Reactions of hydrophosphoryl compounds with Schiff bases in the presence of CdI2

Article abstract of DOI:10.1023/A:1016578602100

The reaction of hydrophosphoryl compounds with aldimines and ketimines in the presence of catalytic amounts of cadmium iodide was investigated. A simple preparative method for the synthesis of α-aminophosphonates, phosphinates, and tertiary phosphine oxid

Full text of DOI:10.1023/A:1016578602100

Russian Journal of Organic Chemistry, Vol. 38, No. 4, 2002, pp. 480 483. Translated from Zhurnal Organicheskoi Khimii, Vol. 38, No. 4, 2002,
pp. 504 507.
Original Russian Text Copyright
2002 by Kabachnik, Ternovskaya, Zobnina, Beletskaya.
Reactions of Hydrophosphoryl Compounds with Schiff Bases
in the Presence of CdI
2
M. M. Kabachnik, T. N. Ternovskaya, E. V. Zobnina, and I. P. Beletskaya
Lomonosov Moscow State University, Moscow, 119899 Russia
Received August 17, 2001
Abstract The reaction of hydrophosphoryl compounds with aldimines and ketimines in the presence of
catalytic amounts of cadmium iodide was investigated. A simple preparative method for the synthesis of
-aminophosphonates, phosphinates, and tertiary phosphine oxides was developed.
We were the first to apply CdI2 as catalyst in pre-
paration of -trimethylsiloxyphosphines by reaction
of diphenyltrimethylsilylphosphine with ketones [1].
Later several publications appeared on the use of CdI2
as Lewis acid in various organic processes [2, 3]. In
particular, this catalyst was successfully applied to the
synthesis of acetals and ketals under microwave
irradiation [4].
The reaction progress was monitored by IR and
31P NMR spectroscopy. The completion of reaction
was determined by disappearance of absorption bands
in the IR spectra in the regions 1675 1685 (C=N)
1
and 2450 2500 cm [P(O)H].
This reaction was studied in the presence of
catalytic amounts (2 mol%) of Lewis acids ZnCl2,
CdI2, PdCl2, NiCl2, AlCl3, and LaCl3. The reaction
of diethyl phosphite with imine was carried out in
anhydrous benzene at reagents ratio 1: 1 in the
temperature range from 20 to 70 C. The time till
reaction completion depending on the catalyst used
and temperature is given in Table 1. It was found that
at 20 C the process with different Lewis acids
completed within 20 60 h. The optimum temperature
was 40 45 C, and heating over this temperature
virtually did not affect the yield of compound Ia.
In this study, a reaction of aldimines and ketimines
with hydrophosphoryl compounds (HPC) in the
presence of CdI2 was investigated, and catalytic
activity of the latter was compared to that of the other
Lewis acids.
The catalytic activity of Lewis acids was compared
on an example of reaction between O,O-diethyl
phosphite with N-tert-butylbutyralimine.
The best catalysts were CdI2 and AlCl3 (Table 1).
With these catalysts the reaction between diethyl
phosphite and N-tert-butylbutyralimine is easily
finished at 40 45 C in 1.5 h. Yet without catalyst the
reaction at room temperature goes to completion for
11 days, and at 40 45 C for 36 h.
Further we used as catalyst cadmium iodide. Note
that the addition of diethyl phosphite to N-tert-butyl-
butyralimine in the presence of aluminum chloride
strongly depends on the purity of the latter. The best
results were obtained with AlCl3 Merk or write
common substance subjected to sublimation and dry-
ing just before use. The application of CdI2 is more
convenient for preparative targets because the
recrystallized and dehydrated salt can be stored for a
long time unchanged.
Table 1. Reaction of O,O-diethyl phosphite with
N-tert-butylbutyralimine in the presence of Lewis acids
Catalyst
Time at 20 C, h Time at 40 45 C, h
11 days
20
36
1.5
CdI2
ZnCl2
PdCl2
AlCl3
NiCl2
LaCl3
>48
22
20
4
3
1.5
2
8
Under the conditions developed for the reaction
between diethyl phosphite and N-tert-butylbutyral-
imine in the presence of CdI2 we involved into this
>60
1070-4280/01/3804-480$27.00 2002 MAIK Nauka/Interperiodica

REACTIONS OF HYDROPHOSPHORYL COMPOUNDS
481
1
Table 2. Yields, boiling and melting points, n2D0 values, and some parameters of 31P and H NMR spectra of compounds
Ia i, IIa, b, III
bp,
(p, mm Hg),
mp,
C
31P NMR
spectrum,
, ppm
n2D0
1H NMR spectrum, , ppm
Compd. Yield,
no.
%
C
Ia
77
69 71 (14) 1.4250
76 77 (14) 1.4206
97 100 (20) 1.4470
97 100 (14) 1.4947
90 91
29.09
29.04
29.22
29.12
26.20
0.87 s (3H, CH3CH2CH2), 1.04 s [9H, C(CH3)3], 1.26 t (6H,
CH2CH2O), 1.45 m (4H, CH3CH2CH2), 1.68 m (2H, CH3CH2CH2),
2.86 m (1H, CHP, J 17 Hz), 4.06 q (4H, CH3CH2O)
0.96 d [6H, CH(CH3)2], 1.08 s [9H, C(CH3)3], 1.34 t (6H,
CH3CH2O), 2.06 m [1H, CH(CH3)2], 2.67 m (1H, CHP, J 16.9 Hz),
4.06 q (4H, CH3CH2O)
1.1 m (11H, C6H11-cyclo), 1.24 t (6H, CH3CH2O), 1.42 m (2H,
CH3CH2), 1.78 m (2H, CH3CH2), 2.82 m (1H, CHP, J 17 Hz),
4.10 q (4H, CH3CH2O)
1.24 t (6H, CH3CH2O), 2.15 s (3H, NHCH3), 3.98 q (4H,
CH3CH2O), 4.64 d (1H, CHP, J 17.9 Hz), 7.45, 7.50 m (5H,
CHC6H5)
1.22 t (6H, CH3CH2O), 3.92 q (4H, CH3CH2O), 4.68 d (1H, CHP,
J 17.9 Hz), 6.55, 7.30 m (5H, CHC6H5), 7.07, 7.43 m (5H,
NHC6H5)
Ib
Ic
81
80
80
75
Ida
Iea
If
50
76
99
81
114 116 (8)
96 98 (8) 1.4882
121 122
19.22
21.42
22.60
23.65
1.02 m (11H, C6H11-cyclo), 1.15 s (8H, C5H8-cyclo), 1.25 t (6H,
CH3CH2O), 4.08 q (4H, CH3CH2O)
1.08 m (11H, C6H11-cyclo), 1.14 s (10H, C6H10-cyclo), 1.24 t
(6H, CH3CH2O), 4.01 q (4H, CH3CH2O)
1.22 t (6H, CH3CH2O), 4.08 q (4H, CH3CH2O), 4.54 d (1H, CHP,
J 16.4 Hz), 7.16 m (5H, NHC6H5), 7.60, 8.40 m (4H, C5H4N)
1.24 t (6H, CH3CH2O), 2.42 s (3H, CHC6H5), 3.98 q (4H,
CH3CH2O), 4.68 d (1H, CHP, J 17.9 Hz), 6.60, 7.22 m (15H,
CHC6H5)
Ig
Iha
Ii
105 106
IIa
69
180
41.94, 1.06 s [9H, C(CH3)3], 1.29 t (3H, CH3CH2O), 1.34 d [6H,
42.53
CH(CH3)2], 1.50 m [2H, CHCH2CH(CH3)2], 1.95 m [1H,
CHCH2CH(CH3)2], 2.36 m (1H, CHP), 4.12 q (4H, CH3CH2O),
7.11 m (5H, CHC6H5)
IIba
III
78
52
171
210
40.50, 1.24 t (3H, CH3CH2O), 4.01 q (4H, CH3CH2O), 4.24 d (1H, CHP,
41.02
J 17.9 Hz), 6.85, 7.22 m (5H, CHC6H5), 7.10, 7.52 m (5H,
NHC6H5)
19.30
0.96 d [6H, CH2CH(CH3)2], 1.34 t (6H, CH3CH2O), 2.06 m [1H,
CH2CH(CH3)2], 4.67 m (1H, CHP, J 17.9 Hz), 6.44, 7.12 m
(10H, C6H5)
a
The constants of compounds Id, e, h and IIb are identical to published data [8 11].
process a number of aldimines and ketimines of
aliphatic and aromatic series. As show IR and
31P NMR spectroscopy the reaction of aldimines and
ketimines with phosphite occurred virtually quantita-
tively. -Aminophosphonates Ia i were isolated in
50 99% yield depending on the structure of the Schiff
base.
I, R1 = H, R2 = Pr, R3 = t-Bu (a); R1 = H, R2 = i-Pr,
R3 = t-Bu (b); R1 = H, R2 = Et, R3 = cyclo-C6H11
(c); R1 = H, R2 = Ph, R3 = Me (d); R1 = H, R2 =
Ph, R3 = Ph (e); R1 = H, R2 = cyclo-C5H8, R3 =
cyclo-C6H11 (f); R1 = R2 = cyclo-C6H10, R3 = cyclo-
C6H11 (g); R1 = H, R2 = 3-Py, R3 = Ph (h); R1 = H,
R2 = Ph, R3 = CHPh2 (i).
It should be noted that methods of synthesis of
-aminophosphonates are known, and quite a number
of publications and reviews treats this topic [5 7].
However up till now no simple and general procedure
existed for preparation of these compounds. The
method we developed is easy to perform and provides
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 38 No. 4 2002

482
KABACHNIK et al.
Table 3. Elemental analyses of compounds Ia d, f, g, i, IIa, b, III
Found, %
Calculated, %
H
Compd.
no.
Formula
C
H
P
C
P
Ia
Ib
Ic
Id
If
Ig
Ii
IIa
IIb
III
52.03
53.97
56.15
55.97
59.36
60.50
69.51
65.59
71.81
73.40
10.38
10.51
10.09
7.74
9.84
10.01
6.77
9.35
6.30
8.65
11.69
11.46
11.15
11.97
10.15
9.71
7.55
10.05
8.83
C12H28NO3P
C12H28NO3P
C13H28NO3P
C12H20NO3P
C15H30NO3P
C16H32NO3P
C24H28NO3P
C17H30NO2P
C21H22NO2P
C21H30NOP
54.34
54.34
56.32
56.03
59.41
60.57
70.42
65.59
71.79
73.47
10.57
10.57
10.11
7.78
9.90
10.09
6.85
9.64
6.27
8.75
11.70
11.70
11.19
12.06
10.23
9.78
7.58
9.97
8.83
9.04
8.98
a possibility of preparation of a wide range of
-aminophosphonates of versatile structures.
(Ia) (general procedure). To 0.06 mol (8.3 g, 7.7 ml)
of O,O-diethyl phosphite in 20 ml of anhydrous
benzene was added 0.44 g of cadmium iodide, and the
mixture was stirred to complete dissolution of the
catalyst. Then was added 0.06 mol (7.6 g, 9.3 ml) of
N-tert-butylbutyralimine. The reaction was carried out
at 40 45 C for 1.5 h. The solvent was removed, the
residue was distilled in a vacuum. Yield of compound
Ia 12.3 g (77%).
Besides diethyl phosphite the reaction with ald-
imines was carried out with phenyl ethyl phosphonite
and diethenylphosphonous acid.
Reaction of O,O-diethyl phosphite with N-tert-
butyl-iso-butyralimine (Ib). Likewise was obtained
compound Ib from 0.06 mol (8.3 g, 7.7 ml) of
O,O-diethyl phosphite and 0.06 mol (7.6 g, 9.2 ml)
of N-tert-butyl-iso-butyralimine. Yield 12.8 g (81%).
R1 = EtO, R2 = i-Bu, R3 = t-Bu (IIa); R1 = EtO,
R2 = R3 = Ph (IIb); R1 = Ph, R2 = i-Bu, R3 = t-Bu
(III).
Reaction of O,O-diethyl phosphite with N-cyclo-
hexylpropylideneimine (Ic). Likewise was obtained
compound Ic from 0.06 mol (8.3 g, 7.7 ml) of
O,O-diethyl phosphite and 0.06 mol (8.3 g, 10.6 ml)
of N-cyclohexylpropylideneimine. Yield 13.4g (80%).
In both cases the reaction occurred under standard
conditions yielding aminophosphinates IIa, b and
aminophosphine oxide III in 52 78% yield. Com-
pounds IIa, b contain asymmetric phosphorus and
carbon atoms and form as mixtures of two stereoiso-
mers. In the 31P NMR spectrum of compounds IIa, b
appeared two signals in the region 40.5 41.9 and 41
42.5 ppm in 1.2 : 1 ratio.
Reaction of O,O-diethyl phosphite with
N-methylbenzalimine (Id). Likewise was obtained
compound Id from 0.06 mol (8.3 g, 7.4 ml) of
O,O-diethyl phosphite and 0.06 mol (7.1 g, 7.4 ml)
of N-methylbenzalimine. Yield 12.3 g (80%).
Physico-chemical characteristics, some parameters
1
of 31P and H NMR spectra, and elemental analyses
of compounds synthesized are given in Tables 2 and 3.
Reaction of O,O-diethyl phosphite with
N-phenylbenzalimine (Ie). The reaction was carried
out as above using 0.06mol (8.3g, 7.7 ml) of O,O-di-
ethyl phosphite and 0.06 mol (10.9 g) of N-phenyl-
benzalimine. The reaction mixture was cooled to
room temperature, 20 ml of ether was added, and the
mixture was stirred for 3 h. The precipitate of phos-
phonate was filtered off and recrystallized from
alcohol. Yield of compound Ie 14,4 g (75%).
EXPERIMENTAL
1H NMR spectra were recorded on spectrometer
Tesla BS-147 with TMS as external reference.
31P NMR spectra were registered on Varian FT-80
instrument with TMS as internal reference, 85%
H3PO4 as external reference.
Reaction of O,O-diethyl phosphite with N-tert-
butylbutyralimine in the presence of Lewis acids
Reaction of O,O-diethyl phosphite with N-cyclo-
hexylcyclopentylideneamine (If). The reaction was
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 38 No. 4 2002

REACTIONS OF HYDROPHOSPHORYL COMPOUNDS
483
carried out as above using 0.06 mol (8.3 g, 7.7 ml)
of O,O-diethyl phosphite and 0.06 mol (6.6 g,
6.6 ml) of N-cyclohexylcyclopentylideneamine. The
heating to 40 45 C continued for 4.5 h. Yield of
compound If 6 g (50%).
mixture was added 4 ml of hexane. The separated
precipitate was filtered off, 15 ml of ether was added,
and the mixture was stirred 3 h at room temperature.
The compound obtained was purified by recrystalliz-
ation from alcohol. Yield of compound IIa 5.36 g
(69%).
Reaction of O,O-diethyl phosphite with N-cyclo-
hexylcyclohexylideneamine (Ig). The reaction was
carried out as above using 0.015 mol (2 g, 1.9 ml) of
O,O-diethyl phosphite and 0.01 mol (1.8 g, 1.8 ml)
of N-cyclohexylcyclohexylideneamine. The heating to
40 45 C continued for 7 h. Yield of compound Ig
2.4 g (76%).
Reaction of phenyl ethyl phosphonite with
N-phenylbenzalimine
(IIb).
Likewise
from
0.025 mol (4.25 g, 3.7 ml) of phenyl ethyl phospho-
nite and 0.025 mol (3.53 g, 4.1 ml) of N-phenylbenz-
alimine was obtained compound IIb, yield 6.9 g
(78%).
Reaction of diphenylphosphinous acid with
N-tert-butyl-iso-pentalimine (III). The reaction was
carried out as above using 0.005 mol (1.01 g) of
diphenylphosphinous acid and 0.005 mol of N-tert-
butyl-iso-pentalimine. Phosphine oxide III was re-
crystallized from alcohol. Yield of compound III
0.89 g (52%).
Reaction of O,O-diethyl phosphite with N-phen-
yl-3-pyridinecarboxaldimine (Ih). To a solution of
0.11 mol (11.8 g, 10.4 ml) of nicotinaldehyde in
toluene (50 ml) was added 0.11 mol (10.2 g, 10 ml)
of aniline. The mixture was stirred for 1 h, and the
solvent was removed on a rotary evaporator. The
imine thus obtained was mixed with 0.11 mol (15.2g,
14.2 ml) of O,O-diethyl phosphite, the reaction mix-
ture was heated for 1 h at 40 45 C in the presence of
2 mol% of CdI2. The mixture was cooled to room
temperature, 30 ml of ether was added, and the mix-
ture was stirred for 3 h. The precipitate was filtered
off and recrystallized from a mixture hexane toluene
(1: 1). Yield of compound Ih 35 g (99%).
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16.3 g) of N-benzhydrylbenzalimine. After heating
the reaction mixture was cooled to room temperature,
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Reaction of phenyl ethyl phosphonite with
N-tert-butyl-iso-pentalimine (IIa) (general proce-
dure). To a solution of 0.025 mol (4.25 g, 3.7 ml) of
phenyl ethyl phosphonite in benzene (5 ml) was added
0.183 g of cadmium iodide. The mixture was stirred
at room temperature till complete dissolution of the
catalyst. Then 0.025 mol (3.53 g, 4.1 ml) of N-tert-
butyl-iso-pentalimine was added. The reaction was
carried out at 40 45 C for 4 h. Then to the reaction
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 38 No. 4 2002