Formation of 2-methylene-1,3-oxathiole derivatives in the rhodium(II) acetate-catalyzed reaction of α-diazocarbonyl compounds with carbon disulfide

Article abstract of DOI:10.1080/10426500902856313

The rhodium(II) acetate-catalyzed reaction of α-diazocarbonyl compound with carbon disulfide gave 1,3-oxathiole-2-thione, 2-methylene-1,3- oxathiole, and 2,2′-spirobis(1,3-oxathiole) derivatives depending on the substituent on the diazo compounds via 1,5- or 1,3-electrocyclization of thiocarbonyl ylide intermediate formed by the reaction of rhodium carbenoid with thiocarbonyl group. Taylor & Francis Group, LLC.

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Formation of 2-Methylene-1,3-
oxathiole Derivatives in the
Rhodium(II) Acetate-Catalyzed
Reaction of α -Diazocarbonyl
Compounds with Carbon
Disulfide
Hirofumi Nakano a & Toshikazu Ibata b
a Department of Chemistry , Aichi University of
Education , Aichi, Japan
b Department of Chemistry, Faculty of Science ,
Osaka University , Osaka, Japan
Published online: 28 Apr 2009.
To cite this article: Hirofumi Nakano & Toshikazu Ibata (2009) Formation of 2-
Methylene-1,3-oxathiole Derivatives in the Rhodium(II) Acetate-Catalyzed Reaction
of α -Diazocarbonyl Compounds with Carbon Disulfide, Phosphorus, Sulfur, and Silicon
and the Related Elements, 184:5, 1224-1232, DOI: 10.1080/10426500902856313
To link to this article: http://dx.doi.org/10.1080/10426500902856313
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Phosphorus, Sulfur, and Silicon, 184:1224–1232, 2009
Copyright © Taylor & Francis Group, LLC
ISSN: 1042-6507 print / 1563-5325 online
DOI: 10.1080/10426500902856313
Formation of 2-Methylene-1,3-oxathiole Derivatives
in the Rhodium(II) Acetate-Catalyzed Reaction of
α-Diazocarbonyl Compounds with Carbon Disulfide
Hirofumi Nakano1 and Toshikazu Ibata2
1Department of Chemistry, Aichi University of Education, Aichi, Japan
2Department of Chemistry, Faculty of Science, Osaka University, Osaka,
Japan
The rhodium(II) acetate-catalyzed reaction of α-diazocarbonyl compound with
carbon disulfide gave 1,3-oxathiole-2-thione, 2-methylene-1,3-oxathiole, and 2,2ꢀ-
spirobis(1,3-oxathiole) derivatives depending on the substituent on the diazo com-
pounds via 1,5- or 1,3-electrocyclization of thiocarbonyl ylide intermediate formed
by the reaction of rhodium carbenoid with thiocarbonyl group.
Keywords Diazo compound; electrocyclization; oxathiole; rhodium(II); thiocarbonyl
ylide
INTRODUCTION
1,3-Dipolar cycloaddition1 is a useful reaction for the selective synthesis
of heterocyclic frameworks. Carbonyl ylides2 and thiocarbonyl ylides3
have been extensively studied with respect to their formation, reaction,
and synthetic applications. The chemistry of carbonyl ylides is very
broad; especially, asymmetric 1,3-dipolar cycloaddition has been stud-
ied using chiral catalyst,4−7 and intramolecular 1,3-dipolar cycloaddi-
tion has been used to synthesize complex natural products.8−11 How-
ever, the chemistry of thiocarbonyl ylides is not as much investigated
as that of carbonyl ylides, so we have been interested in the effective
formation and reactions of thiocarbonyl ylides. Methods3 for the for-
mation of thiocarbonyl ylides have been developed, including thermol-
ysis of 2,5-dihydro-1,3,4-thiadiazole or 2,4-dihydro-1,3-oxathiol-5-one,
Received 30 December 2007; accepted 15 February 2008.
Dedicated to Professor Marian Mikolꢀajczyk, CBMiM PAN in Lꢀ o´dz´, Poland, on the
occasion of his 70th birthday.
Address correspondence to Prof. Dr. Hirofumi Nakano, Department of Chem-
istry, Aichi University of Education, Igaya, Kariya, Aichi 448-8542, Japan. E-mail:
hnakano@auecc.aichi-edu.ac.jp
1224

Formation of 2-Methylene-1,3-oxathiole Derivatives
1225
1,3-elimination of halomethyl trimethylsilylmethyl thioethers, depro-
tonation of thiooxonium salts, and reaction of carbene or carbenoid
compounds with thiocarbonyl compounds.
We have described previously the formation of thiocarbonyl ylides 3
by the rhodium(II)-catalyzed reaction of diazo compounds 1 with thio-
carbonyl compounds such as carbon disulfide,12,13 isothiocyanate,14,15
and thioketene16 to give the corresponding 1,3-oxathiole derivatives
4.17
In a previous paper,12 we described the reaction of substituted α-
diazoacetophenones (1: R1 = Ar, R2 = H) with carbon disulfide in the
presence of rhodium(II) acetate to give the corresponding 5-aryl-1,3-
oxathiole-2-thiones (4: R1 = Ar, R2 = H, X = S) through the thiocarbonyl
ylide 3 (X = S), formed from the ketocarbenoid 2 and carbon disulfide
(Scheme 1). In order to investigate the structural effect on the reaction,
the reaction of diazoacetophenones having various substituents on α-
position was studied.
R2
R1
MLn
R2
N2
R2
R1
R1
Rh2(OAc)4
-N2
R1
R2
S
O
S
C
X
O
O
S
C
X
O
X
4
1
2
3
R1=Ar, R, RO
R2=H, COMe, CO2R
X=S, N-R, C(t-Bu)2
SCHEME 1
RESULTS AND DISCUSSION
The reaction of 1-(4-chlorophenyl)-2-diazopropan-1-one (5) with car-
bon disulfide in the presence of rhodium(II) acetate was carried out
at 46◦C. The reaction mixture was separated by medium pressure liq-
uid chromatography to give 5-(4-chlorophenyl)-4-methyl-1,3-oxathiole-
2-thione (6) in 27% yield together with product 7 (20%). The elemental
analysis and mass spectrum measurement of 7 support the molecular
formula C19H14O2SCl, which corresponds to a 2:1 product of the keto-
carbene with carbon disulfide, which has eliminated one sulfur atom
(Scheme 2).
The structure of 7 was confirmed on the basis of its spectroscopic
data. The 13C NMR spectrum of 7 showed the signal of a carbonyl carbon
at 190.9 ppm and that of 5-C of 1,3-oxathiole at 143.1 ppm, which is sim-
ilar to that of 5-C of 1,3-oxathiole-2-thione (ca. 150 ppm).12 The signal

1226
H. Nakano and T. Ibata
Cl
CH3
O
Cl
Cl
S
O
CH3
N2
Rh2(OAc)4
+
S
C S
S
+
O
CH3
H3C
46 °C, –N2
O
S
5
6
Cl
7
SCHEME 2
at 113.9 ppm is assigned to 4-C of 1,3-oxathiole on the basis of its chem-
ical shift, multiplicity, and coupling constant (2JCH = 7 Hz) compared
with those of 1,3-oxathiole-2-thione. These data suggest that prod-
uct 7 is 1-(4-chlorophenyl)-2-[5-(4-chlorophenyl)-4-methyl-1,3-oxathiol-
2-ylidene]-propan-1-one. There are two possible structures of oxathiole
7: E- and Z-isomer. Determination of the geometrical structure based
on the available spectroscopic data is not successful at this time. The
formation of ethylenic compound by the elimination of sulfur atom in
the reaction of carbene or carbenoid with thiocarbonyl compound was
reviewed by Mloston and Heimgartner.3
The catalytic reaction of 2-diazo-1,2-diphenylethan-1-one (8) with
carbon disulfide gave 2,2ꢀ-spirobis(1,3-oxathiole) 9, 2-methylene-1,3-
oxathiole 10, and benzil 11 in 26, 4.0, and 40% yields, respectively,
without affording 1,3-oxathiole-2-thione (Scheme 3).
Ph
Ph
Ph
Ph
N2
O
CS2
S
S
O
O
Ph
Ph
+
+
Ph
Ph
S
O
46 °C, –N2
O
O
O
Ph
11
8
Ph
Ph
Ph
10
9
SCHEME 3
Elemental analysis and mass spectrum data suggested that com-
pound 9 was a 2:1 product of ketocarbene moiety and carbon disulfide.
The 13C NMR spectrum of 9 did not show signals of carbonyl and thio-
carbonyl carbons, but showed a signal of quaternary carbon (127.9
ppm) originating from carbon disulfide. The carbon signals of two aro-
matic units originating from 8 are equivalent. So 9 was identified as
2,2ꢀ-spirobis(1,3-oxathiole) having symmetrical structure.

Formation of 2-Methylene-1,3-oxathiole Derivatives
1227
R2
MLn
R2
R1
N2
R1
R1
CS2
Rh2(OAc)4
46 ºC, -N2
R2
S
O
O
O
S
1
12
2
2
R2
R2
R1
R1
R2
R2
R1
R1
1,5-cyclization
1,3-cyclization
R1
S
S
S
O
S
O
O
O
O
O
S
O
S
O
S
R1
R2
16
R2
R1
R2
15
R1
R2
13
14
SCHEME 4
The reaction under the similar conditions using degassed solvents
gave 9, 10, and 11 in 43%, 14%, and 6.6% yields, respectively, increasing
the yield of 9 sacrificing the yield of 11. The catalytic decomposition of 8
in benzene at 46◦C under air gave 11 in 90% yield. These observations
show that 11 is formed by the reaction of ketocarbenoid with oxygen.
These results indicate that the substituent at the α-position of the
diazoketone affects the distribution of the products.
1,3-Oxathiole-2-thione 12 was formed by cyclization of thiocarbonyl
ylide 3 (X = S) generated by the reaction of ketocarbenoid 2 with carbon
disulfide.12 In the reaction of 8, ketocarbenoid 2 attacks at the sulfur
atom of oxathiole-2-thione 12 to generate thiocarbonyl ylide 13, which
undergoes 1,5-cyclization18,19 to give spiro 1,3-oxathiole 14. In the reac-
tion of 5 or 8, the 1,3-cyclization of thiocarbonyl ylide 13 to give thiirane
15 is followed by desulfurization to afford 2-methylene-1,3-oxathiole 16
(Scheme 4).
Trapping experiments for the thiocarbonyl ylide 13 by dipolarophiles
were not successful. However, the formation of thiocarbonyl ylide 13
by the reaction of ketocarbenoid with 1,3-oxathiole-2-thione was con-
firmed by the following reaction. Rhodium(II) acetate-catalyzed reac-
tion of dimethyl 2-diazomalonate (17) with 4,5-diphenyl-1,3-oxathiole-
2-thione (18) gave the corresponding dimethyl 2-(4,5-diphenyl-1,3-
oxathiol-2-ylidene)malonate 19 in 37% yield (Scheme 5).
Ph
Ph
Ph
Ph
Rh2(OAc)4
46 oC, -N2
S
S
O
MeO2C
CO2Me
O
+
N2
S
MeO2C CO2Me
18
17
19
SCHEME 5

1228
H. Nakano and T. Ibata
Me
S
O
O
N2
MLn
N
S
CS2
O
21
Rh2(OAc)4
46 oC, -N2
O
S
O
N
Me
N
Me
N
Me
22
N
20
23
21
Me
SCHEME 6
Rhodium(II) acetate-catalyzed reaction of 3-diazo-1-methyl-1,3-
dihydroindol-2-one (20) with carbon disulfide also gave 4-methyl-
2-(1-methyl-2-oxo-2,3-dihydro-3-indoylidene)-4H[1,3]-oxathiolo[5,4-
b]indole (23) in 21% yield. Several attempts to isolate the 1,3-oxathiole-
2-thione using medium and high pressure liquid chromatography were
unsuccessful (Scheme 6).
CONCLUSION
In conclusion, the rhodium(II) acetate catalyzed reaction of α-
diazocarbonyl compounds with carbon disulfide gave 1,3-oxathiole-
2-thione, 2-methylene-1,3-oxathiole, and 2,2ꢀ-spirobis(1,3-oxathiole)
derivatives depending on the substituent on the diazo compounds via
thiocarbonyl ylide intermediate formed by the reaction of rhodium car-
benoid with thiocarbonyl group. The product distribution was deter-
mined by substituent at the diazo carbon atom: phenyl and methyl
groups increased a second attack of the carbenoid on the thiocar-
bonyl sulfur atom of 1,3-oxathole-2-thione to form a thiocarbonyl ylide,
phenyl group favored 1,5-cyclization of the thiocarbonyl ylide to give
spirobis(1,3-oxathiole).
EXPERIMENTAL
Melting points were measured with a Yanagimoto melting point appa-
ratus and were not corrected. IR spectra were recorded on a Perkin-
1
Elmer model 983. H NMR (399.65 MHz and 500 MHz) and 13C NMR
(100.40 MHz and 125.65 MHz) spectra were recorded with a JEOL
GSX-400 and a JEOL GX-500 instrument in CDCl3 solution, using
TMS as internal standard. Mass spectra were obtained with a JEOL
JMS-DX303 mass spectrometer.

Formation of 2-Methylene-1,3-oxathiole Derivatives
1229
Materials
1-(4-Chlorophenyl)-2-diazopropan-1-one (5) was prepared by the reac-
tion of 4-chlorobenzoyl chloride with an excess of diazoethane in the
presence of triethylamine according to the method of Newman and
Beal.20 2-Diazo-1,2-diphenylethan-1-one (8) was prepared according to
the reported methods.21 Benzene was purified by distillation after re-
flux on CaH2 and stored over molecular sieves 4 Å. Carbon disulfide was
purified just before use by distillation after reflux over tetraphosphorus
decaoxide.
Rhodium(II) Acetate-Catalyzed Decomposition of
α-Diazocarbonyl Compounds: General Procedure
A solution of diazocarbonyl compound (3.00 mmol) in dry benzene
(50 mL) was added over a period of ca. 4 h to a refluxing suspension
–3
of rhodium(II) acetate (4.3 mg, 9.7 × 10 mmol) in carbon disulfide
(100 mL) under nitrogen atmosphere. The solution was heated at 46
◦C until no more diazo compound was detected by TLC or IR spec-
troscopy. The resulting reaction mixture was concentrated under re-
duced pressure. The residue was separated by medium-pressure liquid
chromatography (silica gel, eluted with ethyl acetate-hexane).
The rhodium(II) acetate-catalyzed reaction of 1-(4-chlorophenyl)-2-
diazoethan-1-one (5) with carbon disulfide gave 1,3-oxathiole-2-thione
6 and 2-methylene-1,3-oxathiole 7 in 27% and 20% yields, respectively.
5-(4-Chlorophenyl)-4-methyl-1,3-oxathiole-2-thione (6)
Colorless prisms; mp 101.0–102.3◦C (from benzene/hexane); 1H
NMR (CDCl3): δ = 2.30 (s, 3H, CH3), 7.42–7.45 (m, 2H, arom-H), 7.50–
7.53 (m, 2H, arom-H); 13C NMR (CDCl3): δ = 11.7 (q, CH3), 117.6 (sq,
2JCH = 7.3 Hz, S-C=), 125.9 (s, arom-C), 128.5 (d, arom-CH), 129.2 (d,
arom-CH), 135.8 (s, arom-C), 149.3 (s, O-C=), 201.6 (s, C=S); IR (KBr):
1592, 1488, 1209, 1193, 1178, 1094, 1015, 996, 831, and 662 cm−1; MS
(EI, rel. intensity %, assignment) 244 (46, M++2), 243 (14, M++1), 242
(100, M+), 226 (11), 182 (45), 155 (13), 149 (24), 138 (80), 111 (24), 103
(12), 75 (16), 59 (13). Calcd for C10H7OS2Cl: C, 49.48; H, 2.91%. Found:
C, 49.49; H, 2.91%.
1-(4-Chlorophenyl)-2-[5-(4-chlorophenyl)-4-methyl-
1,3-oxathiol-2-ylidene]-propan-1-one (7)
1
Pale yellow crystals; mp 166.0–168.2◦C (from benzene/hexane); H
NMR (CDCl3): δ = 2.22 (s, 3H, CH3), 2.34 (s, 3H, CH3), 7.38–7.46 (m,
4H, arom-H), 7.52–7.56 (m, 4H, arom-H); 13C NMR (CDCl3): δ = 11.5

1230
H. Nakano and T. Ibata
2
(q, CH3), 13.7 (q, CH3), 103.1 (sq, JCH = 5.9 Hz, Me-C=), 113.9 (sq,
2JCH = 7.3 Hz, Me-C=), 127.3 (s), 128.1 (s), 128.3 (d), 129.1 (d), 129.3
(d), 134.8 (s), 136.0 (s), 138.4 (s), 143.1 (s), 170.0 (s), 190.1 (s); IR (KBr):
2926, 1632, 1605, 1593, 1566, 1480, 1444, 1395, 1347, 1094, 1003, 988,
832, 753, 679 cm−1; MS (EI, rel intensity %, assignment) 380 (18,
M++4), 379 (24, M++3), 378 (76, M++2), 377 (56, M++1), 376 (100,
M+), 375 (48, M+-1), 265 (11), 182 (42), 150 (11), 139 (64), 111 (25), 83
(12). Calcd for C19H14O2SCl2: C, 60.49; H, 3.74%. Found: C, 60.20; H,
3.90%.
The rhodium(II) acetate-catalyzed reaction of 2-diazo-1,2-
diphenylethan-1-one (8) with carbon disulfide gave spirobis(oxathiole)
9, 2-methylene-1,3-oxathiole 10, and benzil 11 in 26%, 4%, and 40%
yields, respectively.
2,2ꢀ-Spirobis(4,5-diphenyl-1,3-oxathiole) (9)
Colorless needles; mp 154.8–155.3◦C (from acetone); 1H NMR
(CDCl3): δ = 7.20–7.43 (m, 20H, arom-H); 13C NMR (CDCl3): δ = 111.1
(s, =C-S), 127.8 (d, arom-C), 127.9 (s, spiro-C), 128.2 (d, arom-CH),
128.5 (d, arom-CH), 128.8 (d, arom-CH), 129.2 (d, arom-CH), 129.7
(s, arom-C), 130.8 (s, arom-C), 140.3 (s, arom-C); IR (KBr): 3045, 3022,
2918, 1633, 1598, 1571, 1494, 1443, 1222, 1157, 1085, 1065, 1028, 1012,
995, 963, 938, 916, 766, 753, 695 cm−1; MS (EI, rel. intensity %, assign-
ment): 466 (7, M++2), 465 (15, M++1), 464 (40, M+), 432 (6, M+-S),
359 (64, M+-PhCO), 331 (23), 210 (36), 178 (19), 165 (16), 153 (36), 121
(100, PhCS+), 105 (64, PhCO+), 77 (79), 51 (14). Calcd for C29H20O2S2:
C, 74.97; H, 4.30%. Found: C, 75.04; H, 4.53%.
2-(4,5-Diphenyl-1,3-oxathiol-2-ylidene)-1,
2-diphenylethan-1-one (10)
1
Pale yellow crystals; mp 183.0–189.0◦C (from benzene/hexane); H
NMR (CDCl3): δ = 7.15–7.45 (m, 20H, arom-H); 13C NMR (CDCl3): δ =
111.1 (d), 118.1 (s), 126.9 (d), 127.0 (d), 127.5 (d), 128.3 (d), 128.4 (d),
128.6 (d), 129.1 (d), 129.2 (d), 129.3 (d), 129.7 (d), 129.9 (s), 130.1 (d),
130.09 (d), 135.5 (s), 139.4 (s), 143.7 (s), 171.3 (s), 189.5 (s, C=O); IR
(KBr): 1599, 1568, 1496, 1460, 1442, 1346, 1307, 1160, 1062, 1025, 960,
912, 867, 830, 751, 696, 691 cm–1; MS (EI, rel. intensity %, assignment):
434 (12, M++2), 433 (37, M++1), 432 (100, M+), 355 (5), 311 (2), 210
(35), 178 (11), 165 (14), 121 (10), 105 (49, PhCO+), 77 (23). Calcd for
C29H20O2S: C, 80.33; H, 4.87%. Found: C, 80.53; H, 4.66%.

Formation of 2-Methylene-1,3-oxathiole Derivatives
1231
Rhodium(II) Acetate-Catalyzed Reaction of Dimethyl
2-Diazomalonate with 4,5-Diphenyl-1,3-oxathiole-2-thione
A solution of dimethyl 2-diazomalonate (17) (1 mmol) in dry benzene
(10 mL) was added over a period of ca. 1 h to a solution of rhodium(II) ac-
–3
etate (9.1 × 10 mmol) and 4,5-diphenyl-1,3-oxathiole-2-thione (18)22
(0.5 mmol) in benzene (10 mL) at 46◦C under nitrogen atmosphere. The
solution was heated at 46◦C for 2 h. The resulting reaction mixture
was concentrated under reduced pressure. The residue was separated
by medium-pressure liquid chromatography (silica gel, eluted with
ethyl acetate-hexane) to give dimethyl 2-(4,5-diphenyl-1,3-oxathiol-2-
ylidene)malonate (19): yield 37%; colorless crystals; mp 140.0–143.0◦C
(from benzene/hexane); 1H NMR (CDCl3): δ = 3.87 (s, 3H, OCH3), 3.89
(s, 3H, OCH3), 7.28–7.49 (m, 10H, arom-H); 13C NMR (CDCl3): δ = 51.9
(q, OCH3), 52.2 (q, OCH3), 94.6 (s, =C(COOMe)2), 118.1 (s, S-C=), 127.2
(d, arom-CH), 127.9 (s, arom-C), 128.6 (s, arom-C), 128.7 (d, arom-CH),
129.3 (d, arom-CH), 129.4 (d, arom-CH), 129.5 (d, arom-CH), 129.6 (d,
3
3
arom-CH), 145.3 (st, JCH = 4.8 Hz, O-C=), 164.2 (sq, JCH = 4.0 Hz,
3
ester C=O), 167.6 (sq, JCH = 4.0 Hz, ester C=O), 178.3 (s, 2-C=); IR
(KBr): 2924, 1713 (C=O), 1664, 1523, 1484, 1444, 1432, 1324, 1276,
1211, 1190, 1162, 1153, 1110, 1084, 1062, 1028, 1012, 811, 780, 755,
694, 665 cm−1. Calcd for C20H16O5S: C, 65.20; H, 4.38%. Found: C,
65.22; H, 4.49%.
The rhodium(II) acetate-catalyzed reaction of 3-diazo-1-methyl-1,3-
dihydroindol-2-one (20)23 with carbon disulfide gave 1-Methyl-3-(4-
Methyl-4H-[1,3]oxathiolo-[5,4-b]-indole-2-ylidene)-1,3-dihydroindol-2-
one (20): yield 21%; yellow crystals; mp 213.8–215.3◦C (from ben-
1
zene/hexane); H NMR (CDCl3): δ = 3.32 (s, 3H, NCH3), 3.89 (s, 3H,
NCH3), 6.86–7.73 (m, 8H, arom-H); 13C NMR (CDCl3): δ = 26.0 (q,
NCH3), 29.8 (q, NCH3), 88.6 (s), 101.1 (s), 107.7 (s), 110.2 (s), 118.3
(d), 120.1 (s), 120.5 (d), 121.0 (s), 121.3 (d), 121.5 (d), 121.6 (d), 125.7
(d), 136.8 (s), 139.3 (s), 149.9 (s), 167.4 (s), 170.02 (s); IR (KBr): 1675
(C=O), 1626, 1598, 1559, 1514, 1483, 1468, 1449, 1374, 1344, 1318,
1263, 1220, 1116, 1076, 1020, 978, 813, 769, 740, 701, 685, 658 cm−1
;
MS (EI, rel. intensity %, assignment): 336 (8, M++2), 335 (25, M++1),
334 (100, M+), 333 (11, M+-1), 319 (12, M+-CH3), 305 (28, M+-NCH3),
273 (14), 167 (16), 117 (14). Calcd for C19H14N2O2S: C, 68.24; H, 4.22;
N, 8.38%. Found: C, 67.95; H, 4.38; N, 8.28%.
REFERENCES
[1] A. Padwa and W. H. Pearson, Eds, The Chemistry of Heterocyclic Compounds, Vol.
59: Synthetic Applications of 1,3-Dipolar Cycloaddition Chemistry Toward Hetero-
cycles and Natural Products (Wiley, New York, 2002).

1232
H. Nakano and T. Ibata
[2] M. C. McMills and D. Wright, In: The Chemistry of Heterocyclic Compounds, Vol. 59:
Synthetic Applications of 1,3-Dipolar Cycloaddition Chemistry toward Heterocycles
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