Titanocene-catalyzed coupling of aromatic amides in the presence of organosilanes: A novel route to vicinal diamines and a new class of amine-substituted oligomers

Article abstract of DOI:10.1021/jo049220b

The title reaction has been surveyed for a number of substrates with differing substitution patterns. With a few exceptions, the methodology provides a one-pot synthesis of the 1,2-diamines from widely available and inexpensive starting materials, and in high yields. In addition, the coupling of 1,4-and 1,3-bis-(N,N,N′,N′-tetraalkyl)arylenediamides is shown, under the same experimental conditions, to yield oligomers: R₂NC(O)C ₆H₄CH(NR₂)-[CH(NR₂)C ₆H₄CH(NR₂)]_n-CH(NR ₂)C₆H₄C(O)-NR₂ (R = methyl and ethyl; n = 0 to ca. 5). The chemical structures of these unprecedented oligomers are determined by comparison of NMR and MS spectra to those of vicinal diamines, prepared from the analogous N,N-dialkylbenzamides. The origin of the limitation of oligomer chain length is probably due to a specific effect of the internal benzylic amine group, since the substrate 4-Me₂NCH ₂C₆H₄C(O)NMe₂ was found to be uniquely unreactive compared to the other 4-substituted N,N-dialkylbenzamides investigated. N-Methylphthalimide was briefly studied as a monomer and analysis by MS showed that oligomers are formed. Attempts to fully characterize these polymers were unsuccessful.

Full text of DOI:10.1021/jo049220b

Tita n ocen e-Ca ta lyzed Cou p lin g of Ar om a tic Am id es in th e
P r esen ce of Or ga n osila n es: A Novel Rou te to Vicin a l Dia m in es
a n d a New Cla ss of Am in e-Su bstitu ted Oligom er s
Kesamreddy Rangareddy, Kumaravel Selvakumar, and J ohn. F. Harrod*
Chemistry Department, McGill University, 801 Sherbrooke Street West, Montreal, QC H3A 2K6, Canada
john.harrod@staff.mcgill.ca
Received May 9, 2004
The title reaction has been surveyed for a number of substrates with differing substitution patterns.
With a few exceptions, the methodology provides a one-pot synthesis of the 1,2-diamines from widely
available and inexpensive starting materials, and in high yields. In addition, the coupling of 1,4-
and 1,3-bis-(N,N,N′,N′-tetraalkyl)arylenediamides is shown, under the same experimental condi-
tions, to yield oligomers: R
2 6 4 2 2 6 4 2 n 2 6 4 2
NC(O)C H CH(NR )-[CH(NR )C H CH(NR )] -CH(NR )C H C(O)-NR
(
R ) methyl and ethyl; n ) 0 to ca. 5). The chemical structures of these unprecedented oligo-
mers are determined by comparison of NMR and MS spectra to those of vicinal diamines, pre-
pared from the analogous N,N-dialkylbenzamides. The origin of the limitation of oligomer chain
length is probably due to a specific effect of the internal benzylic amine group, since the substrate
4
2 2 6 4 2
-Me NCH C H C(O)NMe was found to be uniquely unreactive compared to the other 4-substituted
N,N-dialkylbenzamides investigated. N-Methylphthalimide was briefly studied as a monomer and
analysis by MS showed that oligomers are formed. Attempts to fully characterize these polymers
were unsuccessful.
In tr od u ction
the presence of a stoichiometric amount of organosilane,
5
catalyzed by [Cp
2
TiX
2
] (Cp ) η -cyclopentadienyl; X )
Chiral vicinal diamines are of great importance, as
they are found in a variety of compounds that display a
broad spectrum of pharmaceutical activity. They are also
used increasingly as stereoselective auxiliaries, or as
metal ligands in catalytic asymmetric synthesis.1 The
regio- and stereoselective synthesis of vicinal diamines
is an active and challenging topic in organic chemistry
5a,b
Me or F).
To our knowledge, such a reaction had not
been previously reported, although there is a very
extensive literature on noncatalytic, titanium-mediated
1
6a
6b
coupling of carbonyl and imine compounds in the
e
6a
presence of strong reducing agents. The intramolecular
coupling of 1,2-acylamido compounds to indoles and
pyrroles has also been extensively studied.7
2
a,b
because of the importance of such derivatives
in
The catalytic coupling reaction described above has
proven to be very useful for the synthesis of a wide range
of ring-functionalized 1,2-diarylbis(1,2-N,N-dialkylami-
no)ethanes, but so far it has shown little, or no, regio- or
enantioselectivity. Nevertheless, because the reactants
are generally widely available and inexpensive, the
chemistry certainly warrants further exploration. The
present paper gives a full report on our work to date.
An interesting feature of the catalytic coupling reaction
is that some of the simple N,N-dialkylbenzamides we
have studied give essentially quantitative yields of vicinal
coordination chemistry2 and medicinal chemistry.
c,d
2e
3
Despite the existence of many synthetic approaches and
useful methodologies, there is still a need for better and
more general methods based on simple and inexpensive
starting materials.
In a preliminary communication we reported a novel
reduction-deoxygenation coupling of aromatic amides in
4
*
Corresponding author, Department of Chemistry, McGill Univer-
sity, Montreal, QC, H3A 2K6 Canada. Phone: (+1) 514-398-6911.
Fax: (+1) 514-398-3797.
(1) (a) Michalson, E. T.; Szmuszkovicz, J . Prog. Drug. Res. 1989,
3
3, 135. (b) Corey, E. J .; Kuhnle, N. M. Tetrahedron Lett. 1997, 38,
631. (c) Bernardi, L.; Gothelf, A. S.; Hazell, R. G.; J orgensen, K. A. J .
8
(4) (a) For an excellent review, see: Lucet, D.; Le Gall, T.; Miosk-
owski, C. Angew. Chem. 1998, 110, 2724; Angew. Chem., Int. Ed. 1998,
37, 2581 and references therein.; For selected leading references, see
also: (b) Alexakis, A.; Aujard, I.; Mangeney, P. Synlett. 1998, 873. (c)
Demay, S.; Kotschy, A.; Knochel, P. Synthesis 2001, 863. (d) Saravanan,
P.; Bisai, A.; Baktharaman, S.; Chandrasekhar, M.; Singh, V. K.
Tetrehedron 2002, 58, 4693.
(5) (a) Selvakumar, K.; Harrod, J . F. Angew. Chem., Int. Ed. 2001,
40, 2129. (b) Rangareddy, K.; Selvakumar, K.; Harrod, J . F. Can. J .
Chem. 2004 In press.
Org. Chem. 2003, 68, 2583. (d) O’Brien, P.; Towers, T. D. J . Org. Chem.
002, 67, 304. (e) See, for example: Togni, A.; Venanzi, L. M. Angew.
Chem. 1994, 106, 517; Angew. Chem., Int. Ed. 1994, 33, 497.
2) (a) Ojima, I. In The organic Chemistry of â-Lactams; Geroge, G.
2
(
I., Ed.; VCH: New York, 1992; pp 197-255. (b) Ojima, I. Acc. Chem.
Res. 1995, 28, 385. (c) Lucet, D.; Le Gall, T.; Mioskowski, C. Angew.
Chem. 1998, 110, 2724; Angew. Chem., Int. Ed. 1998, 37, 2580. (d)
Rosenberg, B.; Vancamp, L.; Trosko, J . E; Mansour, V. H. Nature 1969,
2
22, 385. (e) Vico, A.; Fernandez de la Pradilla, R. Recent Res. Devel.
Org. Chem. 2000, 4, 327.
3) (a) Enders, D.; Schiffers, R. Synthesis 1996, 53 and references
(6) (a) McMurry, J . E. Chem. Rev. 1989, 89, 1513. (b) Talukdar, S.;
Banerji, A. J . Org. Chem. 1998, 63, 3468.
(
therein. (b) Yamada, K.; Harwood, S. J .; Groger, H.; Shibasaki, M.
Angew. Chem. 1999, 111, 3713; Angew. Chem., Int. Ed. 1999, 38, 3504.
(7) Furstener, A.; Bogdanovic, B. Angew. Chem. 1996, 108, 2582;
Angew. Chem., Int. Ed. 1996, 35, 2442.
1
0.1021/jo049220b CCC: $27.50 © 2004 American Chemical Society
Published on Web 09/08/2004
J . Org. Chem. 2004, 69, 6843-6850
6843

Rangareddy et al.
diamines. A C-C bond-forming reaction with this kind
of efficiency is of interest as a source of new polymer
chemistry. We have therefore studied the coupling of a
number of bifunctional arylene diamides with a view to
making polymers of the structure A as shown in (1). The
synthesis of such polymers by other known routes would
be at best difficult and costly.
TABLE 1. Resu lts for Tita n ocen e-Ca ta lyzed Red u ctive
Cou p lin g of Am id es a t 80 °C w ith 10% Ca ta lyst
compd
no.
ratio
yieldc
(%)
R1 R2
Et Et
R3
methoda (meso:rac)
b
1
H
A
B
A
A
A
A
A
A
A
A
A
A
A
A
A
A
52:48
52:48
53:47
52:48
51:49
52:48
53:47
51:49
49:51
56:44
62:28
52:48
49:51
48:52
50:50
54:46
92
80
93
86
93
87
96
84
72
94
91
73
44
44
2
3
4
5
6
7
8
9
Et Et 4-Cl
Et Et 3-Cl
Et Et 4-F
Et Et 3-F
Et Et 4-CF3
Et Et 3-CF3
Et Et 2-CF3
Et Et 4-OCH3
Et Et 4-Me
Et Et 3-Me
Et Et 4-CN
Et Et 4-NMe2
1
1
1
1
1
1
0
1
2
3
4
5
e
d
Me Ph
H
77
83
f
N,N-diethyl-2-
naphthamide
H
1
1
6
7
Me Me
A
B
A
A
A
A
A
A
A
A
A
A
B
A
52:48
52:48
49:51
53:47
52:48
51:49
51:49
52:48
60:40
57:43
54:46
84
80
88
62
86
81
87
84
66
63
59
Polymers such as A are interesting both in their own
right and as potential precursors for a novel class of
polyconjugated polymers. They could, in principle, be
transformed into amine-substituted polyarylenevinylenes
by classical autoxidation, catalytic dehydrogenation, or
dehydroamination reactions.
Me Me 4-Cl
Me Me 3-Cl
Me Me 4-F
18
19
2
2
2
2
2
2
2
0
1
2
3
4
5
6
Me Me 3-F
Me Me 4-CF3
Me Me 3-CF3
Me Me 2-CF3
Me Me 4-Me
Me Me 3-Me
Me Me 4-CH2NMe2
Resu lts
h
NR
NR
27
h
Rea ction s of Mon oa m id es. The effects of a number
of chemical and physical variables on the outcome of the
reactions of several aryl monoamides were investigated
2
7g
27g
N,N-diethyl-
57:43
nicotinamide
a
See Experimental Section. b Ratios of isomers are calculated
[eq 2 and Tables 1 and 2].
1
c
after isolation, or by H NMR analysis. Yields are given for iso-
d
lated compounds. N-Methyl-N-benzylaniline is one of the prod-
ucts (8%). e Isomers were not separated. f N,N-Diethyl-2-naphthyl-
g
amine is formed as a side product (9%). 3-(N,N-Diethylamino-
methyl)pyridine is also formed (25%). h NR ) no reaction.
TABLE 2. Resu lts for [Cp 2TiF 2]-Ca ta lyzed Red u ctive
Cou p lin g of Ar om a tic Mon oa m id es a t 25 °C w ith 10%
Ca ta lyst
At 80 °C, most benzamides yield the 1,2-diamines with
high chemoselectivity, but with low diastereoselectivity.
However, Some aromatic amides, notably nicotinamides,
also undergo to a significant extent the additional side
reactions shown in (2), even when the reaction is carried
out at 80 °C. At 25 °C, the C-N bond cleavage and the
CdO reduction reactions become more important in most
cases (Table 2). Replacement of one of the N-alkyl groups
with a phenyl group does not seriously alter the course
of the reaction, although there is a slight reduction in
the yield of diamines. Replacement of both alkyl groups
with phenyl effectively closes down the coupling reaction.
ratio of products (%)
diamines
mono-
R1
R2
R3
(meso:rac) amines aldehyde
Me
Et
Et
Et
Me
Et
Me
Et
Et 4-Cl
H
H
81.3 (54:46)
97.7 (60:40)
44.8 (53:47)
2.0
16.7
2.3
25.3
29.9
Et 4-OMe 100 (53:47)
Ph
H
14.7 (55:45)
55.9 (53:47)
100 (50:50)
51.2 (48:52)
44.2
20.6
41.1
23.5
Et 4-CF3
Et 4-Me
Et
N,N-diethyl-2-
naphthamide
N,N-diethyl-
nicotinamide
39.6
34.1
9.2
In all of the cases studied, cleavage of the C(O)NPh
2
bond
43.5 (56:44)
22.4
to give high yields of Ph NH was the main reaction. As
2
previously noted, reactions of amides with unsubstituted
N-H bonds, using the conditions described above, are
too slow to be of interest.
of the C-C coupling product in the case of ethyl-
substituted substrates. In the diethylamino products, the
two diastereotopic hydrogens of the methylene group
have different chemical shifts and they couple to give a
widely separated pair of doublets. Each of these doublets
is in turn spilt by the methyl group to give two pairs of
overlapping quartets, with a characteristic pseudosextet
appearance. This pattern is observed for all of the 1,2-
diethylamino products listed in Table 1. In the 1,2-
dimethylamino products, the N-methyl protons all appear
Characterization was greatly aided by the presence of
the chiral centers in the products. The spectra of a
mixture of diastereoisomers of 1 (Table 1) and of the
separated diastereomers of the same product are shown
in Figure 1, parts a-c. The presence of the couplings of
the pairs of inequivalent, diastereotopic hydrogens in the
diethylamino products, 1, and its absence in the di-
methylamino product (16, Table. 1) is clearly diagnostic
6
844 J . Org. Chem., Vol. 69, No. 20, 2004

Titanocene-Catalyzed Coupling of Aromatic Amides
F IGURE 1. 1H NMR spectra of (a) a mixture of the diastereomers of 1,2-diphenyl-1,2-N,N-diethylaminoethane, (b) the pure
meso isomer, and (c) the pure rac isomer (in CDCl at room temperature).
3
as two sharp singlets, characteristic of the two diaster-
eomers, and in the same chemical shift relationship as
found with the analogous diethylamide dimers.
were not isolated and characterized, but which clearly
result from hydrosilation/reduction of the pyridine
nucleus.8 The case of 4-dimethylaminomethyl-N,N-di-
methylbenzamide is special and will be discussed below
in relation to the polymerization of 1,4-arylenediamides.
R ea ct ion s of N,N,N′,N′-Tet r a a lk ylt er ep h t h a ld i-
a m id es. To test the concept of applying reaction 2 to the
synthesis of polymers we have studied the polymerization
of N,N,N′,N′-tetraalkylterephthaldiamides, 29. The reac-
The yields of coupling products are, in general, very
good to excellent. Exceptions to this are the substrates
where the phenyl ring is substituted in the 2-position,
N,N-diethylnicotinamide and 4-dimethylaminomethyl-
N,N-dimethylbenzamide (9, 23, 26, and 27 in Table 1).
In the cases of the 2-substituted substrates, there is a
considerable reduction in the rates of all of the reactions
represented in (2), suggesting a general interference in
the binding of the substrate to the catalyst. A similar
effect was observed in the hydrosilation of 2-substituted
8
pyridines. In the case of N,N-diethylnicotinamide, the
reaction proceeds effectively in terms of conversion of
substrate, but the reduction of the 3-diethylamido func-
tion to 3-dimethylaminomethyl proceeds at about the
same rate as coupling. The remainder of the substrate
in this case is converted to a mixture of products that
tions were run at 80 °C, to minimize side reactions. The
progress of the reaction was followed by removing the
1
reaction mixture and analyzing the product by H NMR.
1
A typical H NMR spectrum of an oligomeric product,
as described above, is shown in Figure 2a, along with the
room temperature spectrum of the monomer, Figure 2b.
(8) Harrod, J . F.; Shu, R.; Woo, H. G. Can. J . Chem. 2001, 79, 1075.
J . Org. Chem, Vol. 69, No. 20, 2004 6845

Rangareddy et al.
F IGURE 2. 1H NMR spectra of (a) N,N,N′,N′-tetraethylterephthaldiamide coupling product and (b) N,N,N′N′-tetraethyltere-
phthaldiamide (in CDCl at room temperature).
3
It is clear from Figure 2a that coupling has taken
place, but that there is still a considerable concentra-
tion of unreacted amide end groups. The ratio of the
integrals for the methylene protons of the terminal
MS. Measurements were taken in both EI and CI modes
as well as MALDI. All three methods supported the same
conclusions.
The CI-MS spectrum of this sample is shown in Figure
3. The salient features of the spectrum are (i) the absence
of monomer, (ii) the presence of a series of peaks
corresponding to oligomers + H up to n ) 5, and possibly
up to n ) 7, (iii) the characteristic loss of a diethylamine
-
C(O)N(CH
2
CH
) groups indicates an average degree of
) for this sample of ca. 1.5. The
3 2
) groups to those of the internal
>
CH(NCH CH
2
3
polymerization (DP
n
relative simplicity of the spectrum also indicates the
presence of low molecular weight material. The methyl
from each oligomer, (iv) a strong peak due to the end
+
resonances of the terminal >C(O)N(CH
2
CH
3
)
2
groups
group, Et
2
N(CO)C
6
H
4
C H(NEt
2
) and the presence of a
(
3.0-3.6 ppm) are broad and lacking in any fine struc-
peak due to the loss of this group from each n-mer, and
(v) the absence of significant peaks which could signify
structural anomalies in the oligomer molecules.
ture, due to the restricted rotation about the >C(O)-N
bond at room temperature (also seen in the monomer),
while the methylenes of the internal >CH[N(CH
2
CH
3
)
2
]
The spectroscopic data clearly show that oligomeriza-
tion has taken place to produce a polymeric species with
the structure A, such as shown in (1). It is also clear,
however, that the yield of polymer is low and only a low
DP is achieved. Reactions were also carried out over
n
much longer times (up to 36 h), and with higher catalyst
concentration, with no significant improvement in either
groups appear as sharp overlapping multiplets in the
range 2.0-3.0 ppm. The methine protons of the
>
2 3 2
CH(NCH CH ) groups of the two diasteroisomers ap-
pear as two quite sharp singlets at 4.38 and 4.43 ppm,
as in the case of the benzamide dimers. The multiplicities
2 3 2
of the methylene resonances of the >CH(NCH CH )
groups are similar to, but more complex than, those of
the simple dimers, indicative of the presence of more than
one species. The two resonances of the methine protons
are due to the diastereomers, but unlike the methylene
resonances, the chemical shift differences are less sensi-
n
yield, or increase in DP . These facts suggest that the
reaction is limited either by catalyst deactivation, or by
the intercession of the side reactions shown in (2). The
latter explanation is unlikely, since the known side
2 2 2
reactions, i.e., reduction of C(O)NR to CH NR , and
tive to the DP
n
and the peaks are broadened but not split.
cleavage of the C-N bond of the amide function, would
give oligomeric species with masses quite easily distin-
guishable from those of the pristine oligomers, contrary
The purified product, whose NMR properties are de-
scribed in the previous paragraph, was also analyzed by
6
846 J . Org. Chem., Vol. 69, No. 20, 2004

Titanocene-Catalyzed Coupling of Aromatic Amides
F IGURE 3. The CI-MS spectrum of the N,N,N′,N′-tetraethylterephthaldiamide coupling product. The peaks at M+ 523, 769,
1
n
015, and 1261 amu correspond to DP ) 2, 3, 4, and 5, respectively.
TABLE 3. Resu lts for Tita n ocen e-Ca ta lyzed
Oligom er iza tion of Ar om a tic Am id es a t 80 °C w ith 10%
Ca ta lyst
to the MS evidence. A decline in catalyst activity is
therefore a more likely explanation.
The coupling of benzamides, under conditions identical
with those used in the current polymerization experi-
ments, shows no serious decline of catalytic activity over
the course of the reaction. Nor does depletion in reactant
concentrations seriously impair the yields of products.
reaction
time (h)
yield
(%)
highest
obsd (DPn)
c
substrate
N,N,N′,N′-tetraethyl-
terephthaladiamide
N,N,N′,N′-tetramethyl-
terephthaladiamide
N,N,N′,N′-tetramethyl-
isophthaladiamide
24
18
18
18
33a
5
3
3
37b
These facts point to the source of the problem of DP
tation as being either a specific electronic effect, charac-
teristic of the 4-CH(NR )C C(O)NR end group of the
n
limi-
43b
52b
2
6
H
4
2
N-methylphthalimide
7
oligomers, or an inhibition of catalyst by the product.
A qualitative comparison of the relative reactivities of
a
b
Polymer purified by precipitation from cyclohexane. Polymer
purified by precipitation from ether. c Based on CI-MS analysis.
PhC(O)NMe
the rate of reaction of PhC(O)NMe
of Me NCH C(O)NMe
2
and Me
2
NCH
2
C
6
H
4
C(O)NMe
2
indicated that
2
. the rate of reaction
2
2
C
6
H
4
2
.
positive aspects of the chemistry are (i) the commercial
availability, or easy synthesis of a wide range of amide
substrates at low to moderate cost, (ii) commercially
available catalyst materials, and (iii) one pot reactions
at acceptable rates and with simple workup. The most
serious limitations of the reaction are the lack of dias-
tereo- and enantioselectivity. Our attempts to control the
stereochemical outcome of the reaction by steric modifi-
cation of the basic titanocene structure have all led to a
reduction, or shutting down, of catalyst activity. We
therefore consider it unlikely that a solution to the lack
of stereocontrol will be found with titanocene-based
catalysts. A more profitable approach might be to inves-
Furthermore, the attempted coupling of samples of
isolated and purified oligomers, to give a product of
higher DP
cluded that the inhibition of polymerization is most likely
a consequence of the generation of the -C CH(NEt) -
n
, was unsuccessful. It may therefore be con-
6
H
4
2
function in the product of the initiation step. The specific
nature of the inhibition remains to be determined.
Rea ction s of Oth er Dia m id es. The reactions of
N,N,N′,N′-tetramethylisophthaldiamides and N-meth-
ylphthalimide were also studied and were found to give
the same types of products as the terephthaldiamides.
The conversions were, however, even lower than those
with the terephthaldimides and the reactions were not
studied in detail. A few results of such reactions are
shown in Table 3.
5
tigate some of the new mono-η -cyclopentadienyl tita-
nium or cyclopentadiene-free catalysts that have recently
9,10
been developed for other catalyses.
Our studies of terephthaldiamide coupling reactions
have established the principle that this type of reaction
may be applied to the synthesis of unusual polymers in
a simple one-pot reaction. However, the chemistry with
Discu ssion
Reaction 2 provides a fairly general route for the
synthesis of 1,2-(dialkyldiamino)-1,2-diarylethanes. The
J . Org. Chem, Vol. 69, No. 20, 2004 6847

Rangareddy et al.
III
•
SCHEME 1. A [Cp
Sequ en ce for th e Gen er a tion of Ar (NR
Ra d ica ls
2
TiH]-Med ia ted Rea ction
nated oxy radical complex (Ti -O ). Thus, the bond
breaking is assisted by stabilizing effects at both the C
atom and the O atom.
2
)CH•
The recycling of the titanyl species in Scheme 1 may
occur by a number of steps, some of which may also be
free radical in nature, and some of which may involve
σ-bond metathesis. The overall exchange of O between
Ti and Si is plausible, since facile metathesis of OR
groups between Ti-OR and Si-H is well-known, as also
1
4
is exchange of fluoride between Ti-F and Si-H.
Con clu sion s
It has been established that the titanocene-catalyzed
reactions of hydrosilanes with aromatic carboxamides
provide a versatile route for the synthesis of substituted
vicinal diamines. The reaction provides a simple one-pot
synthesis from cheap and widely available starting
materials. The utility of the chemistry is limited by the
lack of control over stereochemistry of the reaction. The
proposed free radical process for the coupling reaction is
probably responsible for the relative insensitivity of the
reaction to attempts to influence the stereochemical
outcome.
titanocene-based catalysts is also seriously limited by the
apparent product inhibition of reaction beyond low mo-
lecular weight oligomers.
Rea ction Mech a n ism
It was proposed earlier that the coupling reaction 2 is
5
most likely free radical in nature. The major justification
for this hypothesis is the very low sensitivity of the
diastereoselectivity of the reactions to wide variations in
substrate electronic and steric properties. A second
justification is the fact that the coupling reaction super-
cedes the other reactions shown in (2) at higher temper-
atures, a behavior that is expected for a thermolytic
process. The proposed sequence of steps leading to the
formation of the necessary free radicals is shown in
Scheme 1. In this scheme the organosilane serves as a
source of hydride ligand. There is ample evidence for the
formation of TiH complexes by reaction of organosilanes
with the titanocene precatalysts used in the current
reactions.11 Addition of Ti -H across the CdO bond of
the amide substrate results in species 3, a sterically
hindered alkoxy-titanium(III) complex. The tendency of
the O-C bond of this species to undergo homolysis is
enhanced by steric hindrance within the bulky ligand and
also by the stabilization of the resulting C radical by
electron delocalization through the N-C-Ar moiety.
There is abundant precedent for this type of radical
stabilization.12 A further factor favoring the C-O bond
We have established, in principle, that the coupling
reaction can be used to generate concatenated vicinal
diamines, but a strong inhibitory effect of the product’s
4
-dialkylaminomethyl group on the coupling of chain end
amide groups precludes the buildup of polymers with
molecular weights of practical interest. There is a pos-
sibility that this limitation could be overcome with more
active catalysts.
Exp er im en ta l Section
III
All amides used in this work were synthesized by re-
acting the respective acid chlorides with appropriate amines
according to literature methods (for N,N-dimethylbenza-
mides,15 N,N-diethylbenzamides, N,N-diphenylbenzamides,
16a
16b
1
7
and phthalic acid diamides ). The amides were characterized
by H NMR, IR, and mass spectral data. Where possible, the
1
melting points were determined and compared with literature
values. Cp
2
TiF
2
and Cp
2 2
TiMe were prepared by literature
procedures.1
8,19
The identities of all the products listed in
1
13
Tables 1 and 2 were determined from their H and C NMR
spectra, and where possible by comparison to literature data.
The following general procedures were used:
rupture is the formation of the Cp
2
TidO moiety. Al-
20
though this compound has not been isolated, it is
certainly a plausible reactive intermediate. Convincing
Meth od A. Rea ction s a t 80 °C: N,N′-Diethylbenzamide
(177 mg, 1 mmol), [Cp TiF ] (21 mg, 0.1 mmol), methylphe-
evidence for the transitory existence of (Me
5
C
5
)
2
TidO has
2
2
been reported.13 This species can be regarded as either a
nylsilane (0.28 mL, 2 mmol), and toluene (1 mL) were heated
at 80 °C for 1 h in a Schlenk tube. After the reaction mixture
had cooled to room temperature, ether (20 mL) was added and
the solution was extracted with 1 M HCl solution. The acid
Ti(IV) oxo complex (“titanyl”) or a titanium(III)-coordi-
(9) For example see: (a) Thorn, M. G.; Vilardo, J . S.; Hanna, B.;
Fanwick, P. E.; Rothwell, I. P. Organometallics 2000, 19, 5636. (b)
Stephen, D. W.; Stewart, J . C.; Guerin, F.; Courtenay, S.; Kickham,
J .; Hollink, E.; Beddie, C.; Hoskin, A.; Graham, T.; Wei, P.; Spence, R.
E.; Xu, W.; Koch, L.; Gao, X.; Harrison, D. G. Organometallics 2003,
(14) (a) Berk, S. C.; Buchwald, S. L. J . Am. Chem. Soc. 1991, 113,
5093. (b) Kablaoui, N. M.; Buchwald, S. L. J . Am. Chem. Soc. 1995,
117, 6785. (c) Abizzati, E.; Abis, L.; Peltenati, L.; Giannetti, E. Inorg.
Chim. Acta 1986, 120, 197.
(15) J ackman, L. M.; Kavanagh, T. E.; Haddon, R. C. Org. Magn.
Reson. 1969, 1, 109.
2
2, 1937. (c) Mahanthappa, M. K.; Cole, A. P.; Waymouth, R. M.
Organometallics 2004, 23, 836.
10) See: (a) Liang, L. C.; Schrock, R. R.; Davis, W. M. Organome-
(
tallics 2003, 19, 2526. (b) Thorn, M. G.; Etheridge, Z. C.; Fanwick, P.
E.; Rothwell, I. P. Organometallics 1998, 17, 3636. (c) Cavell, R. G.;
Babu, R. P.; Kasani, A.; McDonald, R. J . Am. Chem. Soc. 1999, 121,
(16) (a) Stenberg, V. I.; Singh. S. P.; Narain, N. K. J . Org. Chem.
1977, 42, 2244. (b) Herbert, R.; Wibberley, D. G. J . Chem. Soc. C 1969,
1505.
(17) Brouser, J . R.; Pamela, J . W.; Kurz, K. J . Org. Chem. 1983, 48,
4111.
(18) (a) Verdaguer, X.; Lange, U. E. W.; Reding, M. T.; Buchwald,
S. L. J . Am. Chem. Soc. 1996, 118, 6784. (b) Verdaguer, X.; Lange, U.
E. W.; Buchwald, S. L. Angew. Chem., Int. Ed. 1998, 37, 1103.
(19) Samuel, E.; Rausch, M. D. J . Am. Chem. Soc. 1973, 95, 6263.
(20) Betschart, C.; Seebach, D. Helv. Chim. Acta 1987, 70, 2215.
5
805.
(
11) Harrod, J . F. Coord. Chem. Rev. 2000, 206-207, 493.
(
12) See example (a) Macinnes, I.; Walton, J . C.; Nonhebel, D. C.
Chem. Commun. 1985, 712. (b) Daniel, K.; Morton R.; Kalman, A.
Chem. Commun. 1986, 346.
(
13) Milton R. S.; Phillip T. M.; Richard A. A. J . Am. Chem. Soc.
1
993, 115, 7049.
6
848 J . Org. Chem., Vol. 69, No. 20, 2004

Titanocene-Catalyzed Coupling of Aromatic Amides
extract was neutralized with 3 M KOH and extracted with
(s, 2H), 6.82 (s, 4H), 6.98 (s, 4H). 13C NMR (CDCl
) (meso) δ
3
ether. The ether layer was dried with anhydrous MgSO
4
and
43.79, 63.97, 124.66, 124.54, 129.57, 142.62; (rac) δ 43.29,
evaporated to give analytically pure N,N,N′,N′-tetraethyl-1,2-
diphenylethylenediamine. The rac-N,N,N′,N′-tetraethyl-1,2-
diphenylethylenediamine was separated from the residual
meso isomer on a silica gel column with use of a 10% ethyl
acetate:hexane mixture as an eluent.
63.62, 124.88, 124.98, 129.24, 142.19.
N,N,N′,N′-Tetr a eth yl-1,2-bis(3-flu or op h en yl)eth ylen e-
1
d ia m in e (5): Mp 126-128 °C. H NMR (CDCl
3
) (meso) δ 0.81
(
t, J ) 6.8 Hz, 12H), 1.87 (q, J ) 6.8 Hz, 4H), 2.53 (q, J ) 5.4
Hz, 4H), 4.29 (s, 2H), 7.02 (m, J ) 6.4 Hz, 4H), 7.39 (m, J )
6.4 Hz, 4H); (rac) δ 1.31 (t, J ) 7.2 Hz, 12H), 2.21 (q, J ) 6.2
Hz, 4H), 2.99 (q, J ) 5.4 Hz, 4H), 4.42 (s, 2H), 6.97-7.27 (m,
J ) 5.6 Hz, 8H).
2 2
Rea ction s a t 25 °C: [Cp TiF ] (21 mg, 0.1 mmol) and
methylphenylsilane (0.28 mL, 2 mmol) were heated at 80 °C
for 10 min to effect activation (reduction) of the precatalyst.
The green solution was cooled to room temperature, and
further aliquots of methylphenylsilane (0.28 mL, 2 mmol) and
N,N-diethylbenzamide (177 mg, 1 mmol) dissolved in toluene-
N,N,N′,N′-Tetr a eth yl-1,2-bis(4-tr iflu or om eth ylp h en yl)-
1
eth ylen ed ia m in e (6): H NMR (CDCl
3
) (meso) δ 0.67 (t, J )
9
4
9
4
.2 Hz, 12H), 1.92 (q, J ) 9.6 Hz, 4H), 2.47 (q, J ) 10.0 Hz,
(
0.5 mL) were added. The reaction was monitored by TLC, and
H), 4.35 (s, 2H), 7.30 (s, 4H), 7.53 (s, 4H); (rac) δ 1.12 (t, J )
1
the ratios of the products were calculated from their H NMR
spectra.
.6 Hz, 12H), 2.08 (q, J ) 8.6 Hz, 4H), 2.83 (q, J ) 6.8 Hz,
13
3
H), 4.46 (s, 2H), 7.13 (s, 4H), 7.37 (s, 4H). C NMR (CDCl )
2 2 2 2
Meth od B. [Cp TiMe ] was used instead of [Cp TiF ].
Typ ica l P r oced u r e for th e N,N-Dip h en ylben za m id e
Cou p lin g Rea ction . N,N-Diphenylbenzamide (1.365 g, 0.005
(
meso) δ 13.94, 43.77, 63.96, 124.34, 128.63, 129.05, 129.7,
142.23; (rac) δ 14.27, 43.30, 63.72, 124.78, 124.83, 129.4,
141.94.
mol), [Cp
2 2
TiF ] (0.1084 g, 0.0005 mol), methylphenylsilane
N,N,N′,N′-Tetr a eth yl-1,2-bis(3-tr iflu or om eth ylp h en yl)-
(1.224 g, 0.01 mol), and toluene (8 mL) were heated at 80 °C
1
eth ylen ed ia m in e (7): Mp 121-123 °C. H NMR (CDCl
3
)
for 4 h in a Schlenk tube under nitrogen. After the reaction
mixture had cooled to room temperature, ether (75 mL) was
added and the solution was extracted with 3 M HCl solution.
The acid extract was neutralized with 5 M KOH and extracted
(
meso) δ 0.69 (t, J ) 8.8 Hz, 12H), 1.87 (q, J ) 8.8 Hz, 4H),
2
4
2
6
.54 (q, J ) 6.4 Hz, 4H), 4.38 (s, 2H), 7.23 (m, J ) 3.6 Hz,
H), 7.39 (m, J ) 3.4 Hz, 4H); (rac) δ 1.26 (t, J ) 8.4 Hz, 12H),
.11 (q, J ) 8.6 Hz, 4H), 2.92 (q, J ) 8.6 Hz, 4H), 4.46 (s, 2H),
.99-7.27 (m, J ) 6.4 Hz, 8H).
with ether. The ether layer was dried with anhydrous MgSO
and evaporated to give a brown solid. (yield 0.61 g.)
4
N,N,N′,N′-Tetr a eth yl-1,2-bis(2-tr iflu or om eth ylp h en yl)-
Typ ica l P r oced u r e for Dia m id e P olym er iza t ion .
N,N,N′,N′-tetraethylterephthalimide (1.38 g, 0.005 mol),
1
eth ylen ed ia m in e (8): Mp 104-106 °C. H NMR (CDCl
3
)
(
meso) δ 0.76 (t, J ) 6.8 Hz, 12H), 2.01 (q, J ) 6.6 Hz, 4H),
2 2
[Cp TiF ] (0.1084 g, 0.0005 mol), methylphenylsilane (1.224
2
.54 (q, J ) 5.4 Hz, 4H), 4.41 (s, 2H), 7.32-7.73 (m, J ) 3.8
g, 0.01 mol), and toluene (5 mL) were heated at 80 °C for 24
h in a Schlenk tube under nitrogen. After the reaction mixture
had cooled to room temperature, ether (50 mL) was added and
the solution was extracted with 1 M HCl solution. The acid
extract was neutralized with 3 M KOH and extracted with
Hz, 8H); (rac) δ 1.13 (t, J ) 7.2 Hz, 12H), 2.10 (q, J ) 6.4 Hz,
4
2
H), 2.82 (q, J ) 5.8 Hz, 4H), 4.46 (s, 2H), 7.12-7.40 (m, J )
.8 Hz, 8H).
N,N,N′,N′-Tet r a et h yl-1,2-b is(4-m et h oxyp h en yl)et h yl-
1
en ed ia m in e (9): H NMR (CDCl
3
) (meso) δ 0.68 (t, J ) 7.6
4
ether. The ether layer was dried with anhydrous MgSO and
Hz, 12H), 1.90 (q, J ) 6.0 Hz, 4H), 2.46 (q, J ) 5.6 Hz, 4H),
.73 (s, 6H), 4.17 (s, 2H), 6.79 (s, 4H), 7.10 (s, 4H); (rac) δ 1.11
t, J ) 9.2 Hz, 12H), 2.05 (q, J ) 6.4 Hz, 4H), 2.80 (q, J ) 6.0
Hz, 4H), 3.68 (s, 6H), 4.30 (s, 2H), 6.66 (s, 4H), 6.98 (s, 4H).
evaporated to give a brown-yellow solid. This solid was
dissolved in cyclohexane (10 mL) and left overnight at 5 °C.
Precipitated solid was filtered off and the cyclohexane solution
was evaporated to give a glassy brown amorphous solid (yield
3
(
1
3
C NMR (CDCl ) (meso) δ 14.12, 43.81, 55.31, 63.67, 112.62,
3
0
.455 g).
1
1
30.68, 158.15; (rac) δ 14.39, 43.29, 55.17, 63.49, 112.94,
30.39, 130.63, 158.01.
Sp ecr oscop ic Da ta for 1,2-Dia m in es. N,N,N′,N′-Tetr a -
1
eth yl-(1,2-d ip h en yl)-eth ylen ed ia m in e (1): H NMR (CDCl
3
)
N,N,N′,N′-Tetr a eth yl-1,2-bis(4-m eth ylp h en yl)eth ylen e-
(
2
meso) δ 0.73 (t, J ) 6.8 Hz, 12H), 1.97 (q, J ) 6.4 Hz, 4H),
1
d ia m in e (10): H NMR (CDCl
1
3
) (meso) δ 0.77 (t, J ) 9.6 Hz,
.53 (q, J ) 6.0 Hz, 4H), 4.32 (s, 2H), 7.20-7.32 (m, J ) 6.4
2H), 2.00 (q, J ) 8.0 Hz, 4H), 2.36 (s, 6H), 2.55 (q, J ) 9.6
Hz, 8H); (rac) δ 1.14 (t, J ) 7.2 Hz, 12H), 2.13 (q, J ) 6.4 Hz,
Hz, 4H), 4.31 (s, 2H), 7.11-7.17 (m, J ) 8.0 Hz, 8H); (rac) δ
1.13 (t, J ) 9.6 Hz, 12H), 2.06 (q, J ) 9.6 Hz, 4H), 2.20 (s,
4
4
1
1
H), 2.86 (q, J ) 5.2 Hz, 4H), 4.41 (s, 2H), 7.05-7.13 (m, J )
13
Hz, 8H). C NMR (CDCl ) (meso) δ 14.07, 43.83, 64.35,
3
6
4
6
H), 2.80 (q, J ) 9.6 Hz, 4H), 4.36 (s, 2H), 6.91-6.98 (m, J )
26.43, 127.30, 129.80, 138.58; (rac) δ 14.41, 43.36, 64.16,
26.52, 127.61, 129.52, 138.37.
.8 Hz, 8H). 13C NMR (CDCl
) (meso) δ 14.12, 21.40, 43.85,
3
3.87, 128.04, 129.69, 135.37, 135.69; (rac) δ 14.41, 21.24,
N,N,N′,N′-Tetr a eth yl-1,2-bis(4-ch lor op h en yl)eth ylen e-
1
43.31, 63.53, 128.35, 129.38, 135.07, 135.77.
d ia m in e (2): Mp 141-143 °C. H NMR (CDCl
3
) (meso) δ
N,N,N′,N′-Tetr a eth yl-1,2-bis(3-m eth ylp h en yl)eth ylen e-
0
.74 (t, J ) 6.8 Hz, 12H), 1.96 (q, J ) 6.4 Hz, 4H), 2.51 (q, J
1
d ia m in e (11): Mp 72-74 °C. H NMR (CDCl
3
) (meso) δ 0.75
)
1
7.2 Hz, 4H), 4.27 (s, 2H), 7.17 (s, 4H), 7.29 (s, 4H); (rac) δ
(
t, J ) 7.2 Hz, 12H), 1.98 (q, J ) 7.2 Hz, 4H), 2.37 (s, 6H),
.27 (t, J ) 7.2 Hz, 12H), 2.24 (q, J ) 6.4 Hz, 4H), 2.97 (q, J
5.6 Hz, 4H), 4.48 (s, 2H), 7.12 (s, 4H), 7.27 (s, 4H). 1 C NMR
3
2.53 (q, J ) 7.2 Hz, 4H), 4.29 (s, 2H), 7.13-7.24 (m, J ) 5.6
)
Hz, 8H); (rac) δ 1.30 (t, J ) 7.2 Hz, 12H), 2.07 (q, J ) 6.4 Hz,
(
CDCl
3
) (meso) δ 14.01, 43.75, 63.76, 127.59, 130.87, 132.19,
36.77; (rac) δ 14.30, 43.26, 63.60, 128.06, 130.56, 132.34,
4
7
H), 2.21 (s, 6H), 2.78 (q, J ) 7.2 Hz, 4H), 4.33 (s, 2H), 6.91-
.28 (m, J ) 4.4 Hz, 8H).
1
1
36.61.
N,N,N′,N′-Tetr a eth yl-1,2-bis(3-ch lor op h en yl)eth ylen e-
N,N,N′,N′-Tetr a eth yl-1,2-bis(4-cya n op h en yl)eth ylen e-
1
1
d ia m in e (3): Mp 132-134 °C. H NMR (CDCl
3
) ! δ 0.72 (t, J
d ia m in e (12). H NMR (CDCl
3
) (meso) δ 0.76 (t, J ) 6.8 Hz,
)
7.2 Hz, 12H), 1.87 (q, J ) 6.4 Hz, 4H), 2.32 (q, J ) 5.8 Hz,
H), 4.21 (s, 2H), 7.07-7.23 (m, J ) 4.2 Hz, 8H); (rac) δ 1.31
t, J ) 7.2 Hz, 12H), 2.31 (q, J ) 6.2 Hz, 4H), 2.99 (q, J ) 6.0
12H), 2.01 (q, J ) 6.4 Hz, 4H), 2.58 (q, J ) 6.4 Hz, 4H), 4.36
(s, 2H), 7.28-7.59 (m, J ) 4.8 Hz, 8H); (rac) δ 1.14 (t, J ) 7.2
Hz, 12H), 2.16 (q, J ) 6.8 Hz, 4H), 2.92 (q, J ) 5.4 Hz, 4H),
4.43 (s, 2H), 7.08-7.46 (m, J ) 4.2 Hz, 8H).
4
(
1
3
Hz, 4H), 4.38 (s, 2H), 6.89-7.21 (m, J ) 3.8 Hz, 8H). C NMR
(
(
CDCl
3
) (meso) δ 43.11, 63.02, 126.87, 127.67, 129.44, 136.63;
N ,N ,N ′,N ′-Te t r a e t h yl-1,2-b is(4-N ,N -d im e t h yla m in o-
1
rac) δ 42.97, 62.91, 127.99, 131.56, 132.66, 137.02.
p h en yl)eth ylen ed ia m in e (13): H NMR (CDCl ) (meso) δ
3
N,N,N′,N′-Tetr a eth yl-1,2-bis(4-flu or op h en yl)eth ylen e-
0.78 (t, J ) 6.8 Hz, 12H), 1.99 (q, J ) 7.8 Hz, 4H), 2.48 (q, J
) 7.8 Hz, 4H), 2.89 (s, 6H), 4.22 (s, 2H), 6.69-7.14 (m, J )
4.8 Hz, 8H); (rac) δ 1.11 (t, J ) 6.4 Hz, 12H), 2.21 (q, J ) 6.8
Hz, 4H), 2.96 (q, J ) 6.4 Hz, 4H), 2.64 (s, 12H), 4.28 (s, 2H),
6.43-6.94 (m, J ) 6.6 Hz, 8H).
1
d ia m in e (4): H NMR (CDCl
3
) (meso) δ 0.75 (t, J ) 9.2 Hz,
1
(
1
2H), 1.99 (q, J ) 8.4 Hz, 4H), 2.51 (q, J ) 9.6 Hz, 4H), 4.27
s, 2H), 7.03 (s, 4H), 7.13 (s, 4H); (rac) δ 1.14 (t, J ) 8.8 Hz,
2H), 2.09 (q, J ) 8.0 Hz, 4H), 2.82 (q, J ) 8.8 Hz, 4H), 4.34
J . Org. Chem, Vol. 69, No. 20, 2004 6849

Rangareddy et al.
1
,2-Bis(N-m et h yl-N-p h en yla m in o)-1,2-p h en ylet h a n e
(meso) δ 1.98 (s, 12H), 4.20 (s, 2H), 7.15-7.46 (m, J ) 5.2 Hz,
8H); (rac) δ 2.29 (s, 12H), 4.31 (s, 2H), 7.09-7.36 (m, J ) 4.8
1
(
2
14): H NMR (CDCl
3
) δ 2.72 (s, 6H), 2.70 (s, 6H), 5.45 (s,
H), 5.40 (s, 2H), 6.63, 6.72, 6.88, 7.12, 7.28 (m, 20H).
,2-Bis(d ieth yla m in o)-1,2-bis(2-n a p h th yl)eth a n e (15):
H NMR (CDCl ) (meso) δ 0.68 (t, J ) 9.2 Hz, 12H), 2.00 (q,
Hz, 4H). 13C NMR (CDCl
) (meso) δ 41.48, 78.43, 124.27,
3
1
125.94, 128.72, 138.02; (rac) δ 41.11, 78.62, 123.97, 124.62,
125.82, 128.44, 139.14.
1
3
J ) 8.8 Hz, 4H), 2.56 (q, J ) 8.8 Hz, 8H), 4.58 (s, 2H),
N,N,N′,N′-Tetr a m eth yl-1,2-bis(3-tr iflu or op h en yl)eth yl-
1
7
1
(
.36-7.81 (m, J ) 4.8 Hz, 8H); (rac) δ 1.18 (t, J ) 9.6 Hz,
2H), 2.18 (q, J ) 8.4 Hz, 4H), 2.92 (q, J ) 9.6 Hz, 8H), 4.71
en ed ia m in e (22): Mp 147-149 °C. H NMR (CDCl ) (meso)
3
δ 1.98 (s, 12H), 4.21 (s, 2H), 7.21-7.57 (m, J ) 4.0 Hz, 8H);
(rac) δ 2.29 (s, 12H), 4.31 (s, 2H), 7.14-7.32 (m, J ) 4.6 Hz,
8H).
1
3
3
s, 2H), 7.26-7.68 (m, J ) 4.6 Hz, 8H). C NMR (CDCl )
(
meso) δ 14.19, 43.93, 64.38, 125.37, 125.72, 126.55, 127.77,
1
6
1
28.16, 128.60, 132.70, 133.28, 136.47; (rac) δ 14.48, 43.67,
4.89, 125.02, 125.98, 126.41, 127.20, 128.19, 128.66, 133.21,
37.02.
N,N,N′,N′-Tetr a m eth yl-1,2-bis(2-tr iflu or op h en yl)eth yl-
1
en ed ia m in e (23): Mp 79-81 °C. H NMR (CDCl
3
) (meso) δ
2
.13 (s, 12H), 4.52 (s, 2H), 7.29-7.66 (m, J ) 4.4 Hz, 8H); (rac)
N,N,N′,N′-Tet r a m et h yl-1,2-d ip h en ylet h ylen ed ia m in e
δ 2.41 (s, 12H), 4.94 (s, 2H), 6.98-7.33 (m, J ) 4.2 Hz, 8H).
N,N,N′,N′-Tet r a m et h yl-1,2-bis(4-m et h ylp h en yl)et h yl-
1
(
16): H NMR (CDCl
3
) (meso) δ 1.96 (s, 6H), 4.13 (s, 2H), 7.23-
7
6
4
6
.41 (m, J ) 2.8 Hz, 8H); (rac) δ 2.24 (s, 6H), 4.23 (s, 2H),
en ed ia m in e (24): 1H NMR (CDCl
Hz 12H), 4.29 (s, 2H), 2.38 (s, 6H), 7.02-7.16 (m, J ) 2.6 Hz,
H); (rac) δ 1.08 (t, J ) 6.8 Hz, 12H), 4.33 (s, 2H), 2.34 (s,
3
) (meso) δ 0.75 (t, J ) 6.6
.98-7.13 (m, J ) 1.6 Hz, 8H). 1 C NMR (CDCl
) (meso) δ
3
3
0.96, 68.62, 127.11, 127.66, 129.56, 135.16; (rac) δ 41.04,
8
6
8.06, 126.83, 127.48, 130.13, 133.96.
13
H), aromatic, 6.82-6.86, 7.16-7.20 (m, J ) 6.8 Hz, 8H).
) (meso) δ 24.37, 41.16, 78.30, 128.14, 129.23,
34.72; (rac) δ 25.2, 41.88, 79.02, 127.94, 129.43, 133.71.
N,N,N′,N′-Tet r a m et h yl-1,2-bis(3-m et h ylp h en yl)et h yl-
C
N,N,N′,N′-Tetr a m eth yl-1,2-bis-(4-ch lor op h en yl)-eth yl-
NMR (CDCl
3
1
en ed ia m in e (17): Mp 140-142 °C. H NMR (CDCl
3
) (meso)
1
(mp 140-142 °C) δ 1.95 (s, 12H), 4.06 (s, 2H), 7.13 (s, 4H),
7
7
1
.33 (s, 4H); (rac) δ 2.25 (s, 12H), 4.21 (s, 2H), 6.89 (s, 4H),
1
3
en ed ia m in e (25): Mp 142-144 °C. H NMR (CDCl ) (meso)
13
.11 (s, 8H). C NMR (CDCl ) (meso) δ 41.08, 78.29, 129.59,
3
δ 0.73 (t, J ) 6.6 Hz, 12H), 4.25 (s, 2H), 2.37 (s, 6H), 7.12-
31.61, 133.10; (rac) δ 41.89, 78.37, 129.02, 130.99, 133.43.
N,N,N′,N′-Tet r a m et h yl-1,2-b is(3-ch lor op h en yl)et h yl-
7
4
.24 (m, J ) 2.6 Hz, 8H); (rac) δ 1.11 (t, J ) 7.2 Hz, 12H),
.37 (s, 2H), 2.39 (s, 6H), 6.73-7.19 (m, J ) 7.2 Hz, 8H).
1
en ed ia m in e (18): Mp 176-178 °C. H NMR (CDCl
3
) (meso)
N,N,N′,N′-Tet r a et h yl-1,2-b is(3-p yr id ylyl)et h ylen ed i-
(
mp 176-178 °C) δ 1.98 (s, 12H), 4.05 (s, 2H), 7.08-7.32 (m,
1
a m in e (27): H NMR (CDCl
3
) (meso) δ 0.69 (t, J ) 6.8 Hz,
J ) 4.0 Hz, 8H); (rac) δ 2.55 (s, 12H), 4.17 (s, 2H), 6.84-7.19
1
3
12H), 1.95 (q, J ) 6.2 Hz, 4H), 2.47 (q, J ) 6.2 Hz, 2H), 4.29
s, 2H), 7.18 (m, J ) 4.6 Hz, 2H), 7.55 (s, 2H), 8.44 (m, J ) 7.2
Hz, 4H); (rac) δ 0.77 (t, J ) 7.2 Hz, 12H), 2.11 (q, J ) 6.6 Hz,
H), 2.58 (q, J ) 8.6 Hz, 4H), 4.37 (s, 2H), 7.27 (m, 2H), 7.61
(
1
1
m, J ) 5.6 Hz, 8H). C NMR (CDCl ) (meso) δ 41.94, 77.79,
3
(
26.03, 130.34, 134.45, 136.28; (rac) δ 41.04, 77.51, 125.98,
28.04, 130.63, 134.11, 136.83.
4
N,N,N′,N′-Tet r a m et h yl-1,2-b is(4-flu or op h en yl)et h yl-
1
3
1
(m, 2H), 8.52 (s, 4H). C NMR (CDCl
3
) (meso) δ 43.83, 62.25,
en ed ia m in e (19): Mp 107-109 °C. H NMR (CDCl
3
) (meso)
1
22.73, 133.37, 136.59, 148.26, 150.92.
δ 1.95 (s, 12H), 4.06 (s, 2H), 7.02 (s, 4H), 7.15 (s, 4H); (rac) δ
.23 (s, 12H), 4.18 (s, 2H), 6.76 (s, 4H), 7.05 (s, 4H). 13C NMR
CDCl
2
(
(
3
) (meso) δ 42.48, 78.54, 116.04, 129.82, 130.69, 156.11;
Ack n ow led gm en t. We thank the Natural Sciences
and Engineering Research Council (Canada) and the
Fonds FCAR du Qu e´ bec for support of this work.
rac) δ 41.91, 78.66, 115.69, 129.42, 130.42, 157.33.
N,N,N′,N′-Tet r a m et h yl-1,2-b is(3-flu or op h en yl)et h yl-
1
en ed ia m in e (20): Mp 99.5-101 °C. H NMR (CDCl
3
) (meso)
δ 1.98 (s, 12H), 4.07 (s, 2H), 6.99-7.35 (m, J ) 4.0 Hz, 8H);
1
Su p p or tin g In for m a tion Ava ila ble: Copies of H NMR
(rac) δ 2.25 (s, 12H), 4.17 (s, 2H), 6.65-7.12 (m, J ) 4.6 Hz,
spectra for meso and rac isomers of compounds 2, 9, 14, 15,
13
8
1
1
H). C NMR (CDCl
3
) (meso) δ 42.41, 78.89, 117.62, 129.78,
13
and 16 and C NMR spectra of meso and rac isomers of
30.41, 156.87; (rac) δ 41.89, 79.46, 115.69, 129.82, 130.77,
58.02.
compounds 6, 10, and 16. This material is available free of
charge via the Internet at http://pubs.acs.org.
N,N,N′,N′-Tetr am eth yl-1,2-bis(4-tr iflu or om eth ylph en yl)-
1
eth ylen ed ia m in e (21): Mp 154-156 °C. H NMR (CDCl
3
)
J O049220B
6
850 J . Org. Chem., Vol. 69, No. 20, 2004