Conversion of alkynes to cyclic imides and anhydrides using reactive iron carbonyls prepared from Fe(CO)5 and Fe3(CO)12

Article abstract of DOI:10.1016/S0022-328X(02)01129-4

Alkyne-iron carbonyl complexes, prepared using Fe(CO)₅-NaBH₄-CH₃COOH-amine-alkyne and Fe₃(CO)₁₂-amine-alkyne reagent systems, react with excess of amine at 25 °C to give cyclic imides in moderate to g

Full text of DOI:10.1016/S0022-328X(02)01129-4

Journal of Organometallic Chemistry 649 (2002) 209–213
www.elsevier.com/locate/jorganchem
Conversion of alkynes to cyclic imides and anhydrides using
reactive iron carbonyls prepared from Fe(CO) and Fe (CO)
5
3
12
Mariappan Periasamy *, Chellappan Rameshkumar, Amere Mukkanti
School of Chemistry, Uni6ersity of Hyderabad, Central Uni6ersity PO, Hyderabad 500 046, India
Received 3 January 2002; accepted 5 January 2002
Abstract
Alkyne–iron carbonyl complexes, prepared using Fe(CO) –NaBH –CH COOH–amine–alkyne and Fe (CO) –amine–alkyne
5
4
3
3
12
reagent systems, react with excess of amine at 25 °C to give cyclic imides in moderate to good yields. Further, unsaturated iron
carbonyl species, prepared using the Fe(CO) –pyridine-N-oxide system, react with alkynes to give the corresponding anhydrides.
5
©
2002 Published by Elsevier Science B.V.
Keywords: Alkynes; Iron carbonyl complexes; Double carbonylation; Cyclic imides
1. Introduction
using Fe(CO) –pyridine-N-oxide, react with alkynes to
5
give the corresponding anhydrides.
Transition metal mediated carbonylation reactions
are of immense interest in synthetic chemistry [1].
Among these, the double carbonylation reactions are of
special importance as they could lead to molecules with
unusual structures that would otherwise require multi-
step synthetic operations [2]. Among various metal
carbonyls, iron carbonyls proved to be very much
useful in the stoichiometric and catalytic mono- and
double carbonylation reactions [3]. In recent years, it
has been reported from this laboratory that alkynes
react with iron carbonyl species, generated using FeCl3,
NaBH –CO; Fe(CO)5, NaBH –CH COOH and
2. Results and discussion
Recently, others and we reported that amines facility
the Pauson–Khand reaction of alkyne–Co (CO) com-
plexes through creating vacant coordination site on
cobalt [8,9]. In continuation of these efforts, we became
interested in examining the effect of different amines on
the reaction of iron carbonyl complexes 1 or 2, formed
2
6
4
4
3
Fe (CO) –amine reagent systems to give a variety of
3
12
products such as cyclobutenediones and benzoquinones
4–6]. These transformations, involving unsaturated
[
iron carbonyl species and alkynes, were rationalised
considering the intermediacy of maleoyl complexes of
the type 1 or hydroxy ferrole complexes of the type 2
in the reaction of alkynes with the Fe(CO)
5 4
–NaBH –
CH COOH reagent system. We have observed that
3
addition of excess of primary amines (25 mmol) to the
iron carbonyl complexes, prepared at 25 °C in THF,
gives the corresponding cyclic imides in moderate to
[2,5,7]. We report here the results of a detailed investi-
gation on the reaction alkynes with iron carbonyl com-
plexes, prepared using Fe(CO) , NaBH –CH COOH
good yields (51–64%) after CuCl ·2H O oxidation (Eq.
2
2
5
4
3
(
1)).
and Fe (CO) –amine reagent systems and excess of
3
12
primary amine to obtain cyclic imides. Also, we report
that unsaturated iron carbonyl species, generated in situ
(1)
*
Corresponding author.
E-mail address: mpsc@uohyd.ernet.in (M. Periasamy).
0022-328X/02/$ - see front matter © 2002 Published by Elsevier Science B.V.
PII: S0022-328X(02)01129-4

210
M. Periasamy et al. / Journal of Organometallic Chemistry 649 (2002) 209–213
Table 1
Reaction of primary amines on alkynes- iron carbonyl complexes
a
Products were identified from the spectral data IR, 13C-NMR, 1H-NMR, mass and elemental analysis and comparison with the data reported
for similar derivatives [2b,14].
b
Yields are of products isolated by column chromatography and based on the amount of the alkynes used.
c
Method A: Fe(CO) /NaBH /CH COOH/alkyne reagent system; Method B: (Fe CO) /RNH /alkyne reagent system.
5
4
3
3
12
2
d
1
Stereochemistry assigned on the basis of H-NMR data. These data are comparable with the data reported for similar derivatives [15].
Several alkynes were converted to the corresponding
cyclic imides using different primary amines [2b]. This
reagent system can tolerate various functional groups
(12.5 mmol) to the iron carbonyl complexes prepared in
this way, leads to the corresponding cyclic imides in
as is evident from Table 1. It was thought that the
−
11
HFe (CO)
species, generated using Fe(CO)5–
3
NaBH –CH COOH, would give the coordinatively un-
4
3
saturated ‘Fe (CO) ’ species which, in turn, could react
3
11
with alkynes to produce the intermediate alkyne–iron
carbonyl complexes of the type 1 or 2 (Scheme 1).
Previously, we have reported that the reaction with
Fe (CO) (6 mmol), n-butylamine (2.75 mmol) and
3
12
alkyne gives the corresponding cyclobutenediones in
8–61% after CuCl ·2H O oxidation under these condi-
2
2
2
tions [6]. However, addition of excess primary amine
Scheme 1.

M. Periasamy et al. / Journal of Organometallic Chemistry 649 (2002) 209–213
211
complexes could be isolated by column chromatogra-
phy. However, these unidentified iron carbonyl com-
plexes upon CuCl ·2H O oxidation gave the
2
2
corresponding cyclic imides. We have also made at-
tempts to prepare acyl and Ph P derivatives of the
3
intermediate iron complexes but these efforts were not
successful. It may be of interest to note that the com-
plexes of the type 1 or 2 have proven applications in the
preparation of highly functionalised aromatic com-
pounds [12].
The Fe(CO) is known to undergo decarbonylation
5
−
+
with R N ꢀO to give the unsaturated ‘Fe(CO) ’ spe-
3
4
cies [13]. Accordingly, it was of interest to examine the
reaction alkynes with unsaturated iron carbonyl species
prepared in this way. We have observed that the reac-
tion of alkynes with Fe(CO) in the presence of pyri-
5
dine-N-oxide (1:1) at 70 °C gives the corresponding
anhydride after CuCl ·2H O oxidation (Eq. (3)). Pre-
Scheme 2.
2
2
sumably, the pyridine-N-oxide further oxidises the in-
termediate alkyne-iron complexes to produce the
corresponding anhydride. It was thought that the use of
lesser amount of the amine-oxide would prevent the
anhydride formation. Accordingly, in another run,
moderate to good yields (50–65%) after CuCl ·2H O
2
2
oxidation (Eq. (2)) along with traces of cyclobutene-
diones (2–5%). Various alkynes were converted to the
corresponding cyclic imides using different amines and
the results are summarised in Table 1. Whereas the use
primary amines gave cyclic amides, secondary and ter-
tiary amines such as pyrrolidine, piperidine and triethy-
lamine led to the formation of a mixture of the
corresponding benzoquinones and cyclobutenediones as
reported [6]. The formation of cyclic imides can be
tentatively explained by the sequence of reactions and
intermediates as shown in the (Scheme 2) [2,6,10a].
Fe(CO) and pyridine-N-oxide were used in 2:1 ratio.
5
Surprisingly, a mixture of benzoquinones (60% yield)
was obtained in this case.
(3)
3
. Conclusion
(
2)
In conclusion, simple, convenient procedures were
developed for the preparation of cyclic imides from
alkynes using the readily available iron carbonyl
reagents. The methods described should be useful for
further synthetic exploitations as the cyclic imide
derivatives are an important class of compounds that
are of interest to medicinal chemistry [16]. Also, the
conversion of alkynes to the corresponding cyclic anhy-
Presumably, the amine would react with Fe (CO) to
3
12
give the Fe (CO) or ‘amine-Fe(CO) ’ and ‘Fe (CO) ’
3
11
4
2
8
species, which on further reaction with alkynes, could
give the intermediate complexes of type 1 or 2. In the
presence of excess amine, the intermediate of the type 5
would result that on subsequent transformations could
lead to the species such as 6 and 7. Finally, decomplex-
ation using CuCl ·2H O would give the corresponding
drides using Fe(CO) and pyridine-N-oxide would fur-
5
2
2
ther illustrate the scope of applications of the reactive
iron carbonyls prepared in this way.
cyclic imides 3.
It is well-known that the hydrido iron carbonyls
reduce a,b unsaturated carbonyl compounds [10,11].
Accordingly, it is reasonable to consider the intermedi-
acy of such complexes under the present conditions.
However, the formation of other iron carbonyl spe-
cies cannot be ruled out. We have attempted to isolate
the intermediate iron carbonyl complexes that would be
formed before CuCl ·2H O oxidation. Unfortunately,
4. Experimental
4.1. General methods
1
13
H-NMR (200 MHz) and C-NMR (50 MHz) spec-
tra were taken in CDCl with Me Si as reference (l=0
2
2
3
4
only a complex mixture of unidentified iron carbonyl
ppm). The chemical shifts are reported in ppm on the l

212
M. Periasamy et al. / Journal of Organometallic Chemistry 649 (2002) 209–213
scale relative to CDCl (77.0 ppm), and coupling con-
stants are reported in hertz. Chromatographic purifica-
tion was conducted by column chromatography using
4.2.3. Compound 3c
3
−
1
Yield: 0.181 g (61%); IR (neat): 1786, 1703 cm
;
1
H-NMR (200 MHz) (CDCl ): l 0.8–1.9 (m, 20H), 2.09
3
1
00–200 mesh silica gel obtained from Acme Synthetic
(m, 1H), 2.3 (d, J=13.3 Hz, 1H), 2.7 (d, J=13.2 Hz,
13
Chemicals, India. The alkynes (except 1-heptyne) were
prepared by following a reported procedure [17]. THF
supplied by E-Merck, India, was distilled over sodium-
benzophenone ketyl before use. Fe (CO) reagent was
1H), 3.4 (t, J=7.2 Hz, 2H); C-NMR (50 MHz)
(CDCl ): l 13.3 and 13.7 (ꢀCH ), 19.8, 22.3, 26.4, 28.8,
3
3
29.5, 31.2, 31.3, 34.1 (ꢀCH ), 38.2 (ꢀCH), 39.6 (ꢀCH ),
2
2
176.4 and179.7 (ꢀCO).
3
12
prepared following a reported procedure [18]. Iron pen-
tacarbonyl supplied by Fluka was used. All reactions
and manipulations were conducted under a dry nitro-
gen atmosphere. All yields reported are isolated yields
of materials judged homogeneous by TLC, IR and
NMR spectroscopy.
4
.2.4. Compound 3d
Yield: 0.195 g (51%); IR (neat): 1778, 1705 cm
−1
;
1
H-NMR (200 MHz) (CDCl ): l 1–1.8 (m, 7H), 3.6 (t,
3
J=7.3 Hz, 2H), 4.1 (d, J=10 Hz, 2H), 7.15–7.6 (m,
13
1
2
0H); C-NMR (50 MHz) (CDCl ): l 13.7 (ꢀCH ),
3
3
0.2, 29.9, 39.1 (ꢀCH ), 55.3 (ꢀCH), 128.2, 128.5, 129.1
2
(
ꢀCH), 136.9 (phenyl C-1), 176.5 (ꢀCO); MS (EI): m/z
4.2. Representati6e procedure for the preparation of
+
3
7
4
07 (M ), 265 (B). Anal. Calc. for C H O N: C,
20 21 2
imides using Fe (CO) and amine
3
12
8.12; H, 6.84; N, 4.56. Found: C, 78.25; H, 6.90; N,
.52%.
A mixture of Fe (CO) (3.02 g, 6 mmol) and n-buty-
3
12
lamine (0.201 g, 2.75 mmol) in THF (50 ml) was stirred
for 30 min at 25 °C. 1-Heptyne (0.12 g, 1.25 mmol) was
added and stirred for 4 h. n-Butylamine (9 g, 12.5
mmol) was added and the contents were further stirred
for 12 h. The metal carbonyl complex was decomposed
using CuCl ·2H O (3.4 g, 20 mmol) in acetone (25 ml).
Saturated aq. NaCl (20 ml) was added and the contents
were extracted with ether (100 ml). The combined or-
ganic extract was washed with brine (15 ml), dried over
4
.2.5. Compound 3e
Yield: 0.25 g (58%); IR (neat): 1766, 1689 cm
−
1
;
1
H-NMR (200 MHz) (CDCl ): l 0.75–1.53 (m, 18H),
3
1
.62 (s, 3H), 2.44 (q, J=5.8 Hz, 1H), 2.7 (d, J=3.8
Hz, 1H) 3.4 (t, J=7.2 Hz, 2H), 7.2–7.4 (m, 5H);
2
2
13
C-NMR (50 MHz) (CDCl ): l 13.4 and 13.7 (ꢀCH ),
9.9, 22.1, 24.6 (ꢀCH ), 25.1 (ꢀCH ), 29.5, 31.2, 31.3
3
3
1
2
3
(
(
ꢀCH ), 38.3 (ꢀCH), 42.7 (ꢀCH ), 57.0 (ꢀCH), 74.8
2
2
quaternary), 125.6, 127.7, 128.2 (ꢀCH), 143.6 (phenyl
anhydrous MgSO and concentrated. The residue was
4
+
C-1), 178.5 and 179.1 (ꢀCO); MS (EI): m/z 347 (M ),
29 (B). Anal. Calc. for C H O N: C, 73.04; H, 8.98;
subjected to column chromatography (silica gel,
3
C H –EtOAc). Ethyl acetate (1%) in C H eluted the
21 31
2
6
12
6
12
N, 4.05. Found: C, 73.10; H, 9.15; N, 4.11%.
cyclic imide derivative (0.182 g, 65%). This procedure
was followed for the conversion of other alkynes to the
corresponding cyclic imides.
4.2.6. Compound 3f
Yield: 0.193 g (50%); IR (neat): 3487, 1766, 1693
−
1
1
cm ; H-NMR (200 MHz) (CDCl ): l 0.8–1.0 (m,
3
4
.2.1. Compound 3a
Yield: 0.182 g (65%); (IR (neat): 1772, 1703 cm
1
4H), 1.2–1.8 (m, 14H), 2.43 (q, J=5.7 Hz, 1H), 2.78
−
1
;
13
(
d, J=3.8 Hz, 1H), 3.45 (t, J=7.1 Hz, 2H); C-NMR
1
H-NMR (200 MHz) (CDCl ): l 0.6–1.87 (m, 18H),
3
(
2
50 MHz) (CDCl ): l 7.2, 7.6, 13.3, 13.6 (ꢀCH ), 19.8,
3
3
1.92 (m, 1H), 2.1 (d, J=13.6 Hz, 1H), 2.6 (d, J=13.2
2.1, 25.1, 28.2, 28.8, 29.2, 29.4, 31.5 (ꢀCH ), 38.2
1
3
2
Hz, 1H), 3.3 (t, J=7.3 Hz, 2H); C-NMR (50 MHz)
(
ꢀCH), 42.1 (ꢀCH ), 51.6 (ꢀCH), 75.6 (quaternary),
2
(
3
CDCl ): l 13.2 and 13.5 (ꢀCH ), 19.7, 22.1, 26.1, 29.4,
+
3
3
1
2
78.9 and 179.5 (CO); MS (EI): m/z 293 (M –H O),
2
1.0, 31.2, 34.0 (ꢀCH ), 38.0 (ꢀCH), 39.5 (ꢀCH ), 176.4
2
2
82 (B). Anal. Calc. for C H O N: C, 69.45; H, 10.61;
+
18 33
3
and 179.6 (ꢀCO); MS (EI): m/z 225 (M ), 168 (B).
Anal. Calc. for C H O N: C, 69.33; H, 10.22; N, 6.22.
N, 4.50. Found: C, 69.51; H, 10.60; N, 5.00%.
1
3
23
2
Found: C, 69.32; H, 10.27; N, 6.21%.
4.2.7. Compound 3g
−
1
Yield: 0.207 g (46%); IR (neat): 1776, 1707 cm
;
1
4
.2.2. Compound 3b
Yield: 0.128 g (45%); IR (neat): 1766, 1707 cm
H-NMR (200 MHz) (CDCl ): l 0.9–1.8 (m, 15H), 3.7
3
−
1
;
(t, J=7.4 Hz, 2H), 4.1 (d, J=10 Hz, 2H), 7.1–7.4 (m,
1
13
H-NMR (200 MHz) (CDCl ): l 0.6–1.8 (m, 5H), 2.81
10H); C-NMR (50 MHz) (CDCl ): l 14.1 (ꢀCH ),
3
3
3
(d, J=13.3 Hz, 1H), 2.85 (d, J=13.5 Hz, 1H), 3.1 (q,
22.6, 26.8, 27.7, 29.1, 31.7, 39.3 (ꢀCH ), 55.3 (ꢀCH),
2
13
2
H), 3.8 (t, 2H), 4.01 (t, 1H), 7–7.5 (m, 5H); C-NMR
127.7, 129.1 (ꢀCH), 136.9 (phenyl C-1), 176.3 (CO); MS
+
(
(
(
50 MHz) (CDCl ): l 10.1 (ꢀCH ), 18.6, 21.5, 27.7
(EI): m/z 363 (M ), 265 (B). Anal. Calc. for
3
3
ꢀCH ), 36.2 (ꢀCH), 38.5 (ꢀCH ), 128.0, 128.8, 132.4
C H O N: C, 79.34; H, 7.98; N, 3.86. Found: C,
79.52; H, 8.10; N, 3.88%.
2
2
24 29
2
ꢀCH), 172.5 and 175.9 (ꢀCO).

M. Periasamy et al. / Journal of Organometallic Chemistry 649 (2002) 209–213
213
4
.2.8. Compound 3h
Yield: 0.177 g (55%); IR (neat): 1766, 1707 cm
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−
1
;
1
[
[
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2
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(
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[
(
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[
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2
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[
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7
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6
12
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(
3%) in C H eluted the anhydride (0.214 g, 64%).
6 12
[
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4.3.1. Compound 8
Yield: 0.214 g (64%); IR (neat): 3111, 1842, 1772
−
1
1
cm ; H-NMR (200 MHz) (CDCl ): l 0.8–1.9 (m,
3
1
3
(
(
b) M.C. Whiting, Chem. Weekblad 53 (1963) 119;
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1
1H), 6.5 (s, 1H); C-NMR (50 MHz) (CDCl ): l 13.7
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(
1
ꢀCH ), 22.1, 25.8, 26.5, 31.1 (ꢀCH ), 128.4 (ꢀCH),
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2
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(
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−
1 1
cm ; H-NMR (200 MHz) (CDCl ): l 7–7.5 (m, 6H);
3
(
b) R. Hernandez, D. Melian, E. Suraez, Synthesis (1992) 653.
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3
C-NMR (50 MHz) (CDCl ): l 127.4, 128.8, 129.2
3
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(
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(
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We are grateful to the UGC, CSIR and DST (New
Delhi) for financial support. We are also thankful to
the UGC for support under Special Assistance
Program.
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