Stereochemistry of phosphite addition to azomethine bond of achiral 2,6-pyridinedicarbaldimines and isophthalaldimines - A comparative study

Article abstract of DOI:10.1080/10426507.2012.718298

The addition of dialkyl H-phosphonates to isophthalaldimines 1a-d and pyridine-2,6-dicarboxaldimines 2a-d was investigated and led to the corresponding aminophosphonates. Diastereoselectivity of the addition to pyridine-2,6-dicarboxaldimines was lower tha

Full text of DOI:10.1080/10426507.2012.718298

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Stereochemistry of Phosphite Addition
to Azomethine Bond of Achiral
2,6-Pyridinedicarbaldimines and
Isophthalaldimines—A Comparative Study
Jarosław Lewkowski a & Marek Dzięgielewski a
a Faculty of Chemistry, Department of Organic Chemistry ,
University of Łódź , Łódź , Poland
Accepted author version posted online: 10 Aug 2012.
To cite this article: Jarosaw Lewkowski & Marek Dzigielewski (2013) Stereochemistry of Phosphite
Addition to Azomethine Bond of Achiral 2,6-Pyridinedicarbaldimines and Isophthalaldimines—A
Comparative Study, Phosphorus, Sulfur, and Silicon and the Related Elements, 188:8, 995-1006, DOI:
10.1080/10426507.2012.718298
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Phosphorus, Sulfur, and Silicon, 188:995–1006, 2013
Copyright ꢀC Taylor & Francis Group, LLC
ISSN: 1042-6507 print / 1563-5325 online
DOI: 10.1080/10426507.2012.718298
STEREOCHEMISTRY OF PHOSPHITE ADDITION TO
AZOMETHINE BOND OF ACHIRAL
2,6-PYRIDINEDICARBALDIMINES AND
ISOPHTHALALDIMINES—A COMPARATIVE STUDY
Jarosław Lewkowski and Marek Dziegielewski
ꢀ
Faculty of Chemistry, Department of Organic Chemistry, University of Ło´dz´,
Ło´dz´, Poland
GRAPHICAL ABSTRACT
Abstract The addition of dialkyl H-phosphonates to isophthalaldimines 1a–d and pyridine-
2,6-dicarboxaldimines 2a–d was investigated and led to the corresponding aminophospho-
nates. Diastereoselectivity of the addition to pyridine-2,6-dicarboxaldimines was lower than to
isophthalaldimines. In contrast, addition of bis(trimethylsilyl) H-phosphonate to both groups of
aldimines demonstrated that the diastereoselectivity in case of pyridine-2,6-dicarboxaldimines
is comparable or even better than that for the isophthalic derivatives.
Keywords Addition; azomethine bond; dialkyl H-phosphonates; diastereoselectivity; isoph-
thalaldimines; pyridine-2,6-dicarboxaldimines
INTRODUCTION
Extensive investigations over last twenty years have shown that the addition of various
phosphorus nucleophiles to azomethine bond of achiral terephthalic and isophthalic Schiff
bases is in a majority of cases diastereoselective and, what is of great importance, a large
number of additions occurred with 100% diastereoselectivity.
Received 8 June 2012; accepted 31 July 2012.
Marek Dziegielewski was the participant of the project entitled Doktoranci—Regionalna Inwestycja w
ꢀ
Młodych naukowco´w—Akronim D-RIM, which is co-financed by the EU from the European Social Fund in the
framework of the Operational Programme Human Capital, Priority VIII, Subaction 8.2.1. and is thankful for the
scholarship.
Address correspondence to Professor Jarosław Lewkowski, Faculty of Chemistry; Department of Organic
Chemistry, University of Lodz, Tamka 12, Ło´dz´ 91-403, Poland. E-mail: jlewkow@uni.lodz.pl
995

996
J. LEWKOWSKI AND M. DZIEGIELEWSKI
ꢀ
For example, the addition of hypophosphorous acid to achiral N-alkyl terephthalic
and isophthalic imines has been reported1,2 to be diastereoselective to 100% and leads to a
meso-form, whereas the reaction performed with N-aryl imines has been noted to depend
on the nature of the substituent at the aromatic ring.2 Similar results have been reported
for the addition of dialkyl H-phosphonates to achiral N-alkyl and N-aryl terephthalic and
isophthalic Schiff bases.1,3–8
Some years ago, we reported that the addition of bis(trimethylsilyl) H-phosphonate
to N,N-terephthalylidene-alkyl (or -aryl) amines leads exclusively to the formation of only
one diastereomeric form of the corresponding 1,4-phenylene-bis-(N-alkylaminomethyl)-
phosphonic acid.9 The investigation of the products identified unexpectedly this diastere-
omeric form as a pair of enantiomers.
These 1,4-phenylene and 1,3-phenylene-bis(N-alkylaminomethyl)-phosphonic deri-
vatives have been found to have coordination abilities toward Cu(II) ions10 or di-
aminophosphonate peptide receptor for lysine and arginine.11 Thus, investigations of these
compounds and their synthesis are not only important regarding the respective mecha-
nism but also because of possible applications. It is therefore well visible that the field of
terephthalic and isophthalic derivatives has been largely explored.
Contrary to this, stereochemical aspects of the addition of phosphorus nucleophiles
to the azomethine bond of achiral Schiff bases, deriving from heteroaromatic di-aldehydes,
have not been investigated at all. Recently, we have contributed to this topic reporting
on the addition of bis(trimethylsilyl) H-phosphonate to achiral 2,5-Diformylfuran Schiff
bases.12 The reaction was not stereoselective except in the case of N-benzyl substituted
imine.
This encouraged us to study another heteroaromatic ring system, i.e., 2,6-diformy-
lpyridine. The stereochemistry of addition of phosphorus nucleophiles to 2,6-
pyridinedicarbaldimines is really unexplored; according to bibliographic databases there
is the only one article in which tetraphenyl 2,6-pyridine-bis-(N-(p-nitrophenylaminome-
thylphosphonate) was described13 as the only compound of this type. This prompted us
to study the addition of dialkyl H-phosphonates and bis(trimethylsilyl) H-phosphonate to
various N-substituted 2,6-diformylpyridine Schiff bases.
RESULTS AND DISCUSSION
Some literature results of the addition of H-phosphonates to isophthalic, achiral
Schiff bases demonstrated interesting stereochemical behavior. Barycki et al.1 reported that
addition of diethyl H-phosphonate to N-benzyl- and N-benzhydryl-isophthalaldimines was
stereoselective to 100%. According to Failla et al.4 addition of diethyl H-phosphonate to
N-phenyl-, N-(2-pyridylethyl)-, and N-(4-phenylazo)phenyl isophthalaldimines was also
highly diastereoselective, as dr oscillated around 9:1.
It was interesting to perform such reactions with Schiff bases of 2,6-diformylpyridine
and to compare the results with those obtained for isophthalic derivatives. Therefore, we
have chosen four model amines: benzylamine, furfurylamine, p-toluidine, and p-anisidine
and three model H-phosphonates: dimethyl and diethyl H-phosphonates applied alternately
as well as dibenzyl H-phosphonate.
Isophthalic aldehyde Schiff bases 1a–d were synthesized following published pro-
cedures.1–9,14,15 Then, the addition of H-phosphonates to their azomethine bond was per-
formed and reactions were carried out in refluxing toluene to obtain bis(aminophosphonates)

PHOSPHITE ADDITION TO DIMINES
997
3Aa–Ad. In the same way, 2,6-diformylpyridine Schiff bases 2a–d were synthesized fol-
lowing the published procedures.1–9,16 Then, the addition of H-phosphonates to their azome-
thine bond was performed and the reactions were carried out in refluxing toluene to obtain
bis(aminophosphonates) 4Aa–Bd. The preparation of 4Bb from dimethyl H-phosphonate
and a Schiff base was, however, carried out in dioxane and catalyzed by trifluoroacetic
acid. This procedure allowed obtaining the bis(aminophosphonates) 3Aa–Ad and 4Aa–Bd
in 50–90% yields. (Scheme 1)
O
O
P
O
P
RNH2
H
P(OR')2
R'O
R'O
OR'
OR'
X
X
X
O
O
N
N
NH
HN
R
R
R
R
X = CH, N
1a d
-
3Aa Ad
- (X = CH)
(X = CH)
2a-d (X = N)
4Aa-Bd (X = N)
a
b
c
d
R = 4-MeOC6H4 ( ), 4-MeC6H4 ( ), CH2Ph ( ), CH2(2'-furyl) ( )
A
B
C
R' = Me ( ), Et ( ), CH2Ph ( )
Scheme 1
1
New bis(aminophosphonates) 3 and 4 were characterized by H and 31P NMR
spectroscopy as well as by microanalysis, except tetraethyl 2,6-pyridine-bis-(N-
furfurylaminomethyl)-bis(phosphonate)(4Bd). This compound turned out to be too
unstable to be purified by chromatography on silica gel and alumina; the routine method
of purification suitable for the rest bis(aminophosphonates) 3 and 4 did not allow to purify
the product 4Bd to a degree enough to give satisfactory results of elemental analysis.
Therefore tetraethyl 2,6-pyridine-bis-(N-furfurylaminomethyl)-bis-phosphonate(4Bd) was
characterized only by 1H and 31P NMR spectroscopy.
We have also performed the synthesis of 1,3-phenylene-bis(aminomethylphosphonic
acids) 5a–d and 2,6-pyridine-bis(aminomethylphosphonic acids) 6a–d, which were pre-
pared by the addition of in situ formed bis(trimethylsilyl) H-phosphonate to imines 1a–d and
2a–d, respectively. The preparation of bis(trimethylsilyl) H-phosphonate was performed
following the published general procedure17 by the action of trimethylsilyl bromide on
dimethyl H-phosphonate. The procedure involving the described methanolysis and precip-
itation with propylene oxide allowed obtaining aminophosphonic acids 5a–d in 70–95%
yield and acids 6a–d in 30–75% yield. (Scheme 2)
O
O
P
O
P
H
HO
HO
OH
OH
RNH2
P(OSiMe3)2
MeOH
X
X
X
O
O
N
N
NH
HN
R
R
R
R
X = CH, N
5a-d (X = N)
6a d
1a-d (X = CH)
2a d
-
(X = CH)
-
(X = N)
R = 4-MeOC6H4 (a), 4-MeC6H4 (b), CH2Ph (c), CH2(2'-furyl) (d)
Scheme 2

998
J. LEWKOWSKI AND M. DZIEGIELEWSKI
ꢀ
Although Barycki et al.1 reported that the addition of diethyl H-phosphonate to N,Nꢁ-
iso-phthalylidenebenzylamine (1c) was highly diastereoselective (de = 95%), which was
in accord with Failla’s et al.4 observations, the addition of the investigated H-phosphonates
to Schiff bases 1a,b and 1d turned out to be slightly diastereoselective.
The addition of dimethyl H-phosphonate to N-furfuryl isophthalic Schiff base turned
out to be not very diastereoselective (dr = 2:1), which was rather astonishing in the
light of studies on terephthalaldehyde-derived aminophosphonates.6,9 On the other hand,
however, such phenomenon has been noticed in the case of addition of hypophosphorous
acid to N-furfuryl terephthalaldimine,2 where a complete lack of diastereoselectivity was
observed. The addition of dimethyl H-phosphonate to N-p-tolyl imine occurred also with
rather low diastereoselectivity (dr = 4:5). Although addition of dibenzyl H-phosphonate
to N-p-methoxyphenyl isophthalic Schiff base was almost not selective (dr = 9:11), the
addition of dimethyl H-phosphonate occurred with dr = 4:1, which undoubtedly confirms
that the addition of dibenzyl H-phosphonate to isophthalic Schiff bases turns out to be
much less diastereoselective than the addition of H-phosphonates with typical alkyl chains.
It is to remind that the addition of diethyl H-phosphonate to N-isophthalilidene-bis(1-
naphthylamine)7 leads to the formation of exclusively one diastereomer, while addition of
dibenzyl H-phosphonate to the same imine was not diastereoselective at all7 (Table 1).
The additions of H-phosphonates to pyridine-2,6-dicarboxaldimines 2a–d turned
out to be slightly less diastereoselective than the addition to the isophthalic derivatives
described above. Reactions of dimethyl and dibenzyl H-phosphonates with 2,6-bis(N-
benzylazomethine)-pyridine (2c) were characterized by complete lack of diastereoselec-
tivity, as the formation of both possible forms of aminophosphonates 4Ac and 4Cc in a
1:1 ratio was observed. In the case of tetramethyl 2,6-pyridine-bis(N-benzylaminomethyl)-
bis(phosphonate)(4Ac),an interesting phenomenon was observed, its 31P NMR spectrum
would have indicated the formation of an exclusive diastereomeric form as it displayed only
one signal. However, two sets of diagnostic signals in the 1H NMR spectrum demonstrated
clearly that two diastereomeric forms occurred in a 1:1 ratio (Table 1).
N-furfuryl and N-p-methoxyphenyl Schiff bases were stereochemically inactive, as
additions of H-phosphonates occurred to give the products in 1:1 diastereomeric ratios. The
only studied case of 2,6-diformylpyridine derivatives, where diastereoselectivity occurred,
Table 1 Results of addition of dialkyl phosphites to isophthalaldimines 1a–d and pyridine-2,6-dicarboxaldimines
2a–d
R
Rꢁ
CH3
CH2Ph
CH3
CH2CH3
CH3
CH3
X
31P NMR
dr
3Aa
3Ca
3Ab
3Bc
3Ad
4Aa
4Bb
4Cc
4Ac
4Bd
4-MeOC6H4
4-MeOC6H4
4-MeC6H4
CH2Ph
CH
CH
CH
CH
CH
N
N
N
N
N
24.88; 24.85
23.46; 23.36
24.83; 24.81
nd
25.38; 25.33
22.74; 22.68
21.42; 21.33
22.77; 22.72
24.35
7 : 2
9 : 11
4 : 5
Single diastereoisomera
CH2Fur
2 : 1
1 : 1
3 : 2
1 : 1
1 : 1b
1 : 1
4-MeOC6H4
4-MeC6H4
CH2Ph
CH2Ph
2-CH2Fur
CH2CH3
CH2Ph
CH3
CH2CH3
21.83; 21.81
aFrom Barycki et al.1
bDiastereoisomeric ratio according to 1H NMR.

PHOSPHITE ADDITION TO DIMINES
999
Table 2 Results of addition of bis(trimethylsilyl) phosphite to isophthalaldimines 1a–d and pyridine-2,6-
dicarboxaldimines 2a–d
R
X
31P NMR
dr
5a
4-MeOC6H4
6.0pt1,65.1pt
4-MeC6H4
CH2Ph
CH
16.50; 16.21
5 : 2
5b
5c
5d
6a
6b
6c
6d
CH
CH
CH
N
N
N
16.61; 16.52
9.70; 9.51
9.68; 9.48
15.14; 14.79
15.21; 14.85
15.83; 15.73
15.77
1 : 2
2 : 1
5 : 4
9 : 1
9 : 1
2 : 1
CH2Fur
4-MeOC6H4
4-MeC6H4
CH2Ph
2-CH2Fur
N
Single diastereoisomer
was the addition of diethyl H-phosphonate to 2,6-bis(N-p-methylphenylazomethine)-
pyridine (2b), where diastereoisomeric forms of 4Bb were formed in a 3:2 ratio. Therefore,
it is to state that stereoselectivity of H-phosphonate additions to isophthalic Schiff bases
1a–d is moderately better than in the case of 2,6-diformylpyridine Schiff bases 2a–d
(Table 1).
Completely different results were observed in the case of addition of bis
(trimethylsilyl) H-phosphonate to isophthalic Schiff bases 1a–d and 2,6-diformylpyridine
Schiff bases 2a–d, which led to the formation of aminophosphonic acids 5a–d and 6a–d.
Addition to isophthalaldimines 1a–d showed rather limited diastereoselectivity starting
from 5:4 for N-furfuryl derivative 5d up to 5:2 for N-p-methoxyphenyl derivative 5a
(Table 2). In contrast to the previous case, addition of bis(trimethylsilyl) H-phosphonate
to 2,6-diformylpyridine Schiff bases 2a–d was highly diastereoselective, and although
the N-benzyl derivative 6c occurred in diastereomeric forms in a 2:1 ratio, the formation
of 2,6-pyridine-bis(N-(p-methoxyphenyl)aminomethylphosphonic acid) (6a) and 2,6-
pyridine-bis(N-(p-methylphenyl)-aminomethylphosphonic acid) (6b) occurred in dr = 9:1
ratio in both cases and 2,6-pyridine-bis(N-furfuryl-aminomethylphosphonic acid) (6d)
formed with 100% diastereoselectivity.
Therefore, it can be concluded that the addition of bis(trimethylsilyl) H-phosphonate
to 2,6-diformylpyridine Schiff bases 2a–d is equally or even more diastereoselective as
compared to the addition to isophthalic Schiff bases 1a–d (Table 2).
The difference in diastereoselectivity between the addition of dialkyl H-phosphonates
to isophthalic and pyridine-2,6-dicarboxaldehyde Schiff bases is surprising because of the
similarity of shape and structure of both compounds, and the question arises, why such
an important difference occurred. The varying degrees of diastereoselectivity observed
appear to result from a complex combination of structural features and further work will
be required to elucidate the factors involved.
EXPERIMENTAL
All solvents (POCh-Poland) were routinely distilled and dried prior to use. Amines,
H-phosphonates, bromotrimethylsilane, isophthalaldehyde, and 2,6-diformylpyridine
(Aldrich) were used as received. NMR spectra of imines 1a–d and 2a–d as well as
of aminophosphonates 3Aa–Ad and 4Aa–Bd were recorded with a Bruker Avance III
600 MHz apparatus operating at 600 MHz (1H) and 243 MHz (31P), whereas the NMR

1000
J. LEWKOWSKI AND M. DZIEGIELEWSKI
ꢀ
spectra of aminophosphonic acids 5a–d and 6a–d were recorded with a Varian Gemini
200 BB apparatus operating at 200 MHz (1H) and 81 MHz (31P). Elemental analyses
were performed in the Centre for Molecular and Macromolecular Science of the Polish
Academy of Science in Ło´dz´, Poland.
Synthesis of Isophthalic and 2,6-Diformylpyridine Schiff Bases 1a–d
and 2a–d: General Procedure
Isophthalaldehyde or 2,6-diformylpyridine (2.5 mmol) was dissolved in methanol
(20 mL) and then the corresponding amine (5 mmol) was added. The mixture was stirred
overnight and the precipitated solid was filtered, dried, and recrystallized and then collected
to obtain the corresponding Schiff bases.
N,N ꢀ-Isophthalylidene-p-anisidine (1a)
Yield: 88% (0.76 g). Mp: 140–143 ◦C. 1H NMR (600 MHz, CDCl3): δ = 8.59 (s, 2H,
CH N), 8.40 (t, 4JHH = 1.5 Hz, 1H, 2-H), 8.04 (dd, 3JHH = 7.4 Hz, 4JHH = 1.5 Hz, 2H,
4-H, 6-H), 7.90 (t, 3JHH = 7.4 Hz, 1H, 5-H), 7.30 (A-part of AA’XX’, 4H, 4-MeOC6H4),
6.98 (X-part of AA’XX’, 4H, 4-MeOC6H4), 3.88 (s, 6H, OCH3). Calcd. for C22H20N2O2:
C, 76.72; H, 5.85; N, 8.13. Found: C, 76.63; H, 5.95; N, 8.15%.
N,N ꢀ-Isophthalylidene-p-toluidine (1b)
Yield: 76% (0.59 g). Mp: 135–138 ◦C, ref 18: 128.5 ◦C. 1H NMR (600 MHz, CDCl3):
δ = 8.58 (s, 2H, CH N), 8.42 (m, 1H, 2-H), 8.06 (dd, 3JHH = 7.8 Hz, 4JHH = 1.8 Hz, 2H,
3
4-H, 6-H), 7.90 (t, JHH = 7.8 Hz, 1H, 5-H), 7.25 (A-part of AA’BB’, 4H, 4-MeC6H4),
7.20 (B-part of AA’BB’, 4H, 4-MeC6H4), 2.42 (s, 6H, CH3).
N,N ꢀ-Iso-phthalylidenebenzylamine (1c)1
1
Yield: 97% (0.76 g), dark yellow oil. H NMR (600 MHz, CDCl3): δ = 8.47–8.46
3
4
(m, 2H, CH N), 8.20–8.19 (m, 1H, H2), 7.92 (dd, JHH = 7.2 Hz, JHH = 1.8 Hz, 2H,
4-H, 6-H), 7.51 (t, 3JHH = 7.2 Hz, 1H, 5-H), 7.41–7.38 (m, 8H, C6H5), 7.33–7.30 (m, 2H,
C6H5), 4.88 (d, 4JHH = 1.2 Hz, 4H, CH2Ph).
N,N ꢀ-Iso-phthalylidenefurfurylamine (1d)
Yield: 81% (0.59 g). Mp: 53–54 ◦C. 1H NMR (600 MHz, CDCl3): δ = 8.38 (s, 2H,
CH N), 8.13–8.12 (m, 1H, 2-H), 7.87 (dd, 3JHH = 7.8 Hz, 4JHH = 1.8 Hz, 2H, 4-H, 6-H),
7.48 (t, 3JHH = 7.8 Hz, 1H, 5-H), 7.42–7.41 (m, 2H, 5-H of 2ꢁ-furyl), 6.38–6.37 (m, 2H, 4-H
of 2ꢁ-furyl), 6.30–6.29 (m, 2H, 3-H of 2ꢁ-furyl), 4.81 (s, 4H, CH2). Calcd. for C18H16N2O2:
C, 73.95; H, 5.52; N, 9.58. Found: C, 73.84; H, 5.67; N, 9.54%.
2,6-bis(N-p-methoxyphenyliminomethyl)-pyridine (2a)
Yield: 92% (0.72 g). Mp: 165–166 ◦C, ref 14: 159 ◦C. 1H NMR (600 MHz, CDCl3):
δ = 8.70 (s, 2H, CH N), 8.24 (d, 3JHH = 7.8 Hz, 2H, H-pyridyl), 7.90 (t, 3JHH = 7.8 Hz,

PHOSPHITE ADDITION TO DIMINES
1001
1H, H-pyridyl), 6.35 (A-part of AA’BB’, 4H, 4-MeOC6H4), 6.95 (B-part of AA’BB’, 4H,
4-MeOC6H4), 3.84 (s, 6H, OCH3).
2,6-bis(N-p-methylphenyliminomethyl)-pyridine (2b)15
Yield: 86% (0.90 g). Mp: 180–182 ◦C. 1H NMR (600 MHz, CDCl3): δ = 8.72 (s, 2H,
CH N), 8.30 (d, 3JHH = 7.8 Hz, 2H, H-pyridyl), 7.95 (t, 3JHH = 7.8 Hz, 1H, H-pyridyl),
7.29 (A-part of AA’BB’, 4H, 4-MeC6H4); 7.26 (B-part of AA’BB’, 4H, 4-MeC6H4); 2.42
(s, 6H, CH3).
2,6-bis(N-benzyliminomethyl)-pyridine (2c)
Yield: 82% (0.70 g). Mp: 78–79 ◦C, ref 16: 80 ◦C. 1H NMR (600 MHz, CDCl3): δ =
8.56 (s, 2H, CH N), 8.12 (d, 3JHH = 7.8 Hz, 2H, H-pyridyl), 7.83 (t, 3JHH = 7.8 Hz, 1H,
H-pyridyl), 7,39 (m, 8H, C6H5), 7.32 (m, 2H, C6H5), 4.93 (s, 4H, CH2).
2,6-bis(N-furfuryliminomethyl)-pyridine (2d)
◦
1
Yield: 83% (0.81 g), light-brown crystals. Mp: 82–84 C. H NMR (600 MHz,
CDCl3): δ = 8.49 (t, 4JHH = 1.2 Hz, 2H, CH N), 8.08 (d, 3JHH = 7.8 Hz, 2H, H-pyridyl),
7.82 (t, 3JHH = 7.8 Hz, 1H, H-pyridyl), 7.42 (dd, 3JHH = 1.8 Hz, 4JHH = 0.6 Hz, 2H, 5ꢁ-H
of 2ꢁ-furyl), 6.38 (dd, 3JHH = 1.8 Hz, 3JHH = 3.3 Hz, 2H, 4ꢁ-H of 2ꢁ-furyl), 7.32 (dd, 3JHH
=
3.3 Hz, 4JHH = 0.6 Hz, 2H, 3ꢁ-H of 2ꢁ-furyl), 4.88 (d, 4JHH = 1.2 Hz, 4H, CH2). Calcd. for
C17H15N3O2: C, 69.61; H, 5.15; N, 14.33. Found: C, 69.63; H, 5.21; N, 14.13%.
Tetraalkyl 1,3-Phenylene-bis(N-alkylaminomethane)-bis
(phosphonates) (3Aa–3Cd) and Tetraalkyl 2,6-Pyridine-bis
(N-alkylaminomethane)-bis(phosphonates) (4Aa–4Cd): General Procedure
Schiff base (1a–d) or (2a–d) (0.5 mmol) was dissolved in toluene (15 mL) and
the respective dialkyl H-phosphonate (1 mmol) was added. For the addition of dimethyl
H-phosphonate to 2b the reaction was carried out in dioxane (15 mL) with 2–3 drops
of trifluoroacetic acid. The mixture was refluxed for 3–5 h. After cooling to r.t. the solids
precipitated were collected by filtration, washed, and dried; oils were isolated by evaporating
solvent in vacuo. Products were purified first by washing their solutions in dichloromethane
with saturated aqueous NaHCO3 (3 × 15 mL) and then, if solids, by crystallization.
Tetramethyl 1,3-Phenylene-bis(N-p-methoxyphenylaminomethyl)-bis
(phospho-nate) (3Aa)
Overall yield: 54% (0.15 g); 4:1 mixture of diastereoisomers. The predominant
diastereoisomer spontaneously crystallized from the postreaction mixture.
Major diastereoisomer: Yield: 0.12 g. Mp: 170–173 ◦C. 1H NMR (600 MHz, CDCl3):
δ = 7.56 (m, 1H, arom-H), 7.40–7.38 (m, 2H, arom-H), 7.36–7.33(m, 1H, arom-H),
6.66 (A-part of AA’BB’, 4H, 4-MeOC6H4), 6.52 (B-part of AA’BB’, 4H, 4-MeOC6H4),
2
3
4.74 (d, JPH = 24.0 Hz, 2H, CHP), 3.70 (s, 6H, OCH3), 3.76 (d, JPH = 10.8 Hz,
3H, POCH3), 3.30 (d, JPH = 10.8 Hz, 3H, POCH3). 31P NMR (243 MHz, CDCl3):
3

1002
J. LEWKOWSKI AND M. DZIEGIELEWSKI
ꢀ
δ = 24.88. Calcd. for C26H34N2O8P2: C, 55.32; H, 6.07; N, 4.96. Found: C, 55.45; H, 6.01;
N, 4.97%.
Minor diastereoisomer: Yield: 0.03 g. Mp: 162–165 ◦C. 1H NMR (600 MHz, CDCl3):
δ = 7.28–7.26 (m, 2H, arom-H), 7.20–7.17 (m, 2H, arom-H), 6.66 (A-part of AA’BB’, 4H,
2
4-MeOC6H4), 6.52 (B-part of AA’BB’, 4H, 4-MeOC6H4), 4.86 (d, JPH = 24.0 Hz, 1H,
CHP), 4.72 (d, 2JPH = 24.0 Hz, 1H, CHP), 3.69 (s, 6H, OCH3), 3.70 (d, 3JPH = 10.2 Hz,
3
3H, POCH3), 3.41 (d, JPH = 10.2 Hz, 3H, POCH3). 31P NMR (243 MHz, CDCl3): δ =
24.85.
Tetrabenzyl 1,3-Phenylene-bis(N-p-methoxyphenylaminomethyl)-bis
(phosphonate) (3Ca)
Yield: 55% (0.24 g), dark yellow oil. Signals of the major isomer are marked by
1
(∗). H NMR (600 MHz, CDCl3): δ = 7.38–7.35 (m, 2H, C6H5), 7.31–7.28 (m, 8H,
C6H5), 7.26–7.21 (m, 10H, C6H5), 7.07–7.06 (m, 2H, arom-H), 7.04–7.03 (m, 2H, arom-
2
H), 6.58–6.56 (m, 4H, 4-MeOC6H4); 6.48–6.46 (m, 4H, 4-MeOC6H4), 4.97 (d, JPH
=
3
3
8.4 Hz, 2H, CHP), 4.92∗ (part of AMX spin system, JPH = 7.8 Hz, JPH = 9.0 Hz,
2JHH = 12.0 Hz, 2H, CH2Ph), 4.78–4.69 (m, 4H, CH2Ph), 4.38 (part of AMX system,
3JPH = 8.4 Hz, JPH = 9.6 Hz, JHH = 11.4 Hz, 2H, CH2Ph), 3.58 (s, 6H, OCH3),
3.57 (s, 6H, OCH3). 31P NMR (243 MHz, CDCl3): δ = 23.46, 23.36∗ (9:11). Calcd.
for C50H50N2O8P2 · CH3OH: C, 67.99; H, 6.04; N, 3.11. Found: C, 67.92; H, 6.04; N,
4.35%.
3
2
Tetramethyl 1,3-Phenylene-bis(N-p-methylphenylaminomethane)-bis
(phospho-nate) (3Ab)
Yield: 67% (0.19 g). Mp: 61–65 ◦C. Signals of the major isomer are marked
1
by (∗). H NMR (600 MHz, CDCl3): δ = 7.57–7.56 (m, 1H, arom-H), 7.40–7.39 (m,
2H, arom-H), 7.36–7.33 (m, 1H, arom-H), 6.89–6.87 (m, 8H, 4-MeC6H4), 6.50–6.46∗
2
2
(m, 8H, 4-MeC6H4), 4.79∗ (d, JPH = 24.0 Hz, 2H, CHP), 4.77 (d, JPH = 24.0 Hz, 2H,
CHP), 3.76∗ (d, JPH = 10.8 Hz, 3H, POCH3), 3.27∗ (d, JPH = 10.8 Hz, 3H, POCH3),
3
3
3
3
3.69 (d, JPH = 10.8 Hz, 3H, POCH3), 3.41 (d, JPH = 10.8 Hz, 3H, POCH3), 2.20
(s, 6H, CH3), 2.19∗ (s, 6H, CH3). 31P NMR (243 MHz, CDCl3): δ = 24.83, 24.81∗ (4:5).
Calcd. for C26H34N2O6P2: C, 58.64; H, 6.44; N, 5.26. Found: C, 58.78; H, 6.79; N,
5.14%.
Tetramethyl 1,3-Phenylene-bis(N-furfurylaminomethyl)-bis
(phosphonate) (3Ad)
1
Yield: 68% (0.17 g). Signals of the major isomer are marked by (∗). H NMR
(600 MHz, CDCl3): δ = 7.51–7.50 (m, 1H, arom-H), 7.44–7.42 (m, 3H, 5ꢁ-H of 2ꢁ-furyl,
arom-H), 7.40–7.39 (m, 2H, arom-H), 6.32–7.30 (m, 1H, 3ꢁ-H of 2ꢁ-furyl), 6.13–7.12 (m,
2
2
1H, 4ꢁ-H of 2ꢁ-furyl), 4.15 (d, JPH = 25.2 Hz, 2H, CHP), 4.14∗ (d, JPH = 25.2 Hz,
2H, CHP), 3.84 (d, J = 15.0 Hz, 4H, CH2), 3.83 (d, J = 15.0 Hz, 4H, CH2), 3.73∗ (d,
3JPH = 10.8 Hz, 6H, POCH3), 3.62∗ (d, JPH = 10.8 Hz, 6H, POCH3), 3.74 (d, JPH
=
3
3
10.8 Hz, 6H, POCH3), 3.66 (d, 3JPH = 10.8 Hz, 6H, POCH3), 3.61∗ (d, J = 15.0 Hz, 4H,
CH2), 3.62∗ (d, J = 15.0 Hz, 4H, CH2). 31P NMR (243 MHz, CDCl3): δ = 25.38∗, 25.33

PHOSPHITE ADDITION TO DIMINES
1003
(2:1). Calcd. for C22H30N2O8P2: C, 51.57; H, 5.90; N, 5.47. Found: C, 51.33; H, 6.03; N,
5.30%.
Tetramethyl 2,6-Pyridine-bis(N-p-methoxyphenylaminomethane)-
bis(phosphonate) (4Aa)
Yield: 85% (0.24 g). 1H NMR (600 MHz, CDCl3): δ = 7.65 (t, 3JHH = 7.8 Hz, 1H,
H-pyridyl), 7.64 (t, 3JHH = 7.8 Hz, 1H, H-pyridyl), 7.26 (dd, 3JHH = 7.8 Hz, 4JPH = 4.2 Hz,
2H, H-pyridyl), 7.25 (dd, 3JHH = 7.8 Hz, 4JPH = 4.2 Hz, 2H, H-pyridyl), 6.71 (A-part of
AA’BB’, 2H, 4-MeOC6H4), 6.70 (A-part of AA’BB’, 2H, 4-MeOC6H4), 6.64 (B-part of
AA’BB’, 4H, 4-MeOC6H4), 4.98 (d, 2JPH = 22.8 Hz, 2H, CHP), 4.96 (d, 2JPH = 22.8 Hz,
2H, CHP), 3.72 (s, 6H, OCH3), 3.71 (s, 6H, OCH3), 3.83 (d, 3JPH = 10.2 Hz, 6H, POCH3),
3.81 (d, 3JPH = 10.2 Hz, 6H, POCH3), 3.61 (d, 3JPH = 10.2 Hz, 6H, POCH3), 3.56 (d, 3JPH
= 10.2 Hz, 6H, POCH3). 31P NMR (243 MHz, CDCl3): δ = 22.74, 22.68 (1:1). Calcd. for
C25H33N3O8P2: C, 53.10; H, 5.88; N, 7.47. Found: C, 53.84; H, 5.97; N, 7.18%.
Tetraethyl 2,6-Pyridine-bis(N-p-methylphenylaminomethane)-bis
(phosphonate) (4Bb)
Yield: 73% (0.22 g). 1H NMR (600 MHz, CDCl3): δ = 7.62 (t, 3JHH = 7.6 Hz, 1H,
3
H-pyridyl), 7.61 (t, JHH = 7.6 Hz, 1H, H-pyridyl), 7.16 (m, 2H, H-pyridyl), 6.93 (A-
part of AA’BB’, 4H, 4-MeC6H4), 6.61 (B-part of AA’BB’, 4H, 4-MeC6H4), 6.90 (A-Part
2
of AA’BB’, 4H, 4-MeC6H4), 6.59 (B-part of AA’BB’, 4H, 4MeC6H4), 5.00 (d, JPH
=
2
22.8 Hz, 2H, CHP), 4.98 (d, JPH = 22.8 Hz, 2H, CHP), 4.21–4.13 (m, 4H, OCH2CH3),
4.02–3.95 (m, 2H, OCH2CH3), 3.87–3.81 (m, 2H, OCH2CH3), 2.22 (s, 6H, CH3), 2.21 (s,
6H, CH3), 1.32 (t, 3JHH = 7.2 Hz, 6H, OCH2CH3), 1.31 (t, 3JHH = 7.2 Hz, 6H, OCH2CH3),
1.16 (t, 3JHH = 7.2 Hz, 6H, OCH2CH3), 1.12 (t, 3JHH = 7.2 Hz, 6H, OCH2CH3). 31P NMR
(81 MHz, NaOD/D2O): δ = 21.42, 21.33 (3:2). Calcd. for C29H41N3O6P2: C, 59.08; H,
7.01; N, 7.13. Found: C, 59.41; H, 7.14; N, 7.35%.
Tetramethyl 2,6-Pyridine-bis(N-benzylaminomethyl)-bis(phosphonate)
(4Ac)
1
3
Yield: 78% (0.21 g). H NMR (600 MHz, CDCl3): δ = 7.42 (ddd, JHH = 7.5 Hz,
4JPH = 2.4 Hz, 4JHH = 1.8 Hz, 2H, H-pyridyl), 7.39 (ddd, 3JHH = 7.5 Hz, 4JPH = 2.4 Hz,
4JHH = 1.8 Hz, 2H, H-pyridyl), 7.32–7.29 (m, 10H, C6H5), 7.26 (m, 1H, H-pyridyl), 4.31
(d, 2JPH = 21.9 Hz, 2H, CHP), 4.28 (d, 2JPH = 21.9 Hz, 2H, CHP), 3.86 (d, J = 13.2 Hz,
2H, CH2Ph), 3.84 (d, J = 13.2 Hz, 2H, CH2Ph), 3.79 (d, 3JPH = 10.2 Hz, 6H, OCH3), 3.77
3
3
3
(d, JPH = 10.2 Hz, 6H, OCH3), 3.67 (d, JPH = 10.2 Hz, 6H, OCH3), 3.65 (2d, JPH
=
10.2 Hz, 6H, OCH3). 31P NMR (243 MHz, CDCl3): δ = 24.35. Calcd. for C25H33N3O6P2:
C, 56.28; H, 6.23; N, 7.88. Found: C, 56.12; H, 6.37; N, 7.73%.
Tetrabenzyl 2,6-Pyridine-bis(N-benzylaminomethyl)-bis(phosphonate)
(4Cc)
1
Yield: 55% (0.23 g). H NMR (600 MHz, CDCl3): δ = 7.62 (m, 1H, H-pyridyl),
7.39–7.20 (m, 32H, C6H5, H-pyridyl), 5.13–5.11 (part of AMX spectrum, 3JPH = 8.4 Hz,

1004
J. LEWKOWSKI AND M. DZIEGIELEWSKI
ꢀ
2JHH = 13.2 Hz, 4H, OCH2Ph), 5.07–5.03 (part of AMX spectrum, 3JPH = 8.4 Hz, 2JHH
=
13.2 Hz, 4H, OCH2Ph); 5.00–4.96 (part of AMX spectrum, 3JPH = 9.0 Hz, 2JHH = 12.0 Hz,
3
2
4H, OCH2Ph), 4.92–4.88 (part of AMX spectrum, JPH = 9.0 Hz, JHH = 12.0 Hz, 4H,
OCH2Ph), 4.34 (d, 2JPH = 20.4 Hz, 2H, CHP), 4.31 (d, 2JPH = 20.4 Hz, 2H, CHP), 3.78
(d, J = 9.6 Hz, 2H, CH2Ph), 3.76 (d, J = 9.6 Hz, 2H, CH2Ph), 3.56 (d, J = 13.2 Hz, 2H,
CH2Ph), 3.55 (d, J = 13.2 Hz, 2H, CH2Ph). 31P NMR (243 MHz, CDCl3): δ = 22.77, 22.72
(1:1). Calcd. for C49H49N3O6P2: C, 70.24; H, 5.89; N, 5.02. Found: C, 70.00; H, 6.03; N,
5.01%.
Tetraethyl 2,6-Pyridine-bis(N-furfurylaminomethyl)-bis(phosphonate)
(4Bd)
The compound turned out to be too unstable to be purified by chromatography on
silica gel or alumina and the routine method of purification did not allow purifying the
product to a degree enough to give satisfactory results of elemental analysis.
1H NMR (600 MHz, CDCl3): δ = 7.68 (t, 3JHH = 7.8 Hz, 1H, H-pyridyl), 7.67 (t, 3JHH
= 7.8 Hz, 1H, H-pyridyl), 7.41–7.37 (m, 2H, H-pyridyl), 7.31 (m, 1H, 5ꢁ-H of 2ꢁ-furyl),
6.28 (dd, 3JHH = 2.4 Hz, 3JHH = 4.8 Hz, 2H, 3ꢁ-H of 2ꢁ-furyl), 6.16–6.15 (m, 2H, 3ꢁ-H of
2ꢁ-furyl), 4.28 (d, 2JPH = 21.0 Hz, 2H, CHP), 4.26 (d, 2JPH = 21.0 Hz, 2H, CHP), 4.20–4.05
2
(m, 6H, OCH2CH3), 4.03–3.95 (m, 3H, OCH2CH3), 3.85 (d, JHH = 14.4 Hz, 2H, CH2-
furyl), 3.83 (d, 2JHH = 14.4 Hz, 2H, CH2-furyl), 3.66 (d, 2JHH = 14.4 Hz, 2H, CH2-furyl),
2
3
3.65 (d, JHH = 14.4 Hz, 2H, CH2-furyl), 1.29 (t, JHH = 7.2 Hz, 6H, OCH2CH3), 1.24
(t, JHH = 7.2 Hz, 6H, OCH2CH3), 1.23 (t, JHH = 7.2 Hz, 6H, OCH2CH3). 31P NMR
3
3
(243 MHz, CDCl3): δ = 21.83, 21.81 (1:1).
1,3-Phenylene-bis(aminomethylphosphonic Acids) (5a–d) and
2,6-Pyridine-bis-(aminomethylphosphonic Acids) (6a–d): General Procedure
Diethyl H-phosphonate(1 mmol, 0.11 g) was dissolved in dry dichloromethane; to this
solution, bromotrimethylsilane (4.2 mmol, 0.65 g) was added dropwise during 15 min. The
mixturewas stirred for 1 h at r.t. Then, a solution of the respective Schiff base (0.5 mmol)
in dry dichloromethane was added and the mixture was refluxed for 4 h. The solution
wasevaporated in vacuo and the residue was dissolvedin dry methanol. It was stirred for
30–45 min until precipitation of a solid occurred, which was filtered off andcollected. In
the cases, in which no precipitate was formed, 10–20 mL of propylene oxide was added
andthe mixture was refrigerated for 3–7 days. Thenthe solid was filtered off and collected.
Products were purified by dissolution in 10% aqueous NaOH followed by precipitation on
acidification with 1 MHCl.
1,3-Phenylene-bis(N-(p-methoxyphenyl)aminomethylphosphonic Acid)
(5a)
Yield: 70% (0.18 g). Mp: 210–215 ◦C. Signals of the major isomer are marked by (∗).
1H NMR (200 MHz, NaOD/D2O): δ = 7.56 (m, 1H, arom-H), 7.28–7.23 (m, 1H, arom-H),
7.12–7.05 (m, 2H, arom-H), 6.50 (A-part of AA’BB’, 8H, 4-MeOC6H4), 6.36 (B-part of
AA’BB’, 8H, 4-MeOC6H4), 4.25∗ (d, 2JPH = 21.8 Hz, 2H, CHP), 4.20 (d, 2JPH = 21.2 Hz,
2H, CHP), 3.56 (s, 6H, OCH3), 3.55∗ (s, 6H, OCH3). 31P NMR (81 MHz, NaOD/D2O):

PHOSPHITE ADDITION TO DIMINES
1005
3
δ = 16.50, 16.21 (5:2). Calcd. for C22H26N2O8P2· /2 H2O: C, 49.35; H, 5.46; N, 5.23.
Found: C, 49.54; H, 5.34; N, 5.02%.
1,3-Phenylene-bis(N-(p-methylphenyl)aminomethylphosphonic Acid)
(5b)
Yield: 79% (0.19 g). Mp: 179–184 ◦C. Signals of the major isomer are marked by (∗).
1H NMR (200 MHz, NaOD/D2O): δ 7.29 (m, 1H, arom-H), 7.06–7.09 (m, 3H, arom-H),
6.78 (A-part of AA’BB’, 4H, 4-MeC6H4), 6.72∗ (A-part of AA’BB’, 4H, 4-MeC6H4), 6.41
(B-part of AA’BB’, 4H, 4-MeC6H4), 6.34∗ (B-part of AA’BB’, 4H, 4-MeC6H4), 4.32 (d,
2
2JPH = 22.0 Hz, 2H, CHP), 4.25∗ (d, JPH = 22.0 Hz, 2H, CHP), 2.08∗ (s, 6H, CH3),
2.06 (s, 6H, CH3). 31P NMR (81 MHz, NaOD/D2O): δ = 16.61, 16.52 (1:2). Calcd. for
3
C22H26N2O6P2 · /2 H2O: C, 52.18; H, 5.84; N, 5.53. Found: C, 52.40; H, 6.09; N, 5.31%.
1,3-Phenylene-bis(N-benzylaminomethylphosphonic Acid) (5c)
Yield: 87% (0.21 g). Mp: 245–248 ◦C, ref 1: 267–272 ◦C. Signals of the major isomer
1
are marked by (∗). H NMR (200 MHz, D2O): δ = 7.56–7.49 (m, 3H, C6H5, arom-H),
7.45–7.36 (m, 11H, C6H5, arom-H), 4.34 (d, 2JPH = 15.7 Hz, 2H, CHP), 4.31∗ (d, 2JPH
=
16.2 Hz, 2H, CHP), 4.29∗ (d, J = 13.4 Hz, 2H, CH2Ph), 4.19 (d, J = 13.4 Hz, 2H, CH2Ph).
31P NMR (81 MHz, D2O): δ = 9.70∗, 9.51 (2:1).
1,3-Phenylene-bis(N-furfurylaminomethylphosphonic Acid) (5d)
◦
Yield: 95% (0.21 g). Mp: 215–218 C. Signals of the major isomer are marked
by (∗). H NMR (200 MHz, D2O): δ = 7.62–7.51 (m, 6H, arom-H, 5ꢁ-H of 2ꢁ-furyl),
1
6.54–6.52 (m, 2H, 3ꢁ-H of 2ꢁ-furyl), 6.46–6.44 (m, 2H, 4ꢁ-H of 2ꢁ-furyl); 4.36–4.19
(m, 6H, CHP, CH2Ph). 31P NMR (81 MHz, D2O): δ = 9.68∗, 9.48 (5:4). Calcd. for
5
C18H22N2O8P2 · /2 H2O: C, 43.12; H, 5.43; N, 5.59. Found: C, 42.89; H, 5.17; N,
5.31%.
2,6-Pyridine-bis(N-(p-methoxyphenylaminomethylphosphonic Acid)
(6a)
◦
Yield: 74% (0.19 g). Mp: 181–183 C. Signals of the major isomer are marked by
(∗). 1H NMR (200 MHz, NaOD/D2O): δ = 7.40 (t, 3JHH = 7.7 Hz, 1H, H-pyridyl), 7.26 (d,
3JHH = 7.7 Hz, 2H, H-pyridyl), 6.62 (A-part of AA’BB’, 4H, 4-MeOC6H4), 6.48 (B-part of
AA’BB’, 4H, 4-MeOC6H4), 4.47∗ (d, 2JPH = 20.6 Hz, 2H, CHP), 4.41 (d, 2JPH = 21.4 Hz,
2H, CHP), 3.54 (s, 6H, OCH3). 31P NMR (81 MHz, NaOD/D2O): δ = 15.14∗, 14.79 (9:1).
3
Calcd. for C21H25N3O8P2 · /2 H2O: C, 47.02; H, 5.26; N, 7.83. Found: C, 46.79; H, 5.42;
N, 7.66%.
2,6-Pyridine-bis(N-(p-methylphenylaminomethylphosphonic Acid) (6b)
◦
Yield: 62% (0.15 g). Mp: 175–177 C. Signals of the major isomer are marked by
(∗). 1H NMR (200 MHz, NaOD/D2O): δ = 7.38 (t, 3JHH = 7.6 Hz, 1H, H-pyridyl), 7.16 (d,
3JHH = 7.6 Hz, 2H, H-pyridyl), 6.93 (A-part of AA’BB’, 4H, 4-MeC6H4), 6.84∗ (A-part

1006
J. LEWKOWSKI AND M. DZIEGIELEWSKI
ꢀ
of AA’BB’, 4H, 4-MeC6H4), 6.62 (B-part of AA’BB’, 4H, 4-MeC6H4), 6.46∗ (B-part of
AA’BB’, 4H, 4-MeC6H4), 4.52 (d, 2JPH = 23.6 Hz, 2H, CHP), 4.51∗ (d, 2JPH = 20.6 Hz,
2H, CHP), 2.07 (s, 6H, CH3), 2.01∗ (s, 6H, CH3). 31P NMR (81 MHz, NaOD/D2O): δ =
5
15.21∗, 14.85 (9:1). Calcd. for C21H25N3O6P2 · /2 H2O: C, 48.28; H, 5.79; N, 8.04. Found:
C, 48.11; H, 5.81; N, 8.32%.
2,6-Pyridine-bis(N-benzylaminomethylphosphonic Acid) (6c)
Yield: 65% (0.16 g). Mp: 244–246 ◦C. 1H NMR (200 MHz, NaOD/D2O): δ = 7.56
(t, 3JHH = 7.8 Hz, 1H, H-pyridyl), 7.20–7.08 (m, 12H, C6H5, H-pyridyl), 3.75 (d, 2JPH
=
17.8 Hz, 2H, CHP), 3.86 (d, J = 13.4 Hz, 2H, CH2Ph), 3.84 (d, J = 13.4 Hz, 2H, CH2Ph).
3
31P NMR (81 MHz, CDCl3): δ = 15.83, 15.73 (2:1). Calcd. for C21H25N3O6P2 · /2 H2O:
C, 50.00; H, 5.60; N, 8.33. Found: C, 50.06; H, 5.84; N, 8.11%.
2,6-Pyridine-bis(N-furfurylaminomethylphosphonic Acid) (6d)
◦
1
Yield: 32% (0.08 g). Mp: 250–251 C. H NMR (200 MHz, NaOD/D2O): δ =
7.44 (t, JHH = 7.8 Hz, 1H, H-pyridyl), 7.21 (m, 2H, 5ꢁ-H of 2ꢁ-furyl), 7.05 (d, JHH
=
3
3
7.8 Hz, 2H, H-pyridyl), 6.11 (m, 2H, 3ꢁ-H of 2ꢁ-furyl), 5.92 (m, 2H, 4ꢁ-H of 2ꢁ-furyl),
2
3.64 (d, JPH = 17.8 Hz, 2H, CHP), 3.47 (d, J = 14.4 Hz, 4H, CH2-furyl), 3.38 (d,
J = 14.4 Hz, 4H, CH2-furyl). 31P NMR (81 MHz, NaOD/D2O): δ = 15.77. Calcd. for
C17H21N3O8P2 · 4 CH3OH: C, 43.08; H, 6.37; N, 7.18. Found: C, 42.87; H, 6.14; N,
7.02%.
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10. Gałezowska, J.; Szyrwiel, Ł.; Młynarz, P.; Sliwin´ska, S.; Kafarski, P.; Kozłowski, H. Polyhedron
ꢀ
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