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Stoichiometric Mono N-Functionalization of Tetraazamacrocycles via Phosphoryl-Protected Intermediates.

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Stoichiometric Mono N-Functionalization
of Tetraazamacrocycles via Phosphoryl-Protected
Intermediates**
Table 1. Mono N-functionalization of tetraazamacrocycles.
By Ayoub Filali, Jean-Jacques Yaouanc, and Henri Handel*
Owing to the cost of polyazacrowns, a stoichiometric and
direct method to introduce mono N-functionalization is needed.['] During the past ten years, some phosphorous P"'- and
Pv-containing tetraazamacrocycles have been reported,"]
but they have surprisingly not yet found any synthetic application. Our previous studies on selective mono N-alkylation
of tetraazamacrocycles~31prompted us to consider the Pvphosphorylated macrocycles as potential precursors of monofunctionalized tetraazamacrocycles, since they could be
seen as cyclic analogues of hexamethylphosphoric triamide
containing, besides three inert nitrogen atoms, a free nitrogen atom available for further reaction.
We now report the reaction of these phosphorylated macrocycles with some electrophiles RX giving rise to mono Nfunctionalized ligands after removal of the phosphoryl protection, as depicted in Scheme 1.
The polyaminophosphoranes 1 were obtained according
to a previously described reaction by transaminating hexamethylphosphoric triamide with the appropriate tetraazacycloalkane. As noted by Atkins and Richman['"] these compounds exist as P'"/PV tautomers. After oxidation with CCI,,
the resulting phosphonium salts 2 were hydrolyzed with sodium hydroxide to yield quantitatively the oxides 3. The
action of a suitable electrophile gave finally, after hydrolysis
of the intermediate 4, the desired mono N-substituted macrocycles 5.
In general, the reaction of alcohols with the phosphonium
salts 2 leads to a stable, distillable pentacoordinated alkoxyphosphorane 6;t2blnevertheless, in the special case of activated alcohols like benzyl, allyl, or propargyl alkohols we
observed that 6 isomerized to the N-alkylated intermediates
* .
-
N
-
N
CP
5
1
I
n
m
R
X
Yield
[%I
cyclen
(2222)
cyclam
(2323)
2
2
C6H,
C6Hs
C,H,
Br
OH
90
80
Br
OH
96
92
3.6
290
Br
OH
8o
75
3.1
240
Br
OH
92
83
3.5
238
OH
Br
Br
Br
8o
85
86
75
75
3.6
384
[c]
[c]
[c]
304
318
368
Br
OH
Br
90
80
92
3.5
318
3.5
346
2
3
C6H5
H,C=CH
H,C=CH
H C d
HCFC
Fc [bl
Fc [bl
C6HSCHZ
"3333"
3
3
C6HdCHz)z
n-C I 1HZ3
C,Hs
"3434"
3
4
C,Hs
C6H5
d('H) [a]
3'7
m/z(Me)
262
[a] Signal of the exocyclic N-CH, group. [b] Fc = ferrocenyl. [c] Masked by the
endocyclic N-CH, signal.
separable by usual techniques. It is thus better suited to
symmetrical macrocycles.
This easy-to-run process constitutes a powerful and stoichiometric method of preparing the mono N-functionalized
tetraazamacrocycles.
- (
6
2
4
5
1
3
Scheme 1
4. Using this principle we alkylated a series of tetraazamacrocycles (Table 1). When applied to less symmetrical
azamacrocycles (for instance isocyclam "3322"), this method led to a mixture of regioisomers which are not easily
[*I
Prof. H. Handel, Dr. J. J. Yaouanc, A. Filali
Unitt de Recherche Associk au CNRS N"322
Chimie, Electrochimie et Photochimie Mofkulaires
Facultt des Sciences et Techniques
6, avenue le Gorgeu, F-29287 Brest (France)
[**I This work was supported by the Centre National de la Recherche Scientifique.
560
0 VCH
Verlagsgesellschaft mbH. W-6940 Weinheim, 1991
Experimental Procedure
General Procedure
The tetraazamacrocycle 1 (1.0 mmol) in dry toluene (30 mL) was refluxed under
nitrogen with hexamethylphosphoric triamide (1 .O mmol) until dimethylamine
evolution ceased. After cooling to 0-5"C. excess CCI, was added upon which
a white solid separated. The solvent was removed under reduced pressure and
the remaining crude phosphonium salt 2 treated with 2 N sodium hydroxide
(5 mL). The aqueous phase was extracted with CHCI, (2 x SO mL); the combined organic phases were dried and finally concentrated to dryness in vacuo
giving the crude phosphorylated tetraazamacrwycle 3 pure enough for the next
rea~tion.'~'
To a solution of 3 (1.0 mmol) in dry DMF (20 mL) was added an excess of dry
Na,CO, and the mixture heated to 100°C. The alkylating agent (1.0 mmol) was
0570-0833/91/0505-0560$3.50+ .25/0
Angew. Chem. Inl. Ed. Engl. 30 (1991) No. 5
introduced by syringe and the temperature maintained at 100°C for 2 hours.
After cooling to room temperature, the solvent was removed in vacuo. The
resulting residue was taken up in 3 N HCI (10 mL) and refluxed for 10 hours.
The pH was then carefully adjusted to 12 with NaOH pellets. After extraction
with CHCI, (2 x 50 mL), drying of the combined organic phases, and evaporation of the solvent, the pure mono N-alkylated tetraazamacrocycle was ohtained, generally as an oily residue.
Modified Procedure: direct alkylarion of the phosphonium salt 2
The suspension of 2 in toluene was treated with the required alcohol (1.O mmol)
(Scheme 1). the solvent was removed and replaced by dry DMF (20 mL), an
excess of Na,CO, was added, and the mixture was heated at 100°Cfor 2 hours.
The subsequent work-up was as described above. All the mono N-alkylated
tetramines gave satisfactory IR, MS, and 'H NMR data.
Received: November 12, 1990 [Z 4277 IE]
German version: Angew. Chem. 103 (1990) 563
NY
NCKCN
N,
1
-2.92
CN
I
/N
N'
'N
2
3
4
-2.51
-2.18
-2.30
Scheme 1. Organic electron acceptors and their LUMO energies calculated with
MNDO-AM1 for the parent compounds.
[l] a) K. E. Krakowiak, J. S. Bradshaw, R. M. Izatt, J. Org. Chem. 55 (1990)
3364; b) T. A. Kaden in F. Vogtle, E Weber (Eds.): Hosr Guest Complex
Chemistry Yo/.111, Springer, Berlin 1984, p. 157; c) I. M. Helps, D. Parker,
T. R. Morphy, J. Chapman, Tetrahedron 45 (1989) 219.
[2) a) T. I. Atkins, J. E. Richman, Tetrahedron Letr. 52 (1978) 5149; b) J. E.
Richman, J. J. Kubala, J. Am. Chem. Soc. 105 (1983) 749; c) J. E. Richman,
R. B. Flay, 0. D. Gupta, ACS. Symp. Ser. 171 (1981) 271; d) J. M. Dupart,
A. Grand, J. G. Riess, J. Am. Chem. SOC.108 (1986) 1167; e) F. Bouvier,
J. M. Dupart, A. Grand, J. G. Riess, Inorg. Chem. 26 (1987) 2090.
[3] H. Handel, H. Chaumeil, European patent, 88400839.2. (1988), CNRS.
[4] The P=O derivative of "3434" exhibits a "P NMR signal at 6 = - 18.4;
for other phosphorylated macrocycles, see ref. [Zc].
Benzene Bis(diaz0cyanides)-the First Acceptors
of the Inverse Wurster Type for Conductive Organic
Materials**
By Hartmut Almen, Thomas Bauer, Siegfried Hiinig,*
Vladimir KupEik, Uwe Langohr, Tobias Metzenthin,
Klaus Meyer, Harald Rieder, Jost UIrich von Schiitz,
Ekkehart Tillmanns, and Hans Christoph Worf
Tetracyanoquinodimethane(TCNQ)['] and N,N'-dicyanoquinonediimine(DCNQI)[21 and derivatives thereof (1 and 2
respectively) have proved to be the most important organic
electron acceptors for charge-transfer(CT) complexes or
radical anion salts with electrical conductivity. Both types of
compound form two-stage reversible redox systems and thus
belong to the Wurster type, in which the defined acceptor end
groups are connected to the six membered 7~ ring system in
such a way that the oxidized stage has quinone character.13]
We wondered whether the as yet unused two-stage redox
systems of inverse Wurster type, that is, with aromatic oxidized stagec3](see Scheme 2), is also suitable as acceptor for
conductive organic materials.
The benzene-I ,4-bis(diazocyanides)3 (dicyanazobenzene
[DCNAB]) appeared to be promising candidates, since the
[*I
[**I
Prof. Dr. S. Hiinig, Dipl.-Chem. T. Metzenthin
Institut fur Organische Chemie der Universitat
Am Hubland, W-8700 Wiirzburg (FRG)
Dip].-Phys. U. Langohr, Dip1.-Phys. K. Meyer, Dipl.-Phys. H. Rieder,
Dr. J. U. von Schiitz, Prof. Dr. H. C. Wolf
3. Physikalisches Institut der Universitat Stuttgart
Dip1.-Min. H. Almen, Dipl.-Min. T. Bauer, Prof. Dr. E. Tillmanns
Mineralogisches Institut der Universitat Wiirzburg
Prof. Dr. V. Kuptik
Mineralogisch-KristallographischesInstitut der Universitat Gottingen
This work was supported by the Volkswagen-Stiftung and the Fonds der
Chemischen Industrie. T Mefrenrhin thanks the Fonds der Chemischen
Industrie for a study grant.
Angew. Chem. Int. Ed. Engf.30 (1991) No.5
0 VCH
LUMO energy as calculated by MNDO-AM1 141 (Scheme 1)
of the almost planar structure lies in a similarly favorable
range to the tried and tested compounds 1 and ZtS1It was,
however, doubtful whether the orbital symmetry of 3, which
is vastly different from that of the quinones, would allow the
stacking in the crystal essential for conduction.
We now use the first examples, which also include naphthalene-I ,4-bis(diazocyanide) 4, to show that these compounds, besides having spectroscopically detectable radical
anionst61,not only form fully reversible two stage redox systems of the inverse Wurster type,L3]but are also potent acceptors in conductive CT complexes and radical anion salts.[''
Table 1 shows that the redox potentials of 3 and 4 lie in the
same region as those of TCNQ, l(R = H) and DCNQI, 2
(R = H). The semiquinone formation constants of Ig KSEM
=
Table 1. Redox potentials E, and E, determined by cyclic voltammetry (Pt
electrode vs. Ag/AgCI/CH,CN, electrolyte nBu,NBF,) and semiquinone formation constants Ig KSEMof 1-4 (see also Scheme 2.)
3a
3b
3c
R'
R2
R3
E, [V]
Me
H
CI
H
H
H
Me
H
Cl
- 0.15
4
1 (R = H) 1.51
2 (R = H) [5]
- 0.15
+ 0.07
- 0.01
- 0.28
- 0.25
E,[V]
IgK,,,
+0.20
5.92
6.10
6.82
6.49
11.42
10.75
+ 0.22
+ 0.47
+ 0.32
+ 0.39
+ 0.39
5.92-6.82 are still very large, although a factor of ca. lo4
smaller than in TCNQ and DCNQI. That is predictable,
because the Coulomb repulsion in the longer systems of 3
and 4 (they contain two more atoms) has less effect on the
gain of electrons.IS1Surprisingly, a higher acceptor capacity
(LUMO = 2.30 eV) is calculated for 4 than for 3b, which is
also reflected in a higher reducibility (E2 = 0.32 V). The
opposite is true for the transition from DCNQI to the corresponding naphthalene d e r i ~ a t e . ~ ~ '
Furthermore, the MNDO-AM1 calculations show that
during the reduction (OX + SEM + RED) 3b indeed assumes progressively a quinoid structure. Thus the exocyclic
Car,,-N single bond becomes shorter on gain of electrons
(144 (OX) via 138 (SEM) to 133 pm (RED)); the bond between C2 and C3 also shortens (139 (OX), 137 (SEM),
135 pm (RED)). The corresponding experimentally determined bond lengths in DCNQI are 130 (C-N) and 134 pm
(C =C).'9'
On combining solutions of 3 or 4 with solutions of tetrathiofulvalenes(TTF) or tetramethyltetraselenafulvalenes-
VerfagsgesellschajtmbH, W-6940 Weinheim. 1991
+
0570-08333/91/0505-05618 3.50+ ,2510
561
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functionalization, stoichiometry, intermediate, tetraazamacrocycles, mono, via, protected, phosphorus
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