Homolytic base-promoted aromatic alkylations by alkyl halides

Article abstract of DOI:10.1021/jo9818982

Electron-transfer chain reactions leading to regioselective alkylations of benzenes bearing electron-withdrawing substituents can be observed with alkyl halides in the presence of the radical initiator (Bu₃Sn)₂ and the proton acceptor 1,4-diazabicyclo[2.2.2]octane (DABCO). Yields vary from low to high depending on the benzene derivatives. The role of DABCO is to abstract a proton from the substituted cyclohexadienyl adduct radical to form a radical anion which then transfers an electron to RX and is converted to the alkylated product itself. The rate of this electron-transfer step is probably not fast enough to sustain a good radical chain reaction so that further generation of R· from excess (Bu₃Sn)₂ and RX is necessary.

Full text of DOI:10.1021/jo9818982

9
956
J . Org. Chem. 1998, 63, 9956-9959
Hom olytic Ba se-P r om oted Ar om a tic Alk yla tion s by Alk yl Ha lid es1
†
Chen Wang, Glen A. Russell, and Walter S. Trahanovsky*
Department of Chemistry, Iowa State University, Ames, Iowa 50011-3111
Received September 18, 1998
Electron-transfer chain reactions leading to regioselective alkylations of benzenes bearing electron-
withdrawing substituents can be observed with alkyl halides in the presence of the radical initiator
3 2
(Bu Sn) and the proton acceptor 1,4-diazabicyclo[2.2.2]octane (DABCO). Yields vary from low to
high depending on the benzene derivatives. The role of DABCO is to abstract a proton from the
substituted cyclohexadienyl adduct radical to form a radical anion which then transfers an electron
to RX and is converted to the alkylated product itself. The rate of this electron-transfer step is
•
probably not fast enough to sustain a good radical chain reaction so that further generation of R
3 2
from excess (Bu Sn) and RX is necessary.
In tr od u ction
Generally aromatic compounds are not ideal substrates
Sch em e 1
2
in homolytic alkylation. Usually the yields of substitu-
tion products are low due to side reactions, and regiose-
3
lectivity is poor. Among the exceptions are the proto-
nated heteroaromatic compounds reported by Minisci,
which can be alkylated efficiently by alkyl radicals.4
Alkylmercury halides are good precursors of alkyl radi-
cals and can undergo oxidative (substitutive) homolytic
reactions with unsaturated compounds in the presence
of a base, such as 1,4-diazabicyclo[2.2.2]octane (DABCO).5
Recently we reported that alkylations of benzenes bear-
ing electron-withdrawing substituents can proceed readily
with RHgX/DABCO (R ) t-Bu, i-Pr) by the mechanism
shown in Scheme 1 provided the electron-withdrawing
Sch em e 2
2
group Z (Z ) CN, CHO, CO Et) can stabilize the radical
6
adduct 1 and the radical anion 2. DABCO can abstract
a proton from 1, and then a chain reaction is initiated
by electron transfer to RHgX with the regeneration of
•
R . This sequence of reactions is a novel type of homolytic
aromatic alkylation.
Though the tert-butylation of disubstituted benzenes
proceeds smoothly by a chain process with t-BuHgX/
DABCO under photolysis in dimethyl sulfoxide (DMSO),6
we have been interested in replacing the toxic RHgX by
RX to realize a similar process (Scheme 2). This modifi-
cation, though simple, is mechanistically and syntheti-
cally interesting.
However, early attempts failed completely when t-
6
BuBr or t-BuI was substituted for t-BuHgX. No reaction
is observed when the mixture of t-BuX and dicyanoben-
zene is photolyzed in the presence of 4 equiv of DABCO
2 2
and 10 mol % of 2,2′-azobisisobutyronitrile (AIBN), Bz O ,
or (Bu
3
Sn)
2
at 35-70 °C in dimethylformamide (DMF),
. An attempt to initiate the reaction by
DMSO, or C
6
H
6
*
To whom correspondence should be addressed. Phone: 515-294-
using 20 mol % t-BuHgX in DMSO was also unsuccessful.
The reactions stopped after the t-BuHgX was consumed.
We think these observations are theoretically perplexing
because estimated E°-values for t-BuX reductions suggest
that these molecules should participate in electron
transfer with the dicyanobenzene radical anions. Esti-
mated E°-values (NHE) in DMSO and DMF are as
2
886. FAX: 515-294-0105. E-mail: wtrahan@iastate.edu.
†
Deceased: J anuary 1, 1998.
1) Electron-Transfer Process. Part 65. For part 64, see ref 6.
(
(
2) Fossey, J .; Lefort, D.; Sorba, J . Free Radicals in Organic
Chemistry; J ohn Wiley & Sons: New York, 1995; Chapter 14.
3) Tiecco, M.; Testaferri, L. In Reactive Intermediates, Abramovitch,
R. A., Ed.; Plenium Press: New York, 1983; Vol 3, p 61.
(
(
(
4) Minisci, F.; Vismara, E.; Fontana, F. Heterocycles 1989, 28, 489.
5) (a) Russell, G. A.; Kim, B. H.; Kulkarni, S. V. J . Org. Chem. 1989,
5
6
4, 3768. (b) Russell, G. A.; Kim, B. H. Tetrahedron Lett. 1990, 31,
273. (c) Russell, G. A.; Kim, B. H. Synlett 1990, 87. (d) Russell, G. A.;
7
follows: t-BuBr, -0.73, -0.82; t-BuI, -0.56, -0.77 V.
Kulkari, S. V.; Khana, R. J . Org. Chem. 1990, 55, 1080. (e) Russell, G.
A.; Chen, P.; Yao, C.-F.; Kim, B. H. J . Am. Chem. Soc. 1995, 117, 5967.
(7) (a) Eberson, L. Acta Chem. Scand. 1982, B36, 533. (b) Saveant,
J .-M. J . Am. Chem. Soc. 1987, 109, 6788. (c) Butin, K. P.; Magdesieva,
T. V.; Rakhimov, R. D.; Rentov, O. A. Zh. Org. Khim. 1987, 23, 2481.
(6) Russell, G. A.; Chen, P.; Kim, B. H.; Rajaratnam, R. J . Am. Chem.
Soc. 1997, 119, 8795.
1
0.1021/jo9818982 CCC: $15.00 © 1998 American Chemical Society
Published on Web 12/01/1998

Homolytic Base-Promoted Aromatic Alkylations
J . Org. Chem., Vol. 63, No. 26, 1998 9957
Ta ble 2. ter t-Bu tyla tion of P h th a lim id esa
Ta ble 1. ter t-Bu tyla tion of 1,2-Dicya n oben zen ea
b
b
yield (%) of 3 at time given
product yield (%) at time given
t-BuX (X)
DABCO (equiv)
20 h
40 h
substrate
X
product
20 h
60 h
28
100 h
Br, I
Br
Br
I
0
0.5
4
none
63
75
none
88
97
4a
4a
4b
4b
Br
I
Br
I
5a
5a
5b
5b
14
15
27
31
57
75
4
90
a
a
See footnote a of Table 1. b See footnote b of Table 1.
Photolysis of 0.05 M substrate by a 275 W fluorescent sunlamp
b
with 4 equiv of t-BuX and 2 equiv of (Bu3Sn)2. Yield in C6D6 by
H NMR with (Me3Si)2O as an internal standard.
1
Phthalimides also can be alkylated by t-BuX (eq 2,
Table 2). Compound 4b is more reactive than 4a , and
both are less reactive than 1,2-dicyanobenzene. Higher
yields of products (such as 5a ,b) were obtained with
t-BuBr than with t-BuI. With t-BuI, it is likely that t-Bu
was generated so rapidly that most of it went to dispro-
portionation, leaving most starting material unreacted.
Although the observed irreversible electrode reduction
potentials are much more negative than the estimated
values,7b they are in the range of those reported for
t-BuHgX, e.g., for t-BuHgBr, E
SCE), and for t-BuI, E1/2 (DMF) ) -1.84 V (SCE),
whereas the reduction potentials of the dicyanobenzenes
•
1
/ 2
3
(CH CN) ) -1.08 V
(
7
c,8
are in the range of -1.5 to -1.6 V (E°, SCE).
Reminded by our former report6 that 4 equiv of
t-BuHgX was used for the alkylations of 1 equiv of disub-
stituted benzenes even though the reactions were good
chain processes, we thought that the alkylations by t-BuX
•
might be achieved if more than 1 equiv of t-Bu is gen-
erated from t-BuX. Minisci also reported that when only
1
equiv of the radical source was used, the conversions
Phthalic anhydride failed to undergo reaction under
the same conditions, probably because it has a more
of heteroaromatic compounds were as low as 15-50% in
many cases, while the yields based on the converted
heteroaromatic compounds were as high as 82-98%. We
reinvestigated the alkylation reactions with 4 equiv of
alkyl halides in the presence of 2 equiv of (Bu
4
9
negative reduction potential than phthalimide (-1.16 vs
-
0.70 V, SCE, in H
2
O).11 As Minisci pointed out, the
4
•
transition state for attack of the nucleophilic t-Bu upon
3
2
Sn) and
+
•-
an aromatic ring should be stablized by t-Bu Ar , and
this is unfavored for phthalic anhydride which has the
more negative reduction potential.
equiv of DABCO and report the results herein.
Resu lts a n d Discu ssion
. 1,2-Disu bstitu ted Ben zen es. We have found that
2
. 1,3-Disu bstitu ted Ben zen es. Results for the for-
1
mation of the mono and di-tert-butylated products 6a and
7a from 1,3-dicyanobenzene are summarized in Table 3.
The initial chain length was only 3.0 with t-BuI, mea-
sured by using 20 mol % DTBN. This is much shorter
than that with t-BuHgCl which is 22.6
1
,2-dicyanobenzene can be tert-butylated upon photolysis
Sn) , and 4 equiv of
DABCO at 60 °C (eq 1 and Table 1).
with 4 equiv of t-BuX, 2 equiv of (Bu
3
2
Even though for 1,3-disubstituted benzenes the adduct
radicals 8 can be stablized by both substituents, 1,3-
dicyanobenzene is less reactive than 1,2-dicyanobenzene,
as shown by the comparison of their alkylation yields at
2
0 h.
A higher yield of 3 was formed at a faster rate when
t-BuX was t-BuI rather than t-BuBr. This observation is
accounted for by the different rates of formation of the
•
t-Bu from the two tert-butyl halides. Alkylation by RX
gives comparable yields of alkylated products to that by
RHgX but requires a much longer reaction time. The
dibutylated product which is formed when t-BuHgX is
used was not found. Without DABCO, no alkylated
product (such as 3) was found. This shows that without
a base the corresponding adduct radical which is probably
formed reversibly is converted to 3 slowly. Also, no
reaction was observed when AIBN or Bz
instead of (Bu Sn) or when DBU was used instead of
DABCO. The initial kinetic chain length of the reaction
2 2
O was used
3
2
•
was 7.0 with t-BuI as measured by the (t-Bu)
(
2
NO
DTBN) inhibition method.10 All of these results are
consistent with the electron-transfer chain process pre-
sented in Scheme 2.
Diethyl isophthalate cannot be tert-butylated by t-BuBr
or t-BuI in the presence of (Bu Sn) and DABCO.
3
2
(
8) The electrode potential SCE value is +0.241 V greater than the
(10) Walling, C. Free Radicals in Solution; J ohn Wiley & Sons: New
York, 1973; Vol. 2, Chapter 14.
NHE value.
(
9) Minisci, F.; Vismara, E.; Fontana, F.; Morini, G.; Serravalle, M.;
(11) Schwabe, K. Polarographic and Chemische Konstitution Orga-
nische Verbindungen; Academie-Verlag: Berlin, 1957.
Giordano, C. J . Org. Chem. 1986, 51, 441.

9
958 J . Org. Chem., Vol. 63, No. 26, 1998
Wang et al.
Ta ble 3. ter t-Bu tyla tion of 1,3-Dicya n oben zen ea
suggest that base-promoted homolytic aromatic sub-
stitution may be a rather general process for aromatic
compounds bearing electron-withdrawing substituents.
This alkylation method can to some extent serve as a
complementary methodology to the well-known Friedel-
Crafts reaction, which can alkylate benzene derivatives
bearing electron-donating substituents. Alkylations by
alkyl halides have a much shorter kinetic chain length
6a b (%)
7a b (%)
t-BuX (X)
DABCO (equiv)
time (h)
Br, I
Br
Br
Br
Br
I
0
20
20
60
20
60
20
none
23
38
33
65
none
0.5
0.5
4
4
4
15
18
66
a
See footnote a of Table 1. b See footnote b of Table 1.
6
than those involving alkylmercury halides and usually
need a longer reaction time. Yields vary from low to high,
depending on the substrates, and are much higher if the
recovered starting substrates are taken into account. In
most reactions unreacted aromatic compounds remained
after the RX was consumed. The lower reactivity of t-BuX
compared to t -BuHgX is probably due to the slower
electron-transfer rate from the radical anions to t-BuX.
Lund has estimated the rate of electron transfer from
aromatic radical anions to t-BuBr to be only 10 L/(mol‚s)
at 25 °C for an aromatic compound with E° ) -1.5 V
Ta ble 4. ter t-Bu tyla tion of 1,4-Dicya n oben zen ea
t-BuX (X)
DABCO (equiv)
time (h)
9a b (%)
10a b (%)
Br, I
Br
Br
Br
Br
I
0
100
20
100
20
100
20
20
none
6
none
0.5
0.5
4
4
4
27
17
74
38
51
10
3
I
8
a
See footnote a of Table 1. b See footnote b of Table 1.
(
SCE).12 This rate is too slow to sustain an efficient chain
process.
Usually the reactivity and initial kinetic chain length
•
•
However, with i-Pr , which is smaller than t-Bu , the
alkylation takes place. Compound 6b was produced in a
yield of 18% in 20 h with 4 equiv of i-PrI and in a yield
of 35% in 100 h with 4 equiv of i-PrBr. No dialkylated
product 7b, which was observed with t-BuHgX, was
found. However, with n-BuBr or n-BuI, no alkylated
products can be formed from diethyl isophthalate in 3
days. Ethyl 3-cyanobenzoate reacted slowly with 4 equiv
decrease from 1,2- to 1,3- to 1,4-disubstituted benzenes.
For reactive substrates such as 1,2-dicyanobenzene,
alkylations by t-BuI give higher yields of products than
those by t-BuBr. Otherwise, alkylations by t-BuBr give
higher yields of the products.
In comparison to the -CO Et group, the -CN group
2
is a much better activating group with a smaller steric
requirement. The introduction of alkyl substituents is
3 2
of t-BuBr, 2 equiv of (Bu Sn) , and 4 equiv of DABCO.
Compound 6c was formed in yields of 25 and 82% upon
photolysis in 20 and 100 h, respectively. The tert-butyl
group is always introduced ortho to the -CN group,
which is less sterically hindered than the position ortho
very regioselective, and usually monoalkylated products
•
are the major products. Since Bu
3
Sn is incompatible with
the aldehyde group,13 no aldehyde-substituted benzenes
can be alkylated by this method.
to -CO
2
Et. Replacement of t-BuBr by t-BuI yielded only
a trace of 6c.
Dialkylated products were formed from the less reac-
tive 1,3- and 1,4-dicyanobenzenes but not from the more
reactive 1,2-dicyanobenzene. This observation shows that
the formation of dialkylated products is not strongly
related to the reactivity of the starting benzene deriva-
tives but to the reactivity difference between the starting
aromatic compounds and the corresponding monoalky-
lated products.
3
. 1,4-Disu bstitu ted Ben zen es. The 1,4-disubstituted
benzenes are much less reactive than the 1,3-derivatives
eq 4). Table 4 summarizes the results for the alkylations
of 1,4-dicyanobenzene. The dialkylated product 10a was
also formed as well as the monoalkylated product 9a . The
initial kinetic chain length was only 1.3 with t-BuI,
measured by using 20 mol % DTBN. Obviously, this
reaction did not proceed by an efficient chain process.
(
Even though there are many literature methods avail-
able for removal of the tin compounds from the desired
products,14 the use of excess (Bu
3 2
Sn) in this method is
still a drawback in preparative applications. Further
work on replacing the tin radical initiator is highly
desired.
Exp er im en ta l Section
Gen er a l P r oced u r es. The aromatic substrates (0.5 mmol)
and reagents were dissolved in 5 mL of C H under a nitrogen
6 6
Ethyl 4-cyanobenzoate yielded only a trace of 9b with
t-BuI. However, with t-BuBr, 9b was formed in yields of
atmosphere in a Pyrex test tube and irradiated with a 275 W
Sylvania fluorescent sunlamp which was approximately 10 cm
away from the reaction tube. After the reaction stopped, the
solution was concentrated to about 2 mL and cooled to 0 °C,
and some precipitate was removed by filtration. Then 2 mL of
3
9, 57, and 70% upon photolysis for 20, 60, and 100 h,
respectively. No 10b was found. The tert-butyl groups
were always introduced ortho to the -CN group. Unlike
the significant reactivity difference between 1,3- and 1,4-
dicyanobenzenes, the reactivity difference between ethyl
1
M NaOH solution was added to the filtered solution, and
the mixture solution was stirred for 30 min at room temper-
ature for further removal of the tin compounds.14a After the
3
- and 4-cyanobenzoates is small.
4
ethereal extract was dried by MgSO and concentrated, the
(
12) Lund, H.; Daasbierg, K.; Lund, T.; Pedersen, S. U. Acc. Chem.
Con clu sion
Res. 1995, 28, 313.
(
(
13) Enholm, E. J .; Burroff, J . A. Tetrahedron, 1997, 53, 13583.
14) (a) Renaud, P.; Lacote, E.; Quaranta, L. Tetrahedron Lett. 1998,
Overall, we find that homolytic base-promoted aro-
matic alkylations can be observed with alkyl halides,
Bu Sn) , and DABCO in C at 60 °C. These results
3
9, 2123. (b) Crich, D.; Sun, S. J . Org. Chem. 1996, 61, 7200. (c) Curran,
D. P.; Chang, C. J . Org. Chem. 1989, 54, 3140.
(
3
2
6 6
H

Homolytic Base-Promoted Aromatic Alkylations
J . Org. Chem., Vol. 63, No. 26, 1998 9959
reaction products were isolated by thin layer chromatography
184.1002 (21; calcd for C12
114 (5), 57 (4).
Dieth yl 4-(1-Meth yleth yl)isop h th a la te (6b) was isolated
as a colorless liquid.6 FTIR (cm ) 2990, 2906, 2872, 1731,
1717, 1305, 1229.
12 2
H N , 184.1001), 169 (100), 141 (26),
(
TLC) using hexanes-ethyl acetate as the eluent.
1
For reactions monitored by H NMR spectroscopy, the
-1
substrate (0.05 mmol) and added reagents were dissolved in
.6 mL of C in a 5 mm NMR tube with 2 µL of (Me Si)
bp ∼ 101 °C) as an internal standard. A 0.01 mmol amount
of DTBN was added to the solution for inhibition reactions to
0
6
D
6
3
2
O
(
Eth yl 3-Cya n o-4-(1,1-d im eth yleth yl)ben zoa te (6c) was
6
-1
isolated as a colorless liquid. FTIR (cm ) 2990, 2910, 2225,
731, 1607, 1298, 1129.
,4-Dicyan o-1,5-bis(1,1-dim eth yleth yl)ben zen e (7a) was
1
0
measure the initial kinetic chain length.
1
1
13
H and C NMR spectra were obtained in CDCl
3
at 400 and
2
1
00 MHz with δ measured relative to CHCl (7.27 ppm) or
3
-1
isolated as a white solid, mp 176-178 °C. FTIR (cm ) 2959,
1
3
the central C peak of CDCl
3
(77.23 ppm).
1
2
1
3
873, 2224, 1593; H NMR δ 7.94 (s, 1H), 7.64 (s, 1H), 1.54 (s,
Products 6b,c and 9a ,b have H and 13C NMR spectral data
1
13
8H); C NMR δ 158.37, 141.83, 125.10, 118.45, 109.57, 36.77,
0.03; HREIMS m/z (rel intens) 240.1626 (13; calcd for
6
consistent with those reported and give HRMS consistent with
their structure. Additional data for these products and data
for all other products are listed below.
C
16
H
20
N
2
, 240.1627), 225 (100), 210 (4), 197 (6), 57 (5).
1
,4-Dicya n o-2-(1,1-d im eth yleth yl)ben zen e (9a ) was iso-
1
,2-Dicya n o-4-(1,1-d im eth yleth yl)ben zen e (3) was iso-
6
lated as a white solid, mp 150-152 °C (lit., 150-151 °C). FTIR
-
1
lated as a white solid, mp 57-59 °C. FTIR (cm ) 3103, 2962,
-1
(
cm ) 3115, 2988, 2875, 2231, 2226, 1558.
1
2
874, 2234, 1596; H NMR δ 7.82 (t, J ) 1.2 Hz, 1H), 7.75 (d,
13
Eth yl 4-Cya n o-3-(1,1-d im eth yleth yl)ben zoa te (9b) was
J ) 1.2 Hz, 2H), 1.37 (s, 9H); C NMR δ 157.91, 133.57,
31.11, 130.60, 116.02, 115.94, 115.79, 113.03, 35.82, 30.91;
HREIMS m/z (rel intens) 184.1002 (20; calcd for C12
84.1001), 169 (100), 141 (51), 114 (7).
-(1,1-Dim eth yleth yl)p h th a lim id e (5a ) was isolated as
6
isolated as a white solid, mp 44-46 °C (lit., liquid). FTIR
1
-1
(
cm ) 2970, 2873, 2223, 1733.
12 2
H N ,
1
,4-Dicyan o-2,5-bis(1,1-dim eth yleth yl)ben zen e (10a) was
1
-
1
isolated as a white solid, mp 172-174 °C. FTIR (cm ) 2959,
4
1
13
2
1
874, 2223; H NMR δ 7.48 (s, 2H), 1.52 (s, 18H); C NMR δ
51.80, 133.60, 119.30, 114.93, 35.57, 30.05; HREIMS m/z (rel
-
1
a white solid, mp 130-132 °C. FTIR (cm ) 3250, 3050, 2868,
1
1
(
1
748, 1700; H NMR δ 7.91 (s, 1H), 7.85 (brs, 1H), 7.78-7.79
13
intens) 240.1626 (12; calcd for C16
10 (4), 197 (9), 182 (5), 57 (5).
20 2
H N , 240.1627), 225 (100),
m, 2H), 1.39 (s, 9H); C NMR δ 168.73, 168.31, 159.26, 133.03,
31.62, 130.13, 123.65, 120.95, 36.00, 31.35; HREIMS m/z (rel
intens) 203.0947 (23; calcd for C12 , 203.0946), 188 (100),
69 (39), 145 (12), 115 (6).
-(1,1-Dim et h ylet h yl)-N-m et h ylp h t h a lim id e (5b) was
2
H
13NO
2
Ack n ow led gm en t. We thank the donors of the
1
4
Petroleum Research Fund, administrated by the Ameri-
can Chemical Society, for the support of this research.
We also thank Professor Dennis H. Evans for a helpful
discussion.
-
1
isolated as a white solid, mp 87-89 °C. FTIR (cm ) 2968,
1
2
7
1
1
871, 1765, 1709, 1602; H NMR δ 7.87 (d, J ) 1.6 Hz, 1H),
.45 (d, J ) 8.0 Hz, 1H), 7.71 (d, J ) 1.6 Hz, 1H), 3.16 (s, 3H),
1
3
.37 (s, 9H); C NMR δ 169.16, 168.76, 158.64, 132.60, 131.00,
29.70, 123.17, 120.60, 35.98, 31.33, 24.08; HREIMS m/z (rel
Su p p or tin g In for m a tion Ava ila ble: 1H and 13C NMR,
intens) 217.1105 (23; calcd for C13
74 (20), 145 (20), 115 (8).
,4-Dicya n o-1-(1,1-d im eth yleth yl)ben zen e (6a ) was iso-
H
15NO
2
, 217.1103), 202 (100),
and HREIMS data for 6b,c and 9a b and 1H and 13C NMR
1
spectra of 5a ,b, 6a -c, 7a , 9a ,b, and 10a (37 pages). This
material is contained in libraries on microfiche, immediately
follows this article in the microfilm version of the journal, and
can be ordered from the ACS; see any current masthead page
for ordering information.
2
-
1
lated as a white solid, mp 56-58 °C. FTIR (cm ) 3119, 3044,
1
2
1
1
1
988, 2878, 2237, 2230, 1602; H NMR δ 7.96 (d, J ) 2.0 Hz,
H), 7.80 (dd, J ) 8.4, 2.0 Hz, 1H), 7.64 (d, J ) 8.4 Hz, 1H),
1
3
.55 (s, 9H); C NMR δ 159.07, 138.77, 135.95, 127.88, 118.29,
16.97, 112.76, 112.24, 36.57, 30.02; HREIMS m/z (rel intens)
J O9818982