One-pot Synthesis of Aromatic Fused 2,3-Dihydroindanone
zaldehyde 1a with ethylene (Table 1).[15-17] Since the
intermolecular Pauson-Khand reaction between 2a and
ethylene generally gave a low yield, it is crucial to find
an appropriate reaction condition, especially an effec-
tive promoter. Different promoters were tested and the
results were listed in Table 1. The commonly used terti-
ary amine N-oxides, NMO (N-methylmorpholine,
N-oxide), TMANO (trimethylamine, N-oxide) could
only afford moderate yields 56%-59% (Entries 1,
2).[16-18] Mild alkyl methyl sulfide (n-BuSMe, PhSMe,
n-C10H21SMe) also only gave low to moderate yields of
24%-58% (Entries 3-5), which might be attributed to
the bulky phenyl substitute in the cobalt-alkynl com-
plexes hindering the approach of bulk promoters.[19,20]
Thus, a “smaller” promoter DMS (dimethyl sulfide) was
used and worked with improved yields (Entries 6, 7),
and xylene was also a nice solvent (Entry 8).
HRMS (EI) calcd for C13H8NClO3: 261.0191; found
261.0193.
7-Fluoro-4-nitro-2,3-dihydro-1H-cyclopenta[a]-
naphthalen-1-one (3c) Light yellow crystal, 33%,
m.p. 193-195 ℃; 1H NMR (300 MHz, CDCl3) δ: 9.34
(dd, J=9.0, 5.7 Hz, 1H), 8.90 (s, 1H), 7.70 (dd, J=8.7,
2.4 Hz, 1H), 7.64 (td, J=8.4, 2.7 Hz, 1H), 3.67-3.61
(m, 2H), 2.90-2.87 (m, 2H). 13C NMR (101 MHz,
CDCl3) δ: 205.8, 163.0 (d, J=187.4 Hz, 1C), 149.5,
144.5, 134.2, 133.2 (d, J=75.0 Hz, 1C), 130.9 (d, J=
3.9 Hz, 1C), 128.6, 127.0 (d, J=6.4 Hz, 1C), 122.8 (d,
J=18.2 Hz, 1C), 113.4 (d, J=1.62 Hz, 1C), 36.5, 26.5;
IR (KBr) ν: 3447, 3088, 1705, 1609, 1532, 1456, 1349,
1160 cm-1; EI-MS m/z (%): 245 (M+, 74), 170 (100).
HRMS (EI) calcd for C13H8NFO3: 245.0490; found
245.0488.
7-Methyloxy-4-nitro-2,3-dihydro-1H-cyclopenta-
[a]naphthalen-1-one (3d) Light yellow crystal, 69%,
1
m.p. 226-229 ℃; H NMR (300 MHz, DMSO-d6) δ:
Table 1 Influence of promoters to the intermolecular Pauson-
9.16 (s, 1H), 9.07 (d, J=9.0 Hz, 1H), 7.89 (d, J=1.8
Hz, 1H), 7.64 (dd, J=9.0, 2.4 Hz, 1H), 3.94 (s, 3H),
3.56-3.52 (m, 2H), 2.84-2.80 (m, 2H); 13C NMR
(101 MHz, DMSO-d6) δ: 206.7, 159.0, 148.6, 144.4,
133.9, 133.5, 131.1, 126.6, 125.3, 124.9, 109.6, 56.1,
36.8, 26.5; IR (KBr) ν: 3447, 1701, 1600, 1529, 1464,
1376, 1340, 849 cm-1; EI-MS m/z (%): 257 (M+, 67),
240 (100). HRMS (EI) calcd for C14H11NO4: 257.0684;
found 257.0688.
8-Fluoro-4-nitro-2,3-dihydro-1H-cyclopenta[a]-
naphthalen-1-one (3e) Light yellow crystal, 25%,
m.p. 189-190 ℃; 1H NMR (300 MHz, CDCl3) δ: 9.00
(s, 1H), 8.98 (dd, J=10.2, 1.8 Hz, 1H), 8.14 (dd, J=9.0,
5.7 Hz, 1H), 7.52 (td, J=8.7, 2.4 Hz, 1H), 3.71-3.67
(m, 2H), 2.92-2.88 (m, 2H). 13C NMR (101 MHz,
CDCl3) δ: 205.6, 166.7 (d, J=191.3 Hz, 1C), 151.5,
143.1, 133.6 (d, J=4.5 Hz, 1C), 133.2 (d, J=9.0 Hz,
1C), 132.7 (d, J=7.7 Hz, 1C), 131.8, 128.8, 119.2 (d,
J=19.4 Hz, 1C), 109.1 (d, J=17.5 Hz, 1C), 36.5, 26.7;
IR (KBr) ν: 1702, 1624, 1600, 1532, 1451, 1419, 1366,
1174 cm-1. EI-MS m/z (%): 245 (M+, 57), 170 (100).
HRMS (EI) calcd for C13H8NFO3: 245.0492; found
245.0493.
Khand reaction
Co2(CO)8 (1.2 equiv.),
ethylene (30 bar),
CHO
CHO
promotors,
solvents, Δ
O
1a
2a
Entry
Promotor
Solvent
T/℃
t/h
6
Yielda/%
1
2
3
4
5
6
7
8
TMANO
NMO
PhMe/MeOH40
PhMe/DCM 40
59
56
44
24
58
70
71
71
8
n-BuSMe
PhSMe
1,2-DCE
1,2-DCE
83
24
24
2
83
n-C10H21SMe1,2-DCE
120
83
MeSMe
MeSMe
MeSMe
1,2-DCE
1,2-DCE
xylene
8
120
130
2
5
a Isolated yields.
Since α,β-unsaturated aldehydes/ketones readily un-
dergo 1,2-addition with nitroalkanes under basic condi-
tions, both the activation of carbonyl group and the con-
trolling of proper pH are crucial to gain the Michael
addition reaction product.[21] Hanessian group has re-
ported that TDMP (trans-2,5-dimethylpiperazine) was
an effective base in the Michael addition reaction using
nitromethane as an nucleophile.[22] L-Proline was usu-
ally used to activate carbonyl. Based on the above work,
we screened conditions for the Michael/Henry cascade
reaction (Table 2). Product 3a was isolated in 35% yield
when 2a was treated with TDMP (1.0 equiv.), L-proline
(2 mol%) and MeNO2 (2 equiv.) in DCM (Entry 1). The
structure of 3a was confirmed by X-ray analysis. For
other solvents, 3a could also be isolated in 8%-87%
yield (Entries 2-10). When using chloroform as sol-
vent, 87% yield was obtained (Entry 2). Additional ex-
periments showed that L-proline was not necessary
8-Methyl-4-nitro-2,3-dihydro-1H-cyclopenta[a]-
naphthalen-1-one (3f) Light yellow crystal, 54%, m.p.
1
180-181 ℃. H NMR (300 MHz, CDCl3) δ: 9.09 (s,
1H), 8.94 (s, 1H), 7.98 (d, J=8.4 Hz, 1H), 7.55 (dd, J=
8.4, 1.2 Hz, 1H), 3.68-3.64 (m, 2H), 2.89-2.86 (m,
2H), 2.63 (s, 3H); 13C NMR (101 MHz, CDCl3) δ: 206.1,
150.8, 144.2, 142.7, 133.0, 131.8, 131.7, 130.6, 129.9,
129.7, 123.3, 36.5, 26.6, 22.6; IR (KBr) ν: 1691, 1624,
1602, 1527, 1422, 1338, 1111 cm-1; EI-MS m/z (%):
241 (M + , 68), 224 (100). HRMS (EI) calcd for
C14H11NO3: 241.0740; found 241.0739.
Results and Discussion
Initially, analogues of 2a were prepared though
intermolecular Pauson-Khand reaction of 2-ethynylben-
Chin. J. Chem. 2013, 31, 49—54
© 2013 SIOC, CAS, Shanghai, & WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
51