Potassium dodecatungsto cobaltate trihydrate: A new heterogeneous catalyst for the synthesis of homoallylic alcohols and amines

Article abstract of DOI:10.1080/00397910802374109

A simple and efficient procedure has been developed for one-pot synthesis of homoallylic alcohols and amines in good to excellent yields using a variety of aldehydes, amines, and allyltributylstannane in the presence of a catalytic amount of potassium dod

Full text of DOI:10.1080/00397910802374109

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Potassium Dodecatungsto
Cobaltate Trihydrate: A New
Heterogeneous Catalyst for
the Synthesis of Homoallylic
Alcohols and Amines
Lingaiah Nagarapu a , Gopal Paturi a , Satyender
Apuri a , Rajashaker Bantu a & Renuka Bhavanthula a
a Organic Chemistry Division II, Indian Institute of
Chemical Technology, Hyderabad, India
Version of record first published: 22 Dec 2008
To cite this article: Lingaiah Nagarapu, Gopal Paturi, Satyender Apuri, Rajashaker
Bantu & Renuka Bhavanthula (2008): Potassium Dodecatungsto Cobaltate Trihydrate:
A New Heterogeneous Catalyst for the Synthesis of Homoallylic Alcohols and Amines,
Synthetic Communications: An International Journal for Rapid Communication of
Synthetic Organic Chemistry, 39:2, 355-365
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Synthetic Communications1, 39: 355–365, 2009
Copyright # Taylor & Francis Group, LLC
ISSN: 0039-7911 print/1532-2432 online
DOI: 10.1080/00397910802374109
Potassium Dodecatungsto Cobaltate Trihydrate:
A New Heterogeneous Catalyst for the Synthesis
of Homoallylic Alcohols and Amines
Lingaiah Nagarapu, Gopal Paturi, Satyender Apuri,
Rajashaker Bantu, and Renuka Bhavanthula
Organic Chemistry Division II, Indian Institute of Chemical Technology,
Hyderabad, India
Abstract: A simple and efficient procedure has been developed for one-pot
synthesis of homoallylic alcohols and amines in good to excellent yields using a
variety of aldehydes, amines, and allyltributylstannane in the presence of a catalytic
amount of potassium dodecatungsto cobaltate trihydrate (K5CoW12O40 ꢀ 3H2O)
as a heterogeneous catalyst at room temperature. The catalyst exhibited remark-
able reusability.
Keywords: Allyltributylstannane, homoallylic alcohols, homoallylic amines,
potassium dodecatungsto cobaltate trihydrate, reusability
INTRODUCTION
The use of heterogeneous catalysts in different areas of organic synthesis
has now reached significant levels, not only for performing environmen-
tally benign synthesis but also for the good yields, frequently accompa-
nied by heteropoly acids (HPAs) and related compounds. HPAs have
several advantages as catalysts that make them economically and envir-
onmentally attractive. On the one hand, HPAs have a very strong
Brønsted acidity approaching the superacid region; on the other, they
are efficient oxidants, exhibiting fast reversible multielectron redox trans-
formations under rather mild conditions. One such mild acidic catalyst is
Received April 21, 2008.
Address correspondence to Lingaiah Nagarapu, Organic Chemistry Division II,
Indian Institute of Chemical Technology, Hyderabad 500 007, India. E-mail:
nagarapu2@yahoo.co.in
355

356
L. Nagarapu, G. Paturi, and S. Apuri
potassium dodecatungsto cobaltate trihydrate, K5CoW12O40 ꢀ 3H2O
(PDTC). The significant features of this catalyst are that it is easy to
prepare and handle, inexpensive, recyclable, and ecofriendly in nature.
PDTC catalyzes acetylation and formylation of alcohols,[1] esterification
and transestrification reactions,[2] deprotection of dioxolanes and
trimethyl silyl ethers,[3] cleavage of oximes,[4] Biginelli reaction,[5] micro-
wave-assisted synthesis of quinoline and dihydroquinoline derivatives,[6]
a four-component synthesis of b-acetamido ketones,[7] synthesis of aryl-
14H-dibenzo[a.j]xanthenes,[8] and synthesis of amidoalkyl naphthols.[9]
Homoallylic alcohols[10] and amines[11] are important building blocks
for the construction of various biologically active compounds, and hence
the syntheses of these compounds are highly useful. Nucleophilic addition
of allyltin reagents to carbonyl compounds[12] and imines[13] in the presence
of a catalyst is a straightforward method for the synthesis of homoallylic
alcohols and amines, respectively. Lewis acids containing boron, alumi-
num, titanium, and tin, which can catalyze this reaction, are extremely
moisture sensitive and can cause inconveniences in performing the reaction.
RESULTS AND DISCUSSION
In continuation of our work[14] on the development of useful synthetic
methodologies, we report here a facile synthesis of homoallylic alcohols
2 and amines 4 by the allylation of carbonyl compounds and imines
(generated in situ from aldehydes and amines) with allyltributylstannane
in the presence of a catalytic amount of PDTC at room temperature
(Scheme 1). For the first time, this catalyst has been applied successfully
for the synthesis of homoallylic alcohols from various aldehydes (Table 1)
and homoallylic amines using different aldehydes and amines (Table 2).
The products were formed in good to high yields, and no by-products
were detected. The reaction times required here for the preparation of
homoallylic alcohols were 2–3 h, and homoallylic amines ranged between
2 and 4 h except for compounds 4j (24 h) and 4o (24 h) (entries j and o,
Table 2). Aromatic, heteroaromatic, and aliphatic aldehydes underwent
Scheme 1. Synthesis of homoallylic alcohols and amines using PDTC with
aromatic aldehydes.

Homoallylic Alcohols and Amines
357
Table 1. K5CoW12O40 ꢀ 3H2O-catalyzed synthesis of homoallylic alcohols
Entry
Aldehyde (1)
Product (2)a
Time (h) Yield (%)b
a
2
3
87
85
b
c
3
2
82
92
d
e
f
2
2
2
3
3
81
84
83
70
g
h
i
79
(Continued)

358
L. Nagarapu, G. Paturi, and S. Apuri
Table 1. Continued
Entry
Aldehyde (1)
Product (2)a
Time (h) Yield (%)b
j
3
2
2
3
75
78
80
16
k
l
m
aAll products were characterized by 1H NMR, 13C NMR, IR, and mass
spectroscopy.
bIsolated and unoptimized yields.
the conversion smoothly. Upon screening with p-chlorobenzaldehyde
and allyltributylstannane (for homoallylic alcohols), benzaldehyde,
p-fluoroaniline, and allyltributylstannane (for homoallylic amines), it
was found that PDTC (1 mol%) is an efficient catalyst to bring about this
transformation at room temperature. In addition, only 1 mol% of PDTC
is sufficient for the synthesis of homoallylic alcohols and amines from
the reaction of various aldehydes, amines, and allyltributylstannane.
Encouraged by the results obtained for p-chlorobenzaldehyde with ally-
ltributylstannane (Table 1) and benzaldehyde with p-fluoroaniline and
allyltributylstannane (Table 2), we investigated a number of other alde-
hydes and various amines to probe their behavior under the current
catalytic conditions. The aromatic aldehydes containing both electron-
donating and electron-withdrawing groups in the aromatic ring worked
well. However, ketones did not form any product under similar reaction
conditions.

359

360

Homoallylic Alcohols and Amines
361
Scheme 2. Synthesis of homoallylic alcohols and amines using PDTC with sugar-
derived aldehyde.
The generality of the present protocol was then extended to sugar-
derived aldehyde (1,2-O-isopropylidene-3-hydroxy-a-D-xylo-pentadialdo-
1,4-furanose, (entry m, Table 1, and entry s, Table 2), but conversion
was only 16% and 14.8% (Scheme 2).
At the outset, we also studied two- and three-component syntheses of
homoallylic alcohols and amines in aqueous media (4 mL) with aldehyde
(2 mmol), aniline (2 mmol), and allyltributylstannane (2.4 mmol) in the
presence of 1 mol% of water-tolerant PDTC at room temperature, but
the reaction times were longer (12–26 h) and the yields (38–56%) were
comparatively low (Scheme 3).
Next, we investigated the reusability and recycling of PDTC in sub-
sequent reactions. Second and third reactions using recovered PDTC
afforded similar yields to those obtained in the first run. In the fourth
and fifth runs, the yields were gradually decreased. For example, p-chloro
benzaldehyde (20 mmol), aniline (20 mmol), allyltributylstannane
(24 mmol), and 10 mol% of K5CoW12O40 ꢀ 3H2O in acetonitrile (50 mL)
afforded 86%, 84%, 82%, 80%, and 79% over five cycles.
In conclusion, PDTC has efficiently been applied under mild reaction
conditions for the allylation of both aldehydes and imines with allyltribu-
tylstannane to prepare homoallylic alcohols and amines, respectively, in
good to high yields. Present methodology offers very attractive features
such as shorter reaction times and higher yields and will have wide scope
in organic synthesis. This simple procedure, combined with ease of recov-
ery and reuse of the catalyst, is an economic, benign, and a waste-free
chemical process for the synthesis of homoallyl amines.
Scheme 3. Synthesis of homoallylic alcohols and amines using PDTC with
aromatic aldehydes in aqueous media.

362
L. Nagarapu, G. Paturi, and S. Apuri
EXPERIMENTAL
All the commercial reagents and solvents were used without further puri-
fication unless otherwise stated. Melting points were recorded on a Buchi
535 melting-point apparatus and are uncorrected. All the reactions were
monitored by thin-layer chromatography (TLC) performed on precoated
silica-gel 60F254 plates (Merck). IR spectra were recorded on Perkin-
Elmer 683 or 1310 FT-IR spectrometer with KBr pellets. NMR spectra
were recorded on Varian Unity 200-MHz and Bruker AMX 300-MHz
spectrometers using tetramethylsilane as an internal standard. Mass spec-
tra were recorded on VG Micromass 7070H and Finnigan Mat 1020B
mass spectrometers operating at 70 ev.
General Procedure for the Synthesis of Homoallylic Alcohol
To a mixture of aldehyde (2 mmol) and allyltributylstannane (2.4 mmol)
in acetonitrile (5 mL), K5CoW12O40ꢀ3H2O (1.0 mol%) was added. The
mixture was stirred at room temperature, and the reaction was monitored
by thin-layer chromatography (TLC). After completion, the mixture was
diluted with acetonitrile (10 mL) and filtered [to remove the catalyst;
removed catalyst was washed with acetonitrile (2 ꢁ 5 mL)]. The combined
filtrates were concentrated under reduced pressure, and the gummy resi-
due was purified by column chromatography (silica gel, 3% EtOAc in
hexane) to afford the pure homoallylic alcohol.
General Procedure for the Synthesis of Homoallylic Amine
The homoallylic amine was synthesized following this procedure using a
mixture of aldehyde (2 mmol), amine (2 mmol), and allyltributylstannane
(2.4 mmol) in acetonitrile (5 mL). K5CoW12O40 ꢀ 3H2O (1 mol%) was
added to the mixure. After completion of the reaction, this workup
procedure was followed. The crude product was purified by column
chromatography over silica gel using hexane as eluent to obtain pure
homoallylic amine.
Representative Spectral Data
1-(4-bromophenyl)-3-buten-1-ol (2b, Table 1)
Pale yellow liquid, IR (neat): 3380, 3076, 2959, 2925, 1488, 1066, 1010,
1
824 cmꢂ1; H NMR (200 MHz, CDCl3): d 2.23–2.50 (m, 2H, ꢂCH2ꢂ),

Homoallylic Alcohols and Amines
363
4.60–4.70 (m, 1H, ꢂCHꢂ), 5.09 (dd, 1H, J ¼ 7.6 & 5.2 Hz, ¼ CH), 5.18
(dd, 1H, J ¼ 7.4 & 5.3 Hz, ¼CH), 5.65–5.88 (m, 1H, ꢂCHꢂ), 7.20
(d, 2H, J ¼ 9.3 Hz, Ar-H), 7.42 (d, 2H, J ¼ 9.3 Hz, Ar-H).
1-(3-Hydroxyphenyl)-3-buten-1-ol (2i, Table 1)
Pale yellow liquid, IR (KBr): 3336, 3070, 2959, 2930, 1466, 1258, 1022,
1
699 cmꢂ1; H NMR (200 MHz, CDCl3): d 2.40–2.50 (m, 2H, ꢂCH2ꢂ),
4.10–4.69 (m, 1H, ꢂCHꢂ), 5.10–5.19 (dd, 2H, ¼CH), 5.70–5.83 (m,
1H, ꢂCHꢂ), 6.65–7.20 (m, 4H, Ar-H).
1-Naphthalen-3-buten-1-ol (2l, Table 1)
Pale yellow liquid, IR (neat): 3405, 3068, 2924, 1379, 777 cmꢂ1; 1H NMR
(300 MHz, CDCl3): d 2.70–2.80 (m, 2H, ꢂCH2ꢂ), 5.13–5.30 (dd, 2H,
¼CH), 5.48–5.52 (m, 1H, ꢂCH¼ ), 5.82–5.60 (m, 1H, ꢂCHꢂ), 7.70–
8.09 (m, 7H, Ar-H).
N-(1-Isobutylbut-3-enyl)aniline (4n, Table 2)
Pale yellow liquid, IR (neat): 3411, 3054, 2959, 2927, 2871, 1638, 1601,
1
1505, 1317, 912, 747, 691 cmꢂ1; H NMR (300 MHz, CDCl3): d 0.95 (d,
3H, ꢂCH3), 0.98 (d, 3H, ꢂCH3), 1.90 (m, 1H, ꢂCHꢂ), 2.19–2.35 (m, 2H,
ꢂCH2ꢂ), 3.20–3.26 (dd, 1H, J ¼ 7.4 & 5.2 Hz, ꢂCH¼), 3.42 (brs, 1H,
ꢂNH), 5.00–5.06 (dd, 2H, ¼CH), 5.71–5.82 (m, 1H, ꢂCHꢂ), 6.50 (d,
2H, J ¼ 7.5 Hz, Ar-H), 6.60 (t, 1H, J ¼ 6.8 & 2.3 Hz, Ar-H), 7.05 (t,
2H, Ar-H). 13C NMR (CDCl3, 75 MHz): d 18.4, 18.6, 30.8, 35.7, 57.9,
113.1, 116.7, 116.9, 129.2, 135.7, 148.3. MS: m=z ¼ 189 [Mþ], 148
(100%), 104, 77, 55.
N-(4-Butylphenyl)-(1-phenylbut-3-enyl)amine (4r, Table 2)
Pale yellow liquid, IR (neat): 3411, 3062, 3023, 2956, 2925, 2854, 1615,
1
1517, 1455, 1309, 917, 700 cmꢂ1; H NMR (300 MHz, CDCl3): d 0.83
(t, 3H, J ¼ 7.3 & 2.0 Hz, ꢂCH3), 1.25–1.35 (m, 2H, ꢂCH2ꢂ), 1.43–1.51
(m, 2H, ꢂCH2ꢂ), 2.46–2.51 (m, 2H, ArꢂCH2ꢂ), 2.54–2.58 (m, 2H,
ꢂCH2ꢂ), 3.94 (brs, 1H, ꢂNH), 4.30 (dd, 1H, J ¼ 7.8 & 5.2 Hz, ꢂCH¼),
, 5.10–5.19 (dd, 2H, ¼ CH), 5.67–5.79 (m, 1H, ꢂCHꢂ), 6.34 (d, 2H,
J ¼ 8.4 Hz, Ar-H), 6.82 (d, 2H, J ¼ 8.4 Hz, Ar-H), 7.17–7.21 (m, 1H,
Ar-H), 7.24–7.34 (m, 4H, Ar-H). 13C NMR (CDCl3, 75 MHz): d 13.9,
22.3, 33.9, 34.6, 43.3, 57.4, 113.5, 118.1, 126.3, 126.8, 128.5, 128.8,

364
L. Nagarapu, G. Paturi, and S. Apuri
131.7, 134.8, 143.8, 145.3. MS: m=z ¼ 279 [Mþ], 239 (100%), 196, 92.
Anal. calcd. for C20H25N: C, 85.97; H, 9.02. Found: C, 85.95; H, 9.08.
2,2-Dimethyl-5-(1-phenylbut-3-enylamino)-tetrahydrofuro[2,3-
d][1,3]dioxol-6-ol (4s, Table 2)
1
Pale yellow liquid, H NMR (300 MHz, CDCl3): d 1.25 (s, 3H, ꢂCH3),
1.35 (s, 3H, ꢂCH3), 2.35–2.45 (m, 2H, ꢂCH2ꢂ), 3.85–3.95 (m, 2H, H-
3 & -NH), 5.00–5.20 (m, 5H, ¼ CH, ꢂCHꢂ, H-2, H-4), 5.75–5.90 (m,
2H, ꢂCHꢂ, H-1), 6.55–6.60 (m, 3H, Ar-H), 7.10–7.20 (m, 2H, Ar-H).
Anal. calcd. for C17H23NO4: C, 66.86; H, 7.59. Found: C, 66.88; H, 7.60.
ACKNOWLEDGMENT
S. A. thanks Council of Scientific and Industrial Research, New Delhi,
for financial assistance, and authors thank the head, Organic Chemistry
Division II, and director, Indian Institute of Chemical Technology,
Hyderabad, for their constant encouragement and support.
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