted Oxid a tive Ad d ition of 1a to P d (P P h 3)4. Into
a two-necked glass flask equipped with a reflux condenser and
a magnetic stirring bar were placed Pd(PPh3)4 (1.16 g, 1.0
mmol), 1a (217 mg, 1.2 mmol), and pyridine (3.0 mL). After
the mixture was heated at 80 °C for 12 h with magnetic
stirring, the 1H NMR spectrum of the crude the reaction
mixture was taken. However, 1a remained unreacted.
Con fir m a tion of Restin g Sta te of Ca ta lyst. Into a 50-
mL stainless steel autoclave were added 1a (181 mg, 1.0
mmol), Pd(PPh3)4 (58 mg, 0.05 mmol), and pyridine (0.5 mL).
Then the mixture was heated at 80 °C for 3 h under 20 kg/
cm2 of carbon monoxide with magnetic stirring. The 31P NMR
spectrum of the crude homogeneous reaction mixture taken
in benzene-d6 showed the formation of 56% of 4a (δ 31.75 and
δ 33.10 in a ratio of 55/45).
Rea ction of 1a w ith CO w ith [P d (Stol-p)2(P P h 3)]2 (4b)
a s a Ca ta lyst (Eq 2). After the reaction of 1a (181 mg, 1.0
mmol) with CO (20 kg/cm2) was carried out at 80 °C for 3 h in
the presence of 4b (30.8 mg, 0.025 mmol), the reaction mixture
was subjected to preparative TLC. A 72 mg of mixture of 2a
(26%) and 2b (8.3%) was obtained. The ratio of 2a and 2b was
determined by the 1H NMR spectrum.
Th e Rea ction of 6 w ith 1h (Ref 16). Into a dry NMR tube
were placed 6 (25 mg, 0.1 mmol), 1h (16 mg, 0.1 mmol), and
pyridine-d5 (0.5 mL). No reaction was confirmed at room
temperature after 1 h by 1H NMR spectrum. The formation of
2% of 2h was confirmed after 12 h.
Ack n ow led gm en t. Partial support of this work
through Grant-in-Aid for Scientific Research, Ministry
of Education, Science and Culture and CREST of J apan
Science and Technology Corporation is gratefully ac-
knowledged. Thanks are due to the Instrumental Analy-
sis Center, Faculty of Engineering, Osaka University,
for assistance in obtaining mass spectra with a J EOL
J MS-DX303 instrument.
Su p p or tin g In for m a tion Ava ila ble: Listing of experi-
mental procedures and analysis data for the compounds in this
paper. This material is available free of charge via the Internet
at http://pubs.acs.org.
Th e Stoich iom etr ic Rea ction of P h SC(O)SP h (6) w ith
P d (P P h 3)4 in th e P r esen ce of 1h (Eq 3). In a dry 10 mL
two-necked flask with 10 mL dropping funnel were placed Pd-
(PPh3)4 (120 mg, 0.104 mmol), 1h (78 mg, 0.51 mmol), and
pyridine (3 mL). Then the reaction mixture was cooled at -30
J O9823137