peri-Naphthylenediamines 32 *. Reactions of 4,5-bis(dimethylamino)-1-naphthyllithium and 4,5-bis(dimethylamino)-1-naphthylmagnesium bromide with electrophilic agents. New representatives of double naphthalene "proton sponges" with the structures of 1,1′-binaphthyl ketone and 1,1′-binaphthylmethanol

Article abstract of DOI:10.1023/A:1011311226664

The 4-deuterio, 4-methyl, 4-iodo, 4-methylthio, 4-trimethylsilyl, and 4-ethoxycarbonyl derivatives of 1,8-bis(dimethylamino)naphthalene ("proton sponge") and some related alcohols were prepared by the reactions of 4,5-bis(dimethylamino)-1-naphthyllithium or 4,5-bis(dimethylamino)-1-naphthylmagnesium bromide with the corresponding electrophilic reagents. New representatives of double "proton sponges" with the structures of 1,1′-binaphthyl ketone and 1,1′-binaphthylmethanol were synthesized. The pK_a values of selected compounds in DMSO were measured by competitive protonation.

Full text of DOI:10.1023/A:1011311226664

854
Russian Chemical Bulletin, International Edition, Vol. 50, No. 5, pp. 854—859, May, 2001
peri-Naphthylenediamines
32*. Reactions of 4,5-bis(dimethylamino)-1-naphthyllithium and
4,5-bis(dimethylamino)-1-naphthylmagnesium bromide with electrophilic agents.
New representatives of double naphthalene "proton sponges" with the structures of
1,1´-binaphthyl ketone and 1,1´-binaphthylmethanol
O. V. Ryabtsova, A. F. Pozharskii,* V. A. Ozeryanskii, and N. V. Vistorobskii
Rostov State University,
7 ul. Zorge, 344090 Rostov-on-Don, Russian Federation.
Fax: (8 632) 22 3958. E-mail: pozharsk@pozhar.rnd.runnet.ru
The 4-deuterio, 4-methyl, 4-iodo, 4-methylthio, 4-trimethylsilyl, and 4-ethoxycarbonyl
derivatives of 1,8-bis(dimethylamino)naphthalene ("proton sponge") and some related alcohols
were prepared by the reactions of 4,5-bis(dimethylamino)-1-naphthyllithium or 4,5-bis(di-
methylamino)-1-naphthylmagnesium bromide with the corresponding electrophilic reagents.
New representatives of double "proton sponges" with the structures of 1,1´-binaphthyl ketone
and 1,1´-binaphthylmethanol were synthesized. The pKa values of selected compounds in
DMSO were measured by competitive protonation.
Key words: 1-bromo-4,5-bis(dimethylamino)naphthalene, organolithium and organo-
magnesium compounds, addition at the C=O group, acylation, 1,1´-binaphthyl ketone,
1,1´-binaphthylmethanol, "proton sponges".
The strong electron-donating effect of two di-
methylamino groups with respect to the naphthalene
ring is an important feature of 1,8-bis(dimethyl-
amino)naphthalene ("proton sponge").2 In addition to
the fact that electrophilic substitution proceeds excep-
tionally readily, this effect is manifested, in particular,
in the ability of the NMe2 groups to efficiently stabilize
carbocationic centers. Thus, carbocations of type 1
generated in situ readily enter into [4π+2π]-cyclo-
dimerization due to a substantial contribution of reso-
nance structure 1b containing the exo-endo-1,3-diene
fragment.3,4 Taking into account that, on the one hand,
naphthylmethyl carbocations have attracted consider-
able interest5 and, on the other hand, their reactivities
are untypical of the chemistry of naphthalenes, the
synthesis of carbocations 2 and 3 containing two or
three residues of the "proton sponge" is of importance.
+
The most evident procedure for the preparation of
these carbocations involves the synthesis of the corre-
sponding alcohols with the formation of organometallic
derivatives of "proton sponge" 4a in one of the stages.
Until recently, these compounds remained unknown,
except for the only example, viz., 4,5-bis(dimethyl-
amino)naphthyllithium6 (4b) and its conversion into the
corresponding aldehyde un-
der the action of DMF.
The aim of the present
Me2N
NMe2
study was to examine the
procedures for the prepara-
tion of lithium (4b) and mag-
nesium (4c) derivatives of the
"proton sponge" in detail and
to study the reactivities of
these compounds with re-
spect to typical electrophiles.
R
4a—c
R = H (a), Li (b), MgBr (c)
Me2N
NMe2
Me2N
NMe2
Results and Discussion
As in the study performed previously,6 organometal-
lic compounds 4b,c were generated using 1-bromo-4,5-
bis(dimethylamino)naphthalene (5a) as the starting com-
pound. Since 5a is the key compound in the synthesis of
metal derivatives, we simplified the procedure for its
preparation. Previously,6 the procedure, which involved
successive treatment of compound 4a with bromine and
concentrated H2SO4 at –10 °C, took ∼12 h to form the
target product 5a in 73% yield. The reaction of the
"proton sponge" with a solution of NBS in THF at
+CH2
NMe2
CH2
1a
1b
Me2N
Me2N
NMe2
2
3
HC +
C+
2
3
* For Part 31, see Ref. 1.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 817—822, May, 2001.
1066-5285/01/5005-854 $25.00 © 2001 Plenum Publishing Corporation

"Proton sponge": organometallic derivatives
Russ.Chem.Bull., Int.Ed., Vol. 50, No. 5, May, 2001
855
7
–5 °C
proved to be a more
ously unknown compounds 6a—i in yields from moder-
ate to high (Table 1).
Me2N
NMe2
convenient procedure. In the lat-
ter case, the reaction time was 2 h
and the yield of derivative 5a
reached 75%. Magnesium deriva-
tive 4c was then prepared by the
reaction of bromide 5a with mag-
nesium in anhydrous ether or THF
at ∼20 °C. It should be noted
that the "proton sponge," unlike
Me2N
NMe2
Me2N
NMe2
R
5a,b
2
R = Br (a), CHO (b)
R
CHOH
6a—h
6i
N,N-dimethylaniline,8 1-dimethylaminonaphthalene,9
and 1,5-bis(dimethylamino)naphthalene,10 is not metal-
lated with n-butyllithium. Its reactions with sodium
metal11 (–20 °C, dimethoxyethane) or lithium metal12
(–50 °C, THF) afforded a stable radical anion or its
conversion products (1-dimethylaminonaphthalene,
1,1´-binaphthyl, naphthalene, etc.).
In addition, we found that bromide 5a did not react
with lithium metal in boiling ether; however, lithium
derivative 4b was formed in the presence of an equimo-
lar amount of BunBr. This procedure is an alternative to
the synthesis involving BunLi, which is less convenient
to use. The reaction performed at 35 °C was completed
in 1.5—2 h. All experiments described below were car-
ried out with compound 4b generated in situ from BunLi
and bromide 5a.
R = D (a), Me (b), SMe (c), SiMe3 (d), I (e),
CH(OH)Ph (f), C(OH)Ph2 (g), CO2Et (h)
Compounds 4b and 4c would be expected to possess
high nucleophilicity due to the presence of the electron-
donating dimethylamino groups. As can be seen from
Table 1, naphthyllithium 4b is the most efficient reagent
in the majority of reactions due, apparently, to the
higher ionicity of the C—Li bond.13 At the same time,
the preparation of Grignard reagent 4c is less laborious
and the synthesis involving this reagent does not require
an inert atmosphere.
The reactions of organometallic compounds 4b,c
with MeI afforded methylnaphthalene 6b. This is the
second example of the synthesis of C-alkylated "proton
sponges." Previously,14 these compounds have been pre-
pared by alkylation of compound 4a with alkene com-
plexes of platinum.
The subsequent reactions of organometallic com-
pounds 4b,c with different electrophiles (D2O, MeI,
Me2S2, Me3SiCl, iodine, benzaldehyde, benzophenone,
diethyl carbonate, and aldehyde 5b) afforded the previ-
Treatment of compounds 4b,c with carbonyl com-
pounds, including 4,5-bis(dimethylamino)naphthalene-
Table 1. Results of the reactions of organometallic compounds 4b and 4c with different substrates
and the data from elemental analysis for products 6a—i
Reagent Reaction
product
Yield
(%) from
M.p.
/°Ñ
Found
Calculated
Molecular
formula
(%)
4b
4c
Ñ
H
N
D2O
6a
6b
6c
6d
6e
6f
100
57
90
42
87
88
40
44
54
97
271—272a
213—214a
196—197a
240—241a
215—216a
102—104
141—142c
223—224a
114—115
78.02
78.10
78.88
78.90
69.27
69.19
71.35
71.28
49.59
49.43
78.90
78.72
82.00
81.78
71.46
71.30
76.55
76.28
8.84b
8.89b
8.80
8.83
7.83
7.74
9.33
9.16
5.11
5.04
7.63
7.55
7.39
7.12
7.87
7.74
8.13
7.95
13.05
13.01
12.24
12.27
10.82
10.76
9.75
9.79
8.20
8.23
8.79
8.74
7.02
7.06
9.84
9.87
12.23
12.27
C14H17DN2
C15H20N2
MeI
40
30
31
30
67
73
40
22
Me2S2
Me3SiCl
I2
C15H20N2S
C17H26N2Si
C14H17IN2
C21H24N2O
C27H28N2O
C17H22N2O2
C29H36N4O
PhCHO
Ph2CO
(EtO)2CO
5b
6g
6h
6i
a M.p. of the corresponding perchlorate (with decomp., from water).
b H + D.
c From 95% EtOH.

856
Russ.Chem.Bull., Int.Ed., Vol. 50, No. 5, May, 2001
Ryabtsova et al.
Table 2. Hammett constants (σï) of the substituents and the
basicity constants pKa of compounds 4a, 5a, and 6b—e,h
1-carbaldehyde (5b), gave rise to
secondary and tertiary alcohols
6f,g,i. Interestingly, the prepara-
tion of alcohol 6f in the presence
of more than one equivalent of
benzaldehyde was accompanied
by the formation of ketone 7a.
We established that the latter oc-
curred due to oxidation of inter-
mediate alkoxide by an excess of
benzaldehyde (see also Ref. 15). The reactions with the
use of an excess (from two- to fivefold) of all other
reagents (see Table 1) afforded no by-products. It should
be noted that tertiary alcohol 6g has been synthesized
previously16 in low yield from phenylmagnesium bro-
mide and ketone 7a (the major product of this reaction
was an 1,4-addition product involving the carbonyl
group and the naphthalene ring).
The addition—elimination-type reactions of diethyl
carbonate with derivatives 4b,c gave rise to new carbo-
nyl compound 6h. By analogy with the latter reactions,
we attempted to perform the reaction of an organome-
tallic compound with ether 6h to prepare the previously
unknown ketone 8. However, this attempt failed due,
apparently, to an essential decrease in the partial posi-
tive charge on the carbon atom of the C=O group.
Presumably, compounds 7a and 7b 6 and, in particu-
lar, ketone 8 proved to be inert with respect to organo-
metallic compounds for the same reason. We prepared
the latter compound independently in 60% yield by
acylation of 1,8-bis(dimethylamino)naphthalene hydro-
chloride with oxalyl chloride in the presence of AlCl3.*
The structure of compound 8 was confirmed by spectral
data, including mass spectra, and by its reduction to
alcohol 6i.
Me2N
NMe2
Com-
pound
R
σï(H2O)
ðÊà*
R
4a
6b
6d
6c
6e
5a
6h
H
Me
SiMe3
SMe
I
0
7.5
7.7
7.2
7.1
6.6
6.5
5.6
7a,b
–0.14
–0.07
0
0.21
0.23
0.45
R = COPh (a), CN (b)
Br
CO2Et
* DMSO, 25 °C.
Binaphthyl derivatives 6i and 8 are new representa-
tives of double naphthalene "proton sponges." At the
same time, the reaction of ketone 8 with one more
molecule 4b or 4c would be expected to produce very
interesting alcohol 9 containing three residues of di-
amine 4a. Unfortunately, attempts to perform this reac-
tion failed. Apparently, aldehyde 5b is the "limiting"
carbonyl compound capable of
reacting with organometallic
Me2N
NMe2
compounds 4b,c. The low reac-
tivity of ketone 8 resulting from
the +M effect of four NMe2
groups is consistent with the po-
sition of the C=O stretching vi-
bration band in its IR spectrum
(ν(C=O) is 1633 cm–1 compared
3
COH
9
–1
to 1685 cm for aldehyde 5b).6
We estimated the influence of the substituents on the
basic properties of the compounds synthesized by com-
1
petitive protonation based on the data from H NMR
spectroscopy.19 The pKa values for derivatives 6b—e,h
and bromide 5a in DMSO* and the Hammett constants
(σï) of the corresponding substituents20 are given in
Table 2. In addition, the basicity of compound 4a21 is
given for comparison. As expected, the +I effect of the
Me group in 4-methyl derivative 6b leads to an increase
in the basicity by 0.2 pKa units compared to that of
compound 4a.
COClCOCl
4a
Me2N
NMe2
C O
NMe2
Me2N
NMe2
CHOH
NMe2
LiAlH4
The presence of other functional groups leads more
likely to a decrease in basicity of the resulting "proton
sponges" rather than to its increase in spite of the
negative (for SiMe3) or zero (for SMe) values of some
Hammett constants.
Therefore, although there is no strict quantitative
dependence of the pKa values on the σï constants, the
qualitative relationship between these parameters in the
series of compounds under consideration persists: the
higher the basicity, the lower the σï constants. In our
opinion, a slight quantitative inconsistency between the
σï and pKa values may be due both to steric and solvent
Me2N
Me2N
8
6i
* N,N-Dimethylaniline reacted with oxalyl chloride to form the
corresponding diketone.17 Acylation of other substrates under
the conditions of the Friedel—Crafts reaction is often accom-
panied by the cleavage of the C—C bond in oxalyl chloride to
form carboxylic acids or their chlorides along with mono-
ketones.18 Apparently, acylation of compound 4a with oxalyl
chloride also gave rise initially to the 4-chloroformyl derivative,
which then acylated one more molecule 4a to form finally
monoketone 8.
* The basicity constant of deuterated derivative 6a and the pKa
value of diamine 4a are equal within the experimental error
(±0.03 pKa units).

"Proton sponge": organometallic derivatives
Russ.Chem.Bull., Int.Ed., Vol. 50, No. 5, May, 2001
857
with stirring to a solution of bromide 5a (0.3 g, 1 mmol) in
Et2O (2 mL) using a microdispenser (or a syringe) under an
atmosphere of Ar at –30 °C. The reaction was accompanied by
the immediate appearance of the bright-yellow color. The
resulting solution of compound 4b (1 mmol) was kept at
–30 °C in a freezing chamber for 30 min and compound 4b was
used in subsequent conversions without isolation.
4,5-Bis(dimethylamino)-1-naphthylmagnesium bromide (4c).
Magnesium chips (0.1 g, 4 mmol; activated with 0.02 mL of dry
n-butyl bromide) and THF (2 mL) were placed into a flask
equipped with a stirrer, a reflux condenser, and a dropping
funnel with protection from atmospheric moisture. Then a
solution of bromide 5a (0.3 g, 1 mmol) in THF (1.5 mL) was
added with stirring so that the reaction mixture boiled sponta-
neously. After completion of the addition, the transparent
solution was stirred at 50—55 °C for ∼1 h until compound 5a
was completely consumed (TLC control). The solution of the
resulting Grignard reagent 4c (1 mmol) was used in subsequent
reactions without isolation.
effects associated with the use of different solvents
(water or DMSO) in the quantitative measurements.
Experimental
The 1H NMR spectra were recorded on a Bruker DPX-250
instrument (250 MHz) in CDCl3 with SiMe4 as the internal
standard. The IR spectra were measured on a Specord IR-71
spectrometer. The mass spectra were obtained on a Finnigan
4021 instrument (EI, 70 eV, direct inlet of the sample). Chro-
matography was performed and the purities of the compounds
were monitored by TLC on Al2O3 (Brockmann II) using CHCl3
as the eluent; visualization was carried out with iodine vapor.
The melting points were determined in sealed glass tubes on
a PTP instrument and were not corrected. Commercial n-butyl-
lithium (a 1.6 M solution in n-hexane, Fluka), 1,8-bis(dimethyl-
amino)naphthalene (Merck), oxalyl chloride (Aldrich), tri-
methylchlorosilane, and dimethyl disulfide (Fluka) were used.
Other reagents and solvents used in the synthesis of organome-
tallic compounds and in their reactions were purified and dried
according to standard procedures.23 The physicochemical and
spectral characteristics of the resulting compounds are given in
Tables 1 and 3.
1-Bromo-4,5-bis(dimethylamino)naphthalene (5a). A solu-
tion of NBS (0.266 g, 1.5 mmol) in THF (20 mL) was added
dropwise with vigorous stirring to a solution of compound 4a
(0.32 g, 1.5 mmol) in THF (10 mL) cooled to –5 °C for
30 min. Then the reaction mixture was stirred at ∼20 °C for 2 h,
concentrated to 2 mL, and chromatographed. The first major
fraction of bromo derivative 5a was collected (0.33 g, 75%) as a
pale-yellow oil. The properties of 5a are analogous to those of
the specimen prepared previously.6
1,8-Bis(dimethylamino)-4-methylnaphthalene (6b). A.
Iodomethane (1 mL) was added with stirring to a solution of
lithium derivative 4b (1 mmol) prepared as described above at
–30 °C. The reaction mixture was kept at –30 °C for 3 h,
allowed to warm to ∼20 °C, and poured into water. The yellow
ethereal layer was separated and the aqueous layer was ex-
tracted with CHCl3 (2½2 mL). The solvents were removed. The
residue was chromatographed (n-hexane as the eluent) and the
major colorless fraction was collected (TLC control). Com-
pound 6b was obtained in a yield of 0.13 g (57%) as a colorless
oil readily soluble in dilute mineral acids. Perchlorate
6b•HClO4. Found (%): C, 54.75; H, 6.40; Cl, 10.67; N, 8.49.
C15H21ClN2O4. Calculated (%): C, 54.80; H, 6.44; Cl, 10.78;
1
N, 8.52. H NMR (DMSO-d6), δ: 2.70 (br.s, 3 H, Me); 3.11
4,5-Bis(dimethylamino)-1-naphthyllithium (4b). A 1.6 M
solution of BunLi (1.2 mL) in n-hexane (1.9 mmol) was added
and 3.13 (both d, 6 H each, C(1)NMe2 and C(8)NMe2,
JNH,C(1)NMe = 2.7 Hz, JNH,C(8)NMe = 2.4 Hz); 7.61 (dd, 1 H,
Table 3. 1H NMR spectra of compounds 6a—f,h,i and 7a
Com-
pound
δ (J/Hz)
H(5), dd H(6), dd H(7), dd
NMe2
H(2), d H(3), d
R
6a
6b
6c
6d
6e
6f
2.83 (s, 12 H, NMe2)
6.96
(7.9)
6.84
(7.7)
6.86
(8.0)
6.86
(7.6)
6.61
(8.1)
6.84
(7.9)
7.33
(7.9)
7.16
(7.7)
7.40
m
7.50
(7.6)
7.84
(8.1)
7.32
m
7.39
(7.9)*
7.50
7.33
(7.3, 7.9)
7.36
6.96
(7.3)*
6.96
—
2.76 (s, 6 H, C(1)NMe2);
2.80 (s, 6 H, C(8)NMe2)
2.80 (s, 6 H, C(8)NMe2);
2.81 (s, 6 Í, C(1)NMe2)
2.77 (s, 6 H, C(1)NMe2);
2.80 (s, 6 H, C(8)NMe2)
2.76 (s, 6 H, C(8)NMe2);
2.77 (s, 6 H, C(1)NMe2)
2.78 (br.s, 12 Í, NMe2)
2.57 (br.s, 3 H, Me)
2.47 (s, 3 H, SMe)
0.40 (s, 9 H, SiMe3)
—
(1.1, 8.3) (7.5, 8.3) (1.1, 7.5)
7.98
(1.1, 8.3)
7.57
(0.9, 8.3) (7.7, 8.3) (0.9, 7.7)
7.59 7.35 6.95
(1.1, 8.3) (7.6, 8.3) (1.1, 7.6)
7.40
m
7.31
6.97
(1.1, 7.5)
6.91
7.63
(8.1)*
7.32
m
6.92
(7.5)*
2.24 (br.d, 1 Í, CHÎÍ, J = 3.1);
6.42 (d, 1 Í, ÑÍÎÍ, J = 3.1);
7.32 (m, 5 Í, Ph)
6h
6i
2.74 (s, 6 H, C(8)NMe2);
2.86 (s, 6 H, C(1)NMe2)
2.78 (s, 12 H, C(1,1´)NMe2); 6.83
2.81 (s, 12 H, C(8,8´)NMe2) (8.0)
2H
6.78
(8.3)
8.04
(8.3)
7.29
m
2H
7.43
m
8.55
7.39
6.91
1.40 (t, 3 H, ÑÍ2Me);
(1.1, 8.5) (7.6, 8.5) (1.1, 7.6) 4.38 (q, 2 H, CH2Me)
7.61
(8.5)*
2H
7.29
m
2H
7.34
6.92
(7.5)*
2H
2.18 (br.d, 1 H, OH, J = 4.1);
7.05 (br.d, 1 H, CH, J = 4.1)
7a
2.78 (s, 6 H, C(8)NMe2);
2.88 (s, 6 H, C(1)NMe2)
6.74
(8.1)
8.04
6.94
7.43, 7.53, 7.81
(1.1, 8.4) (7.6, 8.4) (1.1, 7.6) (all m, 2 Í, 1 Í, 2 Í, Ph)
Note. For convenience, the atomic numbering scheme for the naphthalene ring in all compounds under consideration is identical
with that used for 1,8-bis(dimethylamino)naphthalene derivatives.
* If the J5,7 constant was not observed in the NMR spectrum, only one value is given.

858
Russ.Chem.Bull., Int.Ed., Vol. 50, No. 5, May, 2001
Ryabtsova et al.
H(3), JH(3),Me = 0.8 Hz, J = 7.8 Hz); 7.78 (dd, 1 H, H(6),
J1 = 7.6 Hz, J2 = 8.5 Hz); 7.99 (d, 1 H, H(2), J = 7.8 Hz);
8.09 (dd, 1 H, H(5), J1 = 0.8 Hz, J2 = 7.6 Hz); 8.17 (dd, 1 H,
H(7), J1 = 0.8 Hz, J2 = 8.5 Hz); 18.59 (br.s, 1 H, NH).
B. A solution of MeI (0.5 mL, 8 mmol) in THF (1.5 mL)
was added to a solution of Grignard reagent 4c (0.34 mmol)
prepared as described above. The reaction mixture was stirred
at 50 °C for 2 h, decomposed with a saturated NH4Cl solution,
and extracted with CHCl3 (3½2 mL). The solvent was removed.
The residue was chromatographed (n-hexane as the eluent) and
the major colorless fraction was collected (TLC control). Com-
pound 6b was isolated in a yield of 0.03 g (40%). It was
identical in properties to the specimen synthesized according to
procedure A.
The reaction with the use of D2O instead of MeI afforded
4-deuterio-1,8-bis(dimethylamino)naphthalene (6a) in virtu-
ally quantitative yield as a colorless oil whose physi-
cochemical characteristics are very similar to those of
crystalline 1,8-bis(dimethylamino)naphthalene (4a). Per-
chlorate 6a•HClO4. Found (%): C, 53.14; H+D, 6.40;
Cl, 11.47; N, 8.48. C14H18ClDN2O4. Calculated (%): C, 53.25;
H+D, 6.38; Cl, 10.78; N, 8.52. 1H NMR (DMSO-d6), δ: 3.12
(d, 12 H, NMe2, JNH,NMe = 2.5 Hz); 7.73 (m, 2 H, H(3),
H(6), J1 = 7.7 Hz, J2 = 8.2 Hz); 8.08 (d, 2 H, H(2), H(7),
J = 7.7 Hz); 8.09 (d, 1 H, H(5), J = 8.2 Hz); 18.35
(br.s, 1 H, NH).
1,8-Bis(dimethylamino)-4-iodonaphthalene (6e). A solution
of I2 (∼0.2 g, 0.78 mmol) in Et2O was added portionwise to a
solution of compound 4b (0.68 mmol) prepared as described
above at –30 °C until the brown color of iodine persisted. The
reaction mixture was kept at –30 °C for 1 h and decomposed by
pouring into water. The ethereal layer was washed successively
with a solution of Na2S2O3 and water and concentrated to
dryness. The residue was chromatographed (n-hexane as the
eluent) and the first colorless fraction containing iodide 6e was
collected. Compound 6e was obtained as a pale-yellow oil in a
yield of 0.2 g (87%). Perchlorate 6e•HClO4. Found (%):
C, 38.09; H, 4.01; Cl+I, 36.73; N, 6.30. C14H18ClIN2O4. Cal-
culated (%): C, 38.16; H, 4.12; Cl+I, 36.84; N, 6.36. 1H NMR
(DMSO-d6), δ: 3.11 and 3.15 (both d, 6 H each, C(4)NMe2
and C(5)NMe2, JNH,C(4)NMe = 1.9 Hz, JNH,C(5)NMe = 2.2 Hz);
7.89 (m, 2 H, H(2), H(7)); 8.22 (m, 2 H, H(3), H(6)); 8.41
(br.d, 1 H, H(8), J = 8.0 Hz); 18.61 (br.s, 1 H, NH).
[4,5-Bis(dimethylamino)-1-naphthyl]phenylmethanol (6f).
Freshly distilled benzaldehyde (0.33 mL, 1 mmol) was slowly
added with stirring to a solution of lithium derivative 4b
(1 mmol) at –30 °C. The reaction mixture was kept at –30 °C
for 1 h and then at ∼20 °C for 4 h and poured into water. The
ethereal layer was separated and the aqueous layer was ex-
tracted with CHCl3 (4½3 mL). The combined extracts were
concentrated. The residue was washed with a 10% solution of
NaOH and chromatographed to isolate alcohol 6f from the
colorless zone with Rf 0.34 (0.28 g, 88%). Compound 6f was
obtained as a colorless caramel, which was crystallized upon
prolonged evacuation and freezing to –20 °C.
The reaction with the use of an excess of benzaldehyde
afforded also 1-benzoyl-4,5-bis(dimethylamino)naphthalene (7a)
as orange crystals in 10—30% yield. Compound 7a was present
in the yellow-orange fraction with Rf 0.55. The properties of
the crystals are identical with those reported in the literature.22
[4,5-Bis(dimethylamino)-1-naphthyl]diphenylmethanol (6g).
A solution of benzophenone (0.74 g, 4 mmol) in THF (2.5 mL)
was added dropwise with intense stirring to a solution of
Grignard reagent 4c (2.7 mmol), which was prepared as de-
scribed above, at ∼20 °C. The reaction mixture was stirred at
40 °C for 1.5 h and hydrolyzed with a saturated NH4Cl
solution. The aqueous layer was extracted with CHCl3 (3½3 mL)
and the solvents were evaporated. The residue was crystal-
lized from n-hexane and crystallized from 95% EtOH. Alco-
hol 6g was obtained as colorless crystals in a yield of
0.79 g (73%).16
Next we describe the procedures giving the best results (see
Table 1).
[4,5-Bis(dimethylamino)-1-naphthyl]methyl sulfide (6c). A
solution of lithium derivative 4b (5.5 mmol), which was pre-
pared according to the procedure described above, was added
with stirring to a solution of dimethyl disulfide (1 mL) in Et2O
(2 mL) at –70 °C. The mixture was kept at –70 °C for 2 h and
then at ∼20 °C for 3 h and poured into water. The ethereal layer
was separated and the aqueous layer was extracted with CHCl3
(3½2 mL). The combined organic extracts were concentrated to
the minimum volume and chromatographed (n-hexane as the
eluent). Compound 6c was obtained in a yield of 0.13 g (90%)
as a dark-yellow oil with weak "sulfide" odor. Perchlorate
6c•HClO4. Found (%): C, 49.78; H, 5.80; Cl, 9.77; N, 7.71,
S, 8.76. C15H21ClN2O4S. Calculated (%): C, 49.93; H, 5.83;
1
Cl, 9.85; N, 7.77; S, 8.88. H NMR (DMSO-d6), δ: 2.65 (s,
3 H, SMe); 3.11 and 3.13 (both d, 6 H each, C(4)NMe2 and
C(5)NMe2, JNH,C(4)NMe = 2.3 Hz, JNH,C(5)NMe = 2.7 Hz);
7.60 (d, 1 H, H(2), J = 8.3 Hz); 7.80 (t, 1 H, H(7), J1 = 7.6 Hz,
J2 = 8.5 Hz); 8.06 (d, 1 H, H(3), J = 8.3 Hz); 8.14 (br.d, 1 H,
H(6), J = 7.6 Hz); 8.26 (br.d, 1 H, H(8), J = 8.5 Hz); 18.54
(br.s, 1 H, NH).
1,8-Bis(dimethylamino)-4-ethoxycarbonylnaphthalene (6h).
Diethyl carbonate (2 mL) was added with stirring to a solution
of lithium derivative 4b (1 mmol) cooled to –30 °C. The
reaction mixture was kept at –30 °C for 2 h, allowed to warm
to ∼20 °C, and poured into water. The ethereal layer was
separated and the aqueous layer was extracted with CHCl3
(3½2 mL). The solvents were removed. The combined residues
were chromatographed and the first bright-yellow fraction was
collected. Ester 6h was obtained as a yellow oil in a yield of
0.12 g (44%). Perchlorate 6h•HClO4. Found (%): C, 52.71;
H, 5.90; Cl, 9.20; N, 7.19. C17H23ClN2O6. Calculated (%):
4,5-Bis(dimethylamino)-1-napthyltrimethylsilane (6d). A
solution of lithium derivative 4b (5 mmol), which was prepared
as described above, was added to a solution of Me3SiCl (1 mL,
0.8 g, 7 mmol) in Et2O (2 mL) at –70 °C under Ar. The
reaction mixture was kept at –70 °C for 2 h and then at ∼20 °C
for 3 h, poured into water, and alkalized with ammonia until a
persistent odor appeared. The ethereal layer was separated and
the aqueous layer was extracted with CHCl3 (4½2 mL). A
needle-like colorless precipitate of compound 6d was obtained
in a yield of 0.06 g (42%). Perchlorate 6d•HClO4. Found (%):
C, 52.48; H, 7.27; Cl, 9.10; N, 7.19. C17H27ClN2O4Si. Calcu-
lated (%): C, 52.77; H, 7.03; Cl, 9.16; N, 7.24. 1H NMR
(DMSO-d6), δ: 0.46 (s, 9 H, SiMe3); 3.12 and 3.15 (both d,
6 H each, C(5)NMe2 and C(4)NMe2, JNH,C(4)NMe = 2.5 Hz,
JNH,C(5)NMe = 2.2 Hz); 7.82 (m, 2 H, H(2), H(7)); 8.04 (d,
1 H, H(3), J = 7.6 Hz); 8.11 (dd, 1 H, H(6), J1 = 0.8 Hz,
J2 = 7.6 Hz); 8.22 (dd, 1 H, H(8), J1 = 0.8 Hz, J2 = 8.3 Hz);
18.69 (br.s, 1 H, NH).
1
C, 52.78; H, 5.99; Cl, 9.17; N, 7.24. H NMR (DMSO-d6),
δ: 1.38 (t, 3 H, CH2Me, J = 7.1 Hz); 3.11 and 3.20 (both s,
6 H each, C(1)NMe2 and C(8)NMe2); 4.45 (q, 2 H, CH2Me,
J = 7.1 Hz); 7.89 (t, 1 H, H(6), J1 = 7.8 Hz, J2 = 8.7 Hz); 8.21
(m, 3 H, H(2), H(3), H(7)); 8.73 (br.d, 1 H, H(5), J = 8.7 Hz);
18.59 (br.s, 1 H, NH).
[4,4´,5,5´-Tetrakis(dimethylamino)-1,1´-dinaphthyl]methanol
6
(6i). A solution of aldehyde 5b (0.25 g, 1 mmol) in Et2O
(2 mL) was added with stirring to a solution of lithium deriva-
tive 4b (1 mmol) cooled to –30 °C. The reaction mixture was

"Proton sponge": organometallic derivatives
Russ.Chem.Bull., Int.Ed., Vol. 50, No. 5, May, 2001
859
kept at –30 °C for 5 h and then at ∼20 °C for 30 min and
poured into water. The ethereal layer was separated, the aque-
ous layer was extracted with CHCl3 (4½2 mL), and the extracts
were combined and concentrated. The reaction product was
isolated by chromatography by collecting the major colorless
fraction (TLC control). After removal of CHCl3, a pale-yellow
viscous substance was obtained, which was crystallized from
n-hexane. Compound 6i was obtained as transparent rhombic
crystals in a yield of 0.21 g (54%). The crystals possess strong
refracting properties and melted with decomposition. MS,
m/z (Irel (%)): 456 [M]+ (77), 441 [M – Me]+ (8), 410
[M – Me – MeNH2]+ (11), 243 (2). IR (CCl4), ν/cm–1: 3613,
3406, 3255 (OH); 3066, 3014, 2934, 2830, 2772 (CH).
4,4´,5,5´-Tetrakis(dimethylamino)-1,1´-dinaphthyl ketone
(8). Freshly sublimed AlCl3 (1 g, 7.5 mmol) and oxalyl chloride
(0.4 mL, 4.7 mmol) in CH2Cl2 (15 mL) were placed in a flask
equipped with a stirrer, a reflux condenser, and a dropping
funnel with protection from atmospheric moisture and refluxed
with stirring for 20 min. Then 1,8-bis(dimethylamino)naph-
thalene hydrochloride (1.45 g, 5.8 mmol) was added with
stirring to the resulting transparent solution at ∼20 °C and the
suspension was refluxed for 1 h after which oxalyl chloride
(0.4 g) and AlCl3 (0.5 g) were added. The reaction mixture was
heated with stirring for 2 h and then carefully poured onto
crushed ice (100 g), alkalized with a 20% NaOH solution to
pH ∼11, and extracted with CHCl3 (3½50 mL). The solvent was
distilled off, the residue was chromatographed, and the first
yellow-orange fraction containing ketone 8 was collected. Com-
pound 8 was obtained in a yield of 0.78 g (60%) as yellow
crystals, m.p. 170—171 °C (from n-octane). Found (%):
C, 77.01; H, 7.50; N, 12.30. C29H34N4O. Calculated (%):
C, 76.62; H, 7.54; N, 12.32. 1H NMR, δ: 2.78 and 2.86 (both s,
12 H each, C(5,5´)NMe2 and C(4,4´)NMe2); 6.69 (d, 2 H,
H(3), H(3´), J = 8.2 Hz); 6.94 (dd, 2 H, H(6), H(6´),
J1 = 0.9 Hz, J2 = 7.6 Hz); 7.35 (dd, 2 H, H(7), H(7´),
J = 8.5 Hz); 7.42 (dd, 2 H, H(2), H(2´), J = 8.2 Hz); 8.25 (dd,
2 H, H(8), H(8´), J1 = 0.9 Hz, J2 = 8.5 Hz). MS, m/z (Irel (%)):
454 [M]+ (100), 439 [M – Me]+ (7), 426 [M – CO]+ (16), 408
[M – Me – MeNH2]+ (12), 256 (29). IR (Nujol mulls),
ν/cm–1: 1633 (C=O); 1561, 1510 (ring).
References
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Reduction of ketone 8 with LiAlH4. A solution of ketone 8
(0.45 g, 1 mmol) in ether (10 mL) was added portionwise to a
suspension of LiAlH4 (0.04 g, 1 mmol) in Et2O (10 mL). The
reaction mixture was heated on a water bath to weak reflux,
kept for 20 min, and carefully hydrolyzed with water (10 mL).
The organic layer was separated and the aqueous layer was
extracted with ether (2½5 mL). The extracts were combined
and dried with anhydrous Na2SO4. The solvent was removed
and alcohol 6i was obtained in a yield of 0.4 g (89%) as
colorless crystals. A mixture with the authentic sample did not
give a melting point depression.
18. H. G. Latham Jr., E. L. May, and E. Mosettig, J. Am.
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Analogously, alcohol 6f was obtained in quantitative yield
by reduction of benzoyl 7a. The physicochemical properties of
the resulting compound are identical with the properties of the
specimen prepared as described above.
This work was financially supported in part by the
Russian Foundation for Basic Research (Project No.
99-03-33133a).
Received August 1, 2000;
in revised form November 24, 2000