Synthesis of α-heterocyclic α-aminophosphonates,1 part II: Morpholine, piperidine, pyrrolidine, tetrahydrofurylmethylamine, N-benzyl-N-methylamine, and aniline derivatives

Article abstract of DOI:10.1080/10426500601093739

α,α-Diaminomethyl phosphonate derivatives were synthesized by N-alkylation of nitrogen heterocycles or primary amines with diethyl α-bromo-α-aminomethyl phosphonate.

Full text of DOI:10.1080/10426500601093739

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Synthesis of α-Heterocyclic
α-Aminophosphonates,
Part II: Morpholine,
Piperidine, Pyrrolidine,
Tetrahydrofurylmethylamine,
N-Benzyl-N-Methylamine, and
Aniline Derivatives
K. Boukallaba a , A. Elachqar a , A. El Hallaoui a , A.
Alami a , S. El Hajji a , B. Labriti a , A. Atmani a , B.
El Bali b , M. Lachkar b , H. Allouchi c , J. Martinez d
& V. Rolland d
a Laboratoire de Chimie Organique, Faculté des
Sciences, Université Sidi Mohamed Ben Abdellah,
Fès, Maroc
b Laboratoire d'Ingénierie des Matériaux
Organométalliques et Moléculaires, Faculté des
Sciences, Université Sidi Mohamed Ben Abdellah,
Fès, Maroc
c Laboratoire de Chimie Physique, Faculté de
Pharmacie, Tours, France
d Laboratoire des Aminoacides, Peptides et
Protéines, UMR5810-CNRS, Université Montpellier II,
France
Version of record first published: 19 Apr 2007.
To cite this article: K. Boukallaba , A. Elachqar , A. El Hallaoui , A. Alami , S. El
Hajji , B. Labriti , A. Atmani , B. El Bali , M. Lachkar , H. Allouchi , J. Martinez
& V. Rolland (2007): Synthesis of α-Heterocyclic α-Aminophosphonates, Part II:

Morpholine, Piperidine, Pyrrolidine, Tetrahydrofurylmethylamine, N-Benzyl-N-
Methylamine, and Aniline Derivatives, Phosphorus, Sulfur, and Silicon and the Related
Elements, 182:5, 1045-1052
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Phosphorus, Sulfur, and Silicon, 182:1045–1052, 2007
Copyright © Taylor & Francis Group, LLC
ISSN: 1042-6507 print / 1563-5325 online
DOI: 10.1080/10426500601093739
Synthesis of α-Heterocyclic α-Aminophosphonates,1
Part II: Morpholine, Piperidine, Pyrrolidine,
Tetrahydrofurylmethylamine, N-Benzyl-N-Methylamine,
and Aniline Derivatives
K. Boukallaba
A. Elachqar
A. El Hallaoui
A. Alami
S. El Hajji
B. Labriti
A. Atmani
Laboratoire de Chimie Organique, Faculte´ des Sciences, Universite´ Sidi
Mohamed Ben Abdellah, Fe`s, Maroc
B. El Bali
M. Lachkar
Laboratoire d’Inge´nierie des Mate´riaux Organome´talliques et
Mole´culaires, Faculte´ des Sciences, Universite´ Sidi Mohamed Ben
Abdellah, Fe`s, Maroc
H. Allouchi
Laboratoire de Chimie Physique, Faculte´ de Pharmacie, Tours, France
J. Martinez
V. Rolland
Laboratoire des Aminoacides, Peptides et Prote´ines, UMR5810-CNRS,
Universite´ Montpellier II, France
α, α-Diaminomethyl phosphonate derivatives were synthesized by N-alkylation
of nitrogen heterocycles or primary amines with diethyl α-bromo-α-aminomethyl
phosphonate.
Keywords Amine; diethyl α-bromo-α-aminomethyl phosphonate; nitrogen heterocycles;
N-alkylation
Received December 13, 2005; accepted October 11, 2006.
Financial support by Programme The´matique d’Appui a´ la Recherche Scientifique
D13/03, Centre National de la Coordination et de la Planification de la Recherche Scien-
tifique et Technique, Morocco is gratefully acknowledged.
Address correspondence to A. Elachqar, Laboratoire de Chimie Organique, Faculte´
des Sciences, B.P. 1796, Fe`s-Atlas, Maroc. E-mail: aelachqar@yahoo.fr
1045

1046
K. Boukallaba et al.
INTRODUCTION
The study of phosphorus analog of the proteinogenic or non proteino-
genic α-amino acids has accelerated in the past twenty years, due to
the finding of molecules with useful biological activity as potent antibi-
otics, enzyme inhibitors, or pharmalogical agents.2 Amino phosphonic
acids are amino acid’s surrogates, and the phosphonic acid group is con-
sidered an isosteric group of the carboxylic function and also a stable
tetrahedral intermediate in reactions including carboxylic acid deriva-
tives.
The biological activity of amino phosphonic acids depends on their
configuration. However, the number of available methods for the syn-
thesis of heterocyclic aminophosphonates is still limited.3
In a very recent article we described the preparation of α-
heterocyclic-α-amino- phosphonates by N-alkylation of α-azido-α-
aminophosphonates1 in good to very good yields. Here we describe
another part of our investigations concerning carboxylic and phospho-
nic amino acids4 with the aim to have access to new active biomolecules.
RESULTS AND DISCUSSION
Our strategy is based on the N-alkylation of amines with diethyl α-
bromo-α-amino- methylphosphonate4 2 (Scheme 1).
Compound 2 was obtained by bromination of 1 applying Steglich’s
procedure5,6 (yield = 86%). The reaction of different amines NuH with
the bromine derivative 2 results in the formation of the compounds 3–8
carrying saturated heterocyclic or aromatic amines.
SCHEME 1

Synthesis of α-Heterocyclic α-Aminophosphonates
1047
TABLE I Synthesis of α,α-Diaminomethyl Phosphonates 3–8
Product
Nu-H
M.P. (◦C)
Reaction Time (h)
Yield (%)
3
4
5
6
7
8
Morpholine
Piperidine
Pyrrolidine
Tetrahydrofurylmethylamine
N-Benzyl-N-methylamine
Aniline
112–114
103–105
123–125
115–117
105–107
130–132
2
8
0.5
16
16
16
90
92
85
80
75
80
The literature reports numerous methods of N-alkylation of amines.7
After several attempts of reactions by phase transfer catalysis or in the
presence of bases such as triethylamine or diethylamine, the reaction
with diisopropylethylamine gave the best results. It was carried out in
dry acetone at r.t. The results are summarized in Table I.
Products 3–8 were obtained in a 75% to 92% overall yield from 2 and
were analyzed by MS and 1H NMR spectroscopy.
Comparison of these results with those obtained in the reaction of 2
with aromatic heterocyclic compounds like triazole, pyrazole, or imida-
zole indicated that saturated cyclic amines are the better reagents.
The structure of compound 4 was also confirmed by single crystal X-
ray diffraction as shown in Figure 1. Experimental details and crystal-
lographic data are reported in Table II. Atomic coordinates are reported
FIGURE 1 ORTEP representation of the molecular structure of 4 in the crys-
tal; displacement ellipsoids are drawn at the 50% probability level.

1048
K. Boukallaba et al.
TABLE II Crystal Data and Structure Refinement for 4 at 173(2) K
Empirical formula
Formula weight
Wavelength (λMoKα
C17H27N2O4P
354.38
0.71073 A
˚
)
Crystal system, (S.G.)
Unit cell dimensions (A,
Monoclinic (P 21/n)
◦
˚
)
a = 9.8118(5)
α = 90
b = 16.2571(11)
β = 106.384 (4)
γ = 90
c = 12.2775(6)
3
˚
Volume (A ), Z
1878.88(18), 4
Absorption coefficient (mm−1
)
0.169
3.68 to 25.64
Theta range for (◦)
Index ranges
Reflections [I > 2sigma(I)];
Final R indices
h:[−11, 11], k:[−19, 19], l:[−14, 14]
34190; R1/wR2: 0.0488/0.1216
in Table III, while Table IV reports the most significant bond distances
and angles. The heterocyclic ring adopts chair conformation.
In contrast to the amines in Table I, which give the alkylation prod-
ucts in very good yields, other amines like 2-aminomethyl pyridine,
2-imidazolidone, and N-ethylbenzylamine induced a cleavage of the
Cα N bond, and benzamide was the major product. It was identified
by 1H NMR spectroscopy and MS FAB ([M+H]+ = 122).
In conclusion, the method described in this article provides a gen-
eral and convenient access to a wide range of α,α-diaminomethyl phos-
phonate derivatives starting from the appropriate bromide 2. The N-
alkylation of different amines with compound 2 occurs under very mild
conditions and leads to amino phosphonates 3–8 in good yields.
EXPERIMENTAL
Melting points were determined with an Electrothermal melting point
1
apparatus and are uncorrected. H NMR spectra were recorded on a
Bruker AC-250 MHz spectrometer in CDCl3 with TMS as an inter-
nal standard; coupling constants are reported in Hz. Mass spectra
were recorded on a JEOL-JMS- DX 300 mass spectrometer (FAB in
glycerol) or on a Polaris Thermoelectron mass spectrometer (CI by
desorption in methane). Compound 2 was prepared using Steglich’s
procedure.5
The X-ray diffraction data for a selected crystal were collected with
a STOE IPDS II two-circle diffractometer using monochromatic MoKα
˚
radiation (λ = 0.71073 A). Data were corrected for Lorentz and polar-
ization effect, and for adsorption effect.8 The structure was solved by

Synthesis of α-Heterocyclic α-Aminophosphonates
1049
TABLE III Atomic Coordinates and Equivalent Isotropic
Displacement Parameters (× 103) for 4
2
˚
x
y
z
Ueq.( A )
P(1)
O(1)
O(2)
0.5912(1)
0.6412(1)
0.5705(2)
0.6064(2)
0.4722(3)
0.6940(1)
0.7644(2)
0.8907(3)
0.4149(2)
0.4163(2)
0.2946(2)
0.3151(3)
0.3329(3)
0.4529(2)
0.4287(2)
0.3113(2)
0.2112(2)
0.2034(2)
0.1074(2)
0.0596(2)
−0.0380(3)
−0.0894(2)
−0.0442(2)
0.0550(2)
0.6154(1)
0.5450(1)
0.5979(1)
0.5206(1)
0.4808(2)
0.6922(1)
0.7222(1)
0.7728(2)
0.6558(1)
0.7084(1)
0.7655(1)
0.8291(1)
0.7879(1)
0.7243(1)
0.6638(1)
0.5876(1)
0.5791(1)
0.6247(1)
0.5090(1)
0.4684(1)
0.4035(2)
0.3812(1)
0.4224(1)
0.4863(1)
0.3916(1)
0.4687(1)
0.2617(1)
0.2168(2)
0.1460(3)
0.4120(1)
0.5272(2)
0.5206(2)
0.3865(2)
0.4831(1)
0.4580(2)
0.5532(2)
0.6674(2)
0.6888(2)
0.5897(2)
0.3656(1)
0.2638(2)
0.1821(1)
0.2556(2)
0.1517(2)
0.1389(2)
0.2287(2)
0.3313(2)
0.3453(2)
20(1)
27(1)
28(1)
35(1)
55(1)
25(1)
27(1)
42(1)
21(1)
22(1)
30(1)
38(1)
39(1)
32(1)
27(1)
23(1)
22(1)
32(1)
23(1)
35(1)
44(1)
37(1)
34(1)
29(1)
C(21)
C(22)
O(3)
C(31)
C(32)
C(1)
N(11)
C(12)
C(13)
C(14)
C(15)
C(16)
N(2)
C(3)
O(31)
C(41)
C(42)
C(43)
C(44)
C(45)
C(46)
the Direct Methods procedure of SIR97,9 and refined by the full ma-
trix least square technique of SHELX-L 97.10 All the hydrogen atoms
were localized from difference Fourier maps. Data of crystal structures
and refinements, such as a full list of bond lengths and angles and
anisotropic thermal parameters, have been deposited with the Cam-
bridge Crystallographic Database. These data can be obtained free
of charge on quoting the depository no. CCDC 621832 using the link
http://www.ccdc.cam.ac.uk or from CCDC, 12 Union Road Cambridge
CB2 1EZ, UK; fax: +44 1223 336033; e-mail: deposit@ccdc.cam.ac.uk.
Typical Procedure for N-alkylation
To a stirred solution of 2.86 mmol of the corresponding amine and 3.12
mmol of diisopropylethylamine in 10 mL of dry acetone, 2.6 mmole
of diethyl 1-bromo-1-(benzoyl- amino)methyl phosphonate were added.
The mixture was stirred at r.t. and the reaction was followed by TLC

1050
K. Boukallaba et al.
◦
˚
TABLE IV Selected Bond Distances (A) and Angles ( ) for 4
P(1) O(1)
P(1) O(2)
P(1) O(3)
P(1) C(1)
1.4780(13)
1.5768(14)
1.5800(13)
1.8340(19)
1.471(2)
1.460(2)
1.477(2)
1.470(2)
1.475(2)
1.530(3)
1.520(3)
1.533(3)
1.529(3)
1.361(2)
1.232(2)
1.514(2)
1.394(3)
1.403(3)
1.384(4)
1.384(3)
1.401(3)
P(1) O(1)
P(1) O(2)
P(1) O(3)
P(1) C(1)
1.4780(13)
1.5768(14)
1.5800(13)
1.8340(19)
1.471(2)
1.460(2)
1.477(2)
1.470(2)
1.475(2)
1.530(3)
1.520(3)
1.533(3)
1.529(3)
1.361(2)
1.232(2)
1.514(2)
1.394(3)
1.403(3)
1.384(4)
1.384(3)
1.401(3)
O(3) C(31)
C(1) N(11)
C(1) N(2)
N(11) C(16)
N(11) C(12)
C(12) C(13)
C(13) C(14)
C(14) C(15)
C(15) C(16)
N(2) C(3)
C(3) O(31)
C(3) C(41)
C(41) C(42)
C(42) C(43)
C(43) C(44)
C(44) C(45)
C(45) C(46)
O(3) C(31)
C(1) N(11)
C(1) N(2)
N(11) C(16)
N(11) C(12)
C(12) C(13)
C(13) C(14)
C(14) C(15)
C(15) C(16)
N(2) C(3)
C(3) O(31)
C(3) C(41)
C(41) C(42)
C(42) C(43)
C(43) C(44)
C(44) C(45)
C(45) C(46)
(Kiesegel Merck 60F524). The solvent was evaporated under reduced
pressure. The residue was quenched with saturated aqueous solution
of ammonium chloride (20 mL) and extracted with dichloromethane
(3 × 20 mL). The organic phase was dried with sodium sulfate (Na2SO4),
and the solvent was removed under reduced pressure. The product
was purified, wherever necessary, by column chromatography on silica
gel using ether/hexane or ether/methanol as an eluent to afford pure
N-alkylated phosphonates.
1
3: Rf: 0.6 (ether). H NMR (CDCl3): 1.19 (t, J = 7.0 Hz, 3H, CH3);
1.38 (t, J = 7.0 Hz, 3H, CH3); 2.64 (m, 2H, NCH2 morpholine); 2.94 (m,
2H, NCH2 morpholine); 3.64 (m, 4H, OCH2 morpholine); 4.05 (m, 2H,
2
3
OCH2); 4.22 (m, 2H, OCH2); 5.35 (dd, JPH = 20.3 Hz, JHH = 9.8 Hz,
1H, P CH<); 6.95 (m, 1H, NH); 7.40 (m, 2H, arom-H); 7.50 (m, 1H,
arom-H); 7.78 (m, 2H, arom-H). MS (FAB+): 356 [M]+ C16H25PN2O5.
1
4: Rf: 0.7 (ether). H NMR (CDCl3): 1.23 (t, J = 7.0 Hz, 3H, CH3);
1.39 (m, 2H, CH2 piperidine); 1.40 (t, J = 7.0 Hz, 3H, CH3); 1.59 (m,
4H, CH2 piperidine); 2.60 (m, 2H, NCH2 piperidine); 2.95 (m, 2H, NCH2
piperidine); 4.07 (m, 2H, OCH2); 4.30 (m, 2H, OCH2); 5.40 (dd, 2 JPH
20.4 Hz, JHH = 9.9 Hz, 1H, P CH<); 7.08 (m, 1H, NH); 7.48 (m, 2H,
arom-H); 7.55 (m, 1H, arom-H); 7.85 (m, 2H, arom-H). MS (FAB+): 354
[M]+ C17H27PN2O4.
=
3

Synthesis of α-Heterocyclic α-Aminophosphonates
1051
5: Rf: 0.48 (ether). 1H NMR (CDCl3): 1.29 (t, J = 7.0 Hz, 3H, CH3) ;
1.40 (t, J = 7.0 Hz, 3H, CH3); 1.75 (m, 4H, CH2); 2.80 (m, 2H, NCH2);
2.90 (m, 2H, NCH2); 4.10 (m, 2H, OCH2); 4.20 (m, 2H, OCH2); 5.65 (dd,
2 JPH = 19.2 Hz, 3 JHH = 9.9 Hz, 1H, P CH<); 7.08 (m, 1H, NH); 7.48 (m,
2H, arom-H); 7.55 (m, 1H, arom-H); 7.85 (m, 2H, arom-H). MS (FAB+):
340 [M]+ C16H25PN2O4.
1
6: Rf: 0.43 (ether). H NMR (CDCl3): 1.27 (t, J = 7.0 Hz, 3H, CH3);
1.32 (t, J = 7.0 Hz, 3H, CH3); 1.40–1.60 (m, 2H, CH2); 1.70–1.90 (m, 2H,
CH2); 2.70–2.95 (m, 2H, NCH2); 3.65–3.80 (m, 3H, NH and OCH2); 3.90–
4.00 (m, 1H, OCH); 4.10 (m, 2H, OCH2); 4.20 (m, 2H, OCH2); 5.45(dd,
2 JPH = 20.4 Hz, 3 JHH = 9.8 Hz, 1H, P CH<); 7.20 (m, 1H, NH); 7.35–
7.60 (m, 3H, arom-H); 7.85 (m, 2H, arom-H). MS DCI (methane): 371
[M + H]+ C17H28PN2O5.
1
7: Rf: 0.7 (ether). H NMR (CDCl3): 1.25 (t, J = 7.0 Hz, 3H, CH3);
1.40 (t, J = 7.0 Hz, 3H, CH3); 2.50 (s, 3H, CH3); 3.80 (d, J = 13.4
Hz, 1H, CHaHb-Ph); 3.95 (d, J = 13.4 Hz, 1H, CHaHb-Ph); 4.10 (m,
2
3
2H, OCH2); 4.25 (m, 2H, OCH2); 5.55 (dd, JPH = 20.4 Hz, JHH = 9.8
Hz, 1H, P CH<); 7.08 (m, 1H, NH); 7.25–7.60 (m, 8H, arom-H); 7.85
(m, 2H, arom-H).MS (FAB+): 390 [M]+ C20H27PN2O4.
1
8: Rf: 0.53 (ether/MeOH 5%). H NMR (CDCl3): 1.27 (t, J = 7.0 Hz,
3H, CH3); 1.32 (t, J = 7.0 Hz, 3H, CH3); 4.10 (m, 2H, OCH2); 4.20 (m,
2H, OCH2); 6.10 (dd, 2 JPH = 20.4 Hz, 3 JHH = 9.8 Hz, 1H, P CH<); 7.08
(m, 1H, NH); 7.25–7.60 (m, 9H, NH and arom-H); 7.85 (m, 2H, arom-H).
MS DCI (methane): 363 [M + H]+ C18H24PN2O4.
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