9832 J . Org. Chem., Vol. 63, No. 26, 1998
Yong et al.
(37), 174 [M - CO]+ (100), 160 [M - COCH2]+ (51), 146 (41);
HRMS for C12H10OS m/e calculated 202.0452, observed m/e
202.0448. Data for 13: TLC, Rf ) 0.41 (1:4 ethyl acetate-
Syn th esis a n d Rh od iu m (II) Aceta te Ca ta lyzed Decom -
position of 1-Diazo-3-(2-fu r an yl)-2-pr opan on e (22). 1-Diazo-
3-(2-furanyl)-2-propanone (22) was prepared from 2-(2-fura-
nyl)acetic acid14 using the general procedure described above.
The reaction mixture was purified by column chromatography
using silica gel using ethyl acetate-hexanes (1:4) as the eluent
yielding 22 as a yellow oil. The yield was 82%: TLC, Rf ) 0.36
(1:2 ethyl acetate-hexanes); 1H NMR (CDCl3, 300 MHz) δ 3.63
(2H, s, CH2), 5.19 (1H, s, CHN2), 6.20 (1H, d, J ) 3 Hz, Ar H),
6.33 (1H, dd, J ) 2, 3 Hz, Ar H), 7.36 (1H, d, J ) 2 Hz, Ar H);
13C NMR (CDCl3, 75 MHz) δ 40.31, 54.55, 108.56, 110.74,
142.35, 148.27, 190.24; MS [EI+] m/z (RI%) 150 [M]+ (30), 136
[M - N2]+ (72), 94 (100), 81 [M + 1 - COCHN2]+ (80); HRMS
for C7H6N2O2 calculated m/e 150.0429, observed m/e 150.0446.
1
hexane); H NMR (CDCl3, 300 MHz) δ 2.87 (2H, t, J ) 7 Hz,
CH2), 3.30 (2H, t, J ) 7 Hz, CH2), 3.67 (2H, s CH2), 7.39 (2H,
m, Ar H), 7.54 (1H, d, J ) 7 Hz, Ar H), 7.82 (1H, d, J ) 7 Hz,
Ar H); 13C NMR (CDCl3, 75 MHz) δ 25.10, 39.07, 39.54, 120.80,
122.97, 124.83, 124.91, 127.30, 135.52, 138.96, 140.07, 210.04;
MS [EI+] m/z (RI%) 202 [M]+ (64); 173 (19); 160 [M - CH2d
CdO]+ (100); 147 (11); HRMS for C12H10OS calculated m/e
202.0452, observed m/e 202.0449.
Syn th esis a n d Rh od iu m (II) Aceta te Ca ta lyzed Decom -
p osition of 1-Dia zo-3-(2-ben zoth ien yl)-2-p r op a n on e (14).
1-Diazo-3-(2-benzothienyl)-2-propanone (14) was prepared
from 2-(2-benzothienyl)acetic acid13 using the general proce-
dure described above. The reaction mixture was purified by
column chromatography using silica gel with hexanes-dichlo-
romethane (1:2) as eluent. The yield was of 14 (oil) was 76%:
TLC, Rf ) 0.64 (1:1 ethyl acetate-hexanes); 1H NMR (CDCl3,
300 MHz) δ 3.85 (2H, s, CH2), 5.31 (1H, s, CHN2), 7.14 (1H, s,
Ar H), 7.26-7.35 (2H, m, Ar H), 7.70 (1H, d, J ) 6.8 Hz, Ar
H), 7.77 (1H, d, J ) 7.1 Hz, Ar H); 13C NMR (CDCl3, 75 MHz)
δ 42.44, 54.97, 122.15, 123.23, 123.87, 124.27, 124.43, 136.69,
139.74, 140.05, 190.71; MS[EI+], m/z (RI%) 216 [M]+ (13), 188
[M - N2]+ (69), 160 [M - CO-N2]+ (100), 147 [M - COCHN2]+
(90), 115 (57); HRMS for C11H8N2OS calculated m/e 216.0357,
observed m/e 216.0368.
Diazo ketone 14 (140 mg, 0.66 mmol) in dichloromethane
(1 mL) was added to a solution of rhodium(II) acetate (1 mg)
in dichloromethane (50 mL) via a syringe pump over 12 h. The
solvent was evaporated under reduced pressure and the
products separated by silica gel column chromatography using
dichloromethane-hexanes (1:1) as the eluent. The reaction
yielded 2,3-dihydro-1H-benzo[b]cyclopenta[d]thiophen-2-one
(10) (26 mg, 0.14 mmol, 21% yield) and the dimeric product
16 (71.0 mg, 0.19 mmol, 58% based on starting material) which
was recrystallized from ethyl acetate. Data for 16: TLC, Rf )
0.71 (1:1 ethyl acetate-hexanes); 1H NMR (CDCl3, 500 MHz)
δ 3.44 and 3.49 (2H each, each d, J ) 15 Hz, 2 × CH2), 5.88
(1H, d, J ) 6 Hz, CH), 7.10 (2H, s, 2 × SCCH), 7.27-7.32 (4H,
m, Ar-H), 7.39 (1H, d, J ) 6 Hz, CH), 7.68 (2H, d, J ) 7 Hz,
Ar H), 7.75 (2H, d, J ) 7 Hz, Ar H); 13C NMR (CDCl3, 75 MHz)
δ 38.62, 89.45, 122.54, 123.43, 123.69, 124.72, 124.82, 125.22,
136.84, 140.00, 140.38, 157.26, 168.05; MS[EI+] m/z (RI%) 376
[M]+ (18), 147 (100); HRMS for C22H16O2S2 calculated m/e
376.0592, observed m/e 376.0570.
Syn th esis a n d Rh od iu m (II) Aceta te Ca ta lyzed Decom -
position of 1-Diazo-3-(3-fu r an yl)-2-pr opan on e (19). 1-Diazo-
3-(3-furanyl)-2-propanone (19) was prepared from 2-(3-fura-
nyl)acetic acid14 using the general procedure described above.
The reaction mixture was purified by column chromatography
using silica gel with hexanes-dichloromethane (1:2) as eluent
yielding a yellow oil. The yield was 75%: TLC, Rf ) 0.26 (1:2
hexanes-dichloromethane); 1H NMR (CDCl3, 300 MHz) δ 3.42
(2H, s, CH2), 5.22 (1H, s, CHN2), 6.31 (1H, d, J ) 3 Hz, Ar H),
7.34 (1H, d, J ) 3 Hz, Ar H), 7.38 (1H, s, Ar H); 13C NMR
(CDCl3, 75 MHz) δ 37.12, 54.49, 111.25, 117.85, 140.60, 143.43,
192.34; MS[EI+] m/z (RI%) 150 [M]+ (4), 136 [M - N2]+ (80),
94 [M - C(O)N2]+ (100), 81 [M - COCHN2]+ (99); HRMS for
C7H6N2O2 calculated m/e 150.0429, observed m/e 150.0430.
Rhodium acetate decomposition of 19 was carried out using
the general procedure outlined above to yield 2-(4-oxo-2-
cyclopentenylidene)acetaldehyde (21) in quantitative yield (as
evidenced by NMR). Attempts to purify 21 using silica gel
resulted in decomposition. Data for the product: 1H NMR
(CDCl3, 300 MHz) δ 3.14 (2H, s, CH2), 6.14 (1H, d, J ) 7.0 Hz,
CH), 6.70 (1H, d, J ) 6 Hz, CH), 8.55 (1H, d, J ) 6 Hz, CH),
10.14 (1H, d, J ) 7 Hz, CH); 13C NMR (CDCl3, 75 MHz) δ
39.66, 124.49, 141.47, 151.68, 154.74, 188.51, 202.15; MS[EI+]
m/z (RI%) 122 [M]+ (100), 94 [M - CO]+ (37), 66 (37); HRMS
for C7H6O2 m/e calculated 122.0368, observed m/e 122.0372.
Rhodium(II) acetate (approximately 1 mg) is added to a
stirred solution containing 1-diazo-3-(2-furanyl)-2-propanone
(22) (100 mg, 0.67 mmol) in dichloromethane (100 mL) and
water (0.5 mL). The reaction was stirred for 1 h at which time
the solvent is evaporated under reduced pressure. Silica gel
column chromatography using ethyl acetate-hexanes (1:1) as
eluent yielded 2-(2-methyl-3-furanyl)acetic acid (27, amor-
phous solid) in 60% (56.3 mg, 0.40 mmol) and 6a-methyl-
2,3,3a,6a-tetrahydrofuro[2,3-b]furan-2-one (28, oil) in 15%
(14.2 mg, 0.10 mmol). Data for 27: TLC, Rf ) 0.28 (ethyl
acetate); 1H NMR (CDCl3, 300 MHz) δ 2.22 (3H, s, CH3), 3.38
(2H, s, CH2), 6.28 (1H, d, CHdCHO), 7.24 (1H, d, CHdCHO);
13C NMR (CDCl3, 75 MHz) δ 11.82, 31.05, 111.02, 111.92,
140.30, 149.24, 176.85 (CdO); MS [EI+], m/z (RI%) 140 [M]+
(55), 95 (100); HRMS for C7H8O3 calculated m/e 140.0473,
observed m/e 140.0479. Data for 28: TLC, Rf ) 0.24 (dichlo-
1
romethane); H NMR (CDCl3, 300 MHz) δ 1.74 (3H, s, CH3),
2.58 (1H, dd, J ) 2, 18 Hz, one of CH2), 2.86 (1H, dd, J ) 9, 18
Hz, one of CH2), 3.40 (1H, m, CH), 4.99 (1H, m, Ar H), 6.33
(1H, m, Ar H); 13C NMR (CDCl3, 75 MHz) δ 23.55, 34.79, 46.52,
104.67, 116.43, 144.99, 173.87; MS [EI+] m/z (RI%) 140 [M]+
(100), 98 [M-CH2CdO]+ (90), 97 (66), 81 (69); HRMS for
C7H8O3 calculated m/e 140.0473, observed m/e 140.0475.
Syn th esis a n d Rh od iu m (II) Aceta te Ca ta lyzed Decom -
p osition of 1-Dia zo-3-(2-ben zofu r a n yl)-2-p r op a n on e (29).
1-Diazo-3-(2-benzofuranyl)-2-propanone (29) was prepared
from 2-(2-benzofuranyl)acetic acid13,15 using the general pro-
cedure described above. The reaction mixture was purified by
column chromatography using silica with dichloromethane-
hexanes (1:1) as eluent. The yield of 29 (oil) was 66%: TLC,
Rf ) 0.28 (dichloromethane); 1H NMR (CDCl3, 300 MHz) δ 3.77
(2H, s, CH2), 5.31 (1H, s, CHN2), 6.60 (1H, s, Ar-H), 7.15-
7.28 (2H, m, Ar-H), 7.43 (1H, d, J ) 8 Hz, Ar-H), 7.52 (1H,
d, J ) 8 Hz, Ar-H); 13C NMR (CDCl3, 75 MHz) δ 40.76, 55.04,
105.62, 111.06, 120.79, 122.92, 124.18, 128.40, 151.18, 155.01,
184.55; MS [EI+], m/z (RI%) 200 [M]+ (34), 172 [M - N2]+ (82),
144 [M - CO-N2]+ (62), 131 [M - COCHN2]+ (100), 115 (56);
HRMS for C11H8N2O2 calculated m/e 200.0586, observed m/e
200.0574.
Rhodium(II) acetate (approximately 1 mg) was added to a
stirred solution of 1-diazo-3-(2-benzofuranyl)-2-propanone (29)
(100 mg, 0.5 mmol) in dichloromethane (50 mL) and methanol
(0.1 mL). The reaction solution was stirred at room temper-
ature for 2 h at which time the solvent was evaporated under
reduced pressure. The residue was purified by column chro-
matography using silica gel and dichloromethane-hexanes (1:
2) as eluent to yield methyl 2-(2-methylbenzo[b]furan-3-
yl)acetate (34, oil) as the only isolable product. The yield was
58% (42 mg, 0.29 mmol): TLC, Rf ) 0.20 (dichloromethane);
1H NMR (CDCl3, 300 MHz) δ 2.42 (3H, s, CCH3), 3.60 (2H, s,
CH2), 3.67 (3H, s, OCH3), 7.13-7.26 (2H, m, Ar H), 7.32-7.4
(1H, m, Ar H), 7.41-7.47 (1H, m, Ar H); 13C NMR (CDCl3, 75
MHz) δ 12.37, 30.03, 52.41, 108.11, 111.02, 119.22, 122.81,
123.79, 129.55, 152.55, 154.88, 171.65; MS [EI+] m/z (RI%)
204 [M]+ (52), 145 [M - COOMe]+ (100); HRMS for C12H12O3
calculated m/e 204.0786, observed m/e 204.0789.
(13) Degenhartdt, C. R. Synth. Commun. 1982, 12, 415.
(14) J anda, M.; Srogl, J .; Korblova, E.; Stibor, I. Collect. Czech.
Chem. Commun. 1980, 45, 1361.
(15) Kasahara, A.; Izumi, T.; Suzuki, A.; Takeda, T. Bull. Chem.
Soc. J pn. 1976, 49, 5711.