Iodine atom transfer addition reaction of 1-iodoalkyl phosphonates to alkenes in the presence of α,α′-azoisobutyronitrile (AIBN): Mechanistic aspects

Article abstract of DOI:10.1039/b005882n

The objectives of this work were to elucidate the mechanistic pathway of the title reaction, which constitutes the first example of a radical iodine atom transfer addition reaction of non-fluorine-containing phosphonates, and to determine whether 2-iodo-2-methylpropionitrile, 8, can serve as a competing iodine donor with the starting diethyl 1-iodoalkyl phosphonates, 1a,b. The title reaction was found to proceed with AIBN as the sole radical initiator, not requiring poisonous tin reagents as co-initiators, and gave diethyl 3-iodoalkylphosphonates 3a-e (the final products of the propagation step, isolated in 59-95% yield), tetramethylsuccinodinitrile, 9, diethyl methylphosphonate, 4 and tetraethyl ethylenebisphosphonate 5 (all termination products, 0-10% yields). The radical character of this reaction was demonstrated using TEMPO as a radical trap. 8 (the intermediate of the initiation step), synthesized independently from AIBN and iodine, caused complete inhibition of the reaction when added to the reaction mixture, indicating that it does not behave as an iodine donor in the transfer stage, but rather as an inhibitor.

Full text of DOI:10.1039/b005882n

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Iodine atom transfer addition reaction of 1-iodoalkyl phosphonates to
alkenes in the presence of a,aº-azoisobutyronitrile (AIBN):
mechanistic aspects¤”
Piotr Ba¡czewski* and Marian Miko¡ajczyk
Centre of Molecular and Macromolecular Studies, Polish Academy of Sciences, 90-363 ¢odz,
Sienkiewicza 112, Poland. E-mail: pbalczew=bilbo.cbmm.lodz.pl; Fax: ]48 42 684 7126
Received (in Strasbourg, France) 19th July 2000, Accepted 4th January 2001
First published as an Advance Article on the web 7th March 2001
The objectives of this work were to elucidate the mechanistic pathway of the title reaction, which constitutes the
Ðrst example of a radical iodine atom transfer addition reaction of non-Ñuorine-containing phosphonates, and to
determine whether 2-iodo-2-methylpropionitrile, 8, can serve as a competing iodine donor with the starting diethyl
1-iodoalkyl phosphonates, 1a,b. The title reaction was found to proceed with AIBN as the sole radical initiator, not
requiring poisonous tin reagents as co-initiators, and gave diethyl 3-iodoalkylphosphonates 3aÈe (the Ðnal products
of the propagation step, isolated in 59È95% yield), tetramethylsuccinodinitrile, 9, diethyl methylphosphonate, 4 and
tetraethyl ethylenebisphosphonate 5 (all termination products, 0È10% yields). The radical character of this reaction
was demonstrated using TEMPO as a radical trap. 8 (the intermediate of the initiation step), synthesized
independently from AIBN and iodine, caused complete inhibition of the reaction when added to the reaction
mixture, indicating that it does not behave as an iodine donor in the transfer stage, but rather as an inhibitor.
Atom or group transfer radical reactions, particularly easy in
the case of organic iodides, have recently joined fundamental
methods for the formation of carbonÈcarbon bonds in both
organic synthesis2 and polymer chemistry.3 The commonly
accepted mechanism (Scheme 1) of these reactions comprises
three basic steps: generation of the substrate radical, either
photolytically or thermally [eqn. (1)], addition of the latter to
a multiple bond [eqn. (2)] and the appropriate iodine atom
transfer step4h7 [eqn. (3)].
The driving force behind iodine atom transfer reactions is
the formation of a more stable starting radical in comparison
to a less stable adduct radical. Moreover, the latter reactions
must be faster than other competing reactions of the adduct
radical, such as telomerization or termination.2 The mecha-
nisms of the iodine atom transfer reactions have been investi-
gated mostly for iodides that do not contain additional
heteroatoms geminal to the transferred iodine atom.
Recently, we have begun a sustained program that is
designed to exploit the characteristic features of novel reac-
tions involving 1-diethoxyphosphorylalkan-1-, 2- and 3-yl
radicals as new, reactive intermediates and their applications
in organic synthesis. In a series of papers8h15 we have demon-
strated the considerable synthetic value of the tributyltin
hydride-mediated reactions [Scheme 2, eqn. (1)].
Now, we extend our interest to the iodine atom transfer
addition reactions, which certainly possess a greater synthetic
value due to the possible further synthetic transformations of
the iodine atom in the product [Scheme 2, eqn. (2)]. The
mechanisms of these reactions have not been broadly investi-
gated due to the limited number of reported cases. According
to the Beilstein CrossÐre database, there are only two exam-
ples of the iodine atom transfer reaction reported in the liter-
ature, involving diethyl iododiÑuoromethylphosphonate16
and diethyl iodoÑuoromethylphosphonate.17 For these reac-
tions, performed in the presence of Cu(0) or Pd(PPh ) , a
3 4
single electron transfer, radical mechanism was proposed. In
our hands the use of these initiators failed for non-Ñuorine-
containing phosphonates. However, we succeeded in carrying
out, for the Ðrst time, the iodine atom transfer addition reac-
tion with a,a@-azoisobutyronitrile (AIBN) as the sole reaction
initiator without it being necessary to use poisonous tin
reagents like (n-Bu Sn) or n-Bu SnH as co-initiators. The
3
2
3
results concerning the mechanism of this reaction are dis-
closed in this paper. It is also noteworthy that transfer reac-
tions of other halogen atoms via radical-type mechanisms are
also represented in the literature by a very limited number of
examples. The bromine atom was transferred from diethyl
bromodiÑuoromethylphosphonate onto oleÐns in
a free
radical addition reaction.17 The chlorine atom was transferred
Scheme 1 A general mechanism for the iodine atom transfer addition
reaction of non-phosphorus-containing iodides to alkenes and
alkynes.
¤ Electronic supplementary information (ESI) available: 13C DEPT
and 2D 1HÈ13C correlation spectra for 3a,cÈe. See http://
www.rsc.org/suppdata/nj/b0/b005882n/
” Part VIII of the series Phosphorus containing radicals. For part VII,
Scheme 2 Free radical addition reaction under reductive and atom
transfer reaction conditions.
see: ref. 1.
DOI: 10.1039/b005882n
New J. Chem., 2001, 25, 659È663
659
This journal is ( The Royal Society of Chemistry and the Centre National de la Recherche ScientiÐque 2001

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Table 1 Optimization of the reactant stoichiometry for the reaction
of 1a with 2a in the presence of AIBN in C H (80 ¡C, 6È7 h)
from diethyl trichloromethylphosphonate onto oleÐns in
reactions initiated by CuCl/amine18 and FeCl or
CuCl /Et N É HCl/benzoin systems.19 While the latter reac-
tion proceeds via a redox chain, the former is a nonchain cata-
lytic reaction. The above examples show that di†erent
reaction mechanisms operate for the halogen atom transfer
reactions in a-hetero (Cl, Br, I) substituted phosphonates,
depending on the structure of the starting phosphonates and
the mode of the initiation step.
6
6
3
1a : AIBN : 2a/equiv.
3a (%)
1a (%)
2
3
1 : 0 : 10
1 : 0.05 : 10
1 : 0.1 : 10
1 : 0.2 : 10
1 : 0.5 : 10
1 : 1 : 10
1 : 1 : 5
0
17
21
33
63
71È83
46
100
73
78
67
21
17È20
48
1 : 1 : 2
1 : 1 : 1
10
3
90
97
Results and discussion
Optimization of the reaction conditions and characterization of
the reaction products
1HM31PN-, 13CM31PN-NMR decoupled spectra. The 13C-NMR
(DEPT) and (1HÈ13C)-NMR (2D) experiments were helpful in
assignment of characteristic 1H- and 13C-NMR signals to the
It is known from the literature that the efficiency of iodine
atom transfer reactions carried out for non-phosphorus-con-
taining substrates, in the presence of AIBN as the sole reac-
tion initiator, varies with the structure of the reactants. For
instance, the reaction of electrophilic 1-iodoperÑuoropropane
with electron-rich 1-heptene gave perÑuoropropyl-2-iodohep-
tane in 99% yield (1% AIBN, 6 h, 70 ¡C).20 On the other
hand, the similar addition reaction of propargyl iodomalon-
ates with 1-hexene resulted in only 15% conversion and cycli-
zation of iodoalkynes in the presence of AIBN, hexa-n-
butylditin, led to unidentiÐed decomposition products.4
Therefore, an accurate determination of the optimal reaction
conditions was the Ðrst task in our studies. As a model reac-
tion for the mechanistic studies, the reaction of diethyl 1-
iodoalkylphosphonates 1a,b with 1-hexene, 2a, 1-heptene, 2b
and 1-hexadecene, 2c, in reÑuxing benzene in the presence of
AIBN was chosen, which resulted in the formation of the
adducts 3aÈe (Scheme 3).
CH groups of long phosphonate chains and showed that
2
some of these groups were diastereotopic. Moreover, the two-
dimensional correlations revealed unequivocally the exact
1H-NMR position of the CHÈI multiplets that were com-
pletely hidden under the diethoxyphosphoryl methylene
multiplets at around d \ 4.1.
H
When the reaction was performed in the presence of a cata-
lytic amount of AIBN (10%), the expected phosphonates 3
were formed in much lower yields. Thus, with 1-hexene, 2a,
and the higher boiling 1-heptene, 2b and 1-hexadecene, 2c, the
3-iodoalkylphosphonates 3a–c were obtained in 21, 40 and
48% yield, respectively. Based on the 1H- and 31P-NMR
experiments and GLC comparative analyses, the following
further observations were made: (1) substrates were recovered
in the absence of the radical initiator AIBN; (2) tetra-
methylsuccinodinitrile, 9, as the dimerization product of iso-
butyronitrile radical 10, was isolated in 80È95% yield,
depending on the reaction scale (Scheme 5, vide infra); (3) two
termination phosphorus-containing products were found in
small quantities in the reaction mixture of 1a with alkenes
2a–c: diethyl methylphosphonate, 4 [0È10%, d (CDCl ) \
We found that the best results could be obtained upon
mixing reagents in
a ratio 1 : AIBN : 2 varying from
1 : 0.5 : 10 to 1 : 1 : 10 and heating the resulting mixture in
reÑuxing benzene for 6 h. Under these reaction conditions the
yields of the phosphonates 3aÈe was in the range 59È95% (see
Experimental). Optimization of the reaction conditions was
carried out on the synthesis of 3a, 3c, 3d/3e and representative
data for 3a are given in Table 1.
P
3
30.9] and tetraethyl ethylenebisphosphonate, 5 [0È2%, d
P
(CDCl ) \ 30.2], proving the formation of diethoxyphos-
phorylmethyl radicals 11 (Scheme 5, vide infra). In the reaction
3
The structure of the products 3 was conÐrmed not only by
the MS, IR and standard 1H-, 13C-, 31P-NMR but also by the
of 1b with 1-hexene, a 1 : 1 mixture of diastereoisomers 3d and
3e was almost quantitatively isolated and only trace amounts
of 4 were formed.
When the investigated reactions were carried out in the
presence of TEMPO (2,2,6,6-tetramethyl-1-piperidinyloxy
radical) as the radical trap, a typical inhibitory e†ect was
observed (regardless of the use of catalytic or stoichiometric
amounts of AIBN as the radical initiator), indicating their
radical character (Table 2).
Is 2-iodo-2-methylpropionitrile an iodine donor in the transfer
reaction step?
In the atom transfer reactions the starting iodide usually
behaves as a donor of the iodine atom [Scheme 1, eqn. (3)].
We were intrigued by the question whether 2-iodo-2-methyl-
propionitrile 8 [Scheme 5, vide infra; see also Scheme 1, eqn.
(1)], can be consumed as a second competing source of the
iodine atom. To the best of our knowledge, this problem was
Table 2 Reaction of 1a with 2a in the presence and absence of
TEMPO
AIBNa/equiv.
TEMPOa/equiv.
Yield 3ab (%)
0.1
1
0.1
1
5(30)
7(76)
a With respect to 1a. b With TEMPO and without TEMPO (in
parentheses).
Scheme 3 The iodine atom transfer addition reaction of diethyl
iodoalkylphosphonates 1 to alkenes 2.
660
New J. Chem., 2001, 25, 659È663

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not considered earlier. According to Schemes 1 and 5, 8 must
be formed in the initiation step as the result of isobutyronitrile
radical 10 attack on the iodine atom of the starting iodide 1. A
preliminary analysis of the 1H-NMR spectra of the crude
reaction mixtures showed, however, the absence of the iodide
8, which means that it is apparently formed in trace quantities
during the initiation step or is subsequently consumed in the
transfer step as the iodine atom donor. We synthesized this
iodide independently by the reaction of AIBN with molecular
iodine (2 or 3 equiv.) in a reÑuxing benzene solution within
4È6 h in 78È86% yields (Scheme 4, Table 3).
amount of AIBN, to the reaction of 1a with 2a had, as
expected, no e†ect, either beneÐcial or detrimental, and con-
Ðrmed earlier conclusions for non-phosphorus substrates.22
Mechanistic pathway of the iodine atom transfer addition
reaction of diethyl 1-iodoalkylphosphonates to alkenes
In the radical-type mechanism postulated for the iodine atom
transfer addition reaction of 1 to 2, three main steps can be
distinguished (Scheme 5).
In the Ðrst, initation step, isobutyronitrile radical 10, gener-
ated by thermal decomposition of AIBN, reversibly reacts
with the starting iodides 1 to give the key radicals 11 and the
iodide 8. Another possibility to explain the formation of 1123
involves the addition of isobutyronitrile radical 10 to alkenes
2, followed by the iodine atom transfer reaction with the start-
ing iodides 1. However, such a route to 11 is of minor impor-
tance and does not occur to a large extent because the
corresponding adducts have not been found. Moreover, the
high yields of the isolated tetramethylsuccinodinitrile 9 (80È
95% for the reaction of 1a with 2c) and of the regenerated
alkenes (96% for 2c) after column chromatography on silica
gel provide convincing evidence that the radical 10 is mostly
involved in the dimerization reaction leading to the dinitrile 9
rather than in the addition reaction to alkenes 2.
In the second, propagation step, the radicals 11 undergo
addition to alkenes 2 to give the adduct radicals 12. They, in
turn, are trapped by the starting iodides 1 to a†ord the Ðnal
phosphonates 3 and radicals 11, which are capable of reacting
further with alkenes 2. The radicals 12 are not trapped by the
iodide 8. The latter is an inhibitor of the iodine atom transfer
reaction, as demonstrated above. Accumulation of the Ðnal
3-iodoalkylphosphonates 3 in the reaction mixtures is possibly
due to the fact that isobutyronitrile radical 10 does not
abstract an iodine atom from non-stabilized iodides. This con-
clusion was conÐrmed by the reaction of the pure phos-
Indeed, the 1H-NMR spectra of the crude reaction mixtures
(i.e. 1a with 2a and 2c; 1b with 2a) showed no characteristic
singlet at d \ 2.24 (CDCl ) due to the presence of the iodide 8.
3
Considering addition and transfer steps as rapid reactions and
the fact that the iodine atom in the iodide 8 could subse-
quently be transferred to the adduct radical, thus shifting the
equilibrium of the initiation step, we anticipated that addition
of this iodide from an external source to the reaction mixture
would cause higher conversions of phosphonates 1 to pro-
ducts. However, when reactions of 1a with 2a or 2c were
carried out with a stoichiometric amount of the iodide 8
(Table 4) in the presence of both catalytic or stoichiometric
amounts of AIBN, only the starting 1-iodoalkylphosphonate,
1a, the unreacted 2-iodo-2-methylpropionitrile, 8, and AIBN
and tetramethylsuccinodinitrile, 9, could be detected in the
crude reaction mixtures after 6 h.
Thus, the iodide 8 turns out not to be an iodine donor in
the propagation step but an inhibitor of the initiation step,
according to the Le ChatelierÈBrown principle.21 This experi-
ment gave the additional conclusion that the initiation step
has to be a reversible process and the concentrations of both
resulting products, the iodide 8 and the radical 11, are small
during the reaction course, even with a stoichiometric amount
of AIBN. This is consistent with the observation (31P- and
1H-NMR assay) of small quantities of the phosphorus termi-
nation products 4 (0È10%) and 5 (0È2%). The addition of
another iodine donor, n-propyl iodide, used either in stoichio-
metric or threefold excess together with a stoichiometric
phonate 3c with 1-hexene, 2a, in the presence of
a
stoichiometric amount of AIBN and in which only starting
materials were recovered.
In the third, termination step, three reactions occur: the
Scheme 4 Independent synthesis of 2-iodo-2-methylpropionitrile, 8,
from AIBN and iodine.
Table 3 Optimization of conditions for the reaction of 6 with I
2
I /equiv.
8 (%)
9 (%)
6 (%)
2
1
2
3
38
78
86
10
11
14
52
11
0
Table 4 Inhibitory e†ect of externally added 8 on the reaction of 1a
with 2a
AIBN/equiv.a
8/equiv.a
Yield 3a (%)b
1
1
0.1
1
0(21)
0(73)
Scheme 5 Mechanism of the iodine atom transfer addition reaction
of diethyl iodomethylphosphonates 1 to alkenes 2 in the presence of
AIBN.
a With respect to 1a. b With 8 and without 8 (in parentheses).
New J. Chem., 2001, 25, 659È663
661

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dimerization of the radicals 10 and 11 to tetra-
methylsuccinodinitrile, 9, and tetraethyl ethylenebis-
phosphonate, 5, respectively, and the reduction of the radicals
11 to diethyl alkylphosphonates 4 (the source of hydrogen
atoms is not clear).
IR (Ðlm): l/cm~1 3482 (br), 2981, 2931, 2908, 2869, 1644 (br),
1446, 1392, 1240, 1162, 1135, 1097, 1020, 966, 792, 775, 711,
561, 524; MS-LR-EI (70 eV): m/z (%) 292 (M`, 37); 165 (36);
137 (50); 109 (100); 91 (16); 81 (29), 65 (11); MS-LR-CI
(isobutane): m/z (%) 293 (MH`, 100).
Conclusions
General procedure for synthesis of diethyl 3-iodoalkyl-
phosphonates, 3a–e. To a stirred solution of diethyl 1-
iodoalkylphosphonate 1a or 1b (5 mmol) in dry benzene (70
mL), AIBN (820 mg, 5 mmol) and the corresponding alkene
2a, 2b or 2c (50 mmol) were added. The resulting solution was
stirred for 10 min at room temperature and reÑuxed under
argon atmosphere for 6È7 h. Then, benzene was evaporated
and the residue was distilled using a Kugelrohr apparatus or
chromatographed with silica gel. When column chromatog-
raphy was employed for puriÐcation of the crude phosphonate
3c, n-hexadecene 2c and the starting phosphonate 1a were
regenerated in 96 and 71% yields, respectively. Tetra-
methylsuccinodinitrile 9 was isolated in 80È95% yield.
In summary, in this paper we disclose the mechanistic
pathway of the radical iodine atom transfer addition reaction
of diethyl 1-iodoalkylphosphonates 1 to alkenes 2, which con-
stitutes the Ðrst example of the reaction involving non-
Ñuorine-containing phosphonates. We conÐrmed the presence
of all intermediate and Ðnal products of the reaction: 3È5, 8
and 9 and found that this reaction may be radically initated
solely with AIBN, without the necessity of using poisonous tin
compounds as co-initiators. We also conclude that 2-iodo-2-
methylpropionitrile, 8, as an intermediate of the initiation
step, is formed in trace quantities and for kinetic and react-
ivity reasons it does not compete with the starting iodide 1 as
the iodine donor. This might be a general conclusion for other
iodine transfer reactions involving AIBN as an initiator. The
synthetic protocol presented is a general one for a radical-type
synthesis of 3-iodoalkylphosphonates 3.
Diethyl 3-iodo-n-heptylphosphonate, 3a.
Experimental
General
110 ¡C/0.01 mmHg; n25 \ 1.4740; yield 74%. 1H-NMR (500
D
MHz, CDCl ): d 0.91 (t, 3H, 3J
\ 7.1, C7H ); 1.33 (t, 6H,
3
HhH
3
3J
\ 7.1 Hz, 2 ] CH CH OP); 1.25È1.42 (m, 2H, C5H );
HhH
3
2
2
The 1H-NMR (200 and 500 MHz), 13C-NMR (50 and 125
MHz) and 31P-NMR spectra (81 and 202 MHz) were record-
ed using Bruker AC-200 and Bruker 500 DRX spectrometers.
Coupling constants (J) are given in Hz. The mass spectra were
obtained using a Finnigan Mat 95 spectrometer. The IR
spectra were recorded using an ATI Mattson InÐnity FTIR 60
spectrometer. The preparative thin layer chromatography was
performed using 20 ] 20 cm Merck silica gel plates (0.5 mm)
with a concentrated zone. The column chromatography was
1.45È1.57 (m, 2H, C6H ); 1.64È1.74 (m, 1H, C4HA); 1.76È1.95
2
(m, 2H, PCHA, C4HB); 1.96È2.10 (m, 3H, PCHB, C2H ); 4.06È
2
4.18 (m, 5H, 2 ] CH CH OP, CHÈI); 13C-NMR (125 MHz,
3
2
CDCl ):
d
13.60 (s, C7H ); 16.24 (d, 3J \ 5.8,
3
3
ChP
CH CH OP); 21.63 (s, C6H ); 25.80 (d, 1J \ 141.7, PC);
3
2
2
ChP
31.31 (s, C5H ); 33.24 (d, 2J \ 3.0, C2H ); 39.07 (d,
ChP
3J \ 19.2, C3HÈI); 39.86 (s, C4H ); 61.45 (2 ] d, 2J
ChP
4.7 Hz, CH CH OP); 31P-NMR (81 MHz, CDCl ): d 31.20;
2
2
\
2
ChP
3
2
3
IR (Ðlm): l/cm~1 2957, 2931, 1871, 1465, 1391, 1242, 1054,
1031, 963, 820, 788; MS-LR-CI (isobutane): m/z (%) 363
(M` ] 1, 100); 235 (M` ] 1 [ I, 45); 154 (23); MS-LR-EI (70
eV): m/z (%) 235 (M` [ I, 100); 207 (11); 179 (27); 152 (11);
149 (35); 137 (15); 125 (10); 121 (16); 97 (16); 81 (11); 55 (25);
done using Merck silica gel (F
mesh). Organic solvents were puriÐed by standard procedures.
All alkenes used were commercial reagents.
60, 70È230 and 270È400
254
Syntheses
41 (17); MS-HR-CI: M` ] 1, found 363.0575, C
requires 363.0586.
H
O PI
11 25
3
Diethyl iodomethylphosphonate, 1a, was prepared according
to ref. 8.
Diethyl 3-iodo-n-octylphosphonate, 3b. Oil; preparative TLC
on silica gel (petroleum etherÈacetone \ 2 : 1); yield 70%
Diethyl 1-iodoethylphosphonate, 1b. To a stirred solution of
diethyl ethylphosphonate (9.96 g, 0.06 mol) in THF (1 mL),
the following reagents were added, at [78 ¡C under argon
atmosphere, in 10È15 min intervals in the given order: LDA
(0.066 mol), TMSCl (6.51 g, 7.61 ml, 0.06 mol), LDA (0.066
mol), iodine (15.2 g, 0.06 mol). After warming to room tem-
perature, a EtONaÈEtOH solution (prepared by dissolving
1.38 g, 0.06 mol of sodium in 30 mL ethanol) was added. Stir-
ring was continued at this temperature for 1 h and then at
50 ¡C for 10 min. Next a saturated solution of ammonium
chloride (50 mL) was added at room temperature and after
stirring for 10 min, the THF was evaporated. To the residue
H O (50 mL) and CH Cl (150 mL) were added and the crude
(purity 73% based on 31P-NMR). 1H-NMR (CDCl , 200
3
MHz): d 0.88 (t, 3H, 3J
\ 6.5, C8H ); 1.32 (t, 6H, 3J
\
HhH
3
HhH
7.1 Hz, 2 ] CH CH OP); 1.24È2.09 [m, 12H, PCH CH ,
3
2
2
2
C4H (CH ) C7H ]; 4.09 (m, 5H, 2CH CH OP, CHÈI);
2 2
13C-NMR (CDCl , 50 MHz): d 13.96 (s, C8H ); 16.39 (d,
2
2
3
2
3
3
3J \ 5.5, CH CH OP); 22.43 (s, C7H ); 26.07 (d, 1J
ChP
141.26, PC); 29.07 (s, C6H ); 30.91 (s, C5H ); 33.42 (d,
\
3
2
2
ChP
2
2
2J \ 3.2, C2H ); 39.38 (d, 3J \ 19.25, CHÈI); 40.33 (s,
ChP ChP
2
C4H ); 61.65 (d, 2J \ 6.4 Hz, CH CH OP); 31P-NMR
2
ChP
3
2
(CDCl ): d 31.26; IR (Ðlm): l/cm~1 2979, 2956, 2929, 2871,
3
2836, 1467, 1437, 1391, 1366, 1096, 1056, 1030, 964, 788, 530;
MS-LR-EI (70 eV): m/z (%) 249 (M` [ I, 100); 137 (11);
MS-LR-CI (isobutane): m/z (%) 377 (M` ] 1, 100); 249 (73);
2
2 2
product was extracted into the organic layer, which was then
MS-HR-CI: M` ] 1, found 377.072 27; C
377.074 25.
H
O PI requires
washed with water (50 mL), dried over anhydrous MgSO ,
Ðltered and evaporated. The crude product was isolated using
a Kugelrohr apparatus under vacuum: 87 ¡C/0.02 mmHg,
12 27
3
4
Diethyl 3-iodo-n-heptadecylphosphonate, 3c.
n24 \ 1.4842; yield 71% (purity 87% based on 31P-NMR).
D
Lit.24 yield 83%. 1H-NMR (200 MHz, CDCl ): d 1.33 (t, 6H,
3
3J
\ 7.1, 2 ] CH CH OP); 1.98 (dd, 3H, 3J
\ 7.4,
HhH
3
2
HhH
3J \ 17.1, PCHCH ); 3.84 (dq, 1H, 3J
\ 7.4, 2J
\
HhP
3
HhH
HhP
9.9, PÈCHI); 4.18 (dq, 4H, 3J
] CH CH OP); 13C-NMR (125 MHz, CDCl ): d 7.22 (d,
B 3J \ 7.2 Hz,
2
Non-distillable oil; m.p. 17.5È18.5 ¡C; column chromatog-
raphy on silica gel (petroleum etherÈacetone gradient); yield
HhH
HhP
3
2
3
1J \ 156.06, PCI); 16.24 (d, 3J \ 5.7, POCH CH );
ChP ChP
21.71 (d, 2J \ 3.4, PCCH ); 63.41 and 63.44 (2 d, 2J
ChP
3.3 Hz, POCH CH ); 31P-NMR (202 MHz, CDCl ): d 23.54;
52%. 1H-NMR (500 MHz, CDCl ): d 0.83 (t, 3H, 3J
\ 7.0,
2
3
3
HhH
\
C17H ); 1.21 and 1.25È1.53 (br s and m, 24H, C5H ÈC16H );
2
ChP
3
2
2
1.28 (t, 6H, 3J
\ 7.1 Hz, 2 ] CH CH OP); 1.61È1.68 (m,
2
3
3
HhH
3
2
662
New J. Chem., 2001, 25, 659È663

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1H, C4HA); 1.74È1.87 (m, 2H, PCHA, C4HB); 1.92È2.04 (m,
3H, PCHB, C2H ); 4.01È4.11 (m, 5H, 2 ] CH CH OP,
(%) 249 (M` [ I, 100), 111 (19), 69 (33), 55 (19); HR-MS-CI:
M` ] 1, found 377.072 05; C
H
O PI requires 377.0731.
2
3
2
12 27
3
CHÈI); 13C-NMR (125 MHz, CDCl ): d 13.90 (s, C17H );
3
3
16.24 (d, 3J \ 5.9, CH CH OP); 22.46 (s, C16H ); 25.85 (d,
ChP
1J \ 141.6, PCH ); 28.54, 29.13, 29.20, 29.32, 29.38, 29.42,
ChP
29.45, 31.70 (s, C5H ÈC15H ); 33.26 (d, 2J \ 2.5, C2H );
ChP
39.00 (d, 3J \ 19.1, C3HÈI); 40.18 (s, C4H ); 61.45 (2 ] d,
ChP
2J \ 4.3 Hz, CH CH OP); 31P-NMR (81 MHz, CDCl ): d
3
2
2
2
2-Iodo-2-methylpropionitrile, 8. AIBN (1.04 g, 6.3 mmol)
and molecular iodine (3.22È4.80 g, 12.6È18.9 mmol, see Table
3) were dissolved in benzene (25 mL) and reÑuxed with stirring
for 4È6 h under argon atmosphere. The resulting solution was
cooled to room temperature and decolorized with solid
Na S O (shaking with sodium thiosulfate for 1 min). Then,
2
2
2
2
ChP
3
2
3
31.22; IR (Ðlm): l/cm~1 2982, 2957, 2924, 2853, 1465, 1247,
1057, 1030, 962, 821, 792; MS-LR-CI (isobutane): m/z (%) 503
(M` ] 1, 100); 375 (M` [ HI, 38); MS-LR-EI (70 eV): m/z
(%) 375 (M` [ I, 100); MS-HR-CI: M` ] 1, found 503.2126;
2 2
3
benzene was evaporated and the crude product was distilled
using a Kugelrohr apparatus (115 ¡C/water pump) to give 0.65
C
H
O PI requires 503.2151. Anal. found C 50.64, H 9.03,
21 45
3
g (53%, n25 \ 1.4980) of the dark brown product. It was again
P 6.17; C
6.16%.
H
O PI (502.45) requires C 50.20, H 8.82, P
D
21 44
3
dissolved in benzene and decolorized as described above with
solid Na S O . After evaporation of benzene, the yellow
2 2
3
product should be stored in a refrigerator to prevent decom-
Reaction of 1b with 2a. The crude reaction mixture,
obtained by the general procedure, was distilled using a
position. 1H-NMR (200 MHz, CDCl ): d 2.24; IR (Ðlm):
3
l/cm~1 3281, 2949, 2242, 2229, 1745, 1682, 1471, 1390, 1380,
Kugelrohr apparatus: 122 ¡C/0.01 mmHg, n20 \ 1.4680, and
1109, 1204, 1060, 991, 705, 592; MS-EI (70 eV): m/z 195 (M`,
27); 127 (I, 42); MS-CI (isobutane): m/z 196 (M` ] 1);
MS-HR-EI: M`, found 195.9631; C H NI requires 195.9623.
D
then chromatographed using silical gel TLC plates and pet-
roleum etherÈacetone (2 : 1) as the eluent in order to separate
4
7
the diastereoisomers 3d (R \ 0.454) and 3e (R \ 0.380).
F
F
Overall yield 95% (purity 100% based on 31P-NMR,
3d : 3e \ 1 : 1).
Acknowledgement
Diethyl 3-iodo-1-methylheptylphosphonate (trans), 3d.
Financial support by the State Committee for ScientiÐc
Research (Grant no. T09A 128 12) is gratefully acknowledged.
1H-NMR (500 MHz, CDCl ): d 0.91 (t, 3H, 3J
\ 7.2,
3
HhH
References and notes
C7H ); 1.19 (dd, 3H, 3J
\ 7.1, 3J \ 18.7, PCHCH );
3
HhH
HhP
3
1.32 (2 ] t, 6H, 3J
\ 7.0, 2 ] CH CH OP); 1.27È1.47 (m,
1
P. Ba¡czewski and W. M. Pietrzykowski, T etrahedron, 1997, 53,
7291.
HhH
3
2
3H, C6H , C5HA); 1.49È1.59 (m, 1H, C4HA); 1.64È1.75 (m,
2
1H, C5HB); 1.77È1.84 (m, 1H, C4HB); 1.87È1.97 (m, 1H,
2
3
D. P. Curran, Synthesis, 1988, 489.
J.-S. Wang and K. Matyjaszewski, J. Am. Chem. Soc., 1995, 117,
C2HB); 2.09È2.20 [m, 2H, P(O)CH, C2HA]; 4.04È4.25 (m, 4H,
2 ] CH CH OP); 4.35È4.39 (m, 1H, CHÈI); 13C-NMR (125
5614.
3
2
3
4
D. P. Curran, M.-H. Chen, E. Spletzer, C. M. Seong and C.-T.
Chang, J. Am. Chem. Soc., 1989, 111, 8872.
MHz, CDCl ): d 13.92 (s, C7H ); 14.61 (d, 2J \ 4.7,
3
ChP
PCHCH ); 16.47 (d, 3J \ 5.0, CH CH OP); 21.88 (s,
ChP
C6H ); 31.00 (d, 1J \ 141.04, PCH); 31.40 (s, C5H ); 37.73
ChP
(d, 3J \ 7.39, C3HÈI); 40.15 (s, C4H ); 42.71 (s, C2H );
ChP
5
6
7
8
9
D. P. Curran and G. Thoma, T etrahedron L ett., 1991, 32, 6307.
D. P. Curran and G. Thoma, J. Am. Chem. Soc., 1992, 114, 4436.
D. P. Curran and C. M. Seong, T etrahedron, 1992, 48, 2157.
P. Ba¡czewski and M. Miko¡ajczyk, Synthesis, 1995, 392.
P. Ba¡czewski, W. M. Pietrzykowski and M. Miko¡ajczyk, T etra-
hedron, 1995, 51, 7727.
3
3
2
2
2
2
2
61.62 and 61.97 (2 ] d, 2J \ 6.9 Hz, CH CH OP);
ChP
3
2
31P-NMR (81 MHz, CDCl ): d 33.73; IR (Ðlm): l/cm~1 2960,
3
2931, 2874, 2254, 1747, 1464, 1382, 1093, 1055, 1027; MS-LR-
10 P. Ba¡czewski and W. M. Pietrzykowski, T etrahedron, 1996, 52,
13681.
CI (isobutane): m/z (%) 249 (M` [ I, 100), 166 (11), 69 (20), 55
(13); MS-LR-EI (70 eV): m/z (%) 377 (M` ] 1, 100), 251 (15),
249 (M` [ HI, 21); MS-HR-CI: M` ] 1, found 377.072 10;
11 P. Ba¡czewski, T etrahedron, 1997, 53, 2199.
12 P. Ba¡czewski and M. Miko¡ajczyk, Rev. Heteroat. Chem., 1998,
18, 37.
C
H
O PI requires 377.074 25.
12 27
3
13 P. Ba¡czewski, Phosphorus, Sulfur, Silicon Relat. Elem., 1995, 104,
Diethyl 3-iodo-1-methylheptylphosphonate (cis) 3e.
113.
14 P. Ba¡czewski, Heteroat. Chem., 1997, 8, 67.
15 P. Ba¡czewski, M. Miko¡ajczyk and W. M. Pietrzykowski, Phos-
phorus, Sulfur, Silicon Relat. Elem., 1999, 144–146, 605.
16 Z.-Y. Yang and D. J. Burton, J. Org. Chem., 1992, 57, 4676.
17 X. Zhang, W. M. Qin and D. J. Burton, J. Fluorine Chem., 1998,
89, 39.
1H-NMR (500 MHz, CDCl ): d 0.91 (t, 3H, 3J
\ 7.3,
3
HhH
C7H ), 1.12 (dd, 3H, 3J
\ 7.1, 3J \ 18.7, PCHCH );
3
HhH
HhP
3
1.33 (2 ] t, 6H, 3J
\ 7.1 Hz, 2 ] CH CH OP); 1.27È1.46
18 D. Villemin, F. Sauvaget and M. Hajek, T etrahedron L ett., 1994,
35, 3537.
HhH
3
2
(m, 3H, CH CH OP, C5HA, C6H ); 1.49È1.59 (m, 2H, C5HB,
3
2
2
19 H. Rosin and M. Asscher, J. Org. Chem., 1975, 40, 3298.
20 N. O. Brace, J. Org. Chem., 1966, 31, 2879.
21 J. W. Moor, W. G. Davies and R. W. Collins, Chemistry,
McGrawÈHill, Inc., New York, 1978, p. 455; G. K. Vemulapalli,
Physical Chemistry, PrenticeÈHall Int., London, 1993, p. 267.
22 D. P. Curran and J. Tamine, J. Org. Chem., 1991, 56, 2746.
23 This possibility was suggested by Curran et al. for
(phenylseleno)malononitriles: D. P. Curran, E. Eichenberger, M.
Collis, M. G. Roepel and G. Thoma, J. Am. Chem. Soc., 1994,
116, 4279.
C2HA); 1.73È1.80 (m, 1H, C4HA); 1.90È1.98 (m, 1H, C4HB);
2.14È2.26 [m, 2H, P(O)CH, C2HB]; 4.06È4.17 (m, 5H, 2
] CH CH OP, CHÈI); 13C-NMR (125 MHz, CDCl ): d
3
2
3
11.76 (d, 2J \ 5.05, PCCH ); 13.88 (s, C7H ); 16.46 (d,
ChP
3J \ 4.9, CH CH OP); 21.90 (s, C6H ); 31.42 (d, 1J
ChP ChP
142.08, PCH); 31.64 (s, C5H ); 37.58 (d, 3J \ 18.01,
ChP
C3HÈI); 40.17 (s, C2H ); 40.93 (s, C4H ); 61.70 (2 ] d,
3
3
\
3
2
2
2
2
2
2J \ 7.8 Hz, POCH CH ); 31P-NMR (81 MHz, CDCl ): d
ChP
2
3
3
34.32; IR (Ðlm): l/cm~1 2959, 2929, 2859, 1460, 1243, 1146,
1096, 1055, 1028; MS-LR-CI (isobutane): m/z (%) 377
(M` ] 1, 100); 249 (M` [ HI, 33); MS-LR-EI (70 eV): m/z
24 Diethyl 1-iodoethylphosphonate, 1b, was independently prepared
by us according to a modiÐed protocol, described in: B. Jorga, F.
Eymery and P. Savignac, Synthesis, 2000, 576.
New J. Chem., 2001, 25, 659È663
663