New rearrangement in the adamantylation reaction of 4-iodophenol and 4-iodoanisole

Article abstract of DOI:10.1007/s11172-011-0265-x

A reaction of 2-iodophenol and 2-iodoanisole with 1-adamantanol in trifluoroacetic acid gives the corresponding 4-(1-adamantyl) derivatives. Similar adamantylation of 4-iodophenol and 4-iodoanisole is accompanied by migration of the iodine atom from para- to ortho-position, giving 4,6-di(1-adamantyl)-2-iodophenol and 4-(1-adamantyl)-2-iodoanisole, respectively, as the reaction products.

Full text of DOI:10.1007/s11172-011-0265-x

Russian Chemical Bulletin, International Edition, Vol. 60, No. 8, pp. 1776—1777, August, 2011
1776
New rearrangement in the adamantylation reaction
of 4ꢀiodophenol and 4ꢀiodoanisole
W. A. Sokolenko,a N. M. Svirskaya,a and A. I. Rubailoa,b
aInstitute of Chemistry and Chemical Technology, Siberian Branch of the Russian Academy of Sciences,
42 ul. K. Marksa, 660049 Krasnoyarsk, Russian Federation.
Fax: +7 (391) 212 4720. Eꢀmail: williamsokol@yandex.ru
bSiberian Federal University,
79 Svobodnyi prosp., 660041 Krasnoyarsk, Russian Federation.
Fax: +7 (391) 212 4672. Eꢀmail: rai@icct.ru
A reaction of 2ꢀiodophenol and 2ꢀiodoanisole with 1ꢀadamantanol in trifluoroacetic acid
gives the corresponding 4ꢀ(1ꢀadamantyl) derivatives. Similar adamantylation of 4ꢀiodophenol
and 4ꢀiodoanisole is accompanied by migration of the iodine atom from paraꢀ to orthoꢀposition,
giving 4,6ꢀdi(1ꢀadamantyl)ꢀ2ꢀiodophenol and 4ꢀ(1ꢀadamantyl)ꢀ2ꢀiodoanisole, respectively,
as the reaction products.
Key words: iodophenols, 1ꢀadamantanol, alkylation, trifluoroacetic acid, electrophilic subꢀ
stitution, the Reverden rearrangement.
Nitration of halophenols and their ethers, as a rule, is
phenol 1 at 20 °C and the ratio of reactants 1 : 1 furnished
4ꢀ(1ꢀadamantyl)ꢀ2ꢀiodophenol (5) as the reaction prodꢀ
uct (Scheme 1), which has been obtained earlier by iodinaꢀ
tion of 4ꢀ(1ꢀadamantyl)phenol.4
Under similar conditions, phenol 2 is converted to
4,6ꢀdi(1ꢀadamantyl)ꢀ2ꢀiodophenol (6). Adamantylation
of anisoles 3 and 4 leads to the same product, 4ꢀ(1ꢀadaꢀ
mantyl)ꢀ2ꢀiodoanisole (7) (Scheme 2).
Products of adamantylation of phenol 2 and ether 4
significantly differ. In the first case, a dialkylating product
is formed already at the ratio of reactants 1 : 1 (see
Scheme 1). Adamantylation of ether 4 gives the monoꢀ
not a simple process:1,2 the nitro group usually substitutes
for both the proton to give the corresponding nitro derivaꢀ
tives and the halogen atom at paraꢀposition with respect
to the hydroxy or alkoxy group, which is accompanied by
migration of the halogen atom to orthoꢀposition. Such
a reaction is known as the Reverden rearrangement.3 Inforꢀ
mation on such a rearrangement of halophenols and their
ethers in the alkylation reactions in the literature is absent.
We studied the reaction of 2ꢀiodophenol (1), 4ꢀiodoꢀ
phenol (2), 2ꢀiodoanisole (3), and 4ꢀiodoanisole (4) with
1ꢀadamantanol in trifluoroacetic acid. Alkylation of
Scheme 1
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1748—1749, August, 2011.
1066ꢀ5285/11/6008ꢀ1776 © 2011 Springer Science+Business Media, Inc.

Adamantylation of iodophenols
Russ.Chem.Bull., Int.Ed., Vol. 60, No. 8, August, 2011
1777
Scheme 2
H(5), J = 8.5 Hz, J = 2.3 Hz); 7.61 (d, 1 H, H(3), J = 2.3 Hz).
13C NMR (150 MHz), δ: 28.81 (C(γ)); 35.50 (C(α)); 36.57 (C(δ));
43.19 (C(β)); 85.77 (C(2)); 114.46 (C(6)); 126.82 (C(5)); 134.65
(C(3)); 145.90 (C(4)); 152.40 (C(1)).
alkylated product even at the ratio 4 : 1ꢀAdOH = 1 : 2
(see Scheme 2).
Formation of product 6 (see Scheme 1) can be princiꢀ
pally explained by the reaction taking pathways A or B.
However, since phenol 5 is not alkylated with 1ꢀAdOH in
trifluoroacetic acid, the pathway A can be excluded, and
the process apparently takes the pathway B.
Compounds 6 and 7 were obtained similarly.
4,6ꢀDi(1ꢀadamantyl)ꢀ2ꢀiodophenol (6) was obtained from
phenol 2 (0.220 g, 0.001 mol) and 1ꢀAdOH (0.304 g, 0.002 mol)
in CF3COOH (4 mL). The yield was 0.350 g (72%), m.p.
240—242 °C (PriOH). When the ratio 2 : 1ꢀAdOH was 1 : 1, the
yield was 50%. Found (%): C, 64.23; H, 6.42. C26H33IO. Calcuꢀ
lated (%): C, 64.07; H, 7.02. 1H NMR (600 MHz), δ: 1.81, 1.91,
2.15 (30 H, Ad); 5.40 (d, 1 H, OH, J = 0.5 Hz); 7.24 (dd, 1 H,
H(5), J = 2.2 Hz, J = 0.5 Hz); 7.51 (d, 1 H, H(3), J = 2.2 Hz).
13C NMR (150 MHz), δ: 29.43, 29.52 (C(γ)); 36.31, 38.29 (C(α));
37.18, 37.51 (C(δ)); 40.75, 43.82 (C(β)); 90.45 (C(2));
124.87 (C(5)); 132.67 (C(3)); 136.84 (C(6)); 145.49 (C(4));
150.89 (C(1)).
4ꢀ(1ꢀAdamantyl)ꢀ2ꢀiodoanisole (7) was obtained from aniꢀ
sole 3 or anisole 4 (0.234 g, 0.001 mol) and 1ꢀAdOH (0.152 g,
0.001 mol) in CF3COOH (2 mL). The yields were: from anisole
3, 89%, from anisole 4, 75%, m.p. 128—129 °C. Found (%):
C, 55.51; H, 5.69. C17H21IO. Calculated (%): C, 55.45; H, 5.74.
1H NMR (600 MHz), δ: 1.80 (6 H, H(δ)), 1.90 (6 H, H(β)), 2.12
(3 H, H(γ)) (15 H, Ad); 3.90 (3 H, OMe); 6.81 (d, 1 H, H(6),
J = 8.74 Hz); 7.32 (dd, 1 H, H(5), J = 2.35 Hz, J = 8.74 Hz);
7.78 (d, 1 H, H(3), J = 2.35 Hz). 13C NMR (150 MHz), δ: 28.82
(C(γ)); 35.45 (C(α)); 36.58 (C(δ)); 43.18 (C(β)); 56.31 (OMe);
85.97 (C(2)); 110.50 (C(6)); 125.89 (C(5)); 136.26 (C(3)); 145.96
(C(4)); 155.88 (C(1)).
The reaction can proceed according to the following
mechanism. The first step includes adamantylation of
phenol 2 to give compound 8, i.e., the adamantyl group
commonly substitutes for the hydrogen atom. The second
(fast) step includes an ipsoꢀattack on the carbon atom
bearing the iodine atom with the formation of σꢀcomplex 9,
in which the iodine atom migrates to the orthoꢀposition,
that leads to phenol 6. In the case of ether 4, the first step
includes an attack of the adamantyl cation to form the
σꢀcomplex 10, which further rearranges to the ether 7.
The difference in the behavior of phenol 2 and anisole 4 in
this reaction can be explained by greater steric hindrance,
which is created by the methoxy group, as compared to
that created by the hydroxy group. Alkylation of comꢀ
pound 3 leads to the usual substitution for the proton in
paraꢀposition by the adamantyl group.
Special experiments showed that iodophenols and
iodoanisoles under study do not undergo isomerization in
trifluoroacetic acid.
To sum up, we found a new rearrangement of 4ꢀiodoꢀ
phenol and 4ꢀiodoanisole consisting in the migration of
the iodine atom from position 4 to position 2 with simulꢀ
taneous adamantylation of the aromatic ring.
References
1. D. V. Nightingale, Chem. Rev., 1947, 40, 117.
2. K. V. Vatsuro, G. L. Mishchenko, Imennye reaktsii v organiꢀ
cheskoi khimii [Named Reactions in Organic Chemistry],
Khimiya, Moscow, 1976, p. 346 (in Russian).
Experimental
3. D. I. Makhon´kov, A. V. Cheprakov, I. P. Beletskaya, Zh. Org.
Khim., 1988, 24, 2251 [J. Org. Chem. USSR (Engl. Transl.),
1988, 24].
4. V. I. Shvedov, O. A. Safonova, I. Ya. Korsakova, N. S.
Bogdanova, I. S. Nikolaeva, V. V. Peters, G. N. Pershin,
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1980, 14].
1
H and 13C NMR spectra were recorded on a BrukerꢀAvance
IIIꢀ600 spectrometer in CDCl3 (at the Community Center of the
Krasnoyarsk Division of Siberian Branch of the RAS).
4ꢀ(1ꢀAdamantyl)ꢀ2ꢀiodophenol (5). A mixture of phenol 1
(0.220 g, 0.001 mol) and 1ꢀAdOH (0.152 g, 0.001 mol) in
CF3COOH (2 mL) was kept at ~20 °C for 48 h, then poured into
water, a precipitate was filtered off, washed with water, and
dried. The yield was 0.32 g (90%), m.p. 110—112 °C (PriOH)
(see Ref. 4: m.p. 110—112 °C). 1H NMR (600 MHz), δ:
1.73 (6 H, H(δ)), 1.83 (6 H, H(β)), 2.09 (3 H, H(γ)) (15 H, Ad);
5.09 (1 H, OH); 6.95 (d, 1 H, H(6), J = 8.5 Hz); 7.26 (dd, 1 H,
Received December 6, 2010;
in revised form March 29, 2011