Synthesis and aggregation properties of two- and three-armed nitrogen-rich chelate ligands: Novel bis(N-acylamidines), tris(N-acylamidines) and bis(triazapentadienes) with flexible or rigid spacers

Article abstract of DOI:10.1002/ejoc.201100218

Two- and three-armed ligands, like bis(N-acylamidines) 7 and 9, tris(N-acylamidines) 8 and bis(1,3,5-triazapenta-1,3-dienes) 10 with different spacers between the ligand moieties, have been easily prepared in moderate-to-good yields starting from diamines

Full text of DOI:10.1002/ejoc.201100218

FULL PAPER
DOI: 10.1002/ejoc.201100218
Synthesis and Aggregation Properties of Two- and Three-Armed Nitrogen-Rich
Chelate Ligands: Novel Bis(N-acylamidines), Tris(N-acylamidines) and
Bis(triazapentadienes) with Flexible or Rigid Spacers[‡]
Juliana Isabel Clodt,[a] Christof Wigbers,[a] Ralph Reiermann,[a] Roland Fröhlich,[a] and
Ernst-Ulrich Würthwein*[a]
Keywords: Supramolecular chemistry / N,O ligands / N ligands / Amidines / Imidates
Two- and three-armed ligands, like bis(N-acylamidines) 7
and 9, tris(N-acylamidines) 8 and bis(1,3,5-triazapenta-1,3-
dienes) 10 with different spacers between the ligand moie-
ties, have been easily prepared in moderate-to-good yields
starting from diamines, triamines or dicarboxylic acid deriva-
tives. Thus, the reaction of diamines and triamines with N-
obtained starting from dicarboxylic acid dichlorides and
amidines. Bis(triazapentadienes) 10, linked through carbon
atoms, were synthesized from a diamide, which was con-
verted into a bis(N-imidoylimidate) 17 followed by reactions
with deprotonated amines. These compounds show variable
aggregation behaviour in the solid state as a result of intra-
acylimidates 3 led to bis(N-acylamidines) 7 and tris(N-acyl- and intermolecular hydrogen bonding. All compounds were
amidines) 8, respectively, linked through the amino group.
Ligands 9, interconnected through the carbonyl groups, were
thoroughly characterized including by X-ray diffraction.
Introduction
The development of novel ligands suitable for metal co-
ordination to construct metallamacrocycles or the respec-
tive cavities is one of many challenges for chemists in the
field of supramolecular chemistry. N-Acylamidines[1,2]
1
and 1,3,5-triazapenta-1,3-dienes[3] 2 are effective nitrogen-
rich mono- or bidentate ligands for metal-ion coordination
(Scheme 1). Compared with β-imino ketones[4] or β-di-
imines,[5] the nitrogen atom at the 3-position alters the elec-
tronic structures considerably so that conjugation over all
five atoms is observed, even in the neutral form. Further-
more, this central nitrogen atom may also act as a ligand
site for metal complexation.
Primary and secondary N-acylamidines 1 as well as
1,3,5-triazapentadienes 2 are subject to tautomerism in
which a proton might be positioned at the amino group
(tautomer A), at the central nitrogen atom (tautomer B)
or at the oxygen atom (tautomer C; Scheme 1). A detailed
discussion of this tautomerism was recently published by
Wigbers et al.[6] For 1,3,5-triazapentadienes 2,[7] two tauto-
mers may be formulated. With respect to stability and to
possible metal–ion coordination, the U forms with intramo-
lecular hydrogen bonding are of special interest.
Scheme 1. N-Acylamidines 1 and 1,3,5-triazapentadienes 2 and
their different tautomers.
and benzoic acid anhydride.[8] The treatment of N-acylimid-
ates 3 with amines is another useful pathway for the synthe-
sis of N-acylamidines 1 (Scheme 2).[6]
The synthesis of N-acylamidines 1 was first described by
Pinner in 1889 by reaction of benzamidine hydrochloride
[‡] Unsaturated Hetero Chains, XX. Part XIX: Ref.[2]
[a] Organisch-Chemisches Institut, Westfälische Wilhelms-
Universität,
Corrensstraße 40, 48149 Münster, Germany
Fax: +49-251-83-39772
E-mail: wurthwe@uni-muenster.de
Scheme 2. Synthesis of N-acylamidines 1 reported by Wigbers et
al.[6]
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An analogous reaction for the preparation of tertiary and triazapentadienes were adjusted for the synthesis of such
quaternary 1,3,5-triazapenta-1,3-dienes 2 was investigated ligands with two and three chelating moieties and on the
by Häger et al. (Scheme 3).[9] Starting from imidates 4, other hand we reveal that the novel derivatives form inter-
which were treated with imidoyl chlorides 5 to give N-imid- esting assemblies in the solid state as a result of hydrogen
oyl imidates 6, it was possible to generate triazapentadienes bonding.
2. Another method was described by Ley and Müller in
1907 based on the reaction of N-imidoyl halides 5 with
amidines.[10] Additional reaction pathways for the synthesis
Results and Discussion
of 1,3,5-triazapenta-1,3-dienes 2 have been described by
Cooper, Partridge and Short.[11]
Bis(N-acylamidines) 7 Linked Through Amino Groups
In our previous report we described the synthesis of
bis(N-acylamidines) from dicarboxylic acid or dinitriles as
commercially available starting materials.[21] This method
was limited to the generation of bis(N-acylamidines) linked
through the carbonyl groups of the amidine unit. To synthe-
size bis(N-acylamidines) 7, linked through the amino
groups, another procedure starting from diamines was re-
quired. Therefore the synthesis of N-acylamidines reported
previously was adjusted to molecules with flexible or inflex-
Scheme 3. Synthesis of tertiary 1,3,5-triazapenta-1,3-dienes 2 by
Häger et al.[9]
ible spacers separating the chelating subgroups.[6]
To prepare the novel N-linked bis(N-acylamidines) 7a–o,
1 equiv. of a diamine 11 was treated with at least 2 equiv.
of N-acylimidate 3 (Scheme 5). The reactions took place
either in solvent-free conditions at 80–90 °C for 5 h or at
reflux temperature in dioxane for 16 h. By these methods,
15 different bis(N-acylamidines) (7a–o) with flexible or ste-
rically constrained spacer units were synthesized in moder-
ate-to-good yields (Table 1).
The use of two- and three-armed ligands with flexible or
inflexible spacer groups between two or more ligand moie-
ties for manifold metal coordination is a current topic of
interest in the field of supramolecular chemistry.[12] To ex-
tend our research from ligands with one chelating coordina-
tion site like N-acylamidines 1 and triazapentadienes 2, we
started to investigate the suitable synthesis of N- and C-
linked bis(N-acylamidines) 7 and 9, tris(N-acylamidines) 8
and C-linked bis(triazapentadienes) 10 (Scheme 4).
Scheme 4. N- and C-linked bis(N-acylamidines) 7 and 9, tris(N-
acylamidines) 8 and bis(triazapentadienes) 10.
Scheme 5. Synthesis of bis(N-acylamidines) 7 linked through the
amino moiety. Reaction conditions: a) 80–90 °C, 5 h; b) dioxane,
101 °C, 16 h.
In this context, bis(triazapentadienes) and oligomers
with small spacer molecules have been reported by Greving
The choice of ligands and substituents was based on as-
and co-workers[13] and poly(triazapentadienes) have been pects of flexibility (7a–f) combined with variable steric bulk
described in a patent by Dorfman et al.[14] Similar com- and electronic effects exerted by aliphatic and aryl groups.
pounds, such as bis(N-acylthioureas),[15,16] bis(N-acylguan- These patterns proved to be important for the structural,
idines)[17,18] and bis(N-acylisoureas),[19,20] have also been catalytic and supramolecular properties of various metal
described in the literature. In 2010 we reported a method coordination compounds.[22] Two examples (7g,h) are based
for the synthesis of bis(N-acylamidines) 9 linked through on the chiral diamine trans-1,2-diaminocyclohexane, which
carbonyl moieties using N-acylbenzotriazoles as acylation offers the possibility of asymmetric complexes. Compounds
agents.[21] In this paper we report our results on the prepa- 7i–o contain aromatic moieties with varying structural and
ration of bis(N-acylamidines) 9, N-linked bis(N-acyl- electronic properties, 7j with its pyridine-based spacer offers
amidines) 7, tris(N-acylamidines) 8 and C-linked bis(triaza- an additional site for coordination and hydrogen bonding.
pentadienes) 10. On the one hand we will demonstrate how Compounds 7i–m contain a central spacer group with lim-
procedures for the synthesis of mono-N-acylamidines and ited flexibility and thus offer varying steric constraints but
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Two- and Three-Armed Nitrogen-Rich Chelate Ligands
Table 1. Bis(N-acylamidines) linked through the amino moiety.
dated by single-crystal X-ray diffraction. In the solid state,
7a and 7g form one-dimensional networks (open-chain tau-
tomer A, Scheme 1) interconnected by the intermolecular
hydrogen bonding of both NH subunits to the carbonyl
functions of two neighbouring molecules (7a: NH···O dis-
tance 1.94 Å, N···O distance 2.78 Å; 7g: NH···O distance
2.06 Å, N···O distance 2.88 Å; sum of the van der Waals ra-
dii:[23] O + H 2.72 Å, N + O 3.07 Å; compare also Fig-
ure 4).
The molecular structure of compound 7j is depicted in
Figure 1. Interestingly, unsymmetrical intramolecular hy-
drogen bonds are formed exclusively between the amino
protons and the nitrogen atom of the pyridine spacer unit
(tautomer B, Scheme 1), whereas other bis(N-acylamidines)
are characterized by the intermolecular hydrogen bonding
of amino protons (see below, compare Figures 2 and 4). The
NH···N distances are 1.98 and 2.21 Å (N···N distances: 2.71
and 2.82 Å; sum of the van der Waals radii:[23] N + H
2.75 Å, N + N 3.10 Å).
Figure 1. Molecular structure of 7j as obtained by X-ray diffraction
(hydrogen atoms have been omitted for clarity).
Figure 2. Part of the molecular assembly of 9c (U and Z isomers)
as obtained by X-ray diffraction.
[a] 80–90 °C, 5 h. [b] Dioxane, 101 °C, 16 h.
Tris(N-acylamidines) 8
allow rotation about one or at most two single bonds. The
Three novel tris(N-acylamidines) 8a–c, linked through
last two compounds 7n and 7o restrict the relative positions the amino moiety, were synthesized under similar condi-
of both chelating parts almost completely. tions using tris(2-aminoethyl)amine (12) and 3 equiv. of N-
All the compounds are crystalline solids and are stable acylimidates 3 as starting materials. The reaction was car-
at room temperature. The conformation and configuration ried out in dioxane at 70–90 °C for 16 h (Scheme 6 and
in the solid state of compounds 7a, 7g and 7j were eluci- Table 2).
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Table 3. Bis(N-acylamidines) 9 linked through the carbonyl moiety.
Scheme 6. Synthesis of tris(N-acylamidines) 8 linked through the
amino moiety.
Table 2. Tris(N-acylamidines) 8a–c.
N-Acylimidate
Product
R
Yield [%]
[a] KOtBu, THF 10 °C to r.t., 24 h. [b] Et3N, DCM, 0 °C to r.t.,
16 h.
3a
3b
3c
8a
8b
8c
tBu
Ph
4-CF3Ph
8
30
18
the hydrogen bonds in the supramolecular network are
formed between amino protons and oxygen atoms (tauto-
mer A, Scheme 1). In the framework, two different con-
formers, the U- and Z-shaped isomers, form as a result of
rotation of the central bond of the biphenyl system (Fig-
ures 2 and 3). The intramolecular hydrogen bonds have O–
N distances of 2.53 and 2.63 Å in the case of the U-shape
isomer and 2.65 Å in the case of the Z-shape, whereas we
find for the intermolecular hydrogen bonds distances of
2.88 and 2.91 Å.
Bis(N-acylamidines) 9 Linked Through the Carbonyl
Groups
Bis(N-acylamidines) 9, linked through the carbonyl moi-
ety, were synthesized from dicarboxylic acid dichlorides and
amidines in good yields in analogy to the work of Katritzky
and co-workers on mono(N-acylamidines) (Scheme 7 and
Table 3)[24] using two different reaction conditions de-
pending on the nature of the spacer. The amidines 14 were
deprotonated with potassium tert-butoxide and then treated
with the diacid dichlorides in tetrahydrofuran to give low
yields of products 9a and 9b. The synthesis of the primary
bis(N-acylamidines) linked by inflexible spacers (9c and 9d)
using triethylamine as the deprotonating agent in dichloro-
methane or chloroform solution was more successful. The
products were obtained in good yields. They are crystalline
solids and their structures were confirmed by X-ray diffrac-
tion.
Bis(1,3,5-triazapentadienes) 10 Linked Through the Carbon
Atoms
To synthesize bis(1,3,5-triazapentadienes), we adapted
the procedure of Häger et al. using N-imidoylimidates and
deprotonated amines as precursors.[9] Thus, bis(N-imid-
oylimidate) 17 was synthesized starting from diamide 15 via
the bis(imidoyl chloride) 16 (Scheme 8). The structure of
compound 17 was proven by X-ray diffraction. The reaction
of bis(N-imidoylimidate) 17 with 5 equiv. of deprotonated
primary amines gave the novel tertiary bis(1,3,5-tri-
azapenta-1,3-dienes) 10a–c in moderate-to-good yields
(Scheme 8 and Table 4).
All compounds are crystalline solids and stable at room
temperature. The structure of compound 10a was charac-
terized by single-crystal X-ray diffraction (Figure 4 and Fig-
ure 5).
Compound 10a assembles to form a supramolecular
chain (Figure 5). One side of the bis(triazapentadiene) is
connected to another bis(triazapentadiene) through inter-
molecular hydrogen bonding and the other side forms a hy-
drogen bond to a tetrahydrofuran solvent molecule. The in-
teraction takes place between two terminal nitrogen atoms
within the N–C–N–C–N chain (open-chain tautomer A,
Scheme 7. Synthesis of bis(N-acylamidines) 9a–d linked through
the carbonyl moiety. Reaction conditions: a) for 9a,b: KOtBu,
THF, 10 °C to r.t., 24 h; b) for 9c,d: Et3N, CH2Cl2 or CHCl3,
–10 °C to r.t., overnight.
The crystal structures of the bis(N-acylamidines) 9c and Scheme 1). In the resulting structure, N–N distances of the
9d are both characterized by inter- and intramolecular hy- intermolecular hydrogen bonds measure 3.03 Å. This means
drogen bonding leading to supramolecular networks. Exem- that the interaction is weak considering the sum of the
plarily, the structure of 9c is shown in Figures 2 and 3. All van der Waals radii N + N of 3.10 Å.[23]
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Two- and Three-Armed Nitrogen-Rich Chelate Ligands
Figure 3. Supramolecular structure of 9c as obtained by X-ray diffraction.
Figure 5. Supramolecular structure of 10a as obtained by X-ray
diffraction (hydrogen atoms have been omitted for clarity).
Scheme 8. Synthesis of bis(triazapentadienes) 10 via bis(N-imid-
oylimidate) 17.
Conclusions
We have reported the synthesis of 19 different bis(N-acyl-
amidines) 7 and 9 linked either through the amino or the
carbonyl moieties. The compounds have quite different
spacer groups, which affects the geometry: more and less
flexible aliphatic chains or inflexible aromatic groups.
Furthermore, three tris(N-acylamidines) 8 and three bis(tri-
azapentadienes) 10 have been reported. The compounds
show interesting aggregation behaviour in the solid state,
giving supramolecular arrangements as a result of intra-
and intermolecular hydrogen bonding, leading to the for-
mation of polymeric linear chains or large cyclic superstruc-
tures. Reports on the coordination chemistry of the bis(N-
acylamidines) and their catalytic properties in cross-cou-
pling reactions are in preparation.[12,22]
Table 4. Bis(triazapentadienes) 10a–c prepared from bis(N-imid-
oylimidate) 17.
Product
R
Yield [%]
10a
10b
10c
Ph
pTol
4-ClPh
59
75
52
Experimental Section
Materials and Methods: IR: Nicolet 5DXC spectrometer (KBr pel-
lets), Varian 3100 FT-IR spectrometer using a Specac Golden Gate
Single Reflection ATR sampling system. 1H NMR: Bruker WM
Figure 4. Molecular structure of 10a as obtained by X-ray diffrac-
tion (hydrogen atoms have been omitted for clarity).
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300 (300.13 MHz) and Bruker AMX 400 (400.13 MHz) spectrome-
ters; internal reference: tetramethylsilane or solvent. 13C NMR:
Bruker WM 300 (75.47 MHz) and Bruker AMX 400 (100.61 MHz)
spectrometers; internal reference: solvent; Sp = spacer. CHN ele-
mental analysis: Elementar Vario El III Instrument. All solvents
were rigorously dried by the standard methods. When necessary,
the experiments were carried out with complete exclusion of moist-
ure (argon, septum/syringe technique) in glassware that had been
thoroughly dried by repeated heating under argon and subsequent
evacuation.
C13H17NO2 + Na 242.1151; found 242.1158. C13H17NO2 (219.28):
calcd. C 71.21, H 7.81, N 6.39; found C 71.02, H 7.89, N 6.35.
Ethyl N-(2,2-Dimethylpropionyl)benzylacetimidate (3g): From ethyl
phenylacetimidate hydrochloride (9.98 g, 50.0 mmol),[27] triethyl-
amine (11.13 g, 110.0 mmol) and pivaloyl chloride (6.03 g,
50.0 mmol). Kugelrohr distillation (0.04 mbar; 80 °C) gave 9.14 g
(36.9 mmol, 74%) of a colourless oil. IR (NaCl): ν = 3088 (m),
˜
3065 (m), 3032 (s, CHarom), 2976 (vs), 2932 (s), 2905 (s), 2870 (s,
CHaliph), 1686 (vs, C=O), 1645 (vs, C=N), 1603 (vs), 1585 (s), 1497
(s), 1477 (vs), 1456 (vs), 1427 (s), 1393 (s), 1367 (vs), 1317 (s), 1267
(vs), 1167 (vs), 1140 (vs), 1107 (s), 1032 (vs), 941 (vs), 928 (vs), 878
(s), 812 (m), 791 (m), 733 (s), 702 (vs), 619 (w), 609 (m), 579
(m) cm–1. 1H NMR (400 MHz, CDCl3): δ = 1.09 [s, 9 H,
C(CH3)3], 1.27 (t, 3J = 7.1 Hz, 3 H, OCH2CH3), 3.64 (s, 2 H,
PhCH2), 4.13 (q, 3J = 7.1 Hz, 2 H, OCH2), 7.26–7.30 (m, 5 H,
CHarom) ppm. 13C NMR (75 MHz, CDCl3): δ = 13.9 (OCH2CH3),
27.1 [C(CH3)3], 38.1 (PhCH2), 41.2 [C(CH3)3], 62.8 (OCH2), 126.9
(p-Carom), 128.4, 129.3 (o/m-Carom), 134.8 (i-Carom), 162.5 (C=N),
191.4 (C=O) ppm. HRMS (ESI): calcd. for C15H21NO2 + Na
270.1465; found 270.1464. C15H21NO2 (247.33): calcd. C 72.84, H
8.56, N 5.66; found C 72.65, H 8.55, N 5.62.
The amidines were prepared either from lithiated amines (using n-
butyllithium as base) and nitriles[25] or by reaction of amines and
nitriles in the presence of aluminium chloride.[26]
General Procedure for the Synthesis of N-Acylimidates 6: Imidates
6 were prepared partially in analogy to a literature procedure.[27]
Crude imidate hydrochlorides were dissolved in anhydrous dichlo-
romethane and stirred at room temperature. Then triethylamine
(2.2 equiv.) was added dropwise to the solution. The reaction mix-
ture was stirred for 1 h and cooled to –15 °C. Acid chloride
(2.2 equiv.), dissolved in dichloromethane, was added dropwise.
The reaction mixture was warmed to room temperature and stirred
for 20 h. The solvent was then removed under reduced pressure and
the residue washed twice with warm pentane or warm tetra-
hydrofuran. The filtrate was evaporated and the crude products
were purified as stated below.
General Procedure for the Synthesis of the Bis(N-Acylamidines) 7a–
j Linked Through the Amino Moiety: Amidines 7a–j were prepared
partially in analogy to a literature procedure.[28] The N-acylimidate
(16.0 mmol) was stirred at 80–90 °C in a dry Schlenk flask under
an inert atmosphere. The diamine (8.0 mmol) was added portion-
wise and the reaction mixture stirred for an additional 5 h at 80–
90 °C. After cooling to room temperature the crude products were
purified as stated below.
Ethyl N-(4-Chlorobenzoyl)benzimidate (3d): Imidate 3d was pre-
pared from ethyl benzimidate hydrochloride (9.30 g, 50.0 mmol),[27]
triethylamine (11.10 g, 110.0 mmol) and p-chlorobenzoyl chloride
(6.5 mL, 8.80 g, 50.0 mmol). The product was purified by
recrystallization from a toluene/cyclohexane mixture (1:1) to give
11.40 g, (40.0 mmol, 80%) of a colourless solid; m.p. 68.4 °C. IR
N-[(2-{[(Benzoylimino)phenylmethyl]amino}ethylamino)phenylmeth-
ylidene]benzamide (7a): From 1,2-diaminoethane (0.48 g, 8.0 mmol)
and ethyl N-benzoylbenzimidate (4.05 g, 16.0 mmol).[27] Crystalli-
zation from chloroform gave 2.33 g (4.9 mmol, 61%) of colourless
(ATR): ν = 3086 (w), 3076 (w), 3042 (w), 2984 (w), 2938 (w), 2905
˜
(w), 1666 (m), 1647 (vs), 1601 (m), 1585 (m), 1572 (m), 1489 (w),
1472 (w), 1447 (w), 1395 (w), 1366 (w), 1325 (m), 1269 (s), 1256
(s), 1161 (m), 1150 (m), 1107 (m), 1092 (m), 1065 (s), 1028 (m),
1013 (m), 1001 (m), 866 (s), 854 (m), 789 (m), 772 (s), 746 (m), 710
(m), 696 (s), 683 (m), 675 (m), 644 (w), 523 (m) cm–1. 1H NMR
crystals; m.p. 202 °C. IR (KBr): ν = 3435 (s, NH), 3292 (s, NH),
˜
3101 (w), 3061 (w, ν-CHarom), 2937 (vw, ν-CHarom), 1616 (sh), 1589
(s, C=O/C=N), 1560 (vs), 1528 (vs), 1489 (s, ν-C=Carom), 1447 (m),
1429 (m, δ-CH2), 1371 (s), 1312 (s), 1294 (s), 1163 (m), 1069 (w),
1022 (w), 874 (w), 847 (w), 791 (m), 716 (m), 696 (s, δ-
CHarom) cm–1. 1H NMR (300.13 MHz, DMSO): δ = 3.80 (br., 4 H,
NCH2), 7.35–7.51 (m, 16 H, CHarom), 7.80 (d, 3J = 7.3 Hz, 4 H,
CHarom), 8.58 (br., 2 H, NH) ppm. 13C NMR (75.47 MHz,
DMSO): δ = 40.7 (NCH2), 127.6, 128.0, 128.2, 128.9 (o,m-CHarom),
130.2, 131.4 (p-CHarom), 134.4 (i-CaromR2), 136.9 (i-CaromR3), 163.2
(C=N), 175.1 (C=O) ppm. MS (70 eV): m/z (%) = 474 (1) [M]+,
353 (2), 250 (24) [OC(Ph)NC(Ph)NHCHCH2]+, 225 (28), 209 (2),
145 (10), 105 (100) [PhCO]+, 77 (31) [Ph]+. C30H26N4O2 (474.56):
calcd. C 75.53, H 5.52, N 11.81; found C 75.50, H 5.38, N 11.72.
3
(300 MHz, CDCl3): δ = 1.48 (t, J = 7.1 Hz, 3 H, OCH2CH3) 4.45
(q, 3J = 7.1 Hz, 2 H, OCH2CH3), 7.28–7.36 (m, 2 H, CHarom) 7.37–
7.45 (m, 3 H, CHarom), 7.53–7.59 (m, 2 H, CHarom) ppm. 13C NMR
(75 MHz, CDCl3): δ = 14.2 (OCH2CH3), 64.1 (OCH2CH3), 128.5,
128.6, 128.9 (o/m-CHarom), 130.4 (i-Carom), 130.8 (CHarom), 131.8
(p-CHarom), 133.2, 139.2 (i-Carom), 159.4 (C=N), 175.0 (C=O) ppm.
HRMS (ESI): calcd. for C16H14ClNO2 + Na 310.0605; found
310.0600. C16H14ClNO2 (287.7): calcd. C 66.79, H 4.90, N 4.87;
found C 66.58, H 4.79, N 4.96.
Ethyl N-Benzoylisobutyrimidate (3f): From isobutyrimidate hydro-
X-ray Crystal Structure Analysis for 7a:[29] Formula C30H26N4O2,
M = 474.55, colourless crystal, 0.70ϫ0.10ϫ0.05 mm, a = 9.678(1),
b = 10.558(1), c = 13.155(1) Å, α = 104.04(1), β = 108.77(1), γ =
91.99(1)°, V = 1225.3(2) Å3, ρcalcd. = 1.286 gcm–3, μ = 0.655 cm–1,
empirical absorption correction (0.657 Յ T Յ 0.968), Z = 2, tri-
chloride
(7.58 g,
50.0 mmol),[27]
triethylamine
(11.13 g,
110.0 mmol) and benzoyl chloride (7.03 g, 50.0 mmol). Distillation
(0.14 mbar; 94 °C) gave 6.30 g (28.7 mmol, 58%) of a colourless
oil. IR (NaCl): ν = 3084 (m), 3065 (m), 3045 (w), 3020 (w), 2980
˜
(vs), 2937 (s), 2914 (m), 2876 (m), 1720 (s), 1664 (vs), 1607 (s), 1582
(s), 1472 (s), 1448 (s), 1396 (m), 1366 (s), 1344 (s), 1302 (vs), 1252
(vs), 1223 (s), 1169 (s), 1088 (vs), 1069 (s), 1024 (s), 918 (s), 866
¯
clinic, space group P1 (No. 2), λ = 1.54178 Å, T = 223 K, ω and
φ scans, 15706 reflections collected (Ϯh, Ϯk, Ϯl), [(sin θ)/λ] =
0.60 Å–1, 4316 independent (Rint = 0.045) and 3826 observed reflec-
tions [I Ն2σ(I)], 332 refined parameters, R = 0.108, wR2 = 0.330,
max. (min.) residual electron density 0.78 (–0.32) eÅ–3, hydrogen
atoms at N from difference Fourier calculations, others calculated
and refined as riding atoms, quality of the analysis was very poor,
probably due to twinning.
1
(vs), 714 (vs), 689 (s), 665 (m) cm–1. H NMR (300 MHz, CDCl3):
δ = 1.13 [d, 3J = 6.9 Hz, 6 H, 1 H, CH(CH3)2], 1.37 (t, 3J = 7.1 Hz,
3 H, OCH2CH3), 2.73 [sept., 3J = 6.9 Hz, 2 H, CH(CH3)2], 4.27
(q, 3J = 7.1 Hz, 2 H, OCH2CH3), 7.36–7.62 (m, 3 H, m/p-CHarom),
7.96–8.20 (m, 2 H, o-CHarom) ppm. 13C NMR (75 MHz, CDCl3):
δ = 14.0 [CH(CH3)2], 19.8 (OCH2CH3), 32.9 [CH(CH3)2], 62.8
(OCH2CH3), 128.3 (p-CHarom), 129.5, 132.7 (o/m-CHarom), 134.5 N-[(2-{[(2,2-Dimethylpropionylimino)phenylmethyl]amino}ethyl-
(i-Carom), 168.5 (C=N), 177.2 (C=O) ppm. HRMS (ESI): calcd. for amino)phenylmethylidene]-2,2-dimethylpropionamide (7b): From
3202
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© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2011, 3197–3209

Two- and Three-Armed Nitrogen-Rich Chelate Ligands
1,2-diaminoethane (0.48 g, 8.0 mmol and ethyl N-pivaloylbenzim-
idate (3.73 g, 16.0 mmol).[27] Diethyl ether (10.0 mL) was added to
the residue. Ultrasonication led to a yellow solid. The solid was
filtered off and washed with diethyl ether to give 1.94 g (4.5 mmol,
56%) of a colourless solid. The compound consists of different tau-
NCH2CH2), 3.41 (br., 4 H, NCH2), 7.17–7.54 (m, 10 H, CHarom),
11.46 (br., NH) ppm. 13C NMR (75.48 MHz, DMSO): δ = 27.1,
27.4 [C(CH3)3], 27.6 (NCH2CH2), 27.9 [C(CH3)3], 40.2 [br., NCH2,
C(CH3)3], 127.3, 128.0 (o,m-CHarom), 129.8 (p-CHarom), 135.1 (i-
C
arom), 161.4 (C=N), 188.2 (C=O) ppm. MS (70 eV): m/z (%) =
tomers and conformers; m.p. 180–181 °C. IR (KBr): ν = 3433 (s,
448 (5) [M]+, 391 (100) [M – C4H9]+, 348 (5), 290 (2), 245 (51) [M –
˜
NH), 3327 (s), 3271 (s, NH), 3107 (m), 3067 (m, ν-CHarom), 2953 OC(tBu)NC(Ph)NH]+, 231 (6) [OC(tBu)NC(Ph)NHCH2CH2]+,
(m), 2926 (m), 2864 (w, ν-CHaliph.), 1607 (s), 1582 (s, C=O/C=N), 187 (19) [OCNC(Ph)NHCH2CHCH2]+, 162 (19), 113 (8), 57 (30)
1531 (vs), 1475 (s, ν-C=Carom), 1393 (s, tBu), 1364 (s, tBu), 1296
[C4H9]+. C27H36N4O2 (448.60): calcd. C 72.29, H 8.09, N 12.49;
(s), 1246 (s), 1136 (s), 920 (m), 862 (m), 770 (s), 698 (m, δ- found C 72.26, H 8.05, N 12.49.
CHarom) cm–1. 1H NMR (400.13 MHz, CDCl3): δ = 1.09 [br. s, 9
N-[(3-{[(2,2-Dimethylpropionylimino)phenylmethyl]amino}butyl-
H, C(CH3)3], 1.16 [s, 8 H, C(CH3)3], 1.32 [s, 1 H, C(CH3)3], 3.54–
3.80 [br. m, 4 H, NCH2], 5.55–5.66 (br., NH), 7.27–7.55 [br. m, 10
H, CHarom], 11.22 (br., NH) ppm. 13C NMR (100.63 MHz,
CDCl3): δ = 27.5, 27.8 [C(CH3)3], 38.5, 41.1 [C(CH3)3], 42.4
(NCH2), 127.5, 128.4 (br., o,m-CHaromR2), 130.4 (p-CHaromR2),
134.7, 134.8 (i-CaromR2), 153.3, 169.1 (C=N), 181.2, 190.6
(C=O) ppm. MS (70 eV): m/z (%) = 434 (1) [M]+, 419 (1), 377 (100)
[M – C4H9]+, 334 (7) [M – OC(tBu)NH]+, 276 (13) [OCNHC(Ph)
N(CH2 )2 NC(Ph)]+ , 251 (3), 231 (15) [OC(tBu)NC(Ph)
NHCH2CH2]+, 205 (13), 173 (22) [OCNC(Ph)NHCHCH2]+, 147
(13), 128 (14), 104 (10), 57 (35) [C4H9]+. C26H34N4O2 (434.58):
calcd. C 71.86, H 7.89, N 12.89; found C 71.79, H 7.71, N 13.03.
amino)phenylmethylidene]-2,2-dimethylpropionamide (7e): From 1,4-
diaminobutane (0.53 g, 6.0 mmol) and ethyl N-pivaloylbenzimidate
(2.80 g, 12.0 mmol).[27] Diethyl ether (10.0 mL) was added to the
residue. Ultrasonication led to a colourless solid. The solid was
filtered off and washed with diethyl ether to give 1.98 g (4.3 mmol,
71%) of a colourless solid; m.p. 210 °C. IR (KBr): ν = 3449 (m,
˜
NH), 3312 (s, NH), 3105 (vw), 3055 (vw, ν-CHarom), 2949 (m), 2924
(w), 2903 (vw), 2864 (vw, ν-CHaliph.), 1614 (s), 1584 (s, C=O/C=N),
1543 (vs), 1477 (m, ν-C=Carom), 1429 (m, δ-CH2), 1393 (s, tBu),
1367 (s, tBu), 1296 (m), 1128 (m), 1020 (vw), 897 (w), 777 (m), 752
(m), 690 (m, δ-CHarom) cm–1. 1H NMR (300.14 MHz, CDCl3): δ =
1.22 [br. s, 18 H, C(CH3)3], 1.62 (br., 4 H, NCH2CH2), 3.33 (br., 4
H, NCH2), 5.17 (br., NH), 7.44 (br., 10 H, CHarom), 11.29 (br.,
NH) ppm. 13C NMR (300 MHz, TFA, CDCl3): δ = 28.5 [C(CH3)
3], 31.7 (CH2), 28.9 [C(CH3)3], 44.5 (CH2), 49.7 (Cq), 127.5 (i-Ca-
rom), 130.3, 132.3, 133.2, 138.0 (CHarom), 169.7, 170.5 (C=O), 187.6
(C=N) ppm. MS (70 eV): m/z (%) = 461 (1) [M – 1]+, 447 (2), 405
(100) [M – C4H9]+, 347 (2) [M – 2C4H9 – 1]+, 279 (2), 259 (27)
[M – OC(tBu)NC(Ph)NH]+, 201 (21), 176 (24), 174 (25), 159 (6)
[OCNC(Ph)NCH2]+, 147 (7) [OCNC(Ph)NH2]+, 104 (22)-
[PhCNH]+, 70 (11), 57 (50) [C4H9]+. C28H38N4O2 (462.63): calcd.
C 72.69, H 8.28, N 12.11; found C 72.46, H 8.11, N 12.07.
N-[({3-[(Benzoylimino)phenylmethyl]amino}propylamino)phenyl-
methylidene]benzamide (7c): From 1,3-diaminopropane (0.59 g,
8.0 mmol) and ethyl N-benzoylbenzimidate (4.05 g, 16.0 mmol).[27]
Crystallization from ethanol gave 1.13 g (2.2 mmol, 28%) of a
colourless solid (ethanol complex). The compound consists of dif-
ferent tautomers and conformers; m.p. 144–146 °C. IR (KBr): ν =
˜
3406 (s, NH), 3267 (m, NH), 3061 (m), 3032 (w, ν–CHarom), 2926
(w), 2887 (w, ν-CHarom), 1624 (vs), 1618 (vs), 1597 (vs, C=O/C=N),
1570 (vs), 1560 (vs), 1543 (vs), 1526 (vs), 1489 (s, ν-C=Carom), 1447
(s, δ-CH2), 1381 (s), 1352 (s), 1310 (s), 1288 (s), 1163 (m), 1067
(m), 1053 (w), 1024 (m), 881 (w), 843 (w), 787 (m), 714 (m), 698
1
(s, δ-CHarom) cm–1. H NMR (300.13 MHz, CDCl3): δ = 1.94 (br.,
N-[(5-{[(2,2-Dimethylpropionylimino)phenylmethyl]amino}pentyl-
amino)phenylmethylidene]-2,2-dimethylpropionamide (7f): From 1,5-
diaminopentane (0.61 g, 6.0 mmol) and ethyl N-pivaloylbenzimid-
ate (2.80 g, 12.0 mmol).[27] Diethyl ether (10.0 mL) was added to
the residue. Ultrasonication led to a solid. The solid was filtered
off and washed with diethyl ether to give 1.31 g (2.7 mmol, 46%)
2 H, NCH2CH2), 3.55 (br., 4 H, NCH2), 5.99 (br., NH), 6.99–7.51
(m, 16 H, CHarom), 7.86–8.26 (m, 4 H, CHarom), 11.68 (br.,
3
NH) ppm; ethanol: δ = 1.18 (t, J = 7.0 Hz, 1.5 H, CH3CH2OH),
3.64 (q, 3 J = 7.1 Hz, 1 H, CH3 CH2 OH) ppm. 1 3 C NMR
(75.48 MHz, CDCl3): δ = 28.3 (NCH2CH2), 39.5, 43.3, 50.8
(NCH2), 127.2, 128.0, 128.5, 129.3 (o,m-CHarom), 130.7, 131.7 (p-
CHarom), 133.8, 136.5 (i-Carom), 153.7, 164.0, (C=N), 176.9, 179.9
(C=O) ppm; ethanol: δ = 12.1 (br., CH3CH2OH), 45.7 (br.,
CH3CH2OH) ppm. MS (70 eV): m/z (%) = 488 (3) [M]+, 367 (8)
[M – OC(Ph)NH2]+, 341 (2), 265 (12) [M – OC(Ph)NC(Ph)NH]+,
251 (16) [OC(Ph)NC(Ph)NHCH2CH2]+, 237 (9) [OC(Ph)NC(Ph)
NHCH2]+, 225 (11), 159 (20), 105 (100) [PhCO]+, 77 (39) [Ph]+.
C31H28N4O2·0.5C2H5OH (511.62): calcd. C 75.12, H 6.11, N 10.95;
found C 75.15, H 5.81, N 11.33.
of a colourless solid; m.p. 142 °C. IR (KBr): ν = 3441 (m, NH),
˜
3294 (s NH), 3101 (w), 3057 (w, ν-CHarom), 2953 (s), 2934 (s), 2912
(m), 2864 (m, ν-CHaliph.), 1612 (vs), 1582 (vs, C=O/C=N), 1541
(vs), 1477 (s, ν-C=Carom), 1429 (s, δ-CH2), 1393 (s, tBu), 1364 (vs,
tBu), 1298 (s), 1219 (m), 1115 (m), 1026 (vw), 918 (m), 773 (s), 743
1
(m), 694 (s, δ-CHarom) cm–1. H NMR (300.14 MHz, CDCl3): δ =
1.21 [br. s, 18 H, C(CH3)3], 1.33–1.91 [br. m, 6 H, NCH2(CH2)3],
3.31 (br., 4 H, NCH2), 5.37 (br., NH), 7.30–7.66 [br. m, 10 H,
CHarom], 11.31 (br., NH) ppm. 13C NMR (75.48 MHz, CDCl3): δ
= 23.9 (NCH2CH2CH2), 27.8 [C(CH3)3], 30.0 (NCH2CH2), 41.8
[C(CH3)3], 45.2 (NCH2), 128.3 (o,m-CHarom), 130.2 (p-CHarom),
134.6 (i-Carom), 169.5 (C=N), 195.6 (C=O) ppm. MS (70 eV): m/z
(%) = 461 (2), 419 (100) [M – C4H9]+, 405 (2), 361 (1) [M – 2tBu –
1]+, 273 (35) [M – OC(tBu)NC(Ph)NH]+, 215 (16), 190 (24), 181
(33), 159 (11) [OCNC(Ph)NCH2]+, 147 (6) [OCNC(Ph)NH2]+, 104
(33) [PhCNH]+, 57 [C4H9]+. C29H40N4O2 (476.66): calcd. C 73.07,
H 8.46, N 11.75; found C 72.95, H 8.38, N 11.72.
N-[(3-{[(2,2-Dimethylpropionylimino)phenylmethyl]amino}propyl-
amino)phenylmethylidene]-2,2-dimethylpropionamide (7d): From
1,3-diaminopropane (0.59 g, 8.0 mmol) and ethyl N-pivaloylbenzi-
midate (3.73 g, 16.0 mmol).[27] Diethyl ether (10.0 mL) was added
to the residue. Ultrasonication led to a colourless solid. The solid
was filtered off and washed with diethyl ether to give 2.87 g
(6.4 mmol, 80%) of a colourless solid. The compound consists of
different tautomers and conformers; m.p. 159 °C. IR (KBr): ν =
˜
3433 (s, NH), 3275 (s, NH), 3109 (m), 3065 (m, ν-CHarom), 2953
N-{[(1R,2S)-2-{[(Benzoylimino)phenylmethyl]amino}cyclohexyl-
(s), 3926 (m), 2868 (m, ν-CHaliph.), 1620 (s), 1580 (vs, C=O/C=N), amino]phenylmethylidene}benzamide (7g): From rac-trans-1,2-di-
1560 (vs), 1543 (vs), 1477 (s, ν-C=Carom), 1393 (s, tBu), 1362 (m,
tBu), 1300 (s), 1217 (m), 1132 (m), 926 (w), 772 (m), 696 (m, δ-
CHarom) cm–1. 1H NMR (300.13 MHz, DMSO): δ = 1.13 [br. s,
16.0 H, C(CH3)3], 1.26 [br. s, 2.0 H, C(CH3)3], 1.94 (br., 2 H,
aminocyclohexane (0.80 g, 7.0 mmol) and ethyl N-benzoylbenzim-
idate (3.54 g, 14.0 mmol).[27] Addition of ethanol led to an ethanol
complex of the product which was filtered off to give 1.96 g
(3.7 mmol, 53%) of colourless crystals; m.p. 174 °C. IR (KBr): ν =
˜
Eur. J. Org. Chem. 2011, 3197–3209
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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3203

E.-U. Würthwein et al.
FULL PAPER
3437 (m, NH), 3260 (s, NH), 3061 (m, ν-CHarom), 2937 (m), 2858
loylbenzimidate (3.73 g, 16.0 mmol).[27] Diethyl ether (10.0 mL)
(m, ν-CHarom), 1616 (vs), 1595 (vs, C=O/C=N), 1572 (vs), 1526 was added to the residue. Ultrasonication led to a colourless solid.
(vs), 1489 (s, ν-C=Carom), 1447 (s, δ-CH2), 1377 (s), 1315 (vs), 1286 The solid was filtered off and washed with diethyl ether to give
(s), 1265 (s), 1161 (m), 1117 (m), 1070 (m), 1051 (m), 1022 (m), 891 2.54 g (5.0 mmol, 62%) of a colourless solid. The compound con-
(m), 781 (m), 719 (s), 694 (s, δ-CHa ro m) cm–1 1 H NMR sists as different tautomers and conformers; m.p. 168 °C. IR (KBr):
.
(400.14 MHz, CDCl3): δ = 1.21–2.52 (m, 8 H, 3,4,5,6-CH2R1-Sp),
ν = 3424 (m, NH), 3298 (s, NH), 3061 (w), 3030 (w, ν-CHarom),
2953 (s), 2926 (m), 2866 (m, ν-CHaliph.), 1618 (vs), 1584 (vs, C=O/
C=N), 1533 (vs), 1477 (s, ν-C=Carom), 1421 (s, δ-CH2), 1391 (s,
˜
4.16 (br., 2 H, 1,2-CHR1-Sp), 7.22–7.53 (m, 16 H, CHarom), 7.80–
3
8.29 (m, 4 H, CHarom) ppm; ethanol: δ = 1.16 (t, J = 7.0 Hz, 3 H,
CH3CH2OH), 3.62 (q, 3J = 7.0 Hz, 2 H, CH3CH2OH) ppm. 13C tBu), 1364 (s, tBu), 1306 (s), 1215 (m), 1119 (m), 1016 (w), 907 (m),
NMR (100.63 MHz, CDCl3): δ = 24.6 (4,5-CH2R1-Sp), 32.1 (3,6- 773 (s), 696 (s, δ-CHarom) cm–1. 1H NMR (400.14 MHz, CDCl3): δ
CH2R1-Sp), 56.6 (1,2-CH2R1-Sp), 127.4, 128.0, 128.7, 129.2 (o,m-
CHarom), 130.9, 131.6 (p-CHarom), 134.3 (i-CaromR2), 136.5 (i-
CaromR3), 164.1 (C=N), 176.8 (C=O) ppm; ethanol: δ = 18.3
(CH3CH2OH), 58.2 (CH3CH2OH) ppm. MS (70 eV): m/z (%) =
528 (5) [M]+, 407 (1), 304 (100) [M – OC(Ph)NC(Ph)NH2]+, 251
(3), 225 (52), 199 (56) [M – OC(Ph)NC(Ph)NH2 – COPh]+, 183
= 1.17 [s, 16.7 H, C(CH3)3], 1.32 [s, 1.3 H, C(CH3)3], 4.50 (s, 3.7
H, CH2), 4.62 (s, 0.3 H, CH2), 5.65 (br., 1 H, NH), 7.06–7.56 (m,
13 H, CHarom), 7.68–7.80 (m, 1 H, 4-CHaromR1-Sp), 11.50 (br., 1
H, NH) ppm. 13C NMR (100.61 MHz, DMSO): δ = 27.1, 27.7
[C(CH3)3], 40.3 [C(CH3)3], 44.8, 53.8 (CH2), 125.9 (3,5-CHaromR1-
Sp), 126.7 (1-CHaromR1-Sp), 127.3 (o,m-CHaromR2), 127.5 (4-
(48), 105 (91) [PhCO]+, 96 (15) [C6H9NH]+. C34H32N4O2·C2H5OH CHaromR1-Sp), 128.1 (o,m-CHaromR2), 129.9 (p-CHaromR2), 134.8,
(574.72): calcd. C 75.24, H 6.66, N 9.75; found C 74.72, H 6.65, N
9.64.
136.5 (i-CaromR2), 138.9, 140 (2,6-CaromR1-Sp), 150.6, 160.6 (C=N),
176.3, 188.3 (C=O) ppm. MS (70 eV): m/z (%) = 510 (9) [M]+, 495
(3), 453 (100) [M – C4H9]+, 410 (1) [M – OC(tBu)NH]+, 350 (1),
307 (68) [M – OC(tBu)NC(Ph)NH]+, 278 (5), 250 (13) [M –
OC(tBu)NC(Ph)NH – tBu]+, 204 (30) [OC(tBu)NC(Ph)NH2]+, 146
(11) [OCNC(Ph)NH]+, 104 (17), 85 (5) [tBuCO]+, 57 (29) [C4H9]+.
C32H38N4O2 (510.67): calcd. C 75.26, H 7.50, N 10.97; found C
75.24, H 7.31, N 10.96.
X-ray Crystal Structure Analysis for 7g:[29] Formula C34H32N4O2·
C2H5OH, M = 574.70, colourless crystal, 0.25ϫ0.15ϫ0.15 mm, a
= 12.674(1), b = 12.202(3), c = 21.020(2) Å, β = 103.64(1)°, V =
3159.0(9) Å3, ρcalcd. = 1.208 gcm–3, μ = 0.616 cm–1, empirical ab-
sorption correction (0.861Յ T Յ0.913), Z = 4, monoclinic, space
group P21/n (No. 14), λ = 1.54178 Å, T = 223 K, ω/2θ scans, 6610
reflections collected (Ϯh, –k, –l), [(sinθ)/λ] = 0.62 Å–1, 6432 inde-
pendent (Rint = 0.038) and 3435 observed reflections [I Ն2σ(I)],
406 refined parameters, R = 0.053, wR2 = 0.170, max. (min.) resid-
ual electron density 0.28 (–0.28) eÅ–3, hydrogen atoms at N from
difference fourier calculations, others calculated and refined as ri-
ding atoms.
N-[(6-{[(2,2-Dimethylpropionylimino)phenylmethyl]amino}pyridin-2-
ylamino)phenylmethylidene]-2,2-dimethylpropionamide (7j): From
2,6-diaminopyridine (0.49 g, 4.5 mmol) and ethyl N-pivaloylbenz-
imidate (2.10 g, 9.0 mmol).[27] After column chromatography using
acetone/n-pentane (1:3) + 10% of triethylamine as eluent, 0.83 g
(1.7 mmol, 38%) of colourless crystals were obtained. The com-
pound consists of different tautomers and conformers; m.p. 151 °C.
N-{[(1R,2S)-2-{[(2,2-Dimethylpropionylimino)phenylmethyl]amino}-
cyclohexylamino]phenylmethylidene}-2,2-dimethylpropionamide (7h):
From rac-trans-1,2-diaminocyclohexane (0.91 g, 8.0 mmol) and
ethyl N-pivaloylbenzimidate (3.73 g, 16.0 mmol).[27] Addition of
ethanol led to an ethanol complex of the product which was filtered
off to give 1.07 g (2.2 mmol, 27%) of colourless crystals. The com-
pound consists of different tautomers and conformers; m.p. 175 °C.
IR (KBr): ν = 3443 (s, NH), 3248 (m, NH), 3059 (vw, ν-CHarom),
˜
2970 (w), 2930 (w), 2868 (vw, ν-CHaliph.), 1719 (s), 1711 (s, C=O/
C=N), 1620 (vs, C=O/C=N), 1580 (s), 1543 (s), 1475 (m, ν-
C=Carom), 1414 (m), 1396 (m, tBu), 1366 (m, tBu), 1321 (s), 1312
1
(m), 1140 (s), 937 (w), 829 (w), 696 (m, δ-CHarom) cm–1. H NMR
(400.14 MHz, CDCl3): δ = 1.18 [s, 13.2 H, C(CH3)3], 1.32 [s, 4.8
H, C(CH3)3], 7.10 (d, 3J = 7.8 Hz, 2 H, m-CHaromR1-Sp), 7.43–
7.52 (m, 6 H, m,p-CHaromR2), 7.71 (d, 3J = 7.1 Hz, 4 H, o-
CHaromR2), 7.87 (t, 3J = 7.8 Hz, 1 H, p-CHaromR1-Sp), 11.26 (s,
NH) ppm. 13C NMR (100.62 MHz, CDCl3): δ = 27.0 [C(CH3)3],
40.0 [C(CH3)3], 117.3 (m-CHaromR1-Sp), 128.1 (o,m-CHaromR2),
130.9 (p-CHaromR2), 135.9 (i-CaromR2), 141.1 (p-CHaromR1-Sp),
155.0 (C=N), 157.7 (o-CaromR1-Sp), 176.6 (C=O) ppm. MS
(70 eV): m/z (%) = 483 (6) [M]+, 426 (100) [M – C4H9]+, 383 (2)
[M – OC(tBu)NH]+, 342 (5), 325 (39), 280 (7) [M – OC(tBu)-
NC(Ph)NHPy]+, 222 (10), 196 (9) [HNC(Ph)NHPy]+, 179 (9), 154
(1), 105 (23), 85 (5) [tBuCO]+, 57 (39) [C4H9]+. C29H33N5O2
(483.61): calcd. C 72.02, H 6.88, N 14.48; found C 71.73, H 6.79,
N 14.11.
IR (KBr): ν = 3433 (s, NH), 3262 (s, NH), 3090 (m, ν-CHarom),
˜
2934 (s), 2862 (m, ν-CHarom), 1722 (m), 1665 (s), 1626 (s), 1609 (s),
1584 (s, C=O/C=N), 1535 (vs, ν-C=Carom), 1447 (s, δ-CH2), 1393
(m, tBu), 1366 (m, tBu), 1277 (s), 1188 (m), 1117 (m), 934 (w), 773
(m), 692 (m, δ-CHarom) cm–1. 1H NMR (300.14 MHz, CDCl3): δ =
0.95 [br. s, 5.9 H, C(CH3)3], 1.03 [br. s, 12.1 H, C(CH3)3], 1.20–
2.45 (m, 8 H, 3,4,5,6-CH2R1-Sp), 3.55 (br., 1 H, 1,2-CH2R1-Sp),
3.91 (br., 1 H, 1,2-CH2 R1 -Sp), 7.29–7.52 [br. m, 10 H,
CHarom] ppm; ethanol: δ = 1.15 (t, 3J = 7.0 Hz, 3 H, CH3CH2OH),
3.59 (q, 3 J = 7.0 Hz, 2 H, CH3 CH2 OH) ppm. 1 3 C NMR
(75.48 MHz, CDCl3): δ = 24.3, 24.6 (4,5-CH2R1-Sp), 26.8, 27.7
[C(CH3)3], 32.1, 32.8 (3,6-CH2R1-Sp), 39.3, 41.0 [C(CH3)3], 56.3,
64.7 (1,2-CH2R1-Sp), 127.6, 128.5 (o,m-CHarom), 130.4 (p-CHarom),
135.1, 135.7 (i-Carom), 154.1, 162.2 (C=N), 177.0, 190.4
( C = O ) p p m ; e t h a n o l : δ = 1 8 . 3 ( C H 3 C H 2 O H ) , 5 8 . 1
(CH3CH2OH) ppm. MS (70 eV): m/z (%) = 488 (1) [M]+, 431 (100)
[M – C4H9]+, 388 (1) [M – OC(tBu)NH]+, 348 (2), 305 (4), 285 (21)
[M – OC(tBu)NC(Ph)NH]+, 227 (24) [M – OC(tBu)NC(Ph)NH –
tBu]+, 184 (19), 147 (8), 104 (11) [PhCNH]+, 81 (12), 57 (41)
[C4H9]+. C30H40N4O2 (488.67): calcd. C 73.74, H 8.25, N 11.47;
found C 73.39, H 8.16, N 11.40.
X-ray Crystal Structure Analysis for 7j:[29] Formula C29H33N5O2, M
= 483.60, colourless crystal, 0.30ϫ0.10ϫ0.05 mm, a = 10.191(1), b
= 17.369(1), c = 29.866(1) Å, V = 5286.5(6) Å3, ρcalcd.
=
1.215 g cm–3, μ = 0.621 cm–1, empirical absorption correction
(0.836Յ T Յ0.970), Z = 8, orthorhombic, space group Pbca (No.
61), λ = 1.54178 Å, T = 223 K, ω and φ scans, 37692 reflections
collected (Ϯh, Ϯk, Ϯl), [(sinθ)/λ] = 0.60 Å–1, 4748 independent
(Rint = 0.081) and 3539 observed reflections [I Ն2σ(I)], 339 refined
parameters, R = 0.052, wR2 = 0.114, max. (min.) residual electron
density 0.15 (–0.19) eÅ–3, hydrogen atoms at N from difference fou-
rier calculations, others calculated and refined as riding atoms.
N-{[3-({[(2,2-Dimethylpropionylimino)phenylmethyl]amino}methyl)-
benzylamino]phenylmethylidene}-2,2-dimethylpropionamide (7i):
From α,αЈ-diamino-m-xylene (1.09 g, 8.0 mmol) and ethyl N-piva-
3204
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© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2011, 3197–3209

Two- and Three-Armed Nitrogen-Rich Chelate Ligands
General Procedure for the Synthesis of Bis(N-acylamidines) 7k–o
CHarom), 7.56–7.61 (m, 14 H, CHarom), 8.62, 8.66, 9.60, 9.64 (s, 2
Linked Through the Amino Moiety: N-Acylimidate (2 equiv.) was H, NH) ppm. 13C NMR (100 MHz, CDCl3): δ = 17.6, 17.7 (CH3),
dissolved in a small amount of dioxane and heated at 80 °C until
27.7, 28.3 [C(CH3)3], 39.8 (Cq), 118.3, 122.9, 123.2, 123.4, 123.6,
the N-acylimidate had completely dissolved. Then the diamine 127.2, 127.5, 127.8, 128.0, 128.1, 128.6, 128.7 (CHarom), 128.9,
(1 equiv.) was added portionwise, the mixture was heated at reflux
for 16 h and the solvents evaporated. The crude products were puri-
fied as stated below.
129.0 (i-Carom), 130.9, 131.0, 131.4, 131.5 (CHarom), 133.8, 134.5,
135.6, 135.7, 135.8, 136.1, 136.2, 137.7, 138.0, 146.4, 147.0 (i-
Carom), 160.2, 163.2, 165.4 (C=N), 173.3, 173.3 (C=O) ppm.
HRMS (ESI): calcd. for C38H42N4O2 + Na 609.3200; found
609.3210. C38H42N4O2 (586.8): calcd. C 77.78, H 7.21, N 9.55;
found C 77.70, H 7.12, N 9.43.
N-[(4-{4-[(Benzoylimino)-p-tolylmethylamino]benzyl}phenylamino)-
p-tolylmethylidene]benzamide (7k): From ethyl N-benzoylpivalimid-
ate (0.54 g, 2.00 mmol)[27] and 4-[(4-aminophenyl)methyl]aniline
(0.20 g, 1.00 mmol). Crystallization from acetonitrile gave 0.34 g
(0.53 mmol, 53%) of colourless needles; m.p. 157.6 °C. IR (ATR):
N-{1-[5-(1-Benzoylimino-2-methylpropylamino)-1-naphthylamino]-2-
methylpropylidene}benzamide (7n): From ethyl N-benzoylisobutyr-
imidate (0.82 g, 3.71 mmol)[27] and 1,5-diaminonaphthalene
ν = 3264 (m), 3194 (m), 3067 (m), 3030 (m), 2994 (m), 2920 (m),
˜
1609 (m), 1584 (m), 1564 (m), 1506 (s), 1491 (m), 1449 (m), 1406 (0.29 g, 1.81 mmol). The solid was filtered off and washed with
(m), 1383 (m), 1319 (s), 1302 (m), 1267 (m), 1229 (m), 1184 (m), dioxane to give 0.57 g (0.88 mmol, 47%) of a colourless solid; m.p.
1175 (m), 1155 (m), 1119 (m), 1059 (m), 1022 (m), 945 (m), 912 230 °C. IR (KBr): ν = 3375 (m, NH), 3087 (w), 3064 (w), 3051
˜
(m), 895 (m), 868 (m), 818 (m), 795 (m), 777 (m), 758 (m), 710 (s),
(vw), 3030 (w), 2974 (m, CHaliph), 2935 (w), 2869 (w), 1689 (s,
689 (m), 662 (m), 638 (m), 623 (m), 577 (m), 557 (m), 532 (m) cm–1. C=N/C=O), 1644 (vs, C=N/C=O), 1602 (m), 1585 (w), 1488 (s,
1H NMR (300 MHz, CDCl3): δ = 2.36 (s, 6 H, CH3), 3.88 (s, 2 H,
C=C), 1467 (m), 1419 (m), 1397 (m), 1368 (w), 1340 (m), 1324 (m),
3
CH2), 7.01 (br., 8 H, CHarom), 7.13 (d, J = 7.8 Hz, 4 H, CHarom), 1301 (m), 1282 (s), 1249 (s), 1224 (w), 1205 (m), 1185 (s), 1143 (m),
3
7.43–7.56 (m, 10 H, CHarom), 8.33 (d, J = 7.0 Hz, 4 H, CHarom),
12.01 (s, 2 H, NH) ppm. 13C NMR (75 MHz, CDCl3): δ = 21.6 807 (vw), 774 (m), 757 (w), 740 (m), 718 (w), 699 (m), 676 (w), 641
(CH3), 40.6 (CH2), 123.6, 128.2, 129.1, 129.5, 129.6 (CHarom), 131.5
(m), 618 (w), 610 (w), 510 (w), 500 (w), 471 (w) cm–1. 1H NMR
(i-Carom), 132.2 (CHarom), 136.9, 138.1, 141.6 (i-Carom), 164.8 (300 MHz, TFA, CDCl3): δ = 1.46 [d, 3J = 6.8 Hz, 12 H, CH(CH3)
1075 (w), 1064 (w), 1029 (w), 981 (m), 929 (w), 890 (vw), 850 (vw),
(C=N), 179.0 (C=O) ppm. HRMS (ESI): calcd. for C43H36N4O2 +
H 641.2911; found 641.2913. C43H36N4O2 (640.8): calcd. C 80.60,
H 5.66, N 8.74; found C 80.33, H 5.73, N 8.60.
2], 3.13 [m, 2 H, CH(CH3)2], 7.61–7.68 (m, 4 H, CHarom), 7.80–
8.03 (m, 10 H, CHarom), 8.15–8.24 (m, 2 H, CHarom), 10.24, 13.92
(s, NH) ppm. 13C NMR (300 MHz, TFA, CDCl3): δ = 18.2
[CH(CH3)2], 31.7 [CH(CH3)2], 124.7, 126.8, 128.8, 129.0 (CHarom),
129.1, 129.7 (i-Carom), 129.8, 136.8 (CHarom), 171.9 (C=O), 178.4
(C=N) ppm. HRMS (ESI): calcd. for C32H32N4O2 + Na 527.2417;
found 527.2421. C32H32N4O2 (504.60): calcd. C 76.16, H 6.39, N
11.10; found C 75.76, H 6.38, N 10.99.
N-[(4-{4-[(4-Chlorobenzoylimino)-p-tolylmethylamino]benzyl}-
phenylamino)-p-tolylmethylidene]-4-chlorobenzamide (7l): From
ethyl N-(4-chlorobenzoyl)benzimidate (3d; 3.16 g, 11.0 mmol) and
4-[(4-aminophenyl)methyl]aniline (0.99 g, 5.0 mmol). The crude
product was dissolved in chloroform (3 mL), tert-butyl methyl ether
(5 mL) was added and the mixture was sonicated for 30 min. The
precipitate was filtered off and dried at 120 °C under vacuum to
N-(1-{5-[1–(2,2-Dimethylpropionylimino)-2-phenylethylamino]-1-
naphthylamino}-2-phenylethylidene)-2,2-dimethylpropionamide (7o):
give 1.92 g (2.8 mmol, 56%) of a yellow solid; m.p. 109.9–114.4 °C. From ethyl N-(2,2-dimethylpropionyl)benzylacetimidate (3g;
IR (ATR): ν = 3287 (w), 3204 (w), 3061 (w), 3034 (w), 1587 (m), 1.11 g, 4.5 mmol) and 1,5-diaminonaphthalene (0.35 g, 2.2 mmol).
˜
1551 (m), 1510 (s), 1485 (m), 1445 (w), 1410 (m), 1317 (m), 1263 After column chromatography using tert-butyl methyl ether/n-pent-
(m), 1231 (m), 1167 (w), 1152 (w), 1088 (m), 1061 (w), 1024 (w), ane (1:8) + 5% of triethylamine as eluent, 0.65 g (1.2 mmol, 86%,
1013 (m), 920 (w), 897 (w), 847 (w), 762 (m), 692 (m), 621 (w), 588 Rf = 0.93) of a light-yellow solid was obtained. The compound
1
(w), 565 (w), 523 (m) cm–1. H NMR (300 MHz, CDCl3): δ = 3.85 consists of different tautomers and conformers; m.p. 143 °C. IR
(s, 2 H, CH2), 6.93–7.01 (m, 8 H, CHarom), 7.29–7.45 (m, 10 H,
CHarom), 7.57 (d, J = 7.3 Hz, 4 H, CHarom), 8.25 (d, J = 8.4 Hz,
(KBr): ν = 3375 (m, NH), 3088 (w, CH ), 3063 (w, CH ), 3051
˜
ar ar
(vw, CHar), 3028 (w, CHar), 2972 (m, CHaliph), 2934 (w, CHaliph),
3
3
4 H, CHarom), 12.28 (br., 2 H, NH) ppm. 13C NMR (75 MHz, 2870 (w, CHaliph), 1690 (s, C=O/C=N), 1645 (vs, C=O/C=N), 1603
CDCl3): δ = 40.8 (CH2), 124.0, 128.6, 128.6, 129.7, 129.7, 131.3, (m), 1585 (w), 1487 (s, C=C), 1466 (m), 1418 (m), 1396 (m), 1367
131.4 (CHarom), 134.4, 135.7, 136.7, 138.4, 138.6 (i-Carom), 165.7 (w), 1339 (m), 1325 (m), 1300 (m), 1281 (s), 1250 (s), 1223 (w),
(C=N), 178.4 (C=O) ppm. HRMS (ESI): calcd. for C41H30Cl2N4O2
+ H 681.1819; found 681.1811. C41H30Cl2N4O2 (681.6): calcd. C
72.25, H 4.44, N 8.22; found C 72.04, H 4.35, N 8.12.
1205 (m), 1184 (s), 1144 (m), 1074 (w), 1063 (w), 1030 (w), 980 (m),
928 (w), 889 (vw), 785 (w), 775 (m), 758 (w), 739 (m), 717 (w), 698
(m), 675 (w), 640 (m), 617 (w), 611 (w), 509 (w), 501 (w), 473
1
(w) cm–1. H NMR (400 MHz, CDCl3): δ = 0.72, 0.76, 1.20 [s, 18
N-{1-[4Ј-(1-Benzoylimino-2,2-dimethylpropylamino)-3,3Ј-dimethylbi-
phenyl-4-ylamino]-2,2-dimethylpropylidene}benzamide (7m): From
ethyl N-benzoylpivalimidate (2.00 g, 8.6 mmol)[27] and o-tolidine
(0.91 g, 4.3 mmol; caution: tolidine is toxic and possibly carcino-
genic). Crystallization from ethanol gave 1.96 g (3.4 mmol, 79%)
of a colourless solid. The compound consists of different tauto-
H, C(CH3)3], 4.05 (br. s, NH), 4.17, 4.48 (s, 2 H, CH2Ph), 6.90–
7.20 (m, 8 H, m/p-CHspacer, m/p-CHarom), 7.20–7.70 (m, o-CHspacer
,
o-CHarom), 8.14 (br. s, NH) ppm. 13C NMR (100 MHz, CDCl3): δ
= 26.6, 26.7, 26.9, 27.1 [C(CH3)3], 39.9, 40.0 [C(CH3)3], 41.4, 41.4
(CH2Ph), 116.0, 116.2 (o-CHarom), 126.1 (p-CHarom), 126.5 (i-
Carom), 126.6, 126.6, 126.7, 126.8 (m-Carom), 128.2, 128.3, 128.3,
128.4 (m-Carom), 129.4 (o-Carom), 136.5, 136.6 (i-Carom), 143.6 (i-
Carom), 154.5, 154.5 (C=N), 175.4, 175.4 (C=O) ppm. HRMS
(ESI): calcd. for C36H40N4O2 + H 561.3224; found 561.3213.
C36H40N4O2 (560.73): calcd. C 77.11, H 7.19, N 9.99; found C
76.81, H 7.34, N 10.00.
mers; m.p. 205.6 °C. IR (ATR): ν = 3225 (w), 3067 (w), 2968 (w),
˜
2870 (w), 1665 (m), 1609 (s), 1576 (m), 1514 (s), 1491 (m), 1449
(m), 1400 (w), 1369 (m), 1331 (s), 1281 (m), 1250 (m), 1196 (w),
1169 (m), 1121 (w), 1096 (w), 1069 (w), 1026 (w), 908 (m), 893 (m),
839 (w), 787 (m), 725 (m), 696 (s), 658 (s), 592 (w), 567 (m) cm–1.
1H NMR (400 MHz, [D6]DMSO): δ = 1.30, 1.32, 1.38, 1.40 [s, 18
H, C(CH3)3], 2.10, 2.13, 2.17, 2.20 (s, 6 H, CH3), 6.69–6.82 (m, 2
General Procedure for the Synthesis of Tris(N-acylamidines) 8a–c:
H, CHarom), 6.98–7.04 (m, 14 H, CHarom), 7.17–7.61 (m, 11 H, N-Acylimidate (15.0 mmol) was dissolved in dioxane (10.0 mL).
Eur. J. Org. Chem. 2011, 3197–3209
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
3205

E.-U. Würthwein et al.
FULL PAPER
Tris(2-aminoethyl)amine (5.0 mmol) was added dropwise at 70– amide (8c): From tris(2-aminoethyl)amine (0.58 g, 4.0 mmol) and
90 °C. The reaction mixture was stirred overnight at 70–90 °C and
the solvent was evaporated. The crude products were purified as
stated below.
ethyl N-(4-trifluormethylphenyl)benzimidate (3.86 g, 12.0 mmol).[27]
After column chromatography using acetone/n-pentane (1:3) +
10% of triethylamine as eluent, 0.71 g (0.7 mmol, 18%) of a colour-
less solid was obtained. The compound consists of different tauto-
N-(1-{2-[Bis(2-{[(2,2-dimethylpropionylimino)phenylmethyl]amino}-
ethyl)amino]ethylamino}-2,2-dimethylpropylidene)benzamide (8a):
From tris(2-aminoethyl)amine (0.73 g, 5.0 mmol) and ethyl N-piva-
loylbenzimidate (3.50 g, 15.0 mmol).[27] After column chromatog-
raphy using acetone/n-pentane (1:3) + 10% of triethylamine as elu-
ent, 0.30 g (0.4 mmol, 8%) of a colourless solid were obtained. The
compound consists of different tautomers and conformers; m.p.
mers and conformers; m.p. 172–173 °C. IR (KBr): ν = 3429 (m,
˜
NH), 3254 (m, NH), 3071 (w, ν-CHarom), 2964 (w), 2930 (vw), 2851
(vw, ν-CHaliph.), 1595 (vs, C=O/C=N), 1560 (vs, C=O/C=N), 1510
(s, C=Carom.), 1445 (m), 1437 (m, δ-CH2), 1410 (s), 1385 (s), 1323
(vs), 1163 (vs), 1126 (vs, CF3), 1101 (s), 1065 (vs), 1016 (s), 862
(m), 802 (w), 775 (m), 746 (w), 706 (m), 694 (m, δ-CHarom) cm–1.
1H NMR (300.13 MHz, CDCl3):
δ = 2.75 [br., 2.2 H,
127 °C. IR (KBr): ν = 3424 (m, NH), 3262 (m, NH), 3107 (w),
˜
N(CH2CH2)3], 2.87 [br., 1.0 H, N(CH2CH2)3], 2.96 [br., 0.7 H,
N(CH2CH2)3], 3.02 [br., 2.1 H, N(CH2CH2)3], 3.66 [br., 3.3 H,
N(CH2CH2)3], 3.77 [br., 2.7 H, N(CH2CH2)3], 6.87 (t, 3J = 7.9 Hz,
1 H, CHarom), 7.11 (t, 3J = 7.2 Hz, 2 H, CHarom), 7.21 (t, 3J =
6.8 Hz, 1 H, CHarom), 7.32 (d, 3J = 7.3 Hz, 2 H, CHarom), 7.40–
3063 (w, ν-CHarom), 2955 (s), 2928 (m), 2903 (w), 2866 (w), 2801
(w, ν-CHaliph.), 1589 (vs, C=O/C=N), 1560 (vs, C=O/C=N), 1493
(s, C=Carom), 1477 (s), 1456 (s), 1433 (s, δ-CH2), 1396 (s, tBu), 1362
(s, tBu), 1308 (m), 1223 (m), 1171 (vw), 1119 (w), 1072 (w), 1026
1
(w), 920 (w), 772 (m), 735 (w), 689 (m, δ-CHarom) cm–1. H NMR
3
7.78 (m, 16 H, CHarom), 8.11 (d, J = 7.8 Hz, 1 H, o-CHaromR3),
(300.13 MHz, CDCl3): δ = 0.91 [br. s, 6.9 H, C(CH3)3], 1.19 [br. s,
16.8 H, C(CH3)3], 1.28 [br. s, 3.3 H, C(CH3)3], 2.58 [br., 2 H,
N(CH2CH2)3], 2.83 [br., 4 H, N(CH2CH2)3], 3.46 [br., 6 H,
N(CH2CH2)3], 6.84–7.60 (m, 15 H, CHarom), 8.62 (br., NH), 11.62
(br., NH) ppm. 13C NMR (75.48 MHz, CDCl3): δ = 27.8, 28.0, 28.4
[C(CH3)3], 39.6, 40.7 [N(CH2CH2)3], 41.1, 41.6 [C(CH3)3], 43.3
[N(CH2CH2)3], 50.6, 52.7, 54.3 [N(CH2CH2)3], 127.0, 128.1, 128.3,
128.7 (o,m-CHarom), 130.2, 130.9 (p-CHaromR2), 134.7 (i-CaromR2),
160.6, 164.1, 168.7 (C=N), 190.6, 193.7, 195.3 (C=O) ppm. MS
(70 eV): m/z (%) = 650 (8) [M – C4H9]+, 547 (2) [M – 2tBu – Ph]+,
503 (5) [M – OC(tBu)NC(Ph)NH2]+, 490 (8) [M – 2tBu –
PhCN]+, 387 (5) [M – 2tBu – 2PhCN]+, 362 (2), 299 (9), 231 (5),
205 (10), 147 (14), 104 (16), 95 (23), 57 (100) [C4H9]+, 56 (7).
C42H57N7O3 (707.95): calcd. C 71.26, H 8.12, N 13.85; found C
71.02, H 7.95, N 13.76.
3
3
8.22 (d, J = 8.0 Hz, 2 H, o-CHaromR3), 8.32 (d, J = 8.0 Hz, 2 H,
o-CHaromR3), 8.74 (br., 0.4 H, NH), 9.52 (t, 3J = 4.8 Hz, 0.6 H,
NH), 12.01 (br., NH), 12.27 (br., NH) ppm. 13C NMR
(100.13 MHz, CDCl3): δ = 39.8, 41.2, 43.2, 43.9 [N(CH2CH2)3],
50.6, 53.1, 53.7, 54.7 [N(CH2CH2)3], 123.9 (q, 3J = 271.9 Hz, CF3),
124.6, 125.1 (br. m, m-CHaromR3), 127.2, 127.6, 128.5, 128.6, 128.7,
129.0, 129.7, 129.8 (o,m-CHarom), 130.8, 131.5, 131.6 (p-CHaromR2),
132.2–133.8 (m, p-CaromR3), 134.3 (i-CaromR2), 140.0, 140.2, 140.6
(i-CaromR3), 164.8, 167.3, 170.0, 170.3 (C=N), 172.1, 175.1, 177.9,
178.3 (C=O) ppm. MS (ESI): m/z (%) = 997–995 (43) [M + Na]+,
973 (22) [M + H]+, 381 (13), 102 (66), 58 (100); daughters of 973:
972 (27) [M]+, 680 (21), 465 (49), 388 (5), 362 (46), 319 (100), 242
(5), 216 (15), 173 (45), 147 (18), 70 (14). C51H42F9N7O3 (971.92):
calcd. C 63.03, H 4.36, N 10.09; found C 63.27, H 4.42, N 10.11.
General Procedure for the Synthesis of Bis(N-Acylamidines) 9a,b
Linked Through the Carbonyl Moiety: A dry Schlenk flask was
equipped with amidine (20.0 mmol) and potassium tert-butoxide
(20.0 mmol) under an inert atmosphere. The mixture was cooled
with an ice bath. Dry tetrahydrofuran (70.0 mL) was added and
stirred for 10 min at 10 °C. A solution of dicarboxylic acid
(9.8 mmol) dissolved in dry tetrahydrofuran (40.0 mL) was added
dropwise to the mixture. The reaction mixture was warmed to room
temperature and stirred for 24 h. The organic layer was washed
three times with water (30.0 mL). The aqueous layer was extracted
dichloromethane (3ϫ 20.0 mL). All organic layers were dried with
magnesium sulfate and the solvents evaporated. The crude products
were purified as stated below.
N-(1-{2-[Bis(2-{[(benzoylimino)phenylmethyl]amino}ethyl)amino]-
ethylamino}phenylidene)benzamide (8b): From tris(2-aminoethyl)-
amine (0.73 g, 5.0 mmol) and ethyl N-benzoylbenzimidate (3.80 g,
15.0 mmol).[27] Addition of ethanol led to an ethanol complex of
the product which was filtered off to give 1.22 g (1.5 mmol, 30%)
of a colourless solid. The compound consists of different tautomers
and conformers; m.p. 127 °C. IR (KBr): ν = 3431 (s, NH), 3061
˜
(w), 3030 (vw, ν-CHarom), 2953 (vw), 2841 (vw, ν-CHaliph.), 1593
(vs, C=O/C=N), 1558 (vs, C=O/C=N), 1489 (m, C=Carom), 1445
(s, δ-CH2), 1367 (s), 1323 (s), 1296 (s), 1161 (w), 1065 (w), 1051
(w), 1024 (w), 930 (vw), 876 (vw), 849 (vw), 785 (w), 716 (m), 694
(m, δ-CHarom) cm–1. 1H NMR (300.13 MHz, CDCl3): δ = 2.72 [br.,
2.5 H, N(CH2CH2)3], 2.87 [br., 0.9 H, N(CH2CH2)3], 2.99 [br., 2.6
H, N(CH2CH2)3], 3.57 [br., 2.0 H, N(CH2CH2)3], 3.66 [br., 1.2 H,
N(CH2CH2)3], 3.73 [br., 2.8 H, N(CH2CH2)3], 6.84–7.51 (m, 22 H,
CHarom), 7.60–7.65 (m, 4 H, o-CHaromR2, o-CHaromR3), 8.10–8.22
(m, 4 H, o-CHaromR3), 8.42 (br., 0.5 H, NH), 9.26 (br., 0.5 H, NH),
11.95 (br., NH), 12.21 (br., NH) ppm; ethanol: δ = 1.14–1.19 (m,
2.3 H, CH3CH2OH), 3.60–3.65 (m, 1.5 H, CH3CH2OH) ppm. 13C
NMR (100.62 MHz, CDCl3): δ = 39.7, 41.0, 43.1 [N(CH2CH2)3],
50.7, 53.0, 53.9 [N(CH2CH2)3], 127.2, 127.6, 128.0, 128.4, 128.5,
128.7, 129.4 (o,m-CHarom), 130.4, 131.1, 131.6 (p-CHarom), 134.0,
134.1 (i-CaromR2), 136.8, 137.2 (i-CaromR3), 163.3, 165.7, 169.5
(C=N), 174.2, 176.9, 179.8 (C=O) ppm; ethanol: δ = 18.3
(CH3CH2OH), 58.2 (CH3CH2OH) ppm. HRMS (ESI): calcd for
C48H45N7O3 + Na 790.3482; found 790.3463. C48H45N7O3·
0.75C2H5OH (802.48 ): calcd. C 74.09, H 6.22, N 12.22; found C
73.86, H 5.93, N 12.42.
Hexanedioic Acid Bis[phenyl(phenylamino)methylideneamide] (9a):
From N-phenylbenzamidine[26] (3.93 g, 20.0 mmol) and adipoyl
chloride (1.79 g, 9.8 mmol). After column chromatography using
ethanol/n-pentane (1:7) + 5% of triethylamine as eluent, 0.095 g
(0.2 mmol, 2%) of colourless crystals of an ethanol complex were
obtained. The compound consists of different conformers and tau-
tomers; m.p. 144–153 °C. IR (KBr): ν = 3387 (m, NH), 3236 (s,
˜
NH), 3059 (m), 3030 (m, ν-CHarom), 2951 (m), 2868 (m, ν-CHaliph.),
1661 (s, C=O/C=N), 1628 (vs, C=O/C=N), 1591 (vs), 1491 (vs,
C=Carom), 1447 (s, δ-CH2), 1292 (s), 1213 (s), 1173 (m), 1144 (m),
1
1072 (m), 1026 (m), 912 (vw), 754 (s), 694 (vs, δ-CHarom) cm–1. H
NMR (400.13 MHz, CDCl3): δ = 1.44–1.77 (m, 4 H, COCH2CH2),
2.07–2.18 (m, 1.7 H, COCH2CH2), 2.54–2.62 (m, 2.3 H,
COCH2CH2), 6.84–7.46 (m, 18 H, CHarom), 7.71–7.75 (m, 2 H,
CHarom), 11.89 (br., NH) ppm; ethanol: δ = 1.21 (t, 3J = 7.0 Hz,
0.75 H, CH3CH2OH), 3.67 (q, 3J
=
7.0 Hz, 0.5 H,
N-(1-{2-[Bis(2-{[(4-trifluoromethylbenzoylimino)phenylmethyl]- CH3CH2OH) ppm. 13C NMR (75.48 MHz, CDCl3): δ = 23.9, 24.3,
amino}ethyl)amino]ethylamino}phenylidene)-4-trifluoromethylbenz- 24.5, 24.8 (COCH2CH2), 35.8, 36.3, 39.9 (br., COCH2CH2), 120.3
3206
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© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2011, 3197–3209

Two- and Three-Armed Nitrogen-Rich Chelate Ligands
(o-CHaromR1), 122.8 (p-CHaromR1), 124.4, 128.2, 128.3, 128.3,
(m), 808 (m), 766 (s), 691 (s), 646 (s), 619 (s), 613 (s), 598 (s), 579
129.5 (CHarom), 130.8 (p-CHaromR2), 135.3 (i-CaromR2), 148.0 (i- (s), 571 (s), 546 (s), 536 (s), 528 (s), 523 (s) cm–1. 1H NMR
CaromR1), 151.5 (C=N), 166.0 (br., C=N), 171.2 (C=O), 187.8 (br., (300 MHz, [D6]DMSO): δ = 7.53–7.68 (m, 6 H, m/p-CHarom), 7.85–
C=O) ppm;
ethanol:
δ
=
16.0
(CH3CH2OH),
50.2
7.89 (m, 4 H, CHspacer), 8.21–8.25 (m, 4 H, CHspacer), 8.37–8.40 (m,
(CH3CH2OH) ppm. MS (70 eV): m/z (%) = 502 (8) [C32H30N4O2
4 H, o-CHarom), 9.43 (s, 2 H, NH2), 10.51 (s, 2 H, NH2) ppm. 13C
(M)]+, 399 (8), 341 (3), 306 (17) [M – PhNC(Ph)NH]+, 265 (6) NMR (300 MHz, [D6]DMSO):
δ = 126.7 (CHspacer), 130.0
[PhNHC(Ph)NCO(CH2)3]+, 251 (14) [PhNHC(Ph)NCO(CH2)2]+, (CHarom), 128.5 (CHarom), 129.8 (CHspacer), 132.2 (CHarom), 134.5
237 (8) [PhNHC(Ph)NCOCH2]+, 223 (17) [PhNHC(Ph)NCO]+,
196 (85) [PhNHC(Ph)NH]+, 180 (90) [PhNCPh]+, 103 (100)
(i-Carom), 137.3 (i-Cspacer), 142.5 (i-Cspacer), 166.1 (C=N), 177.9
(C=O) ppm. HRMS (ESI): calcd. for C28H22N4O2 + H 447.1812;
[PhCN]+, 93 (77) [PhNH2]+, 77 (90) [Ph]+. C32H30N4O2· found 447.1816. C28H22N4O2 (446.5): calcd. C 75.32, H 4.97, N
0.25C2H5OH (514.13): calcd. C 75.93, H 6.18, N 10.90; found C
75.67, H 5.87, N 11.11.
12.55; found C 74.96, H 4.74, N 12.39.
X-ray Crystal Structure Analysis for 9c:[29] Formula C28H22N4O2,
M
= 446.50, colourless crystal, 0.50ϫ0.10ϫ0.10 mm, a =
Octanedioic Acid Bis[phenyl(phenylamino)methylideneamide] (9b):
From N-phenylbenzamidine[26] (3.93 g, 20.0 mmol) and sebacoyl
chloride (2.34 g, 9.8 mmol). Addition of ethanol led to an ethanol
complex of the product which was filtered off and recrystallized
from ethanol to give 1.03 g (1.8 mmol, 18%) of a colourless solid.
The compound consists of different conformers and tautomers;
14.2876(6), b = 29.4336(11), c = 8.2604(3) Å, β = 105.564(2)°, V =
3346.4(2) Å3, ρcalcd. = 1.329 gcm–3, μ = 0.687 cm–1, empirical ab-
sorption correction (0.725Յ T Յ0.935), Z = 6, monoclinic, space
group P21/c (No. 14), λ = 1.54178 Å, T = 223 K, ω and φ scans,
24644 reflections collected (Ϯh, Ϯk, Ϯl), [(sinθ)/λ] = 0.60 Å–1, 5833
independent (Rint = 0.051) and 4454 observed reflections [I
Ն2σ(I)], 478 refined parameters, R = 0.057, wR2 = 0.150, max.
(min.) residual electron density 0.21 (–0.20) eÅ–3, asymmetric unit
contains 1.5 molecules, hydrogen atoms at N from difference fou-
rier calculations, others calculated and refined as riding atoms.
m.p. 127 and 145 °C. IR (KBr): ν = 3443 (vs, NH), 3267 (s, NH),
˜
3082 (w), 3059 (w), 3030 (vw, ν-CHarom), 2928 (m), 2855 (m, ν-
CHaliph.), 1665 (vs, C=O/C=N), 1628 (vs, C=O/C=N), 1593 (s),
1491 (vs, C=Carom), 1447 (m, δ-CH2), 1313 (m), 1277 (m), 1250
(m), 1217 (m), 1175 (m), 1072 (w), 1026 (w), 908 (vw), 779 (m),
758 (m, δ-CHarom) cm–1. 1H NMR (400.13 MHz, CDCl3): δ = 1.17
(br., 2 H, CH2), 1.23 (br., 2 H, CH2), 1.33 (br., 4 H, CH2), 1.48
(br., 2 H, CH2), 1.67 (br., 2 H, CH2), 2.11 (t, 3J = 7.3 Hz, 2 H,
Naphthalene-2,6-Dicarboxylic Acid Bis[amino(phenyl)methylidene-
amide] (9d): From naphthalene-2,6-dicarbonyl dichloride (0.76 g,
3.0 mmol),[31] triethylamine (1.7 mL, 1.21 g, 12.0 mmol) and benza-
midine (0.70 g, 6.0 mmol). The crude product was recrystallized
from ethanol/chloroform (1:1) to give 0.96 g, (2.3 mmol, 76%) of a
3
COCH2), 2.55 (t, J = 7.4 Hz, 2 H, COCH2), 6.82–7.48 (m, 18 H,
CHarom), 7.72–7.75 (m, 2 H, CHarom) ppm; ethanol: δ = 1.21 (t,
3J = 7.0 Hz, 0.75 H, CH3CH2OH), 3.67 (q, 3J = 7.0 Hz, 0.5 H,
CH3CH2OH) ppm. 13C NMR (100.13 MHz, CDCl3): δ = 24.9,
25.1, 28.9, 29.0, 29.1, 29.2, 36.6, 39.5 (CH2), 120.3 (o-CHaromR1),
122.7 (p-CHaromR1), 124.4, 128.2, 128.8, 129.5 (CHarom), 130.8 (p-
CHaromR2), 133.5, 135.3 (i-CaromR2), 148.0 (i-CaromR1), 151.5
(C=N), 166.9 (br., C=N), 171.5 (C=O), 188.3 (br., C=O) ppm; eth-
anol: δ = 17.1 (CH3CH2OH), 51.2 (CH3CH2OH) ppm. MS (70 eV):
m/z (%) = 558 (1) [C36H38N4O2 (M)]+, 455 (4), 352 (4), 321 (5), 251
(9) [PhNHC(Ph)NCO(CH2)2]+, 237 (6) [PhNHC(Ph)NCO(CH2)]+,
223 (8) [PhNHC(Ph)NCO]+, 196 (35) [PhNHC(Ph)NH]+, 180 (26)
[PhNCPh]+, 103 (100) [PhCN]+, 93 (58) [PhNH2]+, 77 (55) [Ph]+, 41
(16) [CH2=CHCH2]+. C36H38N4O2·0.25C2H5OH (570.24): calcd. C
76.88, H 6.98, N 9.83; found C 76.97, H 6.89, N 9.81.
colourless solid; m.p. 229.3 °C. IR (ATR): ν = 3358 (m), 3208 (m),
˜
3073 (m), 3053 (m), 1599 (m), 1555 (s), 1501 (m), 1466 (s), 1439
(s), 1385 (m), 1331 (m), 1314 (s), 1290 (s), 1198 (m), 1190 (m), 1148
(m), 1126 (s), 1101 (m), 1030 (m), 999 (m), 908 (m), 847 (m), 802
(m), 779 (s), 748 (s), 692 (s), 681 (s), 654 (m), 621 (s), 613 (s), 583
(s), 548 (s), 525 (m), 511 (m) cm–1. 1H NMR (300 MHz, [D6]-
DMSO): δ = 7.56–7.89 (m, 6 H, o/m-CHarom), 8.21–8.32 (m, 6 H,
CHspacer), 8.38–8.41 (m, 2 H, p-CHarom), 8.96 (s, 2 H, CHspacer),
9.49 (s, 2 H, NH2), 10.57 (s, 2 H, NH2) ppm. 13C NMR (300 MHz,
[D6]DMSO): δ = 126.0 (CHspacer), 128.1, 128.5 (o/m-CHarom),
129.2, 129.4 (CHspacer), 132.2 (p-CHarom), 134.0 (i-Cspacer), 134.5 (i-
Carom), 136.8 (i-Cspacer), 166.3 (C=N), 178.1 (C=O) ppm. HRMS
(ESI): calcd. for C26H20N4O2 + H 421.1652; found 421.1659.
C26H20N4O2 (420.5): calcd. C 74.27, H 4.79, N 13.33; found C
74.04, H 4.60, N 13.14.
X-ray Crystal Structure Analysis for 9d:[29] Formula
C26H20N4O2·2CHCl3,
0.25ϫ0.25ϫ0.20 mm,
9.8880(5) Å,
General Procedure for the Synthesis of Bis(N-Acylamidines) 9c,d
Linked Through the Carbonyl Moiety: Prepared partially in analogy
to a literature procedure.[30] A primary amidine (2 equiv.) was dis-
solved in anhydrous chloroform or dichloromethane and stirred at
room temperature in a dry round-bottomed flask. Triethylamine
(4 equiv.) was added slowly to the solution; which was stirred for
30 min and cooled to –10 °C. An aromatic diacid dichloride
(1 equiv.) dissolved in anhydrous dichloromethane or chloroform
was added dropwise to the solution to precipitate the product. The
reaction mixture was warmed to room temperature and stirred
overnight. The solid was filtered off, washed with dichloromethane
and purified as stated below.
M
=
659.20, colourless crystal,
a
=
7.7156(4), b
=
20.5542(10),
c
=
=
β
=
107.627(3)°,
V =
1494.49(13) Å3, ρcalcd.
1.465 gcm–3, μ = 5.523 cm–1, empirical absorption correction
(0.339Յ T Յ0.405), Z = 2, monoclinic, space group P21/c (No.
14), λ = 1.54178 Å, T = 223 K, ω and φ scans, 15208 reflections
collected (Ϯh, Ϯk, Ϯl), [(sinθ)/λ] = 0.60 Å–1, 2663 independent
(Rint = 0.049) and 2429 observed reflections [I Ն2σ(I)], 189 refined
parameters, R = 0.055, wR2 = 0.152, max. (min.) residual electron
density 0.68 (–0.54) eÅ–3, hydrogen atoms at N from difference fou-
rier calculations, others calculated and refined as riding atoms.
Biphenyl-4,4Ј-Dicarboxylic Acid Bis[amino(phenyl)methylidene-
amide] (9c): From biphenyl-4,4Ј-dicarbonyl dichloride (1.67 g,
6.0 mmol),[31] triethylamine (3.3 mL, 2.43 g, 24.0 mmol) and benz-
amidine (1.40 g, 12.0 mmol). The crude product was recrystallized
from chloroform/diethyl ether (3:1) to give 1.80 g, (4.0 mmol, 75%)
Synthesis of the Bis(triazapentadiene) Precursors
N1,N3-Di-p-tolylisophthalodiimidoyl Dichloride (16): N,NЈ-Di-p-tol-
ylisophthalamide (15; 7.69 g, 22.3 mmol)[32] was dissolved in thion-
yl chloride (14.5 mL, 23.80 g, 200 mmol) and heated at 85 °C for
of a colourless solid; m.p. 225–229 °C. IR (ATR): ν = 3389 (m),
˜
3300 (m), 3271 (m), 3179 (m), 3067 (m), 1597 (s), 1574 (s), 1557 3 h. All volatile compounds were removed under reduced pressure.
(s), 1547 (s), 1462 (s), 1439 (s), 1312 (s), 1292 (s), 1190 (m), 1177 The crude product was recrystallized from dry diethyl ether/dichlo-
(s), 1159 (m), 1123 (s), 1034 (m), 1001 (m), 930 (m), 893 (m), 854 romethane (1:1) to give 7.00 g (18.5 mmol, 82%) of yellow needles;
Eur. J. Org. Chem. 2011, 3197–3209
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
3207

E.-U. Würthwein et al.
m.p. 113.3–116.5 °C. IR (ATR): ν = 3277 (w), 3084 (w), 3032 (w), –78 °C and the mixture was stirred for 10 min. Bis(N-imidoylimid-
FULL PAPER
˜
2918 (w), 2858 (w), 1647 (s), 1609 (m), 1578 (m), 1503 (s), 1423
ate) 17 (5 equiv.) dissolved in dry tetrahydrofuran was added drop-
(m), 1134 (s), 1107 (m), 1020 (m), 1007 (m), 934 (m), 922 (m), 887 wise and the reaction mixture was slowly warmed to room tempera-
(m), 839 (m), 802 (s), 762 (m), 710 (m), 648 (vs), 598 (vs), 503 ture and stirred overnight. The organic layer was washed three
(vs) cm–1. 1H NMR (250 MHz, CDCl3): δ = 2.30 (s, 6 H, CH3), times with water whereby precipitation of the product occurred.
6.90 (d, 3J = 8.3 Hz, 4 H, CHarom), 7.14 (d, 3J = 7.7 Hz, 4 H,
The product was filtered off, washed with tetrahydrofuran (5 mL)
3
4
3
CHarom), 7.48 (t, J = 7.9 Hz, 1 H, CHarom), 8.23 (dd, J = 1.9, J and purified as stated below.
4
= 7.9 Hz, 1 H, CHarom), 8.84 (t, J = 1.7 Hz, 1 H, CHarom) ppm.
N-Phenyl-NЈ-[(3-{[(N-phenylbenzimidoyl)amino](p-tolylimino)-
13C NMR (63 MHz, CDCl3): δ = 21.0 (CH3), 120.6, 128.6, 129.5,
130.3, 132.5, 135.1 (CHarom), 136.2 (i-Carom), 141.6 (i-Carom-N),
144.6 (C=N) ppm. C22H18Cl2N2 (381.3): calcd. C 69.30, H 4.76, N
7.35; found C 69.00, H 4.53, N 7.25.
methyl}phenyl)(p-tolylimino)methyl]benzamidine (10a): From bis(N-
imidoylimidate) 17 (0.43 g, 0.7 mmol), aniline (0.32 mL, 0.32 g,
3.5 mmol) and n-butyllithium (2.20 mL, 3.5 mmol, 1.6 m in hex-
ane). Crystallization from chloroform/tetrahydrofuran (1:1) gave
Ethyl
N-[{3-[{[Phenyl(ethoxy)methylidene]amino}(p-tolylimino)- 0.29 g of a light-yellow solid (0.4 mmol, 59%); m.p. 210 °C. IR
methyl]phenyl}(p-tolylimino)methyl]benzimidate (17): The synthesis (ATR): ν = 3063 (w), 3024 (w), 1624 (m), 1591 (m), 1580 (m), 1535
˜
was carried out following a protocol by Häger et al.[9] Ethyl benz-
imidate hydrochloride[27] (3.29 g, 17.8 mmol) was dissolved in anhy- (s), 1179 (w), 1161 (m), 1126 (m), 1057 (m), 1028 (m), 955 (w), 916
(s), 1499 (s), 1489 (s), 1441 (s), 1362 (m), 1310 (m), 1261 (m), 1227
drous dichloromethane (100 mL) and stirred at room temperature.
Triethylamine (3.59 g, 35.5 mmol) was added dropwise to the solu-
tion whereby triethylamine hydrochloride precipitated. The reac-
tion mixture was stirred for 1 h and cooled down to –15 °C. Imid-
oyl chloride 16 (2.72 g, 7.1 mmol) dissolved in anhydrous dichloro-
methane was added dropwise and the reaction mixture was warmed
to room temperature and stirred for 20 h. The solvent was removed
under reduced pressure and the residue was washed several times
with warm pentane. The filtrate was evaporated and the crude
product obtained was purified by column chromatography
[pentane/ethyl acetate (20:1) + 5% triethylamine] to give 1.28 g
(2.1 mmol, 30%) of a yellow solid. Rf = 0.23 (pentane/ethyl acetate,
(w), 901 (w), 829 (m), 770 (m), 754 (vs), 729 (m), 694 (vs), 679 (s),
1
665 (m) cm–1. H NMR (400 MHz, CDCl3 + TFA): δ = 2.58 (s, 6
3
3
H, CH3), 7.28 (d, J = 8.2 Hz, 4 H, CHarom), 7.37 (d, J = 8.1 Hz,
4 H, CHarom), 7.44 (d, 3J = 7.5 Hz, 4 H, CHarom), 7.58–7.67 (m,
15 H, CHarom), 7.80 (t, 3J = 7.5 Hz, 2 H, CHarom), 8.05 (d, 3J =
7.6 Hz, 2 H, CHarom), 8.2 (br. s, 1 H, CHarom), 9.25 (br. s, 2 H,
NH) ppm. 13C NMR (100 MHz, CDCl3 + TFA): δ = 20.2 (CH3),
122.2, 122.9, 126.8, 127.0, 128.4, 129.7, 130.3, 130.8 (CHarom),
131.0, 132.2 (i-Carom), 132.4, 134.3 (CHarom), 135.5, 139.6 (i-Carom),
162.8, 164.1 (C=N) ppm. HRMS (ESI): calcd. for C48H40N6 + H
701.3387; found 701.3377. C48H40N6 (700.9): calcd. C 82.26, H
5.75, N 11.99; found C 81.84, H 5.85, N 12.25.
15:1 + 5% triethylamine); m.p. 129.2 °C. IR (ATR): ν = 3059 (vw),
˜
X-ray Crystal Structure Analysis for 10a:[29] C52H48N6O
3022 (vw), 2984 (vw), 2941 (vw), 2893 (vw), 1655 (m), 1639 (m),
1599 (m), 1580 (s), 1504 (m), 1477 (w), 1449 (w), 1368 (w), 1308
(w), 1298 (w), 1275 (s), 1250 (m), 1223 (w), 1179 (w), 1155 (m),
1126 (w), 1113 (w), 1084 (w), 1070 (w), 1055 (s), 1032 (m), 1016
(w), 1001 (vw), 897 (m), 826 (w), 816 (m), 779 (w), 766 (w), 748
(w), 731 (vw), 719 (m), 692 (vs), 681 (s), 642 (w) cm–1. 1H NMR
(300 MHz, CDCl3): δ = 1.27 (t, 3J = 7.1 Hz, 6 H, OCH2CH3), 2.18
(C48H40N6·C4H8O),
0.35ϫ0.20ϫ0.05 mm,
M
a
=
772.96,
22.7484(9), b
4903.4(3) Å3, ρcalcd.
colourless
crystal,
=
=
12.5454(4),
c
=
=
18.1993(5) Å,
β
=
109.251(2)°,
V
=
1.047 gcm–3, μ = 0.493 cm–1, empirical absorption correction
(0.846Յ T Յ0.976), Z = 4, monoclinic, space group P21/c (No.
14), λ = 1.54178 Å, T = 223 K, ω and φ scans, 41266 reflections
collected (Ϯh, Ϯk, Ϯl), [(sinθ)/λ] = 0.60 Å–1, 8223 independent
(Rint = 0.078) and 5262 observed reflections [I Ն2σ(I)], 540 refined
parameters, R = 0.077, wR2 = 0.247, max. (min.) residual electron
density 0.33 (–0.3) eÅ–3, solvent molecules in the voids could not
be described and therefore the SQUEEZE routine was used, hydro-
gen atoms at N from difference fourier calculations, others calcu-
lated and refined as riding atoms.
3
3
(s, 6 H, CH3), 4.23 (q, J = 7.1 Hz, 4 H, OCH2CH3), 6.48 (d, J =
8.2 Hz, 4 H, CHarom), 6.84 (d, 3J = 8.1 Hz, 4 H, CHarom), 7.27–
7.05 (m, 10 H, CHarom), 7.41 (t, J = 7.8 Hz, 1 H, CHarom), 8.12
3
(dd, 3J = 7.8, J = 1.8 Hz, 2 H, CHarom), 8.45 (t, J = 1.5 Hz, 1 H,
CHarom) ppm. 13C NMR (75 MHz, CDCl3): δ = 14.2 (OCH2CH3),
20.9 (CH3), 63.2 (OCH2CH3), 121.5, 127.6, 127.8, 128.2, 128.5,
128.8, 130.0, 130.9 (CHarom), 131.4, 131.9, 136.7, 146.9 (i-Carom),
157.5, 157.6 (C=N) ppm. HRMS (ESI): calcd. for C40H38N4O2 +
H 607.3068; found 607.3058. C40H38N4O2 (606.8): calcd. C 79.18,
H 6.31, N 9.23; found C 78.90, H 6.05, N 9.22.
4
4
N-(p-Tolyl)-NЈ-[(3-{[(N-p-tolylbenzimidoyl)amino](p-tolylimino)-
methyl}phenyl)(p-tolylimino)methyl]benzamidine (10b): From bis(N-
imidoylimidate) 17 (1.82 g, 3.0 mmol), 4-methylaniline (1.61 g,
15.0 mmol) and n-butyllithium (9.4 mL, 15.0 mmol, 1.6 m in hex-
ane). Crystallization from tetrahydrofuran/ethyl ether (10:1) gave
1.65 g (2.3 mmol, 75 %) of a light-yellow solid; m.p. 223 °C. IR
X-ray Crystal Structure Analysis for 17:[29] C40H38N4O2, M =
606.74, yellow crystal, 0.30ϫ0.20ϫ0.10 mm, a = 9.0854(2), b =
11.2202(3), c = 17.4172(5) Å, α = 107.755(1), β = 100.193(1), γ =
(ATR): ν = 3279 (vw), 3208 (vw), 3115 (vw), 3063 (vw), 3021 (vw),
˜
93.689(1)°,
V = = μ =
1650.94(7) Å3, ρcalcd. 1.221 gcm–3,
2918 (vw), 2864 (vw), 1624 (m), 1593 (s), 1580 (m), 1566 (m), 1531
(vs), 1512 (vs), 1447 (m), 1406 (m), 1360 (m), 1312 (m), 1290 (m),
1273 (m), 1260 (m), 1225 (s), 1159 (m), 1124 (m), 1057 (m), 1028
(m), 955 (w), 916 (w), 851 (m), 816 (s), 781 (m), 773 (m), 752 (m),
727 (m), 696 (s), 679 (s), 658 (m) cm–1. 1H NMR (400 MHz, CDCl3
+ TFA): δ = 2.40 (s, 12 H, CH3), 7.10 (d, 3J = 8.1 Hz, 4 H, CHarom),
7.20 (d, 3J = 8.1 Hz, 4 H, CHarom), 7.22–7.29 (m, 8 H, CHarom),
7.38–7.43 (m, 8 H, CHarom), 7.61 (br. t, 3J = 7.5 Hz, 3 H, CHarom),
7.87 (d, 3J = 7.7 Hz, 2 H, CHarom), 8.04 (s, 1 H, CHarom), 8.57,
9.03 (br. s, 2 H, NH) ppm. 13C NMR (100 MHz, CDCl3 + TFA):
δ = 20.2, 20.2 (CH3), 122.0, 122.9, 126.8, 127.0, 129.7, 130.2, 130.3,
130.7, 130.8 (CHarom), 132.3, 132.3, 133.0, 133.3 (i-Carom), 134.2
(CHarom), 139.3, 139.5 (i-Carom), 162.6, 164.1 (C=N) ppm. HRMS
0.596 cm–1, empirical absorption correction (0.841Յ T Յ0.943), Z
¯
= 2, triclinic, space group P1 (No. 2), λ = 1.54178 Å, T = 223 K,
ω and φ scans, 19024 reflections collected (Ϯh, Ϯk, Ϯl), [(sinθ)/λ]
= 0.60 Å–1, 5747 independent (Rint = 0.054) and 4775 observed
reflections [I Ն2σ(I)], 430 refined parameters, R = 0.047, wR2
=
0.123, max. (min.) residual electron density 0.17 (–0.21) eÅ–3,
group C8B–C11B refined with split positions, hydrogen atoms cal-
culated and refined as riding atoms.
General Procedure for the Syntheses of Bis(triazapentadienes) 10a–
c: The synthesis was carried out following the protocol of Häger et
al.[9] A primary amine (5 equiv.) dissolved in dry tetrahydrofuran
was deprotonated with an equimolar amount of n-butyllithium at
3208
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Eur. J. Org. Chem. 2011, 3197–3209

Two- and Three-Armed Nitrogen-Rich Chelate Ligands
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anas, J. H. Teles, A. G. Altenhoff (BASF SE), DE 10 2008 000
077 A1, 2008.
[13] E. A. Marihart, J.-B. Greving, R. Fröhlich, E.-U. Würthwein,
Eur. J. Org. Chem. 2007, 5071–5754.
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Pat. US348972719700113, 1970 [Chem. Abstr. 1970, 72,
112071].
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Dalton Trans. 1999, 3157–3161.
[17] M. C. Grossel, D. A. S. Merckel, M. G. Hutchings, Crys-
tEngComm 2003, 5, 77–81.
(ESI): calcd. for C50H44N6 + H 729.3700; found 729.3698.
C50H44N6 (728.9): calcd. C 82.39, H 6.08, N 11.53; found C 82.05,
H 6.08, N 11.57.
N-(4-Chlorophenyl)-NЈ-{[3-({[N-(4-chlorophenyl)benzimidoyl]-
amino}(p-tolylimino)methyl)phenyl](p-tolylimino)methyl}benz-
amidine (10c): From bis(N-imidoylimidate) 17 (1.82 g, 3.00 mmol),
4-chloraniline (1.91 g, 15.00 mmol) and n-butyllithium (9.4 mL,
15.00 mmol, 1.6 m in hexane). Crystallization from tetra-
hydrofuran/ethyl ether (10:1) gave 1.19 g (1.54 mmol, 52%) of a
yellow solid; m.p. 136 °C. IR (ATR) ν = 3402 (vw), 3059 (vw), 3030
˜
(vw), 2922 (vw), 1630 (m), 1591 (m), 1568 (m), 1512 (vs), 1491 (vs),
1481 (s), 1447 (m), 1400 (m), 1342 (m), 1312 (m), 1288 (m), 1248
(m), 1221 (m), 1173 (w), 1130 (w), 1090 (m), 1051 (m), 1026 (m),
1011 (m), 910 (m), 812 (s), 775 (m), 762 (m), 739 (m), 723 (m), 694
1
(vs) cm–1. H NMR (300 MHz, CDCl3 + TFA): δ = 2.19 (s, 6 H,
3
3
CH3), 6.86 (d, J = 8.2 Hz, 4 H, CHarom), 6.99 (d, J = 8.1 Hz, 8
H, CHarom), 7.15–7.22 (m, 9 H, CHarom), 7.24–7.34 (m, 5 H, [18] J. Corcoran, F. Rodriguez, I. Rozas, J. J. Meana, L. F. Callado,
3
3
Bioorg. Med. Chem. Lett. 2007, 17, 6009.
CHarom), 7.41 (t, J = 7.7 Hz, 3 H, CHarom), 7.72 (d, J = 7.7 Hz,
2 H, CHarom), 7.91 (s, 1 H, CHarom), 8.94 (br. s, 2 H, NH) ppm.
13C NMR (300 MHz, CDCl3 + TFA): δ = 20.1 (CH3), 122.9, 123.2,
126.7, 127.3, 129.7, 129.8, 130.4, 130.9 (CHarom), 131.0, 132.1 (i-
[19] R. Richter, U. Schröder, L. Beyer, J. Angulo-Cornejo, M. Lino-
Pacheco, Z. Anorg. Allg. Chem. 2001, 627, 1877–1881.
[20] U. Schröder, L. Beyer, J. Angulo-Cornejo, M. Castillo-Mon-
toya, M. Lino-Pacheco, Inorg. Chim. Acta 2003, 353, 59–67.
[21] J. I. Clodt, V. D. Hack, R. Fröhlich, E.-U. Würthwein, Synthe-
sis 2010, 1485–1492.
C
arom), 132.5 (CHarom), 133.1, 134.2, 134.2 (i-Carom), 134.3
(CHarom), 139.9 (i-Carom), 163.4, 164.0 (C=N) ppm. HRMS (ESI):
calcd. for C48H38Cl2N6 769.2593; found 769.2608.
+
H
[22] J. I. Clodt, R. Fröhlich, E.-U. Würthwein, manuscript in prepa-
ration; C. Wigbers, R. Fröhlich, E.-U. Würthwein, manuscript
in preparation.
C48H38Cl2N6 (769.8): calcd. C 74.90, H 4.98, N 10.92; found C
74.47, H 5.12, N 10.90.
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Acknowledgments
[26] In analogy to: P. Oxley, M. W. Partridge, W. F. Short, J. Chem.
Soc. 1947, 1110; see also P. A. Koutentis, S. I. Mirallai, Tetrahe-
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Ber. 1985, 118, 3089–3104, or in analogy to the procedures
given here.
We are grateful to cand chem. Jennifer Längle for experimental
help. This work was supported by the International Research Train-
ing Group 1444, Münster–Amsterdam (Deutsche Forschungsge-
meinschaft, DFG), the Fonds der Chemischen Industrie (Frank-
furt) and by the BASF SE.
[28] B. I. No, Y. L. Zotov, E. V. Shishkin, D. S. Klimov, Russ. J.
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[29] Data sets were collected with Nonius CAD4 and KappaCCD
diffractometers. Programs used: data collection EXPRESS
(Nonius B. V., 1994), and COLLECT (Nonius B. V., 1998),
data reduction MolEN (K. Fair, Enraf–Nonius B. V., 1990),
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CCDC-813178 (for 7a), -814179 (for 7g), -813180 (for 7j),
-813181 (for 9c), -813182 (for 9d), -813183 (for 10a) and
-813184 (for 17) contain the supplementary crystallographic
data for this paper. These data can be obtained free of charge
from The Cambridge Crystallographic Data Centre via
www.ccdc.cam.ac.uk/data_request/cif.
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Received: February 18, 2011
Published Online: May 2, 2011
Eur. J. Org. Chem. 2011, 3197–3209
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
3209