Reactions of benzyl aryl sulfides with excess active halogen reagents

Article abstract of DOI:10.1021/jo961565+

1,2,3-Tribromopyrrolo[1,2-b][1,2]benzothiazin-10-one (2) is produced from 2-[2-(benzylthio)benzoyl]-pyrrole (1) when treated with excess (5 equiv) NBS in CHCl₃. With NCS, a mixture is obtained in which di- and trichloropyrrolo[1,2-b][1,2]benzothiazin-10-ones are present. If ethanol is present in the NCS reaction, compound 4 is formed as the major product. Further, compound 3 is also formed by the reaction of compound 1 or the corresponding disulfide with excess SOCl₂. A novel route to alkyl arenesulfinic esters is also reported. Treatment of a benzyl aryl sulfide with excess (5 equiv) NCS in the presence of an n-alkyl alcohol (7 equiv) produces an n-alkyl arenesulfinic ester in good yield. An arenesulfonyl chloride is the major product in the presence of benzyl alcohol.

Full text of DOI:10.1021/jo961565+

J . Org. Chem. 1996, 61, 9289-9292
9289
Rea ction s of Ben zyl Ar yl Su lfid es w ith Excess Active Ha logen
Rea gen ts
Mingde Xia, Shaowu Chen,† and Dallas K. Bates*
Department of Chemistry, Michigan Technological University, Houghton, Michigan 49931
Received August 12, 1996X
1,2,3-Tribromopyrrolo[1,2-b][1,2]benzothiazin-10-one (2) is produced from 2-[2-(benzylthio)benzoyl]-
pyrrole (1) when treated with excess (5 equiv) NBS in CHCl3. With NCS, a mixture is obtained in
which di- and trichloropyrrolo[1,2-b][1,2]benzothiazin-10-ones are present. If ethanol is present
in the NCS reaction, compound 4 is formed as the major product. Further, compound 3 is also
formed by the reaction of compound 1 or the corresponding disulfide with excess SOCl2. A novel
route to alkyl arenesulfinic esters is also reported. Treatment of a benzyl aryl sulfide with excess
(5 equiv) NCS in the presence of an n-alkyl alcohol (7 equiv) produces an n-alkyl arenesulfinic
ester in good yield. An arenesulfonyl chloride is the major product in the presence of benzyl alcohol.
In tr od u ction
results are found with tert-butyl hypochlorite.11 Finally,
Muchowski and others have used dimethyl succinimi-
dosulfonium chloride (dimethyl sulfide/NCS) extensively
for pyrrole methylsulfenylation.12 Since we were inter-
ested in promoting pyrrole sulfenylation in our systems,
NCS and NBS seemed to be appropriate reagents for
halogen-promoted cyclization of substrates such as 1. In
this paper, we wish to report some reactions of 1 and
other benzyl aryl sulfides with these reagents.
Intramolecular sulfoxide electrophilic sulfenylation
(SES) reactions have been used extensively in our labora-
tory to generate sulfur-bridged heterocyclic compounds.1,2
These reactions are often conducted by simply refluxing
the sulfoxide in p-xylene, producing the product and a
low molecular weight alcohol (methanol or ethanol,
typically) as the sole byproduct. The more traditional
reagents for intermolecular sulfenylation involve active
halogen species which we felt would react competitively
with the electron rich aromatic ring present in our
starting materials. However, the antibiotic activity of
halogenated pyrroles such as pyrrolnitrin,3 pyoluteorin,4
and pentabromopseudilin5,6 has led us to investigate the
reaction of suitably substituted sulfides with active
halogen reagents. Previous work on the reaction of active
halogen reagents with organic sulfides suggests three
paths may result as follows: benzylic C-S bond cleavage
in benzylic sulfides, attack at sulfur followed by Pum-
merer-type chemistry, or attack at sulfur followed by
displacement at sulfur by a nucleophile or rich π-electron
Resu lts a n d Discu ssion
The required sulfide, 2-[2-(benzylthio)benzoyl]pyrrole
(1), was prepared in 83% yield by reacting pyrrole with
methylmagnesium chloride followed by the addition of
ethyl 2-(benzylthio)benzoate to this mixture.13 When 1
was treated with NBS (5 equiv) in chloroform at room
temperature for 18 h, the tribrominated heterocyclic
compound 2 was formed in 19% yield. Use of lesser
amounts of NBS gave inseparable mixtures in which
mono- and dibrominated analogues of 2 as well as 2 and
unreacted starting material were present in varying
amounts, as evidenced by mass spectral analysis of the
crude product.
source. Chlorine,7 Br2,8 and SO2Cl2 convert benzyl
8,9
sulfides into sulfenyl halides with elimination of benzyl
chloride. NCS and NBS in aprotic solvents (CCl4 or
CHCl3) have been found to promote Pummerer-type
reactions in which R-chloro sulfides are formed.10 Similar
* To whom correspondence should be addressed. Tel: (906)487-2059.
Fax: (906)487-2061. E-mail: dbates@mtu.edu.
† Current address: Proscript, Inc., 38 Sidney St, Cambridge, MA
02139.
X Abstract published in Advance ACS Abstracts, December 1, 1996.
(1) (a) Bates, D. K.; Tafel, K. A.; Xu, J . Heterocycl. Commun. 1996,
2, 115. (b) Bates, D. K.; Habib, Q. A. J . Heterocycl. Chem. 1995, 32,
1477. (c) Bates, D. K.; Tafel, K. A. J . Org. Chem. 1994, 59, 8076.
(2) (a) Picard, J . A.; Chen, S.; Bates, D. K. Heterocycles 1994, 38,
1775. (b) Tafel, K. A.; Bates, D. K. J . Org. Chem. 1992, 57, 3676.
(3) Roitman, J . N.; Mahoney, N. E.; J anisiewicz, W. J . Appl.
Microbiol. Biotechnol. 1990, 34, 381.
The reaction of 1 with NCS (5 equiv) in CHCl3
produced 3 as a minor product. The major product
exhibited a substantially lower Rf on TLC and exhibited
intense blue fluorescence under UV light. The H NMR
revealed a pair of complex multiplets which appeared to
be due to an ethyl group adjacent to a chiral center. The
1
(4) (a) Rao, K. A.; Reddy, G. C. J . Agric. Food Chem. 1990, 38, 1260.
(b) Durham, D. G.; Hughes, C. G.; Rees, A. H. Can. J . Chem. 1972, 50,
3223.
(5) Laatsch, H.; Renneberg B.; Hanefeld, U.; Kellner, M.; Pudleiner,
H.; Hamprecht, G.; Kraemer, H.; Anke, H. Chem. Pharm. Bull. 1995,
43, 537.
(6) Renneberg, B.; Kellner, M.; Laatsch, H. Liebigs Ann. Chem. 1993,
847.
(11) Skatteboel, L.; Boulette, B.; Solomon, S. J . Org. Chem. 1967,
32, 3111.
(12) (a) Muchowski, J . M.; Galeazzi, E.; Greenhouse, R.; Guzman,
A.; Perez, V.; Ackerman, N.; Ballaron, S. A.; Rovito, J . R.; Tomolonis,
A. J .; Young, J . M.; Rooks, W. H. J . Med. Chem. 1989, 32, 1202. (b)
Franco, F.; Greenhouse, R.; Muchowski, J . M. J . Org. Chem. 1982,
47, 1682.
(7) Zincke, T. Chem. Ber. 1911, 44, 769.
(8) Kharasch, N.; Langford, R. B. J . Org. Chem. 1963, 28, 1903.
(9) Bekker, R. A.; Popkova, V. Ya. Izv. Akad. Nauk SSSR, Ser. Khim.
1982, 1123.
(13) Nicolaou, K. C.; Claremon, D. A.; Papahatjis, D. P. Tetrahedron
Lett. 1981, 22, 4647.
(10) Buchanan, D. N. Diss. Abstr. Int. B 1970, 31, 3254.
S0022-3263(96)01565-4 CCC: $12.00 © 1996 American Chemical Society

9290 J . Org. Chem., Vol. 61, No. 26, 1996
Xia et al.
Sch em e 1
chemical shift of this complex methylene group signal
was around 3.5 ppm suggesting an ethoxyl group. Struc-
ture 4 is assigned to this product based upon spectral
data and elemental analysis.
a complex mixture of products. Mass spectral analysis
of the mixture indicates the presence of compounds with
molecular weights of 239, 289, 299, 317, and 337, sug-
gesting the presence of compounds 5-9.
Compounds 8 and 9 undoubtedly arise via N-alkylation
of intermediates by ethyl chloride which is formed during
the reaction. Due to the complexity of the mixture, we
did not pursue this reaction further. This reaction of
NCS with 2-benzoylpyrrole is significantly more complex
and less controllable than other procedures reported for
halogenation of 2-aroylpyrroles and alkyl 2-pyrrolecar-
boxylates.16 We also briefly investigated the reaction of
the parent cyclized ring system, pyrrolo[1,2-b][1,2]-
benzothiazin-10-one (the nonhalogenated counterpart to
3), with NCS in CHCl3/EtOH, assuming this compound
might be an intermediate in the pathway to 4. It is not.
No 4 is produced in this reaction although several as yet
unidentified compounds are formed. Neither 2 nor 3
reacts with ethanol on prolonged exposure. Compound
3 is recovered unchanged after treatment with NCS (1
equiv) in ethanol at rt.
Reactions of “simple” benzyl aryl sulfides 10 with
excess NCS/CHCl3 or CH2Cl2 did not produce R-chloro
sulfides in the presence of an added alcohol. Sulfinic
esters and/or sulfonyl chlorides were the major products,
depending on the sulfide and the alcohol. The results
are summarized in Scheme 1.
When benzyl aryl sulfides 10a -c were treated with 5
equiv of NCS in the presence of added ethanol, the ethyl
arenesulfinic esters 11a -c were produced in 30%, 97%,
and 42% yields, respectively, along with benzyl chloride,
The ethoxyl group apparently arises from ethanol
(∼1.1%) which is used to stabilize commerical CHCl3. If
additional ethanol (7 equiv) is added to the reaction
mixture prior to addition of NCS, very little 3 is formed
and 4 may be isolated in 45% yield. If the reaction is
conducted in ethanol-free chloroform, inseparable mix-
tures of the dichlorinated analogue of 3 as well as 3 and
other unidentified materials are present.14 This lack of
selectivity of pyrrole ring halogenation is reminiscent of
the free radical chlorination of 2-pyrrolecarboxylate
esters with tert-butyl hypochlorite.15 Five equivalents of
NCS is an optimal choice for the formation of 4. Addition
of more NCS does not improve the yield of 4. Use of less
than 5 equiv of NCS gave mixtures of various haloge-
nated products and a little 4.
To more fully understand the nature of the reaction
forming 4, we investigated simpler compounds, i.e.,
2-benzoylpyrrole which contains no sulfur and other
benzyl aryl sulfides which contain no pyrrole ring.
Treatment of 2-benzoylpyrrole with NCS (5 equiv) gave
(14) 1,2,3-Trichloropyrrolo[1,2-b][1,2]benzothiazin-10-one is also
formed by the reaction of 2-[2-(benzylthio)benzoyl]pyrrole or the
corresponding disulfide i with excess thionyl chloride in refluxing
p-xylene in 18% and 24% yields, respectively.
i
(16) (a) Anderson, H. J .; Lee, S. F. Can. J . Chem, 1965, 43, 409. (b)
Petruso, S.; Caronna, S. J . Heterocycl. Chem. 1992, 29, 355. (c)
Renneberg, B.; Kellner, M.; Laatsch, H. Ann. Chem. 1993, 847.
(15) Hodges, P.; Richards, R. W. J . Chem. Soc. 1965, 459.

Benzyl Aryl Sulfide Reactions with Halogen Reagents
J . Org. Chem., Vol. 61, No. 26, 1996 9291
Sch em e 2
b][1,2]benzothiazin-10-one is also formed by the reaction
of compound 1 or the corresponding disulfide with excess
SOCl2.
A novel route to alkyl arenesulfinic esters has also been
discovered. Treatment of a benzyl aryl sulfide with
excess (5 equiv) NCS in the presence of a simple n-alkyl
alcohol (7 equiv) produces an n-alkyl arenesulfinic ester
in good yield. An arenesulfonyl chloride is the major
product in the presence of benzyl alcohol.
Exp er im en ta l Section
All reagents were used without purification unless otherwise
noted. Silica gel (70-230 mesh, 60 Å) was used for column
chromatography. Analytical TLC was performed on silica
plates containing a fluorescent indicator developed with
chloroform. Melting points are uncorrected. 1H and 13C NMR
spectra were recorded at 200 and 50 MHz, respectively, in
CDCl3 solution, unless otherwise noted. Mass spectra were
recorded at 70 eV. Elemental analyses were performed by
Galbraith Laboratories, Inc. (Knoxville, TN).
2-[2-(Ben zylth io)ben zoyl]p yr r ole (1). Commercial me-
thylmagnesium chloride in THF (25 mL, 0.075 mol) was added
to toluene (100 mL) at 0 °C. To this cold mixture pyrrole was
added (5.0 g, 0.075 mol) dropwise under N2. The solution was
heated at 60 °C for 30 min and allowed to cool to rt; then a
solution of ethyl 2-(benzylthio)benzoate (9.0 g, 0.033 mol) in
toluene (15 mL) was added dropwise under N2. The resulting
mixture was refluxed for 22 h and cooled to rt, the reaction
was quenched by the addition of saturated NH4Cl solution,
and finally the mixture was acidified to pH 3 with 10% aqueous
HCl solution. Following removal of the organic layer, the
aqueous layer was extracted with CHCl3 (2 × 80 mL), and the
combined organics were washed with water (2 × 80 mL) and
dried (Na2SO4). After the solvent was removed in vacuo, the
resulting crude product was chromatographed (SiO2, CHCl3)
to yield 8.0 g (83%) of 1 as yellow-brown crystals (mp 108-
110 °C): 1H NMR (200 MHz, CDCl3) δ 9.78 (br s, 1H), 7.54 (d,
J ) 7.7 Hz, 1H), 7.38 (m, 2H), 7.25 (m, 6H), 7.12 (m, 1H), 6.57
(m, 1H), 6.27 (m, 1H), 4.10 (s, 2H); IR (KBr) 3279, 1607, 1398
cm-1; MS [m/ z (rel intensity)] 293 (M+, 1.4), 202 (100.0), 91
(79.0). Anal. Calcd for C18H15NOS: C, 73.69; H, 5.15; N, 4.77.
Found: C, 73.61; H, 5.35; N, 4.70.
1,2,3-Tr ib r om op yr r olo[1,2-b][1,2]b e n zot h ia zin -10-
on e (2). A solution of 1 (0.5 g, 1.7 mmol) and N-bromosuc-
cinimide (1.5 g, 8.5 mmol) in CHCl3 (20 mL) was stirred at rt
for 18 h. The reaction mixture was worked up with CHCl3
(50 mL), and H2O (2 × 25 mL) and dried (Na2SO4). After
solvent removal in vacuo, the resulting dark residue was
chromatographed (SiO2, CHCl3) to afford 0.14 g (19%) of 2 as
yellow crystals (mp 245-247 °C): 1H NMR (200 MHz, CDCl3)
δ 8.48 (dd, J ) 1.6, 8.2 Hz, 1H), 7.63 (m, 1H), 7.50 (m, 2H); IR
(KBr) 1703, 1320, 1282 cm-1; UV (methanol) 252 nm (log ꢀ )
4.50); MS [m/ z (rel intensity)] 441 (M + 6, 20.7), 439 (M + 4,
58.5), 437 (M + 2, 58.4), 435 (M+, 20.9), 358 (100.0), 330 (40.8);
Anal. Calcd for C11H4Br3NOS: C, 30.17; H, 0.92; N, 3.20.
Found: C, 30.12; H, 0.93; N, 3.15.
succinimide, and small amounts of arenesulfonyl chlo-
ride. Similar results were obtained in the presence of
added 1-butanol. This is a previously unreported reaction
of benzyl sulfides with NCS and is a simple, convenient
source of alkyl arenesulfinates.17,18
The reaction works well with simple n-alkyl alcohols,
but alcohols having a good leaving group (i.e., benzyl
alcohol) work poorly. This is related to the proposed
mechanism and is discussed below. Added benzyl alcohol
(7 equiv) produces either solely or predominantly an
arenesulfonyl chloride. With 10c an intractable polymer
is formed, perhaps due to linear condensation polymer-
ization of sulfonyl chloride with amide NH2. These data
are consistent with a mechanism in which the benzylic
C-S bond is broken, forming an intermediate sulfenyl
chloride. Douglass and Koop19,20 reported that methane-
sulfenyl chloride and methanol form methyl chloride,
methanesulfinyl chloride, methyl methanesulfinate, and
methanesulfonyl chloride. Their mechanistic rationale,
applied to benzyl aryl sulfides, is as shown in Scheme 2.
Support for this mechanism is provided by the reaction
products in the presence of benzyl alcohol. In this case,
arenesulfinate ester 11 bears a good leaving group (R )
benzyl). One would predict a more facile conversion of
11 to sulfonyl chloride 12 than in other cases where R )
n-alkyl, as observed experimentally. Rather than NCS
providing a chlorine source to form the arenesulfenyl
chloride and benzyl chloride, it is also possible that NCS
reacts with the sulfide directly12 forming benzyl chloride
and an arylsulfenamide. N-Arylthioimides are well-
known sulfenylation reagents.21
It should be noted that in this process some of the
ArSCl originally formed becomes (ArS)2. We did not
observe significant diaryl disulfide in these reactions,
apparently due to its conversion back to ArSCl by excess
NCS present in the reaction.
1,2,3-Tr ich lor op yr r olo[1,2-b][1,2]b e n zot h ia zin -10-
on e (3). Meth od I. A stirred solution of 1 (1.0 g, 3.4 mmol)
and thionyl chloride (8.0 mL, 0.11 mol) in p-xylene (35 mL)
was refluxed for 18 h. After cooling to rt, all the volatiles were
removed in vacuo, and the residue was dissolved in CHCl3 (50
mL), washed with H2O (2 × 20 mL), and dried (Na2SO4). After
the solvent was removed, the dark residue was chromato-
graphed (SiO2, CH2Cl2) to afford 0.19 g (18%) of product 3 as
yellow crystals (mp 208-210 °C): 1H NMR (200 MHz, CDCl3)
δ 8.48 (dd, J ) 1.4, 8.5 Hz, 1H), 7.64 (m, 1H), 7.46 (m, 2H); IR
(KBr) 1700, 1328, 1293 cm-1; UV (methanol) 250 nm (log ꢀ )
4.38); MS [m/ z (rel intensity)] 307 (M + 4, 17.0), 305 (M + 2,
47.9), 303 (M+, 47.9), 267 (100.0), 240 (28.7). Anal. Calcd for
C11H4Cl3NOS: C, 43.28; H, 1.32; N, 4.60. Found: C, 43.28;
H, 1.48; N, 4.24.
Con clu sion
1,2,3-Trihalopyrrolo[1,2-b][1,2]benzothiazin-10-ones are
produced from 2-[2-(benzylthio)benzoyl]pyrrole (1) and
excess (5 equiv) NBS or NCS in CHCl3. However if
ethanol is present in the NCS reaction, compound 4 is
formed. The related compound 1,2,3-trichloropyrrolo[1,2-
(17) Whitesell, J . K.; Wong, M. J . Org. Chem. 1994, 59, 597.
(18) For
a review of sulfinic acids and their derivatives, see:
Sterling, C. J . M. Int. J . Sulfur Chem. B, 1971, 6, 277. Drabowicz, J .;
Kielbasinski, P.; Mikolajczyk, M. In Chemistry of Sulfenic Acids and
Their Derivatives; Patai, S., Ed.; Wiley: Chichester, U.K., 1990.
(19) Douglass, I. B. J . Org. Chem. 1974, 39, 563.
(20) Douglass, I. B.; Koop, D. A. J . Org. Chem. 1962, 27, 1398.
(21) (a) Woulfe, S. R.; Iwagami, H.; Miller, M. J . Tetrahedron Lett.
1985, 26, 3891 and references therein. (b) Gilow, H. M.; Brown, C. S.;
Copeland, J . N.; Kelly, K. E. J . Heterocycl. Chem. 1991, 28, 1025.
Meth od II. A mixture of 2-(2,2′-dithiobenzoyl)pyrrole (dis-
ulfide i; 0.22 g, 0.55 mmol) and thionyl chloride (40 mL, 0.55
mol) treated as in method I gave 0.08 g (24%) of 3.

9292 J . Org. Chem., Vol. 61, No. 26, 1996
Xia et al.
Rep r esen ta tive P r oced u r e for th e Rea ction of Ben zyl
Ar yl Su lfid es w ith Excess NCS. NCS (5 equiv) was added
portionwise to a well-stirred solution of the appropriate benzyl
aryl sulfide (1 equiv) in CHCl3 or CH2Cl2 (appropriate volume
to afford [sulfide] ) 0.1 M) and alcohol (7 equiv) at rt. The
mixture was stirred for 18 h. After most of the succinimide
was removed by filtration, solvent was removed from the
filtrate and the residue was chromatographed (SiO2, CHCl3).
Com p ou n d 4. 0.2 g (45%) obtained from 0.44 g of 1 (in
CHCl3/EtOH); yellow solid which exhibited intense blue
13C NMR (50 MHz, CDCl3) δ 145.9, 133.0, 130.0, 126.2, 65.6,
32.7, 20.0, 14.5; IR (KBr) 1199, 1135 cm-1; MS [m/ z (rel
intensity)] 198 (M+, 2.6), 143 (100.0), 125 (47.9), 57 (67.5).
Eth yl 2-cya n oben zen esu lfin a te (11b): 1.1 g (97%) pre-
1
pared from 1.3 g of 10b (in CHCl3/EtOH); pale yellow oil; H
NMR (200 MHz, CDCl3) δ 7.97 (m, 1H), 7.62-7.77 (m, 3H),
4.26 (m, 1H), 4.02 (m, 1H), 1.31 (t, J ) 7.0 Hz, 3H); 13C NMR
(50 MHz, CDCl3) δ 147.8, 133.8, 133.2, 132.2, 125.3, 115.0,
110.2, 64.9, 15.5; IR (KBr) 2229, 1384, 1138 cm-1; MS [m/ z
(rel intensity)] 195 (M+, 2.1), 167 (7.9), 150 (11.3), 103 (100.0).
2-(Eth oxysu lfin yl)ben za m id e (11c): 0.54 g (42%) obtained
from 1.45 g of 10c (in CHCl3/EtOH); white solid; mp 78-80
1
fluorescence under UV light; 185-188 °C dec; H NMR (400
MHz, CDCl3) δ 8.03 (dd, J ) 1.7, 7.8 Hz, 1H), 7.54 (td, J )
1.7, 7.8 Hz, 1H), 7.31 (m, 2H), 6.66 (br s, 1H), 3.58 (m, 1H),
3.48 (m, 1H), 1.14 (t, J ) 7.0 Hz, 3H); 13C NMR (100 MHz,
CDCl3) δ 187.1, 164.9, 142.9, 135.6, 134.9, 130.6, 127.04,
126.99, 126.4, 125.3, 85.8, 60.0, 15.0; IR (KBr) 3242, 1738,
1703, 1197 cm-1; MS [m/ z (rel intensity)] 295 (M+, 3.4), 260
1
°C; H NMR (200 MHz, CDCl3) δ 8.02 (m, 1H), 7.79 (m, 1H),
7.57 (m, 2H), 5.90 (br s, 2H), 4.37 (m, 2H), 1.35 (t, J ) 7.1 Hz,
3H); 13C NMR (50 MHz, CDCl3) δ 167.8, 141.7, 132.6, 132.1,
130.9, 130.6, 128.5, 62.9, 14.3; IR (KBr) 3311, 1722, 1440, 1140
cm-1; MS [m/ z (rel intensity)] 213 (M+, 94.0), 185 (67.0), 184
(100.0). Anal. Calcd for C9H11NO3S: C, 50.69; H, 5.20; N,
6.57. Found: C, 50.38; H, 5.11; N, 6.46.
(62.1), 232 (100.0), 214 (61.4). Anal. Calcd for C13H10
-
ClNO3S: C, 52.79; H, 3.41; N, 4.74. Found: C, 52.61; H, 3.45;
N, 4.76.
Ben zen esu lfon yl ch lor id e (12a ): 1.1 g (62%) obtained
from 2.0 g of 10a (in CH2Cl2/PhCH2OH); identified by com-
parison with an authentic sample.
Compound 4 is formed in CHCl3 solution even when no
ethanol is added. Commercial CHCl3 is typically stabilized
by addition of ethanol (1.1%), which provides 3 and 4, though
in a different ratio.
2-Cya n oben zen esu lfon yl ch lor id e (12b):23 0.71 g (59%)
obtained from 1.35 g of 10b (in CH2Cl2/PhCH2OH); yellow oil;
1H NMR (200 MHz, CDCl3) δ 8.19 (m, 1H), 7.95 (m, 1H), 7.87
(m, 2H); IR (KBr) 2235, 1385, 1190 cm-1; MS [m/ z (rel
intensity)] 201 (M+, 4.8), 166 (46.5), 102 (100.0).
Eth yl ben zen esu lfin a te (11a ):22 0.51 g (30%) obtained
1
from 2.0 g of 10a (in CH2Cl2/EtOH); yellow oil; H NMR (200
MHz, CDCl3) δ 7.69 (m, 2H), 7.53 (m, 3H), 4.09 (m, 1H), 3.71
(m, 1H), 1.26 (t, J ) 7.1 Hz, 3H); 13C NMR (50 MHz, CDCl3)
δ 147.7, 133.8, 133.2, 132.2, 64.9, 15.4; IR (KBr) 1188, 1143
cm-1; MS [m/ z (rel intensity)] 170 (M+, 24.8), 142 (42.0), 125
(48.7), 51 (100.0).
Su p p or tin g In for m a tion Ava ila ble: Copies of 13C NMR
spectra of 4, 11a -c, and n-butyl benzenesulfinate (6 pages).
This material is contained in libraries on microfiche, im-
mediately follows this article in the microfilm version of the
journal, and can be ordered from the ACS; see any current
masthead for ordering information.
n -Bu tyl ben zen esu lfin a te:22 0.69 g (35%) obtained from
1
2.0 g of 10a (in CH2Cl2/1-butanol); yellow oil; H NMR (200
MHz, CDCl3) δ 7.67 (m, 2H), 7.50 (m, 3H), 4.04 (m, 1H), 3.59
(m, 1H), 1.55 (m, 2H), 1.31 (m, 2H), 0.84 (t, J ) 7.4 Hz, 3H);
J O961565+
(22) Takata, T.; Kim, Y. H.; Oae, S. Tetrahedron Lett. 1978, 44, 4303.
(23) Yoon, Y. J .; Kang, Y. S. Bull. Korean Chem. Soc. 1985, 6, 51.