Highly selective synthesis of 1-phenylpentane-1, 4-diones, and (E)-5-hydroxy-5-phenylpent-3-en-2-ones catalyzed by organophosphorus compounds

Article abstract of DOI:10.1002/hc.20568

1-Phenylpentane-1, 4-diones, and (E)- 5-hydroxy-5-phenylpent-3-en-2-ones were synthesized via organophosphine-catalyzed addition reaction of but-3-en-2-one with aldehydes. The features of the present protocols include high selectivity, operational simplicity, atom economy, and mild reaction conditions without transition metals.

Full text of DOI:10.1002/hc.20568

Heteroatom Chemistry
Volume 20, Number 7, 2009
Highly Selective Synthesis of
1-Phenylpentane-1, 4-Diones, and
(E)-5-Hydroxy-5-phenylpent-3-en-2-ones
Catalyzed by Organophosphorus Compounds
Qing Zhang, Yan-Fei Qiao, Min Huang, Hong-Dong Liang,
and Ru-Jin Zhou
School of Chemistry and Life Science, Maoming University, Maoming 525000,
People’s Republic of China
Received 6 May 2009; revised 30 August 2009, 21 November 2009
metal, and simple implementation of the experiment
ABSTRACT: 1-Phenylpentane-1, 4-diones, and (E)-
[4]. Herein, we report first organophosphorus-
5-hydroxy-5-phenylpent-3-en-2-ones were synthesized
controlled selectively form of 1-phenylpentane-1, 4-
via organophosphine-catalyzed addition reaction of
diones [6], and (E)-5-hydroxy-5-phenylpent-3-en-2-
but-3-en-2-one with aldehydes. The features of the
ones from aromatic aldehydes and but-3-en-2-one in
present protocols include high selectivity, opera-
the presence of a catalytic amount of triphenylphos-
tional simplicity, atom economy, and mild reac-
phine and tris(4-methoxylphenyl)phosphine, respec-
ꢀ
C
tion conditions without transition metals.
2010
tively, in one step [7] (Scheme 1).
Wiley Periodicals, Inc. Heteroatom Chem 20:425–
430, 2009; Published online in Wiley InterScience
(www.interscience.wiley.com). DOI 10.1002/hc.20568
RESULTS AND DISCUSSION
At the beginning, the reaction between but-3-en-2-
one 1 and 4-nitrobenzaldehyde 2a was used as a
model to investigate the efficiency of varied cat-
alysts. The results are described in Table 1. Var-
ious nitrogen-containing organocatalysts, such as
DABCO, Et3N, pyridine, and DBU failed to give
the desired products (Table 1, entries 2, 3, 5, and
6). On the other hand, phosphorus-based catalysts
could induce the reaction to give the adduct 3a
or 4a (Table 1, entries 1, 4, and 7). It is mean-
ingful to find that the production of 3a or 4a can
be selectively controlled by the catalysts: Triph-
enylphosphine resulted in 4a as the major product
(Table 1, entry 1), whereas the relatively electron-
rich catalyst tris(4-methoxyphenyl)phosphine gave
3a as the major product (Table 1, entry 7). To
our best knowledge, this is the first observation
INTRODUCTION
Organocatalytic C C bond formation is one of the
most useful protocols to construct C C bonds in or-
ganic synthesis [1]. There are many reports about
the application of organophosphine up to now, but
the organophosphine-catalyzed additional reactions
between unsaturated C C bonds and aldehydes re-
mains challenging [2,3]. As such process is of great
importance because of the advantages such as highly
atomic economy, requiring no precious transition
Correspondence to: Qing Zhang; e-mail: mmczhang@yeah.net.
Contract grant sponsor: Guangdong Natural Science
Foundation.
Contract grant number: 9152500002000010.
2010 Wiley Periodicals, Inc.
c
ꢀ
425

426 Zhang et al.
OH
O
P(p-PhOCH3)3
O
THF
R
O
CHO
60°C 24 h
R
PPh3
O
R
SCHEME 1
TABLE 1 Reaction of But-3-en-2-one 1 (1.0 equiv) with 4-Nitrobenzaldehyde 2a (1.0 equiv) in the Presence of 0.2 equiv of
Catalyst
O
OH
Catalyst
THF(4 mL)
O
or
O2N
CHO
O
O
60°C 24 h
O2N
O2N
4a
1
2a
3a
Entry
Catalyst
Yield (%)a
1
2
3
4
5
6
7
PPh3
DABCO
Py
PBu3
Et3N
DBU
3a: 5, 4a: 68
None
None
3a: 35, 4a: 45
None
None
3a: 73, 4a: 11
P(p-PhOCH3)3
aGC yields.
TABLE 2 Condition Optimization for the Reaction of But-
3-en-2-one 1 (1.0 equiv) with 4-Nitrobenzaldehyde 2a (1.0
equiv) in the Presence of 0.2 equiv of P(p-PhOCH3)3
of different phosphorus catalysts giving differ-
ent addition products from the same set of sub-
strates/reagents in the same solvent. Moreover,
the tris(4-methoxylphenyl)phosphine-catalyzed re-
actions of vinyl ketones or ketoesters with alkyl
or aryl aldehydes to afford (E)-5-hydroxy-5-(alkyl
or aryl)pent-3-en-2-ones have not been reported
previously.
Next, the effect of various solvents on the reac-
tion was examined to improve the yield of 3a by
using tris(4-methoxylphenyl)phosphine as the cata-
lyst (Table 2, entries 1–6). We found THF was most
suitable for this transformation (Table 2, entry 1),
and increasing the reaction time from 12 to 24 h re-
sulted in an increased GC yield (Table 1, entries 1
vs. 7) as well as increasing the catalyst loading from
0.1 equiv to 0.2 equiv (Table 1, entries 1 vs. 9); nei-
ther the extension of reaction time from 24 to 30 h
(Table 1, entries 1 vs. 8) nor increasing the catalyst
loading from 0.2 equiv to 0.5 equiv influenced the
yield (Table 1, entries 1 vs. 10). Thus, the optimized
OH
Solvent(4 mL)
P(p-PhOCH3)3
O
O2N
CHO
O
60°C 24 h
O2N
1
2a
3a
Entry
Solvent
Time (h)
Yield of 3aa
1
2
3
4
5
6
7
8
THF
CHCl3
Toluene
24
24
24
24
24
24
12
30
24
24
73
61
55
Cyclohexane
DMF
37
Complex
Complex
57
CH3CN
THF
THF
THF
THF
74
31
73
9b
10c
aGC yields.
b0.1 equiv of P(p-PhOCH3)3.
c0.5 equiv of P(p-PhOCH3)3.
Heteroatom Chemistry DOI 10.1002/hc

Highly Selective Synthesis of 1-Phenylpentane-1, 4-Diones, and (E)-5-Hydroxy-5-phenylpent-3-en-2-ones 427
TABLE 3 Scope of the Reaction of But-3-en-2-one 1
(1.0 equiv) with Aldehyde 2 (1.0 equiv) in the Presence of
TABLE 4 Scope of the Reaction of But-3-en-2-one 1
(1.0 equiv) with Aldehyde 2 (1.0 equiv) in the Presence of
0.2 equiv of P(p-PhOCH3)3
0.2 equiv of PPh3
OH
O
THF(4 mL)
P(p-PhOCH3)3
THF(4 mL) PPh3
O
O
CHO
CHO
O
O
60°C 24 h
60°C 24 h
R
R
R
R
1
2
3
1
2
4
Entry
1
Aryl Aldehyde
O2N CHO
Yield of 3a
70 (3a)
Entry
1
Aryl Aldehyde
O2N CHO
Yield of 4a
67 (4a)
2a
2a
2
65 (3b)
2
64 (4b)
CHO
CHO
O2N
F
O2N
F
2b
2b
3
4
5
6
55 (3c)
57 (3d)
57 (3e)
62 (3f)
3
4
5
6
7
51 (4c)
49 (4d)
58 (4e)
63 (4f)
43 (4g)
CHO
CHO
CHO
CHO
CHO
CHO
CHO
CHO
CHO
2c
2d
2e
2f
2c
2d
2e
2f
Cl
Br
I
Cl
Br
I
aIsolated yield.
H3C
2g
8
9
50 (4h)
52 (4i)
reaction conditions could be established as follows:
0.2 equiv of tris(4-methoxylphenyl)phosphine cata-
lyst with THF as the solvent at 60◦C for 24 h.
CHO
2h
CHO
With the optimized conditions in hand, several
other aryl aldehydes were then examined in the re-
action with but-3-en-2-one (Table 3, entries 1–6). As
evident from the results, all the reactions proceeded
smoothly and provided the corresponding products
(E)-5-hydroxy-5-(R-phenyl)pent-3-en-2-ones 3. It is
noteworthy that aryl aldehydes with an electron-
withdrawing group (Table 3, entries 1–2) favor the
reaction compared with the electron-donating group
substituted aryl aldehydes (Table 3, entries 3–6).
When triphenylphosphine was used as the catalyst
for the reaction under the same conditions, the iso-
lated major products were 1-(R-phenyl)pentane-1,4-
diones as described in Table 4 (Table 4, entries 1–9).
It is a very interesting phenomenon, as revealed
in Tables 3 and 4 that the additions are highly
selective. When tris(4-methoxylphenyl)phosphine
was used as the catalyst in the reaction,
O
2i
aIsolated yield.
enylphosphine as the catalyst in the same conditions,
1,4-addition occurred predominantly, namely, aryl
aldehydes 2 added to but-3-en-2-one 1, and provided
new adducts of 1-(substituted-phenyl)pentane-1,4-
diones (Table 4, entries 1–9).
We speculate the mechanism of the reaction
in Scheme 2 on the basis of earlier reports [8]
and our investigations. The main reason for the
selectivity is that the two different phosphines
attack different molecules. When P(p-PhOCH3)3
was employed, it attacks the C C double bond of
but-3-en-2-one 1 and gave the 1,2-addition products
of (E)-5-hydroxy-5-(substituted-phenyl)pent-3-en-2-
ones 3; whereas PPh3 not attacks the C C double
bond of but-3-en-2-one 1 but the C O double
bond of aldehydes 2 and gave the 1,4-addition
products of 1-(substituted-phenyl)pentane-1,4-
diones. As shown in Scheme 2, in the case of
1,2-addition of but-3-en-2-one
1
toward aryl
aldehydes 2 occurred predominantly and (E)-
5-hydroxy-5-(substituted-phenyl)pent-3-en-2-ones 3
were produced (Table 3, entries 1–6), whereas re-
placed tris(4-methoxylphenyl)phosphine with triph-
Heteroatom Chemistry DOI 10.1002/hc

428 Zhang et al.
OH
THF
O
THF PPh3
P(p-PhOCH3)3
O
R
R
R CHO
60°C 24 h
60°C 24 h
O
O
4
2
3
1
P(p-PhOCH3)3
PPh3
Part B
H
O
O
H
O
O
OH
R
O
O
Part A
R
R
H
R
P
9
P
10
P
P
11
5
12
P
RCHO
O
O
HO
O
6
P
8
P
P
7
SCHEME 2
the tris(4-methoxylphenyl)phosphine-catalyzed re-
action (part A), tris(4-methoxylphenyl)phosphine
reacts with but-3-en-2-one 1 to generate a zwitteri-
onic intermediate 5, which is in equilibrium with
tautomers 7 and 8. The tautomer 8 serves as a polar
reactive species for subsequent 1,2-addition with
aldehydes 2. Then the facile 1,4-proton transfer and
elimination take place to give product 3 and regen-
erate catalyst of tris(4-methoxylphenyl)phosphine.
In contrast, the triphenylphosphine-catalyzed path-
way (part B) benefits from the proton transfer
of 10 to produce α-oxo-ylide 11. The subsequent
Michael (1,4-addition) addition reaction, followed
by proton transfer and elimination, produce the
target compound 4 and regenerate the catalyst
triphenylphosphine.
In conclusion, the presented procedure provides
a highly selective synthetic approach for the syn-
thesis of 1-phenylpentane-1, 4-diones, and (E)-5-
hydroxy-5-phenylpent-3-en-2-ones. Besides, opera-
tional simplicity, achievement of selective additions
by the choice of different catalysts, and atom-
economy are also the merits of this protocol.
was obtained using electron ionization (EI). IR spec-
tra were obtained as potassium bromide pellets or as
liquid films between two potassium bromide pellets
with a Brucker Vector 22 spectrometer. TLC was per-
formed using commercially prepared silica gel plates
(GF254), and visualization was effected at 254 nm.
All the other chemicals were purchased from Aldrich
(Beijing, China).
Typical Procedure for the Reaction of But-3-en-2-
one with 4-Nitrobenzaldehyde (Table 3, entry 1). To a
stirring mixture of but-3-en-2-one (70 mg, 1.0 mmol)
and 4-nitrobenzaldehyde (151 mg, 1 mmol), 4 mL
tetrahydrofuran (THF) and tris(4-methoxylphenyl)-
phosphine (P(p-PhOCH3)3) (70.4 mg, 0.2 mmol)
were added successively. The mixture was stirred
under at 60◦C for 24 h in a round bottom flask
After cooling, the resulting mixture was then an-
alyzed by GC and GC-MS. The solvent was sub-
jected to isolation by PTLC (GF254), eluted with a
10:1 petroleum ether–diethyl ether mixture to af-
ford the desired product and (E)-ethyl 4-hydroxy-
4-(4-nitrophenyl)but-2-enoate.
EXPERIMENTAL
General Methods
Characterization Data for Products
(E)-5-Hydroxy-5-(4-nitrophenyl)pent-3-en-2-one
(Table 3, entry 1). Pale yellow viscous oil, IR νmax
(KBr): 3421, 1682, 1522, 1459, 1347, 1106, 970, 685,
All the reactions were carried out at 60◦C in a round
bottom flask equipped with a magnetic stir bar. Sol-
vents and all reagents were used as received. 1 H
NMR spectra were recorded in CDCl3 at 400 MHz,
and 13C NMR spectra were recorded in CDCl3 at
100 MHz at South China Agricultural University. The
chemical shifts (δ) were referenced to TMS. GC–MS
1
cm−1; H NMR (400 MHz, CDCl3): δ = 8.19 (d, 2H),
7.54 (d, 2H), 6.24 (s, 1H), 6.00 (s, 1H), 5.65 (s,
1H), 3.38 (b, 1H), 2.34 (s, 3H); 13C NMR (100 MHz,
CDCl3): δ = 200.1, 148.9, 140.8, 133.2, 127.4, 123.6,
123.4, 72.3, 26.4; GC-MS m/z: 221.8; Anal. Calcd for
Heteroatom Chemistry DOI 10.1002/hc

Highly Selective Synthesis of 1-Phenylpentane-1, 4-Diones, and (E)-5-Hydroxy-5-phenylpent-3-en-2-ones 429
C11H11NO4: C, 59.73; H, 5.01; Found: C, 59.88; H,
5.25.
1-(4-Nitrophenyl)-1,4-dione (Table 4, entry 1).
Pale yellow viscous oil, IR νmax (KBr): 1712, 1687,
1601, 1520, 1345, 1163, 1108, 994, 855, 740, 688,
1
cm−1; H NMR (400 MHz, CDCl3): δ = 8.31 (d, 2H),
(E)-5-Hydroxy-5-(3-nitrophenyl)pent-3-en-2-one
(Table 3, entry 2). Pale yellow viscous oil, IR νmax
(KBr): 3445, 1651, 1575, 1485, 1375, 1195, 1025,
970, 785, 685, cm−1; 1H NMR (400 MHz, CDCl3): δ =
8.23 (s, 1H), 8.10 (d, 1H), 7.64 (t, 1H), 7.48 (d,
1H), 6.10 (s, 1H), 5.90 (s, 1H), 5.70 (s, 2H), 3.19 (s,
1H), 2.34 (s, 3H); 13C NMR (100 MHz, CDCl3): δ =
199.5, 148.0, 143.8, 142.0, 131.6, 129.1, 127.5, 122.6,
121.0, 72.1, 26.5; GC-MS m/z: 221.35; Anal. Calcd for
C11H11NO4: C, 59.73; H, 5.01; Found: C, 59.50; H,
5.48.
8.10 (d, 2H), 3.26 (t, 2H), 2.92 (t, 2H), 2.20 (s, 3H);
13C NMR (100 MHz, CDCl3): δ = 206.8, 197.1, 141.1,
129.1, 127.3, 123.9, 37.0, 32.8, 30.0; GC-MS m/z:
221.18; Anal. Calcd for C11H11NO4: C, 59.73; H, 5.01;
Found: C, 59.99; H, 5.23.
1-(3-Nitrophenyl)-1,4-dione (Table 4, entry 2).
Pale yellow viscous oil, IR νmax (KBr): 1715, 1651,
1529, 1351, 1230, 1092, 938, 732, 673, cm−1; 1H NMR
(400 MHz, CDCl3): δ = 8.79 (s, 1H), 8.41 (d, 1H), 8.29
(d, 1H), 7.66 (t, 1H), 3.44 (t, 2H), 2.93 (t, 2H), 2.25 (s,
3H); 13C NMR (100 MHz, CDCl3): δ = 206.7, 196.4,
148.2, 137.9, 133.6, 129.9, 127.4, 123.0, 37.0, 32.5,
30.0; GC-MS m/z: 221.50; Anal. Calcd for C11H11NO4:
C, 59.73; H, 5.01; Found: C, 59.65; H, 5.11.
(E)-5-Hydroxy-5-(4-fluorophenyl)pent-3-en-2-one
(Table 3, entry 3). Pale yellow viscous oil, IR νmax
(KBr): 3425, 1707, 1509, 1422, 1311, 1150, 1050,
930, 795, 700, cm−1; 1H NMR (400 MHz, CDCl3): δ =
7.32 (d, 2H), 7.00 (d, 2H), 6.18 (s, 1H), 5.95 (s, 1H),
5.59 (s, 1H), 3.96 (b, 1H), 2.33 (s, 3H); 13C NMR
(100 MHz, CDCl3): δ = 200.3, 148.2, 139.6, 131.7,
127.5, 127.1, 120.8, 72.3, 19.8; GC-MS m/z: 194.31;
Anal. Calcd for C11H11FO2: C, 68.03; H, 5.71; Found:
C, 67.91; H, 5.55.
1-(4-Fluorophenyl)-1,4-dione (Table 4, entry 3).
Pale yellow viscous oil, IR νmax (KBr): 1715, 1683,
1599, 1507, 1410, 1360, 1158, 1098, 996, 841, 734,
1
cm−1; H NMR (400 MHz, CDCl3): δ = 7.99 (d, 2H),
7.11 (d, 2H), 3.22 (t, 2H), 2.85 (t, 2H), 2.23 (s, 3H);
13C NMR (100 MHz, CDCl3): δ = 207.3, 196.9, 133.1,
130.6, 126.3, 115.9, 37.0. 30.1. 29.7; GC-MS m/z:
194.62; Anal. Calcd for C11H11FO2: C, 68.03; H, 5.71;
Found: C, 68.20; H, 5.75.
(E)-5-Hydroxy-5-(4-chlorophenyl)pent-3-en-2-one
(Table 3, entry 4). Colorless viscous oil, IR νmax
(KBr): 3422, 1673, 1489, 1367, 1090, 955, 829, 724,
1
cm−1; H NMR (400 MHz, CDCl3): δ = 7.27 (s, 4H),
6.18 (s, 1H), 5.95 (s, 1H), 5.55 (s, 1H), 2.84 (b, 1H),
2.32 (s, 3H); 13C NMR (100 MHz, CDCl3): δ = 200.3,
149.6, 140.0, 133.4, 128.5, 127.9, 127.0, 72.2, 26.4;
GC- MS m/z: 210.78; Anal. Calcd for C11H11ClO2: C,
62.72; H, 5.26; Found: C, 62.55; H, 5.42.
1-(4-Chlorophenyl)-1,4-dione (Table 4, entry 4).
Pale yellow viscous oil, IR νmax (KBr): 1710, 1673,
1591, 1489, 1404, 1211, 1162, 1093, 995, 894, 733,
1
648, cm−1; H NMR (400 MHz, CDCl3): δ = 7.91 (d,
2H), 7.42 (d, 2H), 3.21 (t, 2H), 2.87 (t, 2H), 2.23 (s,
3H); 13C NMR (100 MHz, CDCl3): δ = 207.2, 197.3,
139.6, 134.9, 129.5, 128.9, 37.0, 32.3, 30.1; GC-MS
m/z: 210.55; Anal. Calcd for C11H11ClO2: C, 62.72; H,
5.26; Found: C, 62.85; H, 5.28.
(E)-5-Hydroxy-5-(4-bromophenyl)pent-3-en-2-one
(Table 3, entry 5). Colorless viscous oil, IR νmax
1
(KBr): 3425, 1670, 1487, 1367, 1073, 954, cm−1; H
NMR (400 MHz, CDCl3): δ = 7.45 (d, 2H), 7.20 (d,
2H), 6.18 (s, 1H), 5.95 (s, 1H), 5.54 (s, 1H), 2.70
(b, 1H), 2.32 (s, 3H); 13C NMR (100 MHz, CDCl3):
δ = 200.3, 149.5, 140.5, 131.5, 128.2, 127.0, 121.6,
72.3, 18.0; GC-MS m/z: 254.91; Anal. Calcd for
C11H11BrO2: C, 51.79; H, 4.35; Found: C, 51.66; H,
4.50.
1-(4-Bromophenyl)-1,4-dione (Table 4, entry 5).
Pale yellow viscous oil, IR νmax (KBr): 1715, 1671,
1585, 1473, 1378, 1262, 1153, 1025, 991, 899, 740,
1
cm−1; H NMR (400 MHz, CDCl3): δ = 7.83 (d, 2H),
7.58 (d, 2H), 3.20 (t, 2H), 2.85 (t, 2H), 2.23 (s, 3H);
13C NMR (100 MHz, CDCl3): δ = 207.2, 197.5, 135.3,
131.9, 129.6, 128.3, 37.0, 32.3, 30.1; GC-MS m/z:
255.55; Anal. Calcd for C11H11BrO2: C, 51.79; H, 4.35;
Found: C, 51.81; H, 4.35.
(E)-5-Hydroxy-5-(4-iodophenyl)pent-3-en-2-one
(Table 3, entry 6). Pale yellow viscous oil, IR νmax
(KBr): 3418, 1676, 1362, 1162, 1123, 945, 760, cm−1;
1H NMR (400 MHz, CDCl3): δ = 7.63 (d, 2H), 7.04 (d,
2H), 6.04 (s, 1H), 5.94 (s, 1H), 5.84 (s, 1H), 2.58 (b,
1H), 2.31 (s, 3H); 13C NMR (100 MHz, CDCl3): δ =
200.3, 149.6, 140.8, 131.0, 128.8, 127.1, 121.3, 72.3,
19.2; GC-MS m/z: 302.5; Anal. Calcd for C11H11IO2:
C, 43.73; H, 3.67; Found: C, 43.77; H, 3.90.
1-(4-Iodophenyl)-1,4-dione (Table 4, entry 6).
White viscous oil, IR νmax (KBr): 1712, 1665, 1550,
1490, 1370, 1200, 1075, 999, 890, 800, 690, cm−1; 1H
NMR (400 MHz, CDCl3): δ = 7.81 (d, 2H), 7.67 (d,
2H), 3.19 (t, 2H), 2.86 (t, 2H), 2.23 (s, 3H); 13C NMR
Heteroatom Chemistry DOI 10.1002/hc

430 Zhang et al.
[3] For reviews on phosphine-mediated reactions, see:
(a) Methot, J. L.; Roush, W. R. Adv Synth Catal 2004,
346, 1035–1050; (b) Lu, X.; Zhang, C.; Xu, Z. Acc
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(100 MHz, CDCl3): δ = 207.2, 197.4, 134.3, 130.9,
129.1, 1286, 37.1, 31.3, 29.9; GC-MS m/z: 302.20;
Anal. Calcd for C11H11IO2: C, 43.73; H, 3.67; Found:
C, 43.75; H, 3.66.
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1-m-Tolypentane-1,4-dione (Table 4, entry 7).
Orange viscous oil, IR νmax (KBr): 1715, 1683, 1401,
1357, 1259, 1157, 1087, 794, 760, 690, cm−1; 1H NMR
(400 MHz, CDCl3): δ = 7.76 (d, 2H), 7.34 (m, 2H),
3.24 (t, 2H), 2.84 (t, 2H), 2.38 (s, 3H), 2.25 (s, 3H);
13C NMR (100 MHz, CDCl3): δ = 207.4, 198.7, 138.3,
136.6, 133.9, 128.6, 128.4, 125.2, 37.1, 32.5, 30.1,
21.3; GC-MS m/z: 190.88; Anal. Calcd for C12H14O2:
C, 75.56; H, 7.42; Found: C, 75.37; H, 7.38.
1-Penylpentane-1,4-dione (Table 4, entry 8). Or-
ange viscous oil, IR νmax (KBr): 1717, 1683, 1450,
1359, 1159, 1082, 996, 743, 691, cm−1; 1H NMR
(400 MHz, CDCl3): δ = 7.97 (d, 2H), 7.53 (t, 1H),
7.44 (t, 2H), 3.28 (t, 2H), 2.87 (t, 2H), 2.19 (s, 3H);
13C NMR (100 MHz, CDCl3): δ = 207.4, 198.5, 135.9,
133.2, 128.6, 128.0, 37.1, 32.4, 30.1; GC-MS m/z:
176.33; Anal. Calcd for C11H12O2: C, 74.98; H, 6.86;
Found: C, 75.20; H, 6.90.
1-(Furan-2-yl)pentane-1,4-dione (Table 4, en-
try 9). Orange viscous oil, IR νmax (KBr): 1713, 1670,
1
1569, 1489, 1398, 1190, 1065, 789, cm−1; H NMR
(400 MHz, CDCl3): δ = 7.59 (d, 1H), 7.18 (d, 1H),
6.51 (q, 1H), 3.11 (t, 2H), 2.84 (t, 2H), 2.19 (s, 3H);
13C NMR (100 MHz, CDCl3): δ = 207.1, 187.7, 152.4,
146.3, 117.1, 112.2, 36.7, 32.0, 30.0; GC-MS m/z:
166.20; Anal. Calcd for C9H10O3: C, 65.05; H, 6.07;
Found: C, 64.90; H, 6.30.
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Heteroatom Chemistry DOI 10.1002/hc