Scandium-catalyzed carbon-carbon bond formations using α- organosulfanyl and organoselanyl-α-fluoroacetic acid derivatives

Article abstract of DOI:10.1248/cpb.54.1611

The scandium-catalyzed reactions of α-organosulfanyl and organoselanyl-α-fluoroacetates 1-2, acetamides 3-4 and acetonitrile 5 with soft nucleophiles proceeded to give the products 6a-b, 7a-c, 8a-c, 9a-e in good to high yields. We also successfully perfor

Full text of DOI:10.1248/cpb.54.1611

November 2006
Notes
Chem. Pharm. Bull. 54(11) 1611—1615 (2006)
1611
Scandium-Catalyzed Carbon–Carbon Bond Formations Using
a
a
-Organosulfanyl and Organoselanyl- -fluoroacetic Acid Derivatives
Kohei GOTOH, Teruhisa YAMAMOTO, and Mitsuhiro YOSHIMATSU*
Department of Chemistry, Faculty of Education, Gifu University; Gifu 501–1193, Japan.
Received July 27, 2006; accepted August 29, 2006; published online August 30, 2006
The scandium-catalyzed reactions of a-organosulfanyl and organoselanyl-a-fluoroacetates 1—2, acetamides
3—4 and acetonitrile 5 with soft nucleophiles proceeded to give the products 6a—b, 7a—c, 8a—c, 9a—e in good
to high yields. We also successfully performed the scandium-catalyzed intramolecular cyclization reactions and
obtained the unique 5-methylene-2-oxotetrahydropyrans 16—17.
Key words scandium; catalytic reaction; a-organosulfanyl carbenium ion; a-organoselanyl carbenium ion
Recently, we have reported a Lewis acid-catalyzed genera- same method.
tion and reaction of a-organosulfanyl and a-organoselanyl
In the previous report, we showed that some scandium-cat-
carbenium ions using ethyl a-fluoroacetates.1) The carbon– alyzed reactions of ethyl a-fluoroacetates 1 and 2 with the
fluoride bond of the a-organosulfanyl and organoselanyl-a- soft nucleophiles successfully proceeded in the presence of
fluoroacetates were selectively cleaved by Lewis acids such 5 mol% of scandium triflate.1) The representative examples
as lanthanoide metals and utilized for the C–C and C–het- are shown in entries 1—5 of Table 1. The carbon nucle-
eroatom bond formation reactions. a-Fluoroacetates are ophiles such as allyltrimethylsilane and the silyl enol ether
much superior to the corresponding a-chloro2—4) and a- and the phenylsulfanyltrimethylsilane exclusively provided
bromo derivatives5) in respect of the stability and handling of the products 6a—b and 7a—c in high yields. We also per-
the starting materials. Furthermore, a-fluoroacetates are formed the reactions of a-fluoroacetamides 3 and 4 and the
highly reactive to the Lewis acids and selectively generated results are shown in entries 6—8 of Table 1. Most of the ex-
the a-selanyl and sulfanyl carbenium ions, while the a- periments were performed in 1,2-dichloroethane or nitro-
chloro derivatives gave rise to the formation of bis (organose- methane at room temperature or reflux conditions. It needed
lanyl) acetals and other unknown compounds. In this report, 5 mol% of Lewis acid to complete the allylation of acet-
we describe the Lewis acid-catalyzed reactions of a-sulfanyl
and selanylacetonitrile and acetamides derived from the ethyl
a-fluoroacetate with some nucleophiles and the intramolecu-
lar cyclization reactions.
First, we prepared some a-fluoroacetic acid derivatives as
shown in Chart 1. a-Phenylsulfanyl and a-phenylselanylac-
etamides 3 and 4 were obtained by the reactions with 28%
aqueous NH3. The transformation to the nitrile 5 was suc-
cessfully carried out with the usual dehydrating agent,
polyphosphoric acid trimethylsilyl ester (PPSE)6—8); how-
ever, the corresponding sulfur analog was not obtained by the etamides and Fluoroacetonitriles
Chart 1. Preparations of a-Phenylsulfanyl and Phenylselanyl-Fluoroac-
Table 1. Scandium-Catalyzed Reactions of a-Fluoroacetic Acid Derivatives 1—5
Entry
R1
R2
Conditiona)
Product (Nu) (% yield)
1
2
3
4
5
6
7
8
9
10
11
12
13
PhSe
PhSe
PhS
PhS
PhS
CO2Et
CO2Et
CO2Et
CO2Et
CO2Et
CONH2
CONH2
CONH2
CN
CN
CN
CN
CN
Allyltrimethylsilane/83 °C/3 h
CH2ꢀC(OSiMe3)Ph/rt/4 h
Allyltrimethylsilane/83 °C/3 h
CH2ꢀC(OSiMe3)Ph/rt/4 h
PhSSiMe3/rt/4 h
Allyltrimethylsilane/83 °C/3 h
CH2ꢀC(OSiMe3)Ph/rt/4 h
Allyltrimethylsilane/83 °C/12 h
CH2ꢀC(OSiMe3)Ph/20 °C/10 min
Me2CꢀCH(OSiMe3)/20 °C/30 min
CH2ꢀC(OSiMe3)t-Bu/20 °C/10 min
Anisole/83 °C/10 min
6a (allyl) (87)
6b (CH2COPh) (78)
7a (allyl) (86)
7b (CH2COPh) (89)
7c (SPh) (95)
8a (allyl) (82)
PhS
PhS
8b (CH2COPh) (30)
8c (allyl) (82)
PhSe
PhSe
PhSe
PhSe
PhSe
PhSe
9a (CH2COPh) (75)
9b (CMe2CHO) (81)
9c (CH2COt-Bu) (85)
9d (C6H4-p-OMe) (43)
9e (81)b)
Toluene/83 °C/1 h
a) 5 mol% of Sc(OTf)3 was used in the reactions of ethyl acetate 1—5. b) The isomer ratio is o : pꢀ60 : 40.
∗ To whom correspondence should be addressed. e-mail: yoshimae@cc.gifu-u.ac.jp
© 2006 Pharmaceutical Society of Japan

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Vol. 54, No. 11
Chart 2. Preparations of Ethyl Halophenylselanylacetate and Halo-
phenylselanylacetamide
amides 8a, c. The reaction with 1-phenyl-1-trimethylsilyloxy
ethylene provided the product 8b in low yield (entry 7). The
phenylselanylacetonitrile 5 was a good electrophile for vari-
ous nucleophile as shown in entries 9—13. Some types of
silyl enol ethers gave the corresponding ketones 9a, c and
aldehyde 9b in high yields. The reactions with aromatic com-
pounds also provided 9d, e. However, the regioselectivities of
the reactions were very low.
Chart 3. Scandium-Catalyzed Allylation of Ethyl 2-Chloro-2-(phenyl-
selanyl)acetate 11
In order to clarify the effect of the fluorine atom in the
scandium-catalyzed reactions with nucleophiles, we exam-
ined the reactions of a-chloro- and a-bromoacetates and
amides 10—13. The chloroester 10 and chloroamide 11 were
prepared by our original method using trimethylsilylchloride
in nitromethane (Chart 2) because the known methods were
not practical for the isolation of the corresponding chlorides.
The scandium-catalyzed chlorination of the ester 1 and
amide 3 with trimethylsilyl chloride proceeded in high yields
over 5 min. The unstable chloroester 10 could be isolated
without the usual purification. The bromination also occurred
by the almost same method with bromotrimethylsilane. How-
ever, the iodination of 1 with iodotrimethylsilane provided a
complex mixture. Then, we selected and performed the ally-
lation with allyltrimethylsilane as the representative substrate
for the scandium-catalyzed reaction of the phenylselanylac-
etates 1, 10, 12 and amides 3, 11, 13 in nitromethane. The al-
lylation of the chloroester 10 with 5 mol% of scandium tri-
flate at refluxing condition for 1 h afforded the product 6a
(5%), chloroester 10 (15%) and ethyl bis(phenylselanyl)ac-
Chart 4. Scandium-Catalyzed Allylation of 2-Chloro- and 2-Bromo-2-
(phenylselanyl)acetamide
etate (22%), respectively (Chart 3). The reaction of 10 for 2 h Chart 5. Scandium-Catalyzed Reactions of Ethyl a-Fluoroacetates
gave a complex mixture, while the reaction of fluoroacetate 1
under the same conditions for 10 min exclusively gave the al- carbenium ions with respect to the high-selectivity of the
lylated product 6a in 87% yield, without detection of fluo- cleavage of the C–F bond and the high-reactivity with nucle-
roester 1 in the reaction mixture. The reaction of a-bromo- ophiles.
ester 12 over 3 h/reflux gave 6a in moderate yield. We also
Next, we tried the intramolecular cyclization reactions
examined the reactions of acetamides as shown in Chart 4. using the scandium-catalyzed substitution reaction as shown
The scandium-catalyzed allylation of fluoroamide 3 com- in Chart 5. Since the allylic trimethylsilanes are found to be a
pletely proceeded to give 8c in 82% yield under the same good nucleophile as a scandium-catalyzed reaction using a-
conditions as 5 mol% of scandium triflate/nitromethane/re- fluoroacetates, we performed the reactions with trimethylsi-
flux over 5 min. However, the reaction of chloroacetamide 11 lyloxymethyl derivative in the presence of 0.1 eq of Sc(OTf)3.
with allyltrimethylsilane over 1 h reflux did not complete and The reaction of 1 provided ethyl 4-(hydroxymethyl)-2-
chloride 11 was recovered in 30% yield. The scandium-cat- (phenylselanyl)pent-4-enoate (14) in 56% yield. The struc-
alyzed allylation of bromoacetamide 13 did not proceed ture of 14 was determined supported by the spectral data,
under both conditions of 2 h/rt and 10 min/refluxing; how- which showed the absorption of the hydroxyl group at n
ever, the reaction under 1 h/refluxing effected C–Se bond fis- 3343 cmꢁ1 in the IR spectra, and exhibited three kinds of
sion to provide allyl phenyl selenide (62%), accompanied by double of doublet due to the 3- and 4-H at d 2.55 (Jꢀ6,
the allylated product 8c (28%). From these experiments, the 15 Hz), 2.71 (Jꢀ10, 15 Hz) and 3.85 (Jꢀ6, 10 Hz) ppm and
C–Se bond of the bromo derivatives tend to cleave more eas- the characteristic exo-methylene protons at d 4.90 and
1
ily than that of the fluorides. As a whole, the a-fluoroacetates 5.09 ppm in the H-NMR spectra, and exhibited the molecu-
and a-fluoroacetamides were proved to be excellent precur- lar formula as C14H14O4Se in the mass spectra and the ele-
sors for the scandium-catalyzed generation of the a-selanyl mental analysis. The phenylsulfanyl acetate 2 also afforded

November 2006
1613
The mixture was stirred for 15 min and poured into water (200 ml). The
organic layer was separated and the aqueous layer was extracted with ether.
The combined organic layer was dried over MgSO4. The solvent was
removed under reduced pressure. The residue was washed with n-hexane to
form the white powders. The powders were filtrated to give the almost pure
alcohol 15 in 71% yield. Next, alcohols 14, 15 were treated
with the same Lewis acid in 1,2-dichloroethane under a re-
flux condition and transformed to the corresponding lactone
derivative 16 and 17. The one-pot transformation from the
acetates to the lactones was examined; however, the yields of 3 (2.34 g, 88%). mp 87—89 °C (from CH2Cl2–n-hexane), IR (KBr, cmꢁ1
)
3179 (NH), 1646 (CO), 1185 (NH); 1H-NMR (500 MHz, CDCl3) d: 6.02
(1H, br s, NH2), 6.19 (1H, br s, NH2), 6.42 (1H, d, Jꢀ54 Hz, CHF), 7.26—
7.70 (5H, m, ArH); 19F-NMR (470.5 MHz, CDCl3) d: ꢁ84.3 (1F, d, Jꢀ53
Hz); MS m/z 233 (Mꢂ). Anal. Calcd for C8H8NFOSe: C, 41.40; H, 3.47; N,
6.03. Found: C, 41.26; H, 3.46; N, 5.87.
the lactones could not be improved. 5-Methylene-2-oxate-
trahydropyrans are known to be one of the monoterpenes iso-
lated from both the marine sponge, Plakortis zygompha
(Laubenfels),9) and
a
wild plant, Teucrium marum
(Labiatae),10) which is a powerful lacrimatory essential oil.
However, easy accessible methods to these derivatives have
not been previously described.11,12) Our two-step procedure to
the 5-methylene-2-oxatetrahydropyrans could be utilized to
the more functionalized derivatives by the transformation of
the organoselanyl and organosulfanyl functional groups to
more useful ones. The formations of the 5-methylenelactam
using a-fluoroacetamides 3 and 4 was also examined by the
two routes; however, these failed.
In summary, we have described the details of the scan-
dium-catalyzed C–C bond formation of a-fluoroacetic acid
esters, amides and nitriles. The carbon–fluoride bond selec-
tively cleaved by the scandium triflate and the generated car-
benium ions effectively react with the soft nucleophiles.
2-Fluoro-2-(phenylsulfanyl)acetamide (4) To EtOH (30.0 ml) solution
of ethyl 2-fluoro-2-(phenylsulfanyl)acetate (3.00 g, 14.0 mmol) was added
aqueous NH3 solution (30.0 ml) at room temperature. The mixture was
stirred for 1 h. The usual work-up afforded 2-fluoro-2-(phenylsulfanyl)ac-
etamide (6) (2.16 g, 83%) as white needles (from CH2Cl2–n-hexane). mp
86—87 °C, IR (KBr, cmꢁ1) 3179 (NH), 1673 (CO), 1155 (CN); 1H-NMR
(500 MHz, CDCl3) d: 6.09 (1H, br d, Jꢀ53 Hz, CHF), 6.11 (2H, s, NH2),
7.38—7.40 (3H, m, ArH), 7.58—7.61 (2H, m, ArH); 19F-NMR (470.5 MHz,
CDCl3) d: ꢁ76.5 (1F, d, Jꢀ53 Hz); MS m/z 185 (Mꢂ). Anal. Calcd for
C8H8FNOS: C, 51.88; H, 4.35; N, 7.56. Found: C, 51.58; H, 4.33; N, 7.53.
Preparation of 2-Fluoro-2-(phenylselanyl)acetonitrile (5) Under an
Ar atmosphere, a benzene (3.0 ml) solution of 3 (1.16 g, 5.00 mmol) was
added to a benzene solution of PPSE (prepared from phosphorous pentoxide
(5.00 g, 35.2 mmol) and hexamethyl disiloxane (15.0 ml))8) at room tempera-
ture. The mixture was refluxed for 12 h and poured into water (100 ml). The
organic layer was separated and the aqueous layer was extracted with ether.
The combined organic layer was dried over MgSO4. The solvent was
removed under reduced pressure. The residue was purified by column chro-
matography on silica gel eluting with EtOAc–n-hexane (1 : 10) to give 5
(0.82 g, 77%) as a yellow oil. IR (KBr, cmꢁ1) 2246 (CN); 1H-NMR
Experimental
Melting points were determined on a Yanagimoto micro-melting point ap-
paratus and uncorrected. Elemental analyses were performed by using Micro (500 MHz, CDCl3) d: 6.44 (1H, d, Jꢀ50 Hz, CHF), 7.37—7.70 (5H, m,
Corder (MT-6) of J Science Lob. at the Life Science Research Center, Gifu ArH); 19F-NMR (470.5 MHz, CDCl3) d: ꢁ86.77 (1F, d, Jꢀ49 Hz); MS m/z
1
University. H- and 13C-NMR spectra were determined with JEOL ECA500
215 (Mꢂ). Anal. Calcd for C8H6NFSe: C, 44.88; H, 2.82; N, 6.54. Found: C,
(500 MHz) spectrometer. The 19F-NMR (470.5 MHz) spectra were obtained 44.68; H, 2.78; N, 6.35.
in CDCl3 with trifluoroacetic acid as the external standard. IR spectra were
Scandium Triflate-Catalyzed Allylation of Ethyl 2-Fluoro-2-
determined on JASCO FT/IR-460plus infrared spectrometer and are ex- (phenylselanyl)acetate (1), Typical Procedure Under an Ar atmosphere,
pressed in reciprocal centimeter. Electron impact (EI) mass spectra (MS) scandium triflate (9.4 mg, 0.02 mmol) was added to a CH2Cl2 (1.0 ml) solu-
were obtained using JMS MS700/GI spectrometer with a direct-insertion
probe at an ionization voltage of 70 eV.
Preparation of Ethyl 2-Fluoro-2-(phenylselanyl)acetate (1) NaBH4
(0.49 g, 12.8 mmol) was added portionwise to a EtOH (30.0 ml) solution of
diphenyl diselenide (2.00 g, 6.41 mmol). Ethyl chlorofluoroacetate (1.80 g,
tion of 1 (0.10 g, 0.38 mmol) and allyltrimethylsilane (0.13 g, 1.15 mmol) at
room temperature. The reaction mixture was stirred for 1.5 h and poured into
a saturated NaHCO3. The organic layer was separated and the aqueous layer
was extracted with CHCl3. The combined organic layer was dried over
MgSO4. The solvent was removed under reduced pressure. The residue was
12.8 mmol) was added immediately to a colorless solution (if the color of the purified by preparative TLC on silica gel eluting with EtOAc–n-hexane
reaction mixture became yellow, a small amount of NaBH4 was added to it
(1 : 20) to give ethyl 2-(phenylselanyl)pent-4-enoate (6a) (94 mg, 87%) as a
upto the mixture was colorless). The whole was stirred for 10 min at room pale yellow oil. IR (KBr, cmꢁ1) 3074, 2980, 2935, 2364, 2344, 1727, 1578,
temperature and poured into water (100 ml). The organic layer was separated 1476, 1437, 1369, 1338, 1301, 1272, 1247, 1232, 1185, 1139, 1022, 998,
and the aqueous layer was extracted with ether. The combined organic layer 920, 856, 794, 741; 1H-NMR (500 MHz, CDCl3) d: 1.16 (3H, t, Jꢀ7 Hz,
was dried over MgSO4. The solvent was removed under reduced pressure. Me), 2.49—2.55 (1H, m, CH2), 2.63—2.69 (1H, m, CH2), 3.66 (1H, dd, Jꢀ
The residue was purified by column chromatography on silica gel eluting 6, 9 Hz, SeCH), 4.08 (2H, q, Jꢀ7 Hz, OCH2), 5.07—5.12 (2H, m, olefinic
with EtOAc–n-hexane (1 : 10) to give ethyl 2-fluoro-2-(phenylselanyl)acetate H), 5.75—5.83 (1H, m, olefinic H), 7.26—7.35 (3H, m, ArH), 7.60 (2H, d,
(1) (2.65 g, 79%) as a yellow oil. IR (KBr, cmꢁ1) 1757 (CO); 1H-NMR Jꢀ7 Hz, ArH); 13C-NMR (100 MHz, CDCl3) d: 14.11 (q), 36.06 (t), 42.59
(500 MHz, CDCl3) d 1.17 (3H, t, Jꢀ7 Hz, Me), 4.08—4.13 (2H, m, OCH2),
(d), 61.06 (t), 117.70 (t), 127.80 (s), 128.62 (d), 129.08 (dꢃ2), 134.78 (d),
6.38 (1H, d, Jꢀ52 Hz, CHF), 7.32—7.41 (3H, m, ArH), 7.65—7.67 (2H, m, 135.84 (dꢃ2), 172.51 (s); high-resolution mass calcd for C13H16O2Se:
ArH); 19F-NMR (470.5 MHz, CDCl3) d:ꢁ88.85 (1F, d, Jꢀ51 Hz); MS m/z 284.0315, found m/z 284.0310.
262 (Mꢂ). Anal. Calcd for C10H11FO2Se: C, 45.99; H, 4.25. Found: C, 45.97;
Reaction of 1 with 1-Phenyl-1-(trimethylsilyloxy)ethylene The reac-
tion of (0.10 g, 0.38 mmol), 1-phenyl-1-(trimethylsilyloxy)ethylene
H, 4.22.
1
Ethyl 2-Fluoro-2-(phenylsulfanyl)acetate (2) Triethylamine (7.20 g, (90 mg, 0.38 mmol) and scandium triflate (11 mg, 0.02 mmol) in CH2Cl2
71.2 mmol) was added to a toluene (80.0 ml) solution of thiophenol (4.31 g,
39.1 mmol) and ethyl 2-chloro-2-fluoroacetate (5.00 g, 35.6 mmol). The
reaction mixture was stirred for 40 min and then refluxed for 10 min. The
(1.0 ml) at room temperature afforded ethyl 3-benzoyl-2-(phenylselanyl)pro-
pionate (6b) (0.11 g, 78%) as a pale yellow oil. IR (KBr, cmꢁ1) 3058, 2980,
2924, 2362, 1725, 1685, 1596, 1579, 1476, 1448, 1394, 1371, 1352, 1326,
cooled mixture was poured into water (100 ml). The organic layer was sepa- 1299, 1214, 1160, 1096, 1023, 1000, 986, 858, 742; 1H-NMR (500 MHz,
rated and aqueous layer was extracted with ether. The combined organic CDCl3) d: 1.18 (3H, t, Jꢀ7 Hz, Me), 3.42 (1H, dd, Jꢀ4, 18 Hz, COCH2),
layer was dried over MgSO4. The work-up procedure afforded 2 (4.61 g,
3.70 (1H, dd, Jꢀ10, 18 Hz, COCH2), 4.12 (2H, q, Jꢀ7 Hz, OCH2), 4.21
55%) as a yellow oil. IR (KBr, cmꢁ1) 3061, 2984, 2362, 2355, 1757, 1475, (1H, dd, Jꢀ4, 10 Hz, CHSe), 7.30—7.66 (8H, m, ArH), 7.89—7.98 (2H, m,
1393, 1370, 1324, 1271, 1252, 1186, 1044, 1025, 948, 859, 813, 749, 691;
ArH); 13C-NMR (100 MHz, CDCl3) d: 13.94 (q), 37.08 (d), 41.29 (t), 61.21
1H-NMR (500 MHz, CDCl3) d: 1.19 (3H, t, Jꢀ7 Hz, Me), 4.15 (2H, q, (t), 127.29 (d), 128.05 (dꢃ2), 128.62 (dꢃ2), 128.81 (d), 129.11 (dꢃ2),
Jꢀ7 Hz, OCH2), 6.07 (1H, d, Jꢀ51 Hz, CHF), 7.34—7.39 (3H, m, ArH),
133.43 (d), 135.91 (dꢃ2), 136.18 (s), 172.54 (s), 192.24 (s); MS m/z 362
7.55—7.59 (2H, m, ArH); 19F-NMR (470.5 MHz, CDCl3) d: ꢁ80.7 (1F, d, (Mꢂ). Anal. Calcd for C18H18O3Se: C, 59.84; H, 5.02. Found: C, 60.03; H,
Jꢀ51 Hz); MS m/z 214 (Mꢂ). Anal. Calcd for C10H11FO2S: C, 56.06; H, 5.11.
5.18. Found: C, 55.88; H, 5.02.
Reaction of 2 with Allyltrimethylsilane Reaction of 2 (0.10 g,
Preparation of 2-Fluoro-2-(phenylselanyl)acetamide (3) To EtOH
(30.0 ml) solution of ethyl 2-fluoro-2-(phenylselanyl)acetate (1) (3.0 g,
0.47 mmol), allyltrimethylsilane (0.16 g, 1.40 mmol) and scandium triflate
(11 mg, 0.02 mmol) in 1,2-dichloroethane (1.0 ml) at room temperature
11.5 mmol) was added aqueous 30% NH3 (30.0 ml) at room temperature. afforded ethyl 2-(phenylsulfanyl)pent-4-enoate (7a) (96 mg, 86%) as a pale

1614
Vol. 54, No. 11
yellow oil. IR (KBr, cmꢁ1) 1731, 1438, 1368, 1232, 1155, 1024, 921, 748,
692; H-NMR (500 MHz, CDCl3) d: 1.17 (3H, t, Jꢀ7 Hz, Me), 2.51—2.63
134.83 (dꢃ2), 174.18 (s); MS m/z 255 (Mꢂ). Anal. Calcd for C11H13NOSe:
C, 51.98; H, 5.16; N, 5.51. Found: C, 51.77; H, 4.86; N, 5.52.
1
(2H, m, CH2), 3.68—3.72 (1H, m, SCH), 4.11 (2H, q, Jꢀ7 Hz, OCH2),
5.08—5.16 (2H, m, olefinic H), 5.78—5.85 (1H, m, olefinic H), 7.26—7.32
(3H, m, ArH), 7.46—7.48 (2H, m, ArH); 13C-NMR (100 MHz, CDCl3) d:
14.06 (q), 35.83 (t), 50.25 (d), 61.13 (t), 118.01 (t), 127.23 (s), 128.01 (d),
128.91 (dꢃ2), 133.08 (dꢃ2), 133.86 (d), 171.62 (s); MS m/z 195 (Mꢂ-
allyl). Anal. Calcd for C13H16O2S: C, 66.07; H, 6.82. Found: C, 65.95; H,
6.77.
Reaction of 2 with 1-Phenyl-1-(trimethylsilyloxy)ethylene Reaction
of 2 (0.10 g, 0.47 mmol), 1-phenyl-1-(trimethylsilyloxy)ethylene (0.18 g,
0.93 mmol) and scandium triflate (11 mg, 0.02 mmol) in 1,2-dichloroethane
(1.0 ml) at 0 °C afforded ethyl 3-benzoyl-2-(phenylsulfanyl)propionate (7b)
(0.13 g, 89%) as a yellow oil. IR (KBr, cmꢁ1) 3059, 2980, 2360, 1731, 1684,
1596, 1580, 1473, 1448, 1398, 1328, 1241, 1213, 1159, 1094, 1024, 1001,
949, 857, 754, 690; 1H-NMR (500 MHz, CDCl3) d: 1.15 (3H, t, Jꢀ7 Hz,
Me), 3.36 (1H, dd, Jꢀ4, 18 Hz, COCH2), 3.68 (1H, dd, Jꢀ10, 18 Hz,
COCH2), 4.12 (2H, q, Jꢀ7 Hz, OCH2), 4.24 (1H, dd, Jꢀ4, 10 Hz, SCH),
7.30—7.54 (8H, m, ArH), 7.89—7.91 (2H, m, ArH); 13C-NMR (100 MHz,
CDCl3) d: 13.77 (q), 40.68 (t), 45.03 (d), 61.10 (t), 127.85 (dꢃ2), 128.07
(d), 128.26 (dꢃ2), 128.43 (dꢃ2), 132.27 (s), 133.27 (d), 133.45 (dꢃ2),
135.89 (s), 171.35 (s), 196.54 (s); MS m/z 314 (Mꢂ). Anal. Calcd for
C18H18O3S: C, 68.76; H, 5.77. Found: C, 68.58; H, 5.72.
Scandium Triflate-Catalyzed Reaction of 2-Fluoro-2-(phenylselanyl)
acetonitrile (5) with 1-Phenyl-1-(trimethylsilyloxy)ethylene Under an
Ar atmosphere, scandium triflate (12.0 mg, 0.02 mmol) was added to a 1,2-
dichloroethane (1.0 ml) solution of 2-fluoro-2-(phenylselanyl)acetonitrile (5)
(0.10 g, 0.47 mmol) and 1-phenyl-1-(trimethylsilyloxy)ethylene (0.27 g,
1.40 mmol) at 0 °C. The reaction mixture was stirred for 20 min at room
temperature and then poured into water. The usual work-up afforded 3-ben-
zoyl-2-(phenylselanyl)propionamide (9a) (0.111 g, 75%) as a yellow oil. IR
(KBr, cmꢁ1) 2234 (CN), 1680 (CO); 1H-NMR (500 MHz, CDCl3) d: 3.54—
3.58 (2H, m, CH2), 4.25 (1H, t, Jꢀ7 Hz, CH), 7.35—7.89 (10H, m, ArH);
13C-NMR (100 MHz, CDCl3) d: 19.55 (d), 41.52 (t), 119.67 (s), 125.67 (s),
127.98 (dꢃ2), 128.76 (dꢃ2), 129.53 (dꢃ2), 129.82 (d), 133.92 (d), 135.37
(s), 136.53 (dꢃ2), 194.16 (s); MS m/z 315 (Mꢂ). Anal. Calcd for
C16H13NOSe: C, 61.15; H, 4.17; N, 4.46. Found: C, 61.45; H, 4.20; N, 4.40.
Reaction of 2-Fluoro-2-(phenylselanyl)acetonitrile with 2-Methyl-1-
(trimethylsilyloxy)prop-1-ene Reaction of 2-fluoro-2-(phenylselanyl)ace-
tonitrile (5) (0.10 g, 0.47 mmol), 2-methyl-1-(trimethylsilyloxy)prop-1-ene
(0.20 g, 1.40 mmol) and scandium triflate (12 mg, 0.02 mmol) at room tem-
perature afforded 3-formyl-3-methyl-2-(phenylselanyl)butyronitrile (9b)
(0.10 g, 81%) as a yellow oil. IR (KBr, cmꢁ1) 2971, 2932, 2232 (CN), 1727
1
(CO); H-NMR (500 MHz, CDCl3) d: 1.33 (3H, s, Me), 1.39 (3H, s, Me),
Reaction of
2 with Phenylsulfanyltrimethylsilane Reaction of 2
3.83 (1H, s, CH), 7.26—7.73 (5H, m, ArH), 9.48 (1H, s, CHO); high resolu-
tion mass calcd for C12H13NOSe: 267.0162, found m/z 267.0047. The com-
pound 9b was easily oxidized to the corresponding carboxylic acid. (Anal.
Calcd for C12H13NO2Se: C, 51.07; H, 4.64; N, 4.96. Found: C, 50.57; H,
4.57; N, 4.62.)
(0.10 g, 0.47 mmol), phenylsulfanyltrimethylsilane (0.17 g, 0.93 mmol) and
scandium triflate (11 mg, 0.02 mmol) in 1,2-dichloroethane (1.0 ml) at room
temperature afforded 2,2-bis(phenylsulfanyl)acetate (7c) (0.14 g, 95%) as a
yellow oil. IR (KBr, cmꢁ1) 3437, 2358, 1731, 1714, 1633, 1471, 1439, 1364,
1280, 1141, 1026, 740; 1H-NMR (500 MHz, CDCl3) d: 1.18 (3H, t, Jꢀ7 Hz,
Me), 4.14 (2H, q, Jꢀ7 Hz, OCH2), 4.84 (1H, s, SCH), 7.32—7.34 (6H, m,
ArH), 7.48—7.50 (4H, m, ArH); 13C-NMR (100 MHz, CDCl3) d: 13.93 (q),
58.30 (t), 62.10 (d), 128.62 (dꢃ2), 129.04 (dꢃ4), 132.78 (sꢃ2), 133.37 (dꢃ
4), 171.43 (s); MS m/z 304 (Mꢂ). Anal. Calcd for C16H16O2S: C, 63.13; H,
5.30. Found: C, 62.94; H, 5.27.
Reaction of 5 with 3,3-Dimethyl-2-(trimethylsilyloxy)but-1-ene Re-
action of 5 (0.10 g, 0.47 mmol), 3,3-dimethyl-2-(trimethylsilyloxy)but-1-ene
(0.24 g, 1.40 mmol) and scandium triflate (12 mg, 0.02 mmol) in CH2Cl2
(1.0 ml) afforded 3-pivaloyl-2-(phenylselanyl)propionitrile (9c) (0.12 g,
85%) as a pale yellow oil. IR (KBr, cmꢁ1) 2234 (CN), 1708 (CO); 1H-NMR
(500 MHz, CDCl3) d: 1.19 (9H, s, Meꢃ3), 3.08—3.10 (2H, m, CH2), 4.10
(1H, t, Jꢀ7 Hz, CH), 7.39—7.74 (5H, m, ArH); 13C-NMR (100 MHz,
CDCl3) d: 19.76 (d), 26.07 (qꢃ3), 39.99 (s), 43.94 (t), 119.78 (s), 125.93
(s), 129.58 (dꢃ2), 129.81 (d), 136.38 (dꢃ2), 209.92 (s); MS m/z 295 (Mꢂ).
Anal. Calcd for C14H17NOSe: C, 57.15; H, 5.82; N, 4.76. Found: C, 56.88;
H, 5.78; N, 4.73.
Reaction of 4 with Allyltrimethylsilane Under an Ar atmosphere,
scandium triflate (13 mg, 0.03 mmol) was added to a nitromethane (0.50 ml)
solution of 2-fluoro-2-(phenylsulfanyl)acetamide (4) (0.10 g, 0.54 mmol)
and allyltrimethylsilane (0.31 g, 2.70 mmol). The usual work-up afforded 2-
(phenylsulfanyl)pent-4-enamide (8a) (92 mg, 82%) as pale yellow powders.
mp 80—81 °C (from CH2Cl2–n-hexane), IR (KBr, cmꢁ1) 3381 (NH), 3186
Reaction of 5 with Anisole Reaction of 5 (0.10 g, 0.47 mmol), anisole
(0.15 g, 1.40 mmol) and scandium triflate (23 mg, 0.05 mmol) in 1,2-
dichloroethane (1.0 ml) afforded 2-(p-methoxyphenyl)-2-(phenylselanyl)ace-
tonitrile (9d) (60.0 mg, 43%) as a yellow oil. IR (KBr, cmꢁ1) 2231 (CN),
1
(NH), 1654 (CO), 1157 (C–N); H-NMR (500 MHz, CDCl3) d: 2.52—2.58
(1H, m, CH2), 2.67—2.72 (1H, m, CH2), 3.69 (1H, t, Jꢀ7 Hz, CH), 5.11—
5.18 (2H, m, olefinic H), 5.81—5.89 (1H, m, olefinic H), 6.52 (1H, br s,
NH), 6.54 (1H, br s, NH), 7.21—7.47 (5H, m, ArH); 13C-NMR (100 MHz,
CDCl3) d: 36.21 (t), 51.79 (d), 118.11 (t), 127.31 (d), 129.07 (dꢃ2), 130.69
(dꢃ2), 133.51 (s), 133.71 (d), 173.84 (s); MS m/z 207 (Mꢂ). Anal. Calcd for
C11H13NOS: C, 63.74; H, 6.32; N, 6.76. Found: C, 63.57; H, 6.07; N, 6.68.
Reaction of 4 with 1-Phenyl-1-(trimethylsilyloxy)ethylene Scandium
triflate (13 mg, 0.02 mmol) was added to a nitromethane (1.0 ml) solution of
4 (0.10 g, 0.54 mmol) and 1-phenyl-1-(trimethylsilyloxy)ethylene (0.31 g,
1.62 mmol) at room temperature. The reaction mixture was stirred for 4 h.
The usual work-up afforded 3-benzoyl-2-(phenylsulfanyl)propionamide (8b)
(46 mg, 30%) as yellow powders. mp 154—156 °C (from CH2Cl2–n-
hexane), IR (KBr, cmꢁ1) 3430 (NH), 1680 (CO), 1182 (C–N); 1H-NMR
(500 MHz, CDCl3) d: 3.42 (1H, dd, Jꢀ5, 18 Hz, CH2), 3.79 (1H, dd, Jꢀ7,
18 Hz, CH2), 4.27 (1H, dd, Jꢀ5, 7 Hz, CH), 5.85 (1H, br s, NH), 6.39 (1H,
br s, NH), 7.29—7.36 (3H, m, ArH), 7.44—7.59 (5H, m, ArH), 7.93—7.95
(2H, m, ArH); 13C-NMR (100 MHz, CDCl3) d: 40.78 (t), 46.71 (d), 128.15
(dꢃ2), 128.27 (d), 128.64 (dꢃ2), 129.36 (dꢃ2), 132.44 (dꢃ2), 133.15 (s),
133.50 (d), 136.20 (s), 173.01 (s), 197.08 (s); MS m/z 285 (Mꢂ). Anal.
Calcd for C16H15NO2S: C, 67.34; H, 5.30; N, 4.91. Found: C, 67.14; H, 5.28;
N, 5.28.
1
1251; H-NMR (500 MHz, CDCl3) d: 3.79 (3H, s, Me), 4.92 (1H, s, CH),
6.82—7.21 (4H, m, ArH), 7.31—7.59 (5H, m, ArH); 13C-NMR (100 MHz,
CDCl3) d: 29.27 (d), 55.33 (q), 114.27 (dꢃ2), 118.81 (s), 124.96 (s), 126.83
(s), 128.86 (dꢃ2), 129.34 (dꢃ2), 129.79 (d), 136.76 (dꢃ2), 159.73 (s); MS
m/z 303 (Mꢂ). Anal. Calcd for C15H13NOSe: C, 59.61; H, 4.34; N, 4.63.
Found: C, 59.92; H, 4.48; N, 4.65.
Reaction of 5 with Toluene Reaction of 5 (0.10 g, 0.47 mmol), toluene
(1.0 ml) and scandium triflate (12.0 mg, 0.02 mmol) in 1,2-dichloroethane
(1.0 ml) afforded 2-(p-tolyl)- and 2-(o-tolyl)-2-phenylselanylacetonitrile (9e)
(0.11 g, 81%).
9e: IR (KBr, cmꢁ1) 2234 (CN); 1H-NMR (500 MHz, CDCl3) d: 2.33 (s, p-
Me), 2.42 (s, o-Me), 4.91 (s, p-CH), 4.94 (s, o-Me), 7.07—7.25 (m, ArH),
7.30—7.44 (m, ArH), 7.57—7.58 (m, ArH); high-resolution mass calcd for
C15H13NSe: 287.0210, found m/z 287.0183.
Preparation of Ethyl 2-Chloro-2-(phenylselanyl)acetate (10) Scan-
dium triflate (47 mg, 0.01 mmol) was added to a nitromethane (5.0 ml) solu-
tion of 1 (0.50 g, 1.90 mmol) and chlorotrimethylsilane (0.62 g, 5.7 mmol) at
room temperature. The mixture was refluxed for 5 min and poured into a sat.
NaHCO3 (50 ml) solution. The organic layer was separated and the aqueous
layer was extracted with ether. The combined organic layer was dried over
MgSO4. The solvent was removed under reduced pressure. The residue was
purified by the preparative TLC on silica gel eluting with EtOAc–n-hexane
(1 : 20) to give 10 (0.53 g, quant.) as a pale yellow oil. IR (KBr, cmꢁ1) 1748
Reaction of 2-Fluoro-2-(phenylselanyl)acetamide (3) with Allyl-
trimethylsilane Scandium triflate (11 mg, 0.02 mmol) was added to a ni-
tromethane (1.0 ml) solution of 3 (0.10 g, 0.43 mmol) and allyltrimethylsi-
lane (0.25 g, 2.15 mmol) at room temperature. The reaction mixture was re-
fluxed for 12 h. The usual work-up afforded 2-(phenylselanyl)pent-4-enam-
ide (8c) (89 mg, 82%) as pale yellow powders. mp 66—67 °C (from
CH2Cl2–n-hexane), IR (KBr, cmꢁ1) 1641 (CO), 1170 (C–N); 1H-NMR
(500 MHz, CDCl3) d: 2.52—2.57 (1H, m, CH2), 2.69—2.74 (1H, m, CH2),
3.62 (1H, t, Jꢀ7 Hz, CH), 5.08—5.15 (2H, m, olefinic H), 5.78—5.87 (1H,
m, olefinic H), 5.97 (1H, br s, NH), 6.24 (1H, br s, NH), 7.27—7.33 (3H, m,
ArH), 7.58 (2H, dd, Jꢀ1, 2 Hz, ArH); 13C-NMR (100 MHz, CDCl3) d: 36.21
(t), 45.33 (d), 117.72 (t), 127.91 (s), 128.36 (d), 129.22 (dꢃ2), 134.67 (d),
1
(CO), 1476, 1439, 1367, 1273, 1173, 1134, 1023, 866, 788, 741, 690; H-
NMR (500 MHz, CDCl3) d: 1.23 (3H, t, Jꢀ7 Hz, Me), 4.17 (2H, q, Jꢀ7 Hz,
OCH2), 5.52 (1H, s, CHCl), 7.35—7.37 (2H, m, ArH), 7.39—7.42 (1H, m,
ArH), 7.67—7.70 (2H, m, ArH); 13C-NMR (100 MHz, CDCl3) d: 13.84 (q),
53.04 (d), 62.62 (t), 126.72 (s), 129.26 (dꢃ2), 134.91 (d), 135.96 (dꢃ2),
167.04 (s); MS m/z 278 (Mꢂ). Anal. Calcd for C10H11ClO2Se: C, 43.27; H,
3.99. Found: C, 43.12; H, 3.89.
2-Chloro-2-(phenylselanyl)acetamide (11) Yield 83%, white needles,

November 2006
1615
mp 88 °C (from CH2Cl2–n-hexane), IR (KBr, cmꢁ1) 3333 (NH), 3166 (NH),
1666 (CO), 1630, 1577, 1478, 1436, 1229, 1163, 1071, 1021, 776, 732, 687,
632; 1H-NMR (100 MHz, CDCl3) d: 5.56 (1H, s, CHCl), 6.25 (1H, br s,
NH), 6.63 (1H, br s, NH), 7.27—7.40 (3H, m, ArH), 7.70—7.72 (2H, m,
ArH); 13C-NMR (100 MHz, CDCl3) d: 55.20 (d), 126.21 (s), 129.27 (dꢃ2),
129.67 (d), 136.35 (dꢃ2), 169.26 (s); MS m/z 249 (Mꢂ). Anal. Calcd for
C8H8ClNOSe: C, 38.66; H, 3.24; N, 5.64. Found: C, 38.47; H, 3.17; N, 5.62.
Ethyl 2-Bromo-2-(phenylselanyl)acetate (12) Yield 88%, a yellow oil,
IR (KBr, cmꢁ1) 2982, 1737 (CO), 1577, 1476, 1439, 1367, 1258, 1136,
1022, 862, 779, 742, 690566, 468; 1H-NMR (500 MHz, CDCl3) d: 1.22 (3H,
t, Jꢀ7 Hz, Me), 4.16 (2H, q, Jꢀ7 Hz, OCH2), 5.43 (1H, s, CHBr), 7.33—
7.40 (3H, m, ArH), 7.65—7.66 (2H, m, ArH); 13C-NMR (100 MHz, CDCl3)
d 13.65 (q), 39.64 (d), 62.49 (t), 127.48 (s), 129.13 (dꢃ2), 129.27 (d),
135.19 (dꢃ2), 166.68 (s); high-resolution mass calcd for C10H11BrO2Se:
321.9153, found m/z 321.9180.
Jꢀ1 Hz, olefinic H), 7.32—7.36 (3H, m, ArH), 7.53—7.54 (2H, m, ArH);
13C-NMR (100 MHz, CDCl3) d: 33.17 (t), 46.26 (d), 71.53 (t), 113.18 (t),
128.53 (d), 129.21 (dꢃ2), 132.21 (s), 133.25 (dꢃ2), 135.65 (s), 169.10 (s);
high-resolution mass calcd for C12H12O2S: 220.0558, found m/z 220.0537.
Preparation of Ethyl 4-(Hydroxymethyl)-2-(phenylselanyl)pent-4-
enoate (14) Scandium triflate (56 mg, 0.12 mmol) was added to a 1,2-
dichloroethane (3.0 ml) solution of ethyl 2-fluoro-2-(phenylselanyl)acetate
(1) (0.30 g, 1.14 mmol) and O-trimethylsilyl-2-(trimethylsilylmethyl)prop-2-
en-1-ol (0.50 g, 2.30 mmol) at 0 °C. The reaction mixture was stirred for
30 min at room temperature. Tetrabutylammonium fluoride in THF (3 drops
of 1 M) was added dropwise to the mixture. The whole was stirred for 1 h
and poured into water (100 ml). The usual work-up afforded 14 (0.16 g,
43%) as a pale yellow oil. IR (KBr, cmꢁ1) 3449 (OH), 1725 (CO), 1476,
1439, 1370, 1302, 1260, 1159, 1022, 909, 742, 692; 1H-NMR (500 MHz,
CDCl3) d: 1.13 (3H, t, Jꢀ7 Hz, Me), 2.38 (1H, br s, OH), 2.55 (1H, dd, Jꢀ6,
15 Hz, 3-H), 2.71 (1H, dd, Jꢀ10, 15 Hz, 3-H), 3.85 (1H, dd, Jꢀ6, 10 Hz, 4-
H), 4.02 (2H, s, 5-H), 4.05 (2H, q, Jꢀ7 Hz, OCH2), 4.90 (1H, s, olefinic H),
5.09 (1H, s, olefinic H), 7.27—7.35 (3H, m, ArH), 7.59—7.61 (2H, m,
ArH); 13C-NMR (100 MHz, CDCl3) d: 13.84 (q), 34.93 (t), 41.20 (d), 60.98
(t), 65.53 (t), 112.26 (t), 127.51 (s), 128.53 (d), 128.92 (dꢃ2), 135.64 (dꢃ
2), 145.66 (s), 172.69 (s); MS m/z 312 (MꢂꢁH2O). Anal. Calcd for
C14H18O4Se: C, 53.68; H, 5.79. Found: C, 53.83; H, 5.83.
2-Bromo-2-(phenylselanyl)acetamide (13) Yield 64%, white needles,
mp 130 °C (from CH2Cl2–n-hexane), IR (KBr, cmꢁ1) 3380 (NH), 3176
(NH), 1656 (CO), 1475, 1438, 1411, 1189, 1132, 1095, 1022, 1000, 773,
1
743, 690, 620, 539; H-NMR (500 MHz, CDCl3) d: 5.46 (1H, CHBr), 5.82
(1H, br s, NH), 6.12 (1H, br s, NH), 7.38—7.43 (3H, m, ArH), 7.71 (2H, br
s, ArH); 13C-NMR (100 MHz, CDCl3) d: 42.08 (d), 127.39 (s), 129.43
(dꢃ2), 129.76 (d), 135.89 (dꢃ2), 168.60 (s); MS m/z 294 (Mꢂ). Anal. Calcd
for C8H8BrNOSe: C, 32.79; H, 2.75; N, 4.78. Found: C, 32.60; H, 2.69; N,
4.80.
Preparation of 5-Methylene-3-(phenylselanyl)tetrahydro-2-pyrone
(16) Scandium triflate (13 mg, 0.027 mmol) was added to
a 1,2-
Relative Reactivities of a-Fluoro-, a-Chloro- and a-Bromo-Ethyl Ac-
etaes 1, 10, 12 and Acetamides 3, 11, 13, General Experimental Proce-
dure Scandium triflate (5 mg, 0.01 mmol) was added to a nitromethane
(0.50 ml) solution of ethyl 2-fluoro-2-(phenylselanyl)acetate (1) (50.0 mg,
0.19 mmol) and allyltrimethylsilane (0.11 g, 0.96 mmol) at room tempera-
ture. The reaction mixture was heated under a reflux condition for 5 min and
poured into a sat. NaHCO3 (50.0 ml) solution. The usual work-up afforded
ethyl 2-(phenylselanyl)pent-4-enoate (6a) (54 mg, quant.)
Preparation of Ethyl 4-(Hydroxymethyl)-2-(phenylsulfanyl)pent-4-
enoate (15) Scandium triflate (22 mg, 0.047 mmol) was added to a 1,2-
dichloroethane (1.0 ml) solution of ethyl 2-fluoro-2-(phenylsulfanyl)acetate
(2) (0.10 g, 0.47 mmol) and O-trimethylsilyl-2-(trimethylsilylmethyl)prop-2-
en-1-ol (0.30 g, 1.40 mmol) at 0 °C. The reaction mixture was stirred for 1 h
at room temperature. The usual work-up afforded title compound 15 (93 mg,
71%) as a pale yellow oil. IR (KBr, cmꢁ1) 3438 (OH), 1731 (CO), 1654,
1538, 1473, 1440, 1370, 1332, 1301, 1263, 1174, 1155, 1025, 908, 858,
750, 692; 1H-NMR (500 MHz, CDCl3) d: 1.19 (3H, t, Jꢀ7 Hz, Me), 2.11
(1H, br s, OH), 2.59 (1H, dd, Jꢀ6, 15 Hz, CH2), 2.73 (1H, dd, Jꢀ9, 15 Hz,
CH2), 3.93 (1H, dd, Jꢀ6, 10 Hz, CHS), 4.12 (2H, s, CH2), 4.13 (2H, q, Jꢀ
7 Hz, OCH2), 4.99 (1H, d, Jꢀ1 Hz, olefinic H), 5.17 (1H, s, olefinic H),
7.31—7.35 (3H, m, ArH), 7.50—7.58 (2H, m, ArH); 13C-NMR (100 MHz,
CDCl3) d: 14.01 (q), 34.94 (t), 49.09 (d), 61.06 (t), 65.31 (t), 112.34 (t),
128.00 (d), 128.89 (dꢃ2), 133.05 (dꢃ2), 133.19 (s), 144.40 (s), 171.74 (s);
high-resolution mass calcd for C14H18O3S: 266.0976, found m/z 266.0954.
Preparation of 5-Methylene-3-(phenylsulfanyl)tetrahydro-2-pyrone
dichloroethane (1.0 ml) solution of 14 (85 mg, 0.258 mmol) at room temper-
ature. The reaction mixture was refluxed for 12 h and then poured into a sat-
urated NaHCO3 (50 ml). The usual work-up afforded 16 (22 mg, 32%) as a
yellow oil. IR (KBr, cmꢁ1) 3449, 1734 (CO), 1578, 1560, 1543, 1509, 1476,
1
1459, 1438, 1378, 1300, 1219, 1169, 1129, 1057, 741, 691; H-NMR (500
MHz, CDCl3) d: 2.82 (1H, dd, Jꢀ5, 16 Hz, 4-H), 3.06 (1H, dd, Jꢀ6, 16 Hz,
4-H), 4.05 (1H, t, Jꢀ6 Hz, 3-H), 4.83 (1H, d, Jꢀ14 Hz, 6-H), 5.03 (1H, d,
Jꢀ14 Hz, 6-H), 5.06 (1H, s, olefinic H), 5.12 (1H, s, olefinic H), 7.31—7.36
(3H, m, ArH), 7.65—7.66 (2H, m, ArH); 13C-NMR (100 MHz, CDCl3) d:
33.83 (t), 38.56 (d), 71.71 (t), 113.07 (t), 127.49 (s), 128.84 (d), 129.32 (dꢃ
2), 135.38 (dꢃ2), 135.66 (s), 169.84 (s); MS m/z 268 (Mꢂ). Anal. Calcd for
C12H12O2Se: C, 53.94; H, 4.52. Found: C, 54.19; H, 4.75.
References
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a 1,2-
dichloroethane (1.0 ml) solution of 15 (75 mg, 0.266 mmol) at room temper-
ature. The reaction mixture was refluxed for 4 h and then poured into a satu-
rated NaHCO3 (50 ml). The organic layer was separated and the aqueous
layer was extracted with CHCl3. The combined organic layer was dried over
MgSO4. The solvent was removed under reduced pressure. The residue was
purified by the preparative TLC on silica gel eluting with EtOAc–n-hexane
(1 : 5) to give 17 (30 mg, 51%) as a colorless oil. IR (KBr, cmꢁ1) 1739 (CO),
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1
1481, 1438, 1374, 1302, 1249, 1223, 1143, 1055, 1025, 908, 742, 692; H-
NMR (500 MHz, CDCl3) d: 2.77 (1H, dd, Jꢀ6, 17 Hz, 4-H), 3.03 (1H, dd,
Jꢀ6, 17 Hz, 4-H), 4.01 (1H, t, Jꢀ6 Hz, 3-H), 4.82 (1H, d, Jꢀ14 Hz, 6-H),
5.07 (1H, d, Jꢀ1 Hz, olefinic H), 5.08 (1H, d, Jꢀ14 Hz, 6-H), 5.13 (1H, t,
12) Friedrich M., Savchenko A. I., Waechtler A., de Meijere A., Eur. J.
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