The 'aqueous' Prins cyclization: A diastereoselective synthesis of 4-hydroxytetrahydropyran derivatives

Article abstract of DOI:10.1055/s-2007-1000932

Phosphomolybdic acid (H₃PMo₁₂O₄₀, a heteropoly acid) is found to catalyze efficiently the Prins cyclization of homoallylic alcohols with aldehydes in water at room temperature to provide tetrahydropyran-4-ol derivatives in high yields with all cis-selectivity. Only cyclic ketones can give spirocyclic products. The use of phosphomolybdic acid in water makes this procedure simple, more convenient, cost-effective, and environmentally friendly. Georg Thieme Verlag Stuttgart.

Full text of DOI:10.1055/s-2007-1000932

PAPER
395
The ‘Aqueous’ Prins Cyclization: A Diastereoselective Synthesis of
4-Hydroxytetrahydropyran Derivatives
D
iastereos
h
e
lective Syn
i
thesis
o
l
f
4-H
y
l
droxyte
u
trahydropyran
Der
S
ivatives . Yadav,* Basi V. Subba Reddy, Gunda G. K. S. Narayana Kumar, Seema Aravind
Division of Organic Chemistry, Indian Institute of Chemical Technology, Hyderabad 500 007, India
Fax +91(40)27160512; E-mail: yadavpub@iict.res.in
Received 14 September 2007; revised 25 October 2007
have been reported for the preparation of tetrahydropyran-
4-ols under various reaction conditions.6 However, many
of these classical methods often involve the use of expen-
sive reagents, high temperatures, extended reaction times,
Abstract: Phosphomolybdic acid (H3PMo12O40, a heteropoly acid)
is found to catalyze efficiently the Prins cyclization of homoallylic
alcohols with aldehydes in water at room temperature to provide tet-
rahydropyran-4-ol derivatives in high yields with all cis-selectivity.
Only cyclic ketones can give spirocyclic products. The use of phos- and strongly acidic conditions and they also produce mix-
phomolybdic acid in water makes this procedure simple, more con-
venient, cost-effective, and environmentally friendly.
tures of products. Furthermore, there have been no exam-
ples of the preparation of spirocyclic tetrahydropyran-4-
Keywords: Prins cyclization, phosphomolybdic acid, heteropoly
acid, homoallyl alcohol, tetrahydropyran-4-ols
ols from cyclic ketones and homoallylic alcohols via the
Prins cyclization. This is due to the intrinsic low reactivity
of the ketones compared to aldehydes. Therefore, there is
still scope to develop more general and practical methods
for this transformation.7 Recently, much attention has
been focused on the use of water as a ‘green’ solvent in
various organic transformations. In addition to its abun-
dance and also for economical and safety reasons, water
has naturally become as a substitute and an alternative en-
vironmentally benign solvent in organic synthesis.8 The
use of aqueous media as the solvent also reduces the
harmful effects of organic solvents on the environment.
This becomes more sophisticated if these reactions can be
performed using inexpensive and recyclable solid acids. A
significant benefit of using water for this transformation is
its ability to act as both nucleophile and solvent.
The tetrahydropyrans are important building blocks for
many biologically active natural products (Figure 1).1,2
Thus, considerable efforts have been made to develop re-
liable synthetic procedures for the construction of these
heterocycles. The reaction between homoallylic alcohols
and aldehydes under strongly acidic conditions, known as
the Prins cyclization, is a direct and one of the most wide-
ly used methods for the preparation of tetrahydropyran de-
rivatives.3 A number of methods have been developed
using various Brønsted acids and Lewis acids as promot-
ers to accomplish this transformation;4,5 a few methods
OH
OH
O
OH
O
H
N
O
Me
O
O
O
O
O
OH
diospongin A
epi-apicularen A
prelactone
OH
OH
OMe
O
HO
N
O
OMe
O
N
O
HO
hennoxazole A
catechol derivative
Figure 1
SYNTHESIS 2008, No. 3, pp 0395–0400
x
x
.
x
x
.2
0
0
8
Advanced online publication: 10.01.2008
DOI: 10.1055/s-2007-1000932; Art ID: Z21107SS
© Georg Thieme Verlag Stuttgart · New York

396
J. S. Yadav et al.
PAPER
Recently, the use of heteropoly acids (HPAs) as environ- ducing tetrahydropyran-4-ol derivatives. Accordingly,
mentally friendly and economically viable solid acids has treatment of benzaldehyde with but-3-en-1-ol in the pres-
continuously increased because of their ease of handling ence of phosphomolybdic acid (PMA) for eight hours
and high catalytic activity and reactivity.9 These com- gave 2-phenyltetrahydropyran-4-ol (1a) in 92% yield
pounds possess unique properties, such as well-defined with cis-selectivity (Table 1, entry 1).
structures, Brønsted acidity, the possibility to modify their
A single diastereomer was obtained from each reaction,
acid–base and redox properties by changing their chemi-
the structure of which was confirmed by 1H NMR and also
cal composition (substituted HPAs), the ability to accept
by comparison with authentic samples.6 The formation of
and release electrons, high proton mobility, etc. In addi-
the products may be realized by assuming a chair-like
transition state to give the all-cis-configured products
tion to their abundance, HPAs have naturally become a
substitute or alternative solid acids for economical and
(Scheme 1).
safety reasons.10 HPAs are very strong acids, approaching
the super acid region, with a Brønsted acidity greatly ex-
R1
+
ceeding that of ordinary mineral acids and solid acid cat-
alysts. This makes it possible to carry out a catalytic
process at low concentrations and at lower temperatures.11
Among various heteropoly acids, phosphomolybdic acid
(PMA, H3PMo12O40) is one of the less expensive and com-
mercially available solid acid catalysts.12,13 However,
there have been no reports on the use of phosphomolybdic
acid for the synthesis of tetrahydropyran-4-ols via the
Prins cyclization.
O
R1
H
+
R2
O
+
R2
H
OH
H
–
OH
OH
+
O
R1
H2O
R1
R2
R2
O
H
In the ever-increasing quest for exploration of newer reac-
tions in water, we report herein the phosphomolybdic acid
catalyzed Prins cyclization of aldehydes or ketones with
homoallylic alcohols in water at room temperature pro-
Scheme 1
Table 1 Phosphomolybdic Acid Catalyzed Preparation of Tetrahydropyran-4-ol Derivativesa
Entry Alcohol
Carbonyl compound
Product pyran-4-olb
Time (h) Yieldc (%)
OH
CHO
1
1a
1b
1c
1d
8.0
8.5
8.5
9.5
92
90
89
82
OH
OH
OH
OH
O
OH
CHO
2
3
4
O
Cl
Cl
OH
CHO
O
Me
Me
OH
CHO
O
MeO
MeO
Synthesis 2008, No. 3, 395–400 © Thieme Stuttgart · New York

PAPER
Diastereoselective Synthesis of 4-Hydroxytetrahydropyran Derivatives
397
Table 1 Phosphomolybdic Acid Catalyzed Preparation of Tetrahydropyran-4-ol Derivativesa (continued)
Entry Alcohol
Carbonyl compound
Product pyran-4-olb
Time (h) Yieldc (%)
OH
CHO
5
1e
9.5
80
OH
O
O2N
O2N
OH
6
7
1f
7.5
7.0
90
92
CHO
OH
OH
O
OH
1g
CHO
O
OH
CHO
8
1h
7.5
90
OH
O
OH
O
O
O
9
1i
1j
9.0
9.5
84
88
OH
OH
O
OH
10
O
OH
11
12
1k
1l
9.0
8.0
86
90
OH
O
OH
OH
CHO
O
OH
OH
CHO
13
1m
1n
8.0
8.5
84
88
O
Me
Me
OH
OH
CHO
14
O
Me
Me
Me
Me
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J. S. Yadav et al.
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Table 1 Phosphomolybdic Acid Catalyzed Preparation of Tetrahydropyran-4-ol Derivativesa (continued)
Entry Alcohol
Carbonyl compound
Product pyran-4-olb
Time (h) Yieldc (%)
OH
Cl
OH
OH
OH
Cl
CHO
15
1o
1p
1q
9.0
7.5
8.0
86
90
88
O
Cl
Cl
OH
CHO
16
17
O
OH
CHO
O
a Reaction conditions: PMA (40 mol%), H2O, r.t.
b All products were characterized by 1H NMR, 13C NMR, and IR spectroscopy, and mass spectrometry.
c Yield refers to pure products after chromatography.
A rationale for the cis-selectivity could be explained by obtained in excellent yields and with high diastereoselec-
assuming the formation of an (E)-oxocarbenium ion via a tivity as determined from the NMR spectrum of the crude
chairlike transition state, which has increased stability rel- product. No intrusion of HPA anion was observed in the
–
ative to the open oxocarbenium ion due to delocalization. Prins cyclization because the nucleophilicity of OH is
The optimal geometry for this delocalization places the higher than that of the HPA anion (PMo12O403–). The na-
hydrogen atom at C4 in a pseudoaxial position, which fa- ture of the substituents on the aromatic ring shows some
vors equatorial attack of the nucleophile.14 This result pro- effect on this conversion. It should be noted that aliphatic,
vided the incentive for further study of reactions with simple aromatic, and moderately activated aldehydes such
various aldehydes. Interestingly, a wide range of alde- as methyl-, chloro- or bromo-substituted benzaldehydes
hydes such as 4-chlorobenzaldehyde, 4-methylbenzalde- gave higher yields of products compared to strongly acti-
hyde, 4-methoxybenzaldehyde, 4-nitrobenzaldehyde, vated or deactivated aldehydes. The scope of this process
phenylacetaldehyde, propanal, and cyclohexanecarbalde- is illustrated with respect to various aldehydes and ke-
hyde reacted well with but-3-en-1-ol to produce the corre- tones and homoallylic alcohols and the results are present-
sponding tetrahydropyranols 1b–h in high yields ed in Table 1.
(Table 1, entries 2–8). This reaction was also successful
In summary, the combination of phosphomolybdic acid
with cyclic ketones such as cyclopentanone, cyclohex-
with water has been shown to be a useful and novel cata-
anone, and adamantan-2-one to give spirocyclic tetrahy-
lytic medium to accomplish the Prins cyclization under
mild conditions. The use of phosphomolybdic acid in wa-
ter makes this process convenient, cost-effective, and en-
dropyran-4-ols 1i–k comparably in good yields (Table 1,
entries 9–11).
In addition, substituted homoallylic alcohols like non-1- vironmentally benign. This method provides an easy
en-4-ol, 1-(4-methylphenyl)but-3-en-1-ol, 1-cyclohexyl- access to tetrahydropyran-4-ols with diverse chemical
but-3-en-1-ol, and 1-phenylbut-3-en-1-ol also participat- structures.
ed well in this transformation to give 1l–q (Table 1,
entries 12–17) under similar conditions.
Melting points were recorded on Buchi R-535 apparatus and are un-
corrected. IR spectra were recorded on a Perkin-Elmer FT-IR
In the absence of phosphomolybdic acid, no reaction was
240-c spectrophotometer using KBr optics. 1H NMR spectra were
observed between the aldehyde and homoallylic alcohol
recorded on Gemini-200 spectrometer in CDCl3 using TMS as in-
even under reflux conditions with a long reaction time (12
ternal standard. Mass spectra were recorded on a Finnigan MAT
h). In all cases, the reactions proceeded readily at room
1020 mass spectrometer operating at 70 eV. TLC was monitored on
temperature under mild conditions and the products were
0.25 mm pre-coated silica gel plates (60F-254).
Synthesis 2008, No. 3, 395–400 © Thieme Stuttgart · New York

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Diastereoselective Synthesis of 4-Hydroxytetrahydropyran Derivatives
399
Tetrahydropyran-4-ols 1; General Procedure
HRMS: m/z [M + Na] calcd for C11H20NaO2: 207.1360; found:
207.1366.
A mixture of homoallylic alcohol (1 mmol), aldehyde (1 mmol),
and phosphomolybdic acid (0.4 mmol) in H2O (5 mL)was stirred at
23 °C for the specified time (Table 1). When the reaction was com-
plete (TLC), the mixture was extracted with EtOAc (2 × 10 mL) and
the combined organic layers were dried (anhyd Na2SO4). Removal
of the solvent followed by purification on silica gel (Merck, 60–120
mesh, EtOAc–hexane, 2:8) gave the pure tetrahydropyran-4-ol. The
products thus obtained were characterized by IR, NMR, and mass
spectroscopy. The products 1a–c,e,n,q are known and the spectral
data were found to be consistent with authentic samples.6
6-Oxaspiro[4.5]decan-9-ol (1i)
Colorless liquid.
IR (KBr): 3390, 2955, 2850, 1463, 1369, 1251, 1152, 1084, 1052,
1000, 876, 724 cm–1.
1H NMR (200 MHz, CDCl3): d = 1.26–2.03 (m, 12 H), 3.53 (dt,
J = 3.0, 12.0 Hz, 1 H), 3.75 (m, 1 H), 3.84 (m, 1 H).
13C NMR (75 MHz, CDCl3): d = 83.9, 68.1, 62.4, 46.6, 41.6, 33.1,
23.1.
2-(4-Methoxyphenyl)tetrahydro-2H-pyran-4-ol (1d)
Light yellow liquid.
LC-MS: m/z = 179 (M + Na).
HRMS: m/z [M + Na] calcd for C9H16NaO2: 179.1047; found:
179.1056.
IR (KBr): 3387, 2923, 2851, 1595, 1493, 1365, 1250, 1139, 1083,
1014, 987, 825 cm–1.
1H NMR (200 MHz, CDCl3): d = 1.35–1.65 (m, 2 H), 1.94 (m, 1 H),
2.10 (m, 1 H), 3.52 (m, 1 H), 3.78 (s, 3 H), 3.87 (m, 1 H), 4.13 (dd,
J = 4.5, 12.0 Hz, 1 H), 4.21 (d, J = 11.2 Hz, 1 H), 6.77–6.83 (m, 2
H), 7.17–7.26 (m, 2 H).
13C NMR (75 MHz, CDCl3): d = 140.4, 133.2, 128.5, 127.2, 77.6,
68.2, 66.3, 43.2, 35.3, 29.7.
1-Oxaspiro[5.5]undecan-4-ol (1j)
Colorless liquid.
IR (KBr): 3386, 2932, 2856, 1447, 1366, 1073, 970, 728 cm–1.
1H NMR (200 MHz, CDCl3): d = 1.19–1.91 (m, 14 H), 3.50 (dt,
J = 2.3, 11.7 Hz, 1 H), 3.71–3.90 (m, 2 H).
13C NMR (75 MHz, CDCl3): d = 78.5, 66.9, 61.6, 46.4, 40.6, 32.8,
23.4, 21.0.
LC-MS: m/z = 231 (M + Na).
HRMS: m/z [M + Na] calcd for C12H16NaO3: 231.0997; found:
231.0992.
LC-MS: m/z = 193 (M + Na).
HRMS: m/z [M + Na] calcd for C10H18NaO2: 193.1204; found:
193.1210.
2-Benzyltetrahydro-2H-pyran-4-ol (1f)
Colorless liquid.
IR (KBr): 3445, 2923, 2854, 1458, 1084, 770 cm–1.
1H NMR (200 MHz, CDCl3): d = 1.34–1.64 (m, 2 H), 1.72–1.88 (m,
2 H), 2.77 (m, 1 H), 3.17–3.39 (m, 2 H), 3.64 (m, 1 H), 3.93–4.13
(m, 2 H), 7.06–7.30 (m, 5 H).
Spiro[adamantane-2,2¢-tetrahydropyran]-4¢-ol (1k)
Colorless solid; mp 116–118 °C.
IR (KBr): 3304, 2922, 2853, 1447, 1358, 1246, 1173, 1081, 1036,
955, 720 cm–1.
1H NMR (200 MHz, CDCl3): d = 1.02–1.50 (m, 4 H), 1.62–1.94 (m,
10 H), 1.97–2.14 (m, 2 H), 2.27 (m, 1 H), 2.46 (m, 1 H), 3.56 (dt,
J = 3.0, 12.0 Hz, 1 H), 3.76 (m, 1 H), 3.87 (m, 1 H).
13C NMR (75 MHz, CDCl3): d = 77.6, 64.8, 58.0, 41.4, 39.5, 38.2,
35.9, 34.1, 33.8, 32.7, 31.7, 30.3, 29.7, 27.7, 27.4.
13C NMR (75 MHz, CDCl3): d = 138.1, 129.4, 128.3, 126.3, 77.1,
67.9, 66.0, 42.6, 40.8, 35.4.
LC-MS: m/z = 215 (M + Na).
HRMS: m/z [M + Na] calcd for C12H16NaO2: 215.1047; found:
215.1049.
LC-MS: m/z = 245 (M + Na).
HRMS: m/z [M + Na] calcd for C14H22NaO2: 245.1517; found:
245.1527.
2-Ethyltetrahydro-2H-pyran-4-ol (1g)
Colorless liquid.
IR (KBr): 3388, 2938, 2848, 1458, 1372, 1251, 1147, 1083, 1045,
980, 874 cm–1.
1H NMR (200 MHz, CDCl3): d = 0.93 (t, J = 7.4 Hz, 3 H), 1.02–1.96
(m, 7 H), 3.13 (m, 1 H), 3.33 (dt, J = 1.6, 11.6 Hz, 1 H), 3.71 (m, 1
H), 3.97 (m, 1 H).
13C NMR (75 MHz, CDCl3): d = 77.5, 67.6, 65.6, 40.7, 35.4, 28.7,
9.5.
2,6-Dipentyltetrahydro-2H-pyran-4-ol (1l)
Colorless solid; mp 42–44 °C.
IR (KBr): 3409, 2921, 2852, 1512, 1450, 1357, 1152, 1080, 1037,
988, 803 cm–1.
1H NMR (200 MHz, CDCl3): d = 0.80–1.17 (m, 7 H), 1.22–1.66 (m,
15 H), 1.75–1.99 (m, 4 H), 3.19 (m, 2 H), 3.70 (m, 1 H).
13C NMR (75 MHz, CDCl3): d = 75.5, 68.4, 41.4, 36.0, 31.7, 25.3,
22.6, 14.0.
LC-MS: m/z = 153 (M + Na).
HRMS: m/z [M + Na] calcd for C7H14NaO2: 153.0891; found:
153.0899.
LC-MS: m/z = 265 (M + Na).
HRMS: m/z [M + Na] calcd for C15H30NaO2: 265.2143; found:
265.2150.
2-Cyclohexyltetrahydro-2H-pyran-4-ol (1h)
Colorless liquid.
IR (KBr): 3310, 2927, 2851, 1148, 1320, 1040, 996 cm–1.
1H NMR (200 MHz, CDCl3): d = 0.76–1.45 (m, 10 H), 1.53–1.87
(m, 5 H), 2.22 (br s, OH), 2.88 (m, 1 H), 3.23 (m, 1 H), 3.61 (m, 1
H), 3.90 (m, 1 H).
2-Cyclohexyl-6-(4-methylphenyl)tetrahydro-2H-pyran-4-ol
(1m)
Light brown solid; mp 141–143 °C.
IR (KBr): 3411, 2922, 2853, 1703, 1514, 1449, 1359, 1268, 1152,
1080, 1037, 988, 888, 802 cm–1.
1H NMR (200 MHz, CDCl3): d = 0.96–1.82 (m, 11 H), 1.87–2.00
(m, 3 H), 2.13 (m, 1 H), 2.33 (s, 3 H), 3.19 (m, 1 H), 3.87 (m, 1 H),
4.24 (dd, J = 1.5, 11.3 Hz, 1 H), 7.05–7.21 (m, 4 H).
13C NMR (75 MHz, CDCl3): d = 73.6, 64.4, 58.8, 44.7, 39.5, 35.7,
31.0, 25.8, 21.2.
LC-MS: m/z = 207 (M + Na).
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J. S. Yadav et al.
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13C NMR (75 MHz, CDCl3): d = 139.5, 136.9, 128.9, 125.7, 80.1,
77.0, 69.1, 43.1, 42.7, 37.7, 29.1, 28.7, 26.6, 26.2, 21.1.
(3) (a) Hanschke, E. Chem. Ber. 1955, 88, 1053. (b) Stapp, P.
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Lett. 1987, 28, 3441. (b) Perron, F.; Albizati, K. F. J. Org.
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1999, 40, 1627. (b) Yang, J.; Li, C. J. Synlett 1999, 717.
(c) Chan, K.-P.; Loh, T.-P. Tetrahedron Lett. 2004, 45,
8387. (d) Miranda, P. O.; Diaz, D. D.; Padron, J. I.; Ramirez,
M. A.; Martin, V. S. J. Org. Chem. 2005, 70, 57.
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2004, 6, 3199. (c) De la Herrán, G.; Segura, A.; Csáky, A. G.
Org. Lett. 2007, 9, 961.
LC-MS: m/z = 297 (M + Na).
HRMS: m/z [M + Na] calcd for C18H26NaO2: 297.1830; found:
297.1839.
2-Cyclohexyl-6-(2,4-dichlorophenyl)tetrahydro-2H-pyran-4-ol
(1o)
Pale yellow solid; mp 103–105 °C.
IR (KBr): 3344, 2925, 2852, 1472, 1448, 1364, 1073, 1047, 900,
865, 821 cm–1.
1H NMR (200 MHz, CDCl3): d = 0.92–1.72 (m, 11 H), 1.87–2.20
(m, 3 H), 2.27 (m, 1 H), 3.26 (m, 1 H), 3.91 (m, 1 H), 4.56 (dd,
J = 1.8, 11.1 Hz, 1 H), 7.25 (d, J = 2.0 Hz, 1 H), 7.31 (d, J = 2.0 Hz,
1 H), 7.47 (d, J = 8.4 Hz, 1 H).
(7) (a) Zhang, W. C.; Viswanathan, G. S.; Li, C. J. Chem.
Commun. 1999, 291. (b) Zhang, W. C.; Li, C. J.
13C NMR (75 MHz, CDCl3): d = 139.5, 136.9, 128.9, 125.7, 80.1,
77.0, 69.1, 43.1, 42.7, 37.7, 29.1, 28.7, 26.6, 26.2, 21.1.
Tetrahedron 2000, 56, 2403. (c) Keh, C. C. K.; Namboodiri,
V. V.; Varma, R. S.; Li, C. J. Tetrahedron Lett. 2002, 43,
4993. (d) Yadav, J. S.; Subba Reddy, B. V.; Kumar, G. M.;
Murthy, Ch. V. S. R. Tetrahedron Lett. 2001, 42, 89.
(8) (a) Yadav, J. S.; Subba Reddy, B. V.; Narayana Kumar, G.
G. K. S.; Swamy, T. Tetrahedron Lett. 2007, 48, 2205.
(b) Yadav, J. S.; Subba Reddy, B. V.; Narayana Kumar, G.
G. K. S.; Reddy, M. G. Tetrahedron Lett. 2007, 48, 4903.
(c) Yadav, J. S.; Kumar, N. N.; Reddy, M. S.; Prasad, A. R.
Tetrahedron 2007, 63, 2689. (d) Yadav, J. S.; Reddy, M. S.;
Prasad, A. R. Tetrahedron Lett. 2006, 47, 4995.
LC-MS: m/z = 352 (M + Na).
HRMS: m/z [M + Na] calcd for C17H22Cl2NaO2: 351.0894; found:
351.0906.
2,6-Dicyclohexyltetrahydro-2H-pyran-4-ol (1p)
Colorless solid; mp 111–113 °C.
IR (KBr): 3275, 2927, 2851, 1448, 1364, 1320, 1270, 1123, 1071,
1040, 996, 895, 859 cm–1.
1H NMR (200 MHz, CDCl3): d = 0.70–2.12 (m, 27 H), 2.79–3.02
(m, 2 H), 3.69 (m, 1 H).
13C NMR (75 MHz, CDCl3): d = 79.8, 69.2, 42.8, 38.5, 29.3, 28.9,
26.6, 26.2.
(9) (a) Grieco, P. A. Organic Synthesis in Water; Blackie
Academic and Professional: London, 1998. (b) Li, C. J.;
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Frontiers in Benign Chemical Synthesis and Procedures;
Oxford Science Publications: Oxford, 1998. (b) Ritter, S. K.
Chem. Eng. News 2002, 80 (38), 27.
LC-MS: m/z = 289 (M + Na).
HRMS: m/z [M + Na] calcd for C17H30NaO2: 289.2143; found:
289.2146.
(11) Misono, M.; Ono, I.; Koyano, G.; Aoshima, A. Pure Appl.
Chem. 2000, 72, 1305.
Acknowledgement
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