Ceric(IV) ammonium nitrate: A novel reagent for the synthesis of homoallyl alcohols

Article abstract of DOI:10.1246/cl.2003.248

A rapid and highly efficient method has been developed for the allylation of aldehydes with allyltributylstannane using a catalytic amount of eerie ammonium nitrate in acetonitrile under mild and neutral conditions to afford the corresponding homoallyl al

Full text of DOI:10.1246/cl.2003.248

248
Chemistry Letters Vol.32, No.3 (2003)
Ceric(IV) Ammonium Nitrate: A Novel Reagent for the Synthesis of Homoallyl Alcohols
J. S. Yadav,Ã B. V. S. Reddy, A. D. Krishna, K. Sadasiv, and Ch. Janardhana Chary
Division of Organic Chemistry, Indian Institute of Chemical Technology, Hyderabad 500 007, India
(Received October 4, 2002;CL-020855)
A rapid and highly efficient method has been developed for
Table 1. Cerium(IV)-catalyzed allylation of aldehydes with
allyltributylstannane
the allylation of aldehydes with allyltributylstannane using a
catalytic amount of ceric ammonium nitrate in acetonitrile under
mild and neutral conditions to afford the corresponding homoallyl
alcohols in excellent yields with high chemoselectivity. Allyla-
tion of ketones has also been achieved with tetraallytin under
similar reaction conditions.
Homoallyl alcohola
Time /min
Yield /%b
Entry
Aldehyde
OH
EtO
EtO
CHO
CHO
EtO
a.
b.
92
95
20
30
EtO
OH
OH
Cl
Cl
MeO
CHO
MeO
25
20
c.
d.
e.
f.
90
92
MeO
MeO
The stereoselective addition of allylmetal reagents to
aldehydes is one of the most important carbon–carbon bond
forming reactions in organic synthesis.1 Several methods have
been developed for the allylation of aldehydes with allyl metals to
produce homoallylic alcohols.2 One of the most straightforward
synthetic procedures for the synthesis of homoallylic alcohols
involves the addition of allyltin reagents to aldehydes in the
presence of acid catalysts.3;4 Recently, metal triflates are also
found to be effective for this transformation.5 However, the
development of a neutral alternatives such as ceric ammonium
nitrate would extend the scope and generality of these allylation
reactions. Ceric ammonium nitrate has emerged as powerful
single electron transfer reagent in many carbon–carbon bond-
forming reactions.6
OMe
OMe
OH
CHO
OH
CHO
45
35
87
89
O2N
O2N
O
O
OH
CHO
H
O
O
O
O
90
g.
30
OH
OH
O
CHO
CHO
h.
i.
35
20
91
92
O
O
OH
Ph
95c
90
j.
Ph CHO
CHO
30
25
Ph
OH
Herein, we wish to report that ceric ammonium nitrate (CAN)
is a mild and highly efficient catalyst for the allylation of
aldehydes with allylstannane under neutral conditions (Scheme
1).
OH
Ph
k.
OH
OH
CHO
CHO
Ph
92
95
35
30
l.
OH
The treatment of benzaldehyde with allylstannane in the
presence of 5 mol% CAN in acetonitrile afforded 1-phenyl-3-
buten-1-ol in 95% yield. Similarly, various aliphatic, aromatic,
heterocyclic and a,b-unsaturated aldehydes were convertedto the
corresponding homoallylic alcohols in excellent yields by using
this procedure. In all cases, the reactions proceeded efficiently at
ambient temperature with high chemoselectivity. No bis-allyl-
ated products are obtained with methoxy-substituted aryl alde-
hydes, which are normally observed in the allylation reactions of
methoxybenzaldehydes with allyltrimethylsilane.7 Acid sensitive
aldehydes such as furfural, 2-phenylacetaldehyde and cinnamal-
dehyde were also smoothly reacted with allyltin to afford the
corresponding homoallylic alcohols in excellent yields. In case of
2-phenylpropanal, the product was obtained as a diastereomeric
mixture of syn and anti in 3:1 ratio (entry j, Table 1).8 However,
the treatment of ketones such as acetophenone, tetralone, 1,4-
cyclohexanedione, 4-phenylcyclohexanone and b-ketoesters did
not react with allyltributylstannane by ceric ammonium nitrate
even after a long reaction time and thus this provides chemose-
m.
b
aAll the products were characterized by1H NMR, IR and mass spectroscopy. Isolated and
unoptimized yields.c The product was obtained as a mixture of syn:anti in a ratio of 3:1.
lective allylations of aldehydes without affecting keto function-
ality. The chemoselectivity of the present method was further
studied by using the keto aldehydes (entries f, g).
The allylation reactions of various aldehydes with allyltri-
butylstannane have been studied and the results are presented in
Table 1. Interestingly, ketones reacted smoothly and rapidly with
tetraallytin in the presence of ceric ammonium nitrate to afford
the corresponding homoallylic alcohols in excellent yields
(Scheme 2).
In all cases, the reactions proceeded rapidly at ambient
temperature with high chemoselectivity. A variety of ketones
such as aryl, alkyl, cyclic, a,b-unsaturated, heterocyclic and a-
hydroxy ketones were converted into their corresponding homo-
allylic alcohols in high yields by using this procedure and the
results are presented in the Table 2.
In case of 2-methylcyclohexanone, the product was obtained
as cis-adduct (entry i, Table 2) whereas 4-phenylcyclohexanone
gave trans-cyclohexanol (entry j, Table 2). Similarly, benzoin
afforded the corresponding homoallyl alcohol as syn-adduct
(entry l, Table 2). These results are similar to those obtained with
OH
CAN
R
R-CHO
Bu3Sn
+
CH3CN, r.t.
1
2
Scheme 1.
Copyright ꢀ 2003 The Chemical Society of Japan

Chemistry Letters Vol.32, No.3 (2003)
249
Table 2. Cerium(IV)-catalyzed allylation of ketones with tetra-
allyltin
amount of CAN. Furthermore, the reactions did not proceed in the
presence of NH3 or NH4Cl or NaNO2 and/or tetrabutyl
ammonium nitrate in acetonitrile at room temperature. This
clearly indicates the catalytic role of CAN in this conversion.10
In summary, this paper describes a rapid and highly efficient
protocol for the allylation of carbonyl compounds with allyltin
reagents using a cheap and readily available reagent, cerium
ammonium nitrate under mild and neutral conditions. This
method offers significant advantages such as very short reaction
times, improved yields, cleaner reaction profiles, operational
simplicity and high chemoselectivity, which makes it a useful
process for the synthesis of homoallyl alcohols.
Ketone
Homoallyl alcohola
Yield/%b
Entry
a.
Time/h
OH
Me
COMe
1.0
2.5
95
89
OH
Ph
COPh
O
b.
c.
d.
OH
2.0
2.5
93
88
OH
Cl
Cl
O
Br
Br
BnO
MeO
BnO
MeO
OH
Me
COMe
e.
2.0
1.5
90
87
BVS thanks CSIR, New Delhi for the award of fellowship.
MeO
MeO
O
HO
f.
References and Notes
1
O
HO
a) Y. Yamamoto and N. Asao, Chem. Rev., 93, 2207 (1993). b)
J. A. Marshall, Chem. Rev., 96, 31 (1996).
g.
1.0
2.5
92
90
2
a) C. J. Li and T. H. Chan, Tetrahedron, 55, 11149 (1999). b)
A. Hosomi and H. Sakurai, Tetrahedron Lett., 16, 1295
(1976).
h.
S
S
O
OH
Me
O
HO
Me
i.
j.
89c
91d
3
4
a) C. K. Z. Andrade and R. Azevedo, Tetrahedron Lett., 42,
6473 (2001). b) A. Yanagisawa, H. Nakashima, A. Ishiba, and
H. Yamamoto, J. Am. Chem. Soc., 118, 4723 (1996).
a) I. Hachiya and S. Kobayashi, J. Org. Chem., 58, 6958
(1993). b) S. Hamasaki, Y. Chounan, H. Horino, and Y.
Yamamoto, Tetrahedron Lett., 41, 9883 (2000). c) S. V. Ley
and L. R. Cox, J. Chem. Soc., Perkin Trans. 1, 1997, 3315. d) I.
Shibata, S. Fukuoka, N. Yoshimura, H. Matsuda, and A. Baba,
J. Org. Chem., 62, 3790 (1997).
3.5
3.0
O
HO
Ph
O
Ph
HO
HO
k.
l.
3.0
3.5
4.0
85
O
Ph
Ph
Ph
Ph
87e
Ph
OH
OH
HO
O
5
6
a) S. Nagayama and S. Kobayashi, Angew. Chem., Int. Ed.
Engl., 39, 567 (2000). b) S. Kobayashi, N. Aoyama, and K.
Manabe, Synlett, 2002, 483. c) H. C. Aspinall, J. S. Bissett, N.
Greeves, and D. Levin, Tetrahedron Lett., 43, 319 (2002).
V. Nair, J. Mathew, and J. Prabhakaran, Chem. Soc. Rev.,
1997, 127.
Ph
m.
70
Ph
Ph
aAll the products were characterized by1H NMR, IR and mass spectroscopy.bIsolated and
unoptimized yieldsc 2-Methylcyclohexanone gave only cis-adduct. dtrans-Cyclohexanol
derivative was obtained with 95% de.esyn-Adduct was obtained with 99% de.
O
7
8
V. K. Aggarwal and G. P. Vennall, Synthesis, 1998, 1822.
C. K. Z. Andrade and N. R. Azevedo, Tetrahedron Lett., 42,
6473 (2001).
CAN
HO
(
)
4
Sn
+
R’
R
CH3CN, r.t.
R
R’
1
3
9
a) K. Inoue, M. Yasuda, and A. Baba, Synlett, 1997, 699. b) Y.
Naruta, S. Ushida, and K. Maruyama, Chem. Lett., 1979, 919.
Scheme 2.
other methods.9 Although, aldehydes reacted smoothly with
tetraallyltin even in the absence of catalyst, ketones did not yield
any product even after a long reaction time. The allylation of
ketones was successful only with tetraallyltin and ceric ammo-
nium nitrate. Among various Lewis acids such as CeCl3.7H2O,
Ce(OTf)3, YbCl3, SmCl3 and YCl3 studied for this transforma-
tion, cerium(IV) ammonium nitrate was found to be more
effective than others in terms of conversion and reaction times.
For example, the treatment of benzaldehyde with allyltributyl-
stannane in the presence of 5 mol% CAN and 5 mol% Ce(OTf)3
gave 95%, and 75% yields respectively over 30 min. However,
the stoichiometric amounts of CeCl3.7H2O and NaI were required
to obtain comparable yields to those obtained with catalytic
10 Experimental procedure: A mixture of aldehyde (2 mmol),
allyltributylstannane (2 mmol) or [1 mmol of tetraallyltin for
the allylation of 2 mmol of ketone] and ceric ammonium
nitrate (5 mol%) in acetonitrile (1 mL) was stirred at ambient
temperature for an appropriate time (Tables 1, 2). After
completion of the reaction, as indicated by TLC, the reaction
mixture was diluted with water (20 mL) and extracted with
ethyl acetate (2 Â 15 mL). The combined organic layers were
washed with brine, dried over anhydrous Na2SO4 and
concentrated in vacuo, and the resulting product was purified
by column chromatography on silica gel (Merck, 100–200
mesh, ethyl acetate-hexane, 2:8) to afford pure homoallyl
alcohol.