The difference in reactivity of (-)-mono and dimenthyl vs. diethyl alkylphosphonates in the α-lithiation reaction: Carbanionic synthesis of unknown (-)-dimenthyl 1-iodoalkylphosphonates and their first use in the radical iodine atom transfer addition (I-A

Article abstract of DOI:10.1016/j.jorganchem.2006.10.069

Unknown (-)-dimenthyl and ethyl (-)-menthyl 1-iodoethylphosphonates were synthesized via 1-lithio derivatives in 85-87% yields. Starting (-)-dimenthyl alkylphosphonates (R = Me, Et, i-Pr) were obtained in the Michaelis-Becker reaction (75-81% yields) and/

Full text of DOI:10.1016/j.jorganchem.2006.10.069

Journal of Organometallic Chemistry 692 (2007) 997–1009
www.elsevier.com/locate/jorganchem
The difference in reactivity of (ꢀ)-mono and dimenthyl vs. diethyl
alkylphosphonates in the a-lithiation reaction: Carbanionic synthesis
of unknown (ꢀ)-dimenthyl 1-iodoalkylphosphonates and their first
use in the radical iodine atom transfer addition (I-ATRA) and
cyclisation (I-ATRC) reactions
a,b,
a
a
a
Piotr Bałczewski
*, Aldona Szadowiak , Agnieszka Bodzioch , Tomasz Białas ,
b
b
Wanda M. Wieczorek , Małgorzata Szyrej
a
Department of Heteroorganic Chemistry, Center of Molecular and Macromolecular Studies, Polish Academy of Sciences,
90-363 Ło´dz´, Sienkiewicza 112, Poland
b
Institute of Chemistry and Environmental Protection, Jan Długosz University, 42-200 Czßestochowa, Armii Krajowej 13/15, Poland
Received 25 July 2006; received in revised form 18 October 2006; accepted 25 October 2006
Available online 9 November 2006
Abstract
Unknown (ꢀ)-dimenthyl and ethyl (ꢀ)-menthyl 1-iodoethylphosphonates were synthesized via 1-lithio derivatives in 85–87% yields.
Starting (ꢀ)-dimenthyl alkylphosphonates (R = Me, Et, i-Pr) were obtained in the Michaelis–Becker reaction (75–81% yields) and/or in
the methylation reaction of the corresponding 1-lithio-alkylphosphonates (78–92% yields). An interesting concentration and time corre-
lations, never observed for diethyl alkylphosphonates, were found for the metalation of bulky (ꢀ)-menthyl alkylphosphonates with n-
BuLi and general reaction conditions for the carbanion generation were elaborated. The first example of the I-ATRA reaction of
(ꢀ)-dimenthyl 1-iodoethylphosphonate with 1-hexene (AIBN) gave four diastereomers (1.6:1:1:0.4), separated into two pairs. The I-
ATRC reaction was not effective due to a steric hindrance around the reactive center. The X-ray analysis of (ꢀ)-dimenthyl meth-
ylphosphonate confirmed a considerable steric hindrance in higher (ꢀ)-dimenthyl alkylphosphonate esters in comparison to their diethyl
analogs.
ꢀ 2006 Published by Elsevier B.V.
Keywords: Metalation; Ethyl (ꢀ)-menthyl phosphonate; (ꢀ)-Dimenthyl phosphonate; Steric hindrance; Asymmetric amplification; Radical reaction
1. Introduction
of (ꢀ)-dimenthyl and (ꢀ)-trimenthyl phosphites, starting
materials for the discussed phosphonates.
The comprehensive database search shows attempts of
applications of (ꢀ)-dimenthyl and (ꢀ)-monomenthyl phos-
phonate esters in various stereocontrolled reactions, as for
instance in a multiple asymmetric induction (vide infra).
One of reasons of this interest is an easy availability of
(ꢀ)-menthol which constitutes a cheap reagent in syntheses
Thus, (ꢀ)-dimenthyl alkylphosphonates were synthe-
sized from (ꢀ)-menthol and the corresponding phosphonic
dichlorides [1]. (ꢀ)-Tetramenthyl benzene-1,2-bisphospho-
nate was prepared from the corresponding aromatic phos-
phoryl chloride and potassium menthoxide in the presence
of 18-crown-6 and further used as an effective sensitizer for
the geometrical (Z)/(E) photoisomerisation of cyclooctene
[2]. (ꢀ)-Dimenthyl phosphite was cyclized with 1,6-dienes
under free radical conditions (AIBN) to give the cyclic
product in 58% yields [3]. It was also employed in the
*
Corresponding author. Fax: +48 42 6847126.
E-mail address: pbalczew@bilbo.cbmm.lodz.pl (P. Bałczewski).
0022-328X/$ - see front matter ꢀ 2006 Published by Elsevier B.V.
doi:10.1016/j.jorganchem.2006.10.069

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P. Bałczewski et al. / Journal of Organometallic Chemistry 692 (2007) 997–1009
condensation with carbon disulfide in the synthesis of (ꢀ)-
dimenthyl phosphoryldithioformate and used in spin trap-
ping [4], electrochemical and cyclic voltammetric reduction
[5]. (ꢀ)-Dimenthyl phosphite as well as its sodium and
ethylzinc salts were added by Kolodyazhnyi [6,7] to chiral
C@N and C@C compounds as an example of efficient mul-
tistereoselectivity. The addition of (ꢀ)-trimenthyl phos-
phite to nitrostyrene led to formation of optically active
b-nitroalkylphosphonates [7], while addition to C@N bond
gave (ꢀ)-dimenthyl a-aminoalkylphosphonates [8]. The
condensation with aldehydes [8] afforded (ꢀ)-dimenthyl
a-hydroxyalkylphosphonates and with phenacylchloride
gave (ꢀ)-dimenthyl a-ketophophonates [8].
nucleophilic substitution at phosphoryl group in (ꢀ)-men-
thyl S-methyl(methyl or phenyl)phosphonothioates by
methoxide ion afforded the corresponding (ꢀ)-menthyl
methyl [27] or (ꢀ)-menthyl phenylphosphonothioates [28].
Diethyl [29] and diphenyl [30] phosphonates were used in
the transesterification reaction with the (ꢀ)-menthoxide
ion to give (ꢀ)-monomenthyl phosphonates. Mass frag-
mentation of (ꢀ)-menthyl arylphosphonates was also inves-
tigated [31].
The aim of our research was synthesis of unknown (ꢀ)-
dimenthyl 1-iodoalkylphosphonates and comparison of
their reactivity with diethyl analogs both in carbanion
and radical asymmetric reactions.
Further application of (ꢀ)-dimenthyl phosphite was
demonstrated in addition to aldehydes under conditions
of the Pudovik and the Kabachnik–Fields reactions [9,10].
In particular, its condensation with trioxane (cyclic polymer
of formaldehyde) followed by allylation of the resulted
product, gave (ꢀ)-dimenthyl allyloxymethylphosphonate
which underwent a sigmatropic [2,3] – Wittig rearrange-
ment in 92% d.e [11]. Sulfur [12,13] and nitrogen [14]
versions of this rearrangement were also carried out. Dou-
ble and triple asymmetric induction was demonstrated in
the phosphaaldol addition of (ꢀ)-dimenthyl phosphite to
2,3-isopropylidene (R)-glyceraldehyde [15]. Wiemer et al.
described a rearrangement of (ꢀ)-dimenthyl vinylphosphate
to the corresponding (ꢀ)-dimenthyl b-ketophosphonate
[16]. The one-pot Pummerer reaction of thiolane-S-oxide with
(ꢀ)-trimenthyl phosphite allowed an efficient synthesis of (ꢀ)-
dimenthyl 2-tetrahydrothienylphosphonate in 99% yield [17].
This compounds may be also obtained in the intramolecular
radical addition [12,13] of a-sulfanyl radical to homo-
allylphosphonate. The free radical addition of (ꢀ)-dimenthyl
thiophosphite to 1-octene and 2-methyl-2-propenyl phenyl
ether (Et3B/O2) followed by oxidation of the P@S to the
P@O bond, resulted in formation of the corresponding (ꢀ)-
dimenthyl phosphonates in 85% and 47% yields respectively
[18].
(ꢀ)-Monomenthyl phosphonates were obtained in a very
efficient tetrazol catalyzed synthesis from phosphonic
dichlorides [19]. Both (ꢀ) and (+)-menthyl phosphonic
monochlorides were used to activate Candida rugosa lipase
by binding with Ser 209 [20]. (ꢀ)-Menthyl 1-bromo-
phosphonoamidate was utilized in the menthoxide induced
rearrangement to produce the corresponding (ꢀ)-menthyl
methyl 1-aminomethylphosphonate [21,22]. Methyl phenyl-
phosphonic acid was esterified with (ꢀ)-menthol in 81%
yield using (benzotriazolyloxy)phosphonium hexafluoro-
phosphates [23]. (ꢀ)-Menthyl arylphosphonic acid were
also esterified with diazomethane [24]. Both (ꢀ)-menthyl
and (+)-neomenthyl phenylphosphonic acids may be
obtained from the corresponding phosphinates via the
P–H ! P–OH oxidation [25]. The addition of ethyl (ꢀ)-
menthyl trimethylsilyloxy phosphite (PIII) generated
in situ from the corresponding PIV derivative to a-haloacry-
lates and acrylonitriles provided a general route to the cor-
responding ethyl (ꢀ)-menthyl vinylphosphonates [26]. The
2. Results and discussion
2.1. Synthesis and metalation of (ꢀ)-dimenthyl phosphites
and alkylphosphonates
Our first experiences with functionalization of unknown
(ꢀ)-(mono and di)menthyl alkylphosphonates showed that
their a-lithiation was much more difficult than a-lithiation
of diethyl analogs which were commonly used phospho-
nate reagents in the laboratory practice. Therefore, this
class of compounds required elaboration of new reaction
conditions. For this reason, we synthesized phosphonates
with primary, secondary and tertiary a-P alkyl groups.
Thus, (ꢀ)-dimenthyl methylphosphonate 2 was synthesized
in 81% yield from the corresponding sodium salt of (ꢀ)-
dimenthyl phosphite 1 [30] and methyl iodide in the
Michaelis–Becker reaction. The metalation of the phos-
phite 1 with NaH in THF proceeded effectively at 50 ꢁC
in contrast to diethyl phosphite which was deprotonated
at room temperature (Scheme 1). (ꢀ)-Dimenthyl ethyl-
phosphonate was obtained in a similar way from ethyl
iodide in 75% yield or via methylation of 2-Li. The isopro-
pylphosphonate 4 was synthesized from 3 via methylation
of 3-Li in 70–78% yield. Of these three phosphonates, only
methylphosphonate 2 was a solid and allowed a deeper
insight in an arrangement of bulky dimenthyl groups
around the a-phosphonate carbon atom in crystal.
The crystal structure of 2 contained two crystallograph-
ically independent molecules (A and B) in the asymmetry
unit (Fig. 1).The packing of molecules 2 in the unit cell is
shown in Fig. 2. The PCO3 tetrahedron in both molecules
was deformed. The valency angles in this tetrahedron ran-
ged from 102.9(1) to 115.1(1) and from 102.8(1)ꢁ to
114.9(1)ꢁ in molecules A and B, respectively.The dihedral
angles between mean planes of the two cyclohexane rings
were 42.2(1)ꢁ and 43.1(1)ꢁ in the molecule A and B, respec-
tively. The only significant differences between orientation
of the two menthyl substituents with respect to the phos-
phorus tetrahedron were observed (Torsion angles in mol-
ecules A and B, respectively, C1–P1–O1–C11: ꢀ50.4(2) and
ꢀ47.9(2), O2–P1–O1–C11: 60.2(2) and 62.8(2), O3–P1–
O1–C11: ꢀ176.0(2) and ꢀ173.7(2), C1–P1–O2–C21:
ꢀ144.4(2) and ꢀ147.6(2), O1–P1–O2–C21: 101.5(2) and

P. Bałczewski et al. / Journal of Organometallic Chemistry 692 (2007) 997–1009
999
O
P
H
i
O
2
81%
1: δ31P=5.90ppm
O
P
Me
O
2
ii 75%
2: δ31P=29.00ppm
iii
92%
O
P
Me
O
2
3: δ31P=33.40ppm
iv
70-78%
O
P
Me
Me
O
2
4: δ31P=33.12ppm
Scheme 1. (i) NaH, THF/50 ꢁC/1 h; MeI/25 ꢁC/24 h; (ii) as in i, only MeI
was replaced by EtI; (iii) n-BuLi/ꢀ78 ꢁC, MeI/ꢀ30 ꢁC; (iv) n-BuLi (2 eq.);
MeI/ꢀ78 ꢁC.
Fig. 2. The packing of the molecules in the unit cell.
97.7(2), O3–P1–O2–C21: ꢀ19.1(2) and ꢀ22.6(2), P1–O1–
C11–C12: 140.8(2) and 140.7(2), P1–O1–C11–C16:
ꢀ97.6(2) and ꢀ98.0(3), P1–O2–C21–C22: 121.2(2) and
124.0(2), P1–O2–C21–C26: ꢀ117.1(2) and ꢀ114.4(2).
These data applied to the models of 3 and 4, indeed, sug-
gested an increasing steric hindrance caused by bulky
menthoxy groups around the a-phosphonate carbon atoms
of more substituted (ꢀ)-dimenthyl alkylphosphonates.
As we have already mentioned, the carbanionic pathway
to (ꢀ)-dimenthyl alkylphosphonates 3 and 4 required
metalation of the corresponding 2 and 3 with n-BuLi
followed by alkylation with methyl iodide. This simple
reaction showed that the reactivity of (ꢀ)-dimenthyl
alkylphosphonates was significantly lower than their ethyl
Fig. 1. The structure of two independent molecules of (ꢀ)-dimenthyl methylphosphonate 2 showing 50% probability displacement ellipsoids.

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P. Bałczewski et al. / Journal of Organometallic Chemistry 692 (2007) 997–1009
analogs which were common organophosphorus reagents
in synthesis and decreased in the following order: P–
Me > P–Et > P–i-Pr. Although 31P NMR investigations
at low temperatures revealed that lithiation of both (ꢀ)-
dimenthyl 2 and diethyl methylphosphonates occurred
almost immediately at ꢀ78 ꢁC upon addition of stoichiom-
etric amount of n-BuLi and methylation of the resulting Li-
anions with methyl iodide was fast and effective, the same
reaction sequence (deprotonation and methylation) carried
out with 3 at ꢀ78 ꢁC gave only the starting material. How-
ever, if twofold excess of n-BuLi was used and the lithiation
time was increased to 20 min. (at c = 0.005–0.014 mol/L of
3 in THF depending on reaction scale), the corresponding
phosphonate 4 was obtained in 70–78% yield (Scheme 1,
Table 1). Shorter reaction times (3 min) required applica-
tion of N,N,N0,N0-tetramethylethylenediamine (TMEDA)
that facilitated a generation of 3-Li. In this case, the best
yield of 4 (70%) was achieved when n-BuLi/TMEDA/
MeI in a 2/2/1 ratio was employed. Collignon et al. [11]
confirmed that deprotonation of (ꢀ)-dimenthyl phospho-
nates required an excess of n-BuLi. They use even 5 equiv.
of n-BuLi in order to deprotonate (ꢀ)-dimenthyl ally-
loxymethylphosphonate in the [2,3]-sigmatropic Wittig
rearrangement. Interestingly, the use of bulky lithium
diisopropylamide (LDA) instead of n-BuLi was ineffective
even with an excess of this base and prolonged reaction
time (Table 1).
The large steric hindrance caused by the dimenthyl
groups handicaps a free approach of the bulky, oligomeric
structure of n-BuLi to a hydrogen atoms of the phospho-
nate. This oligomeric structure exists mainly as a mixture
of a tetramer and a dimer, obtained from the irreversible
cleavage of the corresponding hexamer [32,33]. Because
(a) the dimer is more reactive than the tetramer and they
equilibrate and (b) no evidence was obtained for small
monomeric n-BuLi in THF solution, one can conclude that
2 can be deprotonated by both tetrameric and dimeric
forms of n-BuLi but the more hindered 3 is deprotonated
mostly by the dimeric form. This also explains a necessity
to use in our experiments an excess of n-BuLi, prolonged
reaction time and TMEDA for shortening of the reaction
time (TMEDA decreases the state of aggregation of n-BuLi
and increases the dimer concentration).
when around 10 times higher concentration of the substrate
in THF was employed than before. This interesting corre-
lation is shown in Fig. 3. At this concentration (103 mg
of 3/5 mL of THF), it was also revealed that 3-Li was
not very much stable in a function of time (after 5/15/
25 min., ratios 3/4 = 1/3, 1/1.5, 1/0.66 and 5/16/30% of
the anion decay products were found, respectively).
2.2. Synthesis and a-lithiation of (ꢀ)-menthyl 1-
iodoalkylphosphonates
The synthesis of the title compounds was accomplished
applying the modified Savignac’s approach [34] in which
one of the a-P acidic hydrogen atoms was temporarily
replaced by the –SiMe3 group and released in the final step
of the synthesis. In the original work, Savignac et al. [34]
synthesized diethyl 1-iodoalkylphosphonates using LDA
as a base for the a-P deprotonation stage and observed that
n-BuLi was completely ineffective. Opposite to these obser-
vations, we have found that (ꢀ)-dimenthyl alkylphospho-
nates required at least 1.5 equiv. of n-BuLi and the
sterically more requiring LDA did not work in this case
(Table 1). The synthesis proceeded via the intermediate 1-
silylated 1-iodoethylphosphonate (5), which in contrast to
the diethyl series, turned out to be a stable compound, iso-
lable by chromatography on silica gel (Scheme 2).
Analysis of crude reaction mixtures with 31P NMR
showed that silylation/iodination step of the sterically hin-
dered (ꢀ)-dimenthyl phosphonate carbanions occurred in
a stereocontrolled manner (5: 1/1.44–1/2.60). During the
silicagel chromatography it was possible to enrich the prod-
uct in one of diastereomers shifting the obtained ratio even
to 1:5 (full resolution was not possible). However, the
desilylation/protonation step gave 6 in a ratio 1:1. The
resistance of 5 to the desilylation with sodium ethanolate
was higher than in the case of diethyl 1-iodo-1-trimethyl-
silylalkylphosphonates. For instance after the 15 min.
yield of 4 [%]
100
75
50
25
We have also found that a partial deprotonation of 3
was also possible with 1.1 equiv. of n-BuLi within 15 min,
Table 1
Reaction conditions for deprotonation and methylation of 3
Temperature/time
n-BuLi/
n-BuLi/MeI
n-BuLi/
(ꢁC)/(min)
TMEDA/MeI
3 ! 4 (%)
ꢀ78/ 3
1/1 [0]
2/1 [0]
2/1 [0]
1/1 [0]
1/1 [0]
1/1 [0]
1/1/1 [48]
1.5/1.5/1.5
[56]
m3/VTHF [g/mL]
0
2/2/1 [70]
0
5
10
15
20
25
ꢀ78/10
ꢀ78/20
1/1 [0]
2/1 [0]
1/1 [0]
Fig. 3. Plot of dependence between concentration of 3 in THF and yield
of 4.
2/1 [78]

P. Bałczewski et al. / Journal of Organometallic Chemistry 692 (2007) 997–1009
1001
O
O
P
P
Me
ii
Me
i
O
O
3
87%
I
SiMe3
I
H
2
2
δ31P=33.40ppm
5: δ31P=25.51/
23,85ppm (1:1.44-1:2.6)
6: δ31P=20.07/
20.31ppm (1:1)
iii
30%
3
6
Scheme 2. (i) 1, n-BuLi; 2, Me3SiCl; 3, I2/THF, ꢀ78 ꢁC. (ii) EtONa, EtOH/25 ꢁC. (iii) 1, n-BuLi; 2, I2; 3, aq. NH4Cl (sat.)/THF, ꢀ78 ꢁC.
treatment of 5 with EtONa, only the substrate was present
in the 31P NMR spectrum. Longer 2 h reaction gave a mix-
ture of 5 in a ratio 2.6:1 and 6 in a ratio 1:1 (four 31P NMR
signals, (Scheme 2).
It is also worthy to note that a direct a-iodination of
3-Li with elemental iodine I2 gave 6 in 30% yield (Scheme
2, iii route). Some time ago, we reported 15% yield of the
corresponding diethyl 1-iodoethylphosphonate, after opti-
mization, in the a-iodination reaction of diethyl 1-lithio-
ethylphosphonate with I2 [35].
Unsymmetrical ethyl (ꢀ)-menthyl 1-iodoethylphospho-
nate (9) was obtained according to our modified Savignac’s
procedure (see Section 3) in 85% yield as a mixture of four
nonseparable diastereomers (d31P = 21.65, 21.77, 21.89 and
22.02) in a 1:1.2:1.6:1.3 ratio. The starting ethyl (ꢀ)-men-
thyl ethylphosphonate (8) was synthesized from diethyl eth-
ylphosphonate 7 in 94% yield as a mixture of two
nonseparable diastereomers (d31P = 32.75, 32.98) in a
1.8:1 ratio based on a procedure of Naso et al. [29] for syn-
thesis of ethyl (ꢀ)-menthyl 1-sulfinylmethylphosphonates
(Scheme 3). The I-ATRA reaction with 1-hexene in the
presence of AIBN gave a nonseparable complex mixture
of products.
after 16 h. After 24 h, the substrate 6 disappeared almost
completely (10% left) and in the 31P NMR spectrum
remained four signals at d31P = 32.62, 32.26, 31.49 and
31.42 ppm in a ratio of 1.6:1:1:0.4 due to four diastereo-
mers of (ꢀ)-dimenthyl 3-iodo-1-methyl-n-heptylphospho-
nate (Scheme 4).
Using column chromatography over silica gel, these four
products were separated onto two pairs of diastereomers:
32.62/32.26 ppm (1.6:1, the first pair) and 31.49/31.42
(2.5:1, the second pair) in overall 40% yield. It should be
mentioned that general reaction conditions, elaborated in
our lab [36–38] for the I-ATRA reaction of diethyl
1-iodoalkylphosphonates (10 equiv. of alkene, 0.5–1 equiv.
of AIBN, boiling benzene, 7 h) were not effective in the case
(ꢀ)-dimenthyl analogs. After 7 h, the 31P NMR spectrum
showed only a signal of the substrate 6. Similar results were
O
i
P
C4H9
6
O
40%
Me
I
2
10: δ31P=32.62, 32.26, 31.49, 31.42ppm
2.3. The radical iodine atom transfer addition reaction
(I-ATRA) using (ꢀ)-dimenthyl 1-iodoethylphosphonate (6)
(1.6:1:1:0.4)
The title reaction was carried out in boiling 1-hexene in
the presence of 1 equiv. of AIBN. Although 6 was used as a
mixture of 1:1 diastereomers, however, upon the reaction
with AIBN, the racemic pyramidal center should become
flat in the corresponding alkyl radical and the transfer of
chirality should be controlled by menthyl groups only.
The reaction was monitored with 31P NMR showing after
8 h a group of signals in a range of 34–31 ppm. The reac-
tion was continued with additional equivalent of AIBN
O
ii
PCH(Me)
O
6
48%
2
2
11: δ31P=32.06, 31.81ppm
Scheme 4. i: 1-Hexene (solvent)/AIBN/reflux. (ii) 1-Hexene/Et3B-O2/
toluene/ꢀ78 ꢁC.
O
(EtO)2P
O
P
O
ii, iii
i
94%
Me
Me
P
Me
O
O
85%
EtO
EtO
I
7: δ31P=34.00ppm
8: δ31P=32.75, 32.98ppm
9: δ31P=21.65, 21.77
21.89, 22.02ppm (1:1.2:1.6:1.3)
(1.8:1)
Scheme 3. (i) (ꢀ)-MentOK, THF/0 ꢁC ƒ 25 ꢁC, 24 h. (ii) 1, n-BuLi; 2, Me3SiCl; 3, I2/THF, ꢀ78 ꢁC. (iii) EtONa, EtOH/25 ꢁC.

1002
P. Bałczewski et al. / Journal of Organometallic Chemistry 692 (2007) 997–1009
obtained when benzene was replaced by other solvents like
chloroform or 1,2-dichloroethane.
33.4 ppm) from which only 18 (ꢁ3% yield) could be
detected with MS-CI and 31P NMR after column chroma-
tography over silicagel. It is interesting to mention that
the reaction with 1 equiv. of AIBN under standard reaction
conditions for the intramolecular reaction [38] (7 h),
brought in the 31P NMR spectrum signals of mainly unre-
acted substrate (>90%) accompanying by two signals at
Replacement of AIBN for the Et3B/O2 initiating system
which, for a better diastereoselectivity, allowed decreasing
the reaction temperature to ꢀ78 ꢁC, brought unexpectedly
a formation of (ꢀ)-tetramenthyl ethylenebisphosphonate
11 instead of 10 (Scheme 4). Most probably, in the reaction
of ethyl radicals (derived from autooxidation of Et3B) with
6, a bigger concentration of easily dimerizing (ꢀ)-dimenth-
oxyphosphoryloeth-1-yl radicals was achieved than in the
reversible reaction of isobutyronitrile radicals with 6. This
is the first example of the total domination of the termina-
tion over the propagation step in the I-ATRA process
involving phosphonate substrates. For a comparison in
the reaction of diethyl iodomethylphosphonate with 1-hex-
ene, the analogous termination product, i.e. tetraethyl eth-
ylenebisphosphonate was formed only in 0–2% yields [37].
d
31P = 33.4 due to 18 and d31P = 27.3 ppm which might be
attributed to the expected 17 in 4% and 7.5% yields, respec-
tively. The former signal at d31P = 33.4 ppm remained at the
level of 4–14% during the reaction and the latter was grad-
ually increasing from 12% (after 30 h and addition of the
second eq. of AIBN) to 27% (after 50 h and addition of
the third eq. of AIBN). After next 10 h, it remained
unchanged and it finally almost disappeared in the complex
mixture after total 72 h. The formation of 18 was a result of:
(1) the deiodination reaction with isobutyronitrile radical
followed by the reduction of the resulting a-P phosphonate
radical; and (2) addition of two equivalents of isobutyronit-
rile radical to the triple bond combined with a double reduc-
tion of the intermediate radicals.
2.4. The radical iodine atom transfer cyclisation reaction
(I-ATRC)
The starting material 16 for this reaction was synthe-
sized from a commercially available 5-chloro-1-pentyne
(12), which at the outset was converted to 5-chloro-1-trim-
ethylsilyl-1-pentyne (13) [39] in 92% yield (Scheme 5).
The Finkelstein reaction of the latter produced the iodide
14 in 87% yield which was next condensed with
3-Li to give the phosphonate 15 in 60% yield. a-Iodination
of 15-Li to give 16 did not require the Savignac’s procedure
and was carried out directly with I2. Deprotonation of 15 to
15-Li required again 2 equiv. of n-BuLi at ꢀ78 ꢁC (20 min).
The I-ATRC reaction did not bring the required 17 even
after 72 h reflux in benzene with 3 equiv. of AIBN. Instead
the complex mixture of products was formed (d31P = 19.8–
The source of reducing agent was isobutyronitrile radi-
cal decomposing to methacrylonitrile and hydrogen [38].
Such an outcome of the I-ATRC reaction of 16 might be
explained as a consequence of a greater steric hindrance
at the phosphonate reactive center in comparison to 6
(dimenthoxy groups, additional a-P substituent and 1,1-
disubstitution in alkyne) as well as a general lower reactiv-
ity of alkynes in comparison to alkens in radical reactions
(higher LUMO and lower HOMO levels for alkynes and
both SOMO–LUMO and SOMO–HOMO interactions
more difficult).
In a conclusion, both (ꢀ)-dimenthyl phosphite and (ꢀ)-
dimenthyl alkylphosphonates revealed a lower reactivity
iii
i
SiMe3
Cl
X
60%
92%
12
13: X=Cl
ii: 87%
14: X=I
O
O
P
iv
P
O
O
34%
Me
SiMe3
I Me
2
SiMe3
2
15: δ31P=31.91, 32.64ppm
16: δ31P=20.19, 20.58ppm
I
SiMe3
CN
O
O
v
P
P
SiMe3
O
O
Me
2
Me
2
CN
17
18: MSCI-m/z(%): M+1=663(100)
31P-NMR: δ31P=33.4ppm
Scheme 5. (i) 1, n-BuLi/THF/ꢀ78 ꢁC, 2 h; 2, Me3SiCl/ꢀ78 ꢁC ƒ 25 ꢁC, 2 h. (ii) NaI/acetone, reflux, 24 h. (iii) 3-Li/THF/ꢀ78 ꢁC ƒ 25 ꢁC, 2 h. (iv) 1, n-
BuLi/THF, ꢀ78 ꢁC, 20 min; 2, I2/ꢀ78 ꢁC ƒ 25 ꢁC, l h. (v) AIBN/benzene/reflux.

P. Bałczewski et al. / Journal of Organometallic Chemistry 692 (2007) 997–1009
1003
in carbanionic and radical reactions in comparison to their
diethyl analogs. This effect was confirmed in metalation
reactions of (ꢀ)-dimenthyl phosphite and (ꢀ)-menthyl
alkylphosphonates with the aggregated dimeric and/or
tetrameric n-BuLi and bulky LDA as well as in the first
radical I-ATRA and I-ATRC reactions of the unknown
(ꢀ)-dimenthyl 1-iodoalkylphosphonates. The X-ray data
of 2 applied to molecular models of more substituted
(ꢀ)-dimentyl alkylphosphonates confirmed a possibility
of their lower reactivity. Concentration and time correla-
tions versus amounts of the lithiating agent allowed elabo-
ration of synthetic protocols for the effective deprotonation
of this particular group of phosphonates. These protocols
reflect a subtle interplay between generation, stability and
reactivity of the resulting carbanions.
28.5ꢁ), 10605 independent (Rint 0.097). Structure solution:
direct method, anisotropic refinement on F2 (SHELXL 97)
[39] for all non H atoms, hydrogen atoms attached to C
atoms were included using a riding model. The structure
was refined over 7241 reflections with I > 2r(I) (466 refined
parameters with 15.5 reflections on parameter). The correct
absolute structure was proved by Flack parameter [40]
x = 0.04(9). For all data the final wR2 was 0.1205, R1 =
0.0629, S = 1.041, max. Dq = 0.290 e Aꢀ3. Extinction cor-
˚
rection (SHELXL 97), extinction coefficient was 0.0023(4).
3.3. Synthetic part
3.3.1. (ꢀ)-Dimenthyl phosphite (1)
To a mechanically stirred solution of (ꢀ)-menthol
(109.2 g, 0.7 mol) and triethylamine (106.4 g, 146.5 mL,
1.05 mol) in dry toluene (1000 mL), phosphorus trichloride
(48.3 g, 30.7 mL, 0.35 mol) dissolved in toluene (350 mL)
was added dropwise at ꢀ30 ꢁC within 30–45 min. Then
the reaction mixture was slowly warmed to room tempera-
ture and stirred for 2 h at this temperature. The 31P NMR
spectrum showed a signal at d31P = 147.46 ppm assigned to
(ꢀ)-dimenthyl chlorophosphite as the main reaction prod-
uct. The hydrolysis of the chlorophosphite to (ꢀ)-dimen-
thyl phosphite (1) was accomplished by addition of water
(80–100 ml). Then the reaction mixture was vigorously stir-
red for 2 h and the control 31P NMR spectrum showed a
signal at d31P = 5.9 ppm attributed to the phosphite 1
(d31P = 3.6 ppm in CDCl3 was reported in the literature
[11]. Next the toluene layer was separated, dried (MgSO4),
filtered and evaporated. The residue required a removal of
the unreacted (ꢀ)-menthol (19.1 g) using a short path
distillation under vacuum (0.05 Torr/ ꢁ 40 ꢁC, the temper-
ature of the oil bath <145 ꢁC) to give the crude (ꢀ)-dimen-
thyl phosphite (1) (91.6 g, 74% yield) having a satisfactory
purity for further reactions (1H NMR spectrum was free of
menthol signals). Analytically pure phosphite 1 was
obtained after high vacuum distillation (145–150 ꢁC/
0.02 Torr, the temperature of the oil bath must not exceed
200 ꢁC otherwise the phosphite decomposes).
3. Experimental
3.1. General
1
The H NMR (200 and 500 MHz) and 13C NMR (50
and 125 MHz) spectra were recorded using a Bruker
AC-200 and a Bruker DRX-500 spectrometers . The IR
spectra were recorded using an ATI Mattson Infinity FTIR
60 spectrometer. The mass spectra of pure compounds
were obtained using a Finnigan Mat 95 spectrometer. Col-
umn chromatography was done using Merck silica gel (F254
60, 70–230 and 270–400 mesh). Organic solvents were puri-
fied by standard procedures. All optically active menthyl
derivatives were prepared from 1R,2S,5R-(ꢀ)-menthol.
Numbering of atoms in compounds 1–16 is presented in
skeletal fragments A and B.
9
9'
8'
8
O
P
7'
3'
16
7
1'
2'
2
17
13
11
15
3
1
5
12
14
X
O
6
4
4'
10'
5'
6'
2
Me
10
X = C or Si
18
9
Yield: 47–51% (59.5–64 g starting from 0.35 mol of
7
20
O
P
PCl3), n2D0 1:4714; ½aꢂD ꢀ96.6 (c = 2.0, acetone).
8
3
2
12
3
1H NMR0 (500 MHz, CDCl3): d = 0.79 (d, 3H, JH–H
=
1
Me
11
O
3
6.91 Hz C10 H3), 0.80 (d, 3H, JH–H = 6.88 Hz C10H3),
5
4
6
0
0.83–0.86 (m, 2H, C4H, C4 H), 0.89 (2 · d, 12H, JH–H
=
3
10
O
14
0
0
3
6.75 Hz, JH–H = 6.74 Hz, 0 C8H3, C8 H3C9H3, C9 H3),
13
0
0.96–1.13 (m, 04H, C3H, C3 H, C6H, C6 H), 1.15–1.18 (m,
0
2H, C5H, C5 H), 1.26–1.35 (m, 2H, C2H, C2 H), 1.64,
0
0
1.67 (2 · s-br, 4H, C3H, C3 H, C4H, C4 H), 2.10–2.18
3.2. Crystallographic data
0
0
(2 · m, 2H, C7H, C7 H), 2.20–2.24 (m, 2H, C6H, C6 H),
0
4.10–4.20 (m, 2H, C1H, C1 H), 6.89 (d, 1H, JH–P
1
Crystal data for (ꢀ)-dimenthyl methylphosphonate:
C21H41O3P, orthorhombic, space group P212121, a =
= 686.94 Hz, P(O)–H).
3
13C NMR (125 MHz, CDCl3): d = 15.96, 16.07 (2 · s,
˚
˚
5.549(3), b = 20.646(4), c = 39.660(9) A, V = 4544 (3) A ,
0
0
Mr = 372.51, Z = 8, dcalc = 1.089 g/cm3, l = 0.14 mmꢀ1
,
C9H3, C9 H3), 21.09 (s, C8H3, C8 H3), 22.12 (2 · s, C10H3,
0
0
C
10 H3), 23.13, 23.19 (2 · s, C3H2, C3 H2), 25.91, 26.21
0 0
T = 100(2) K, F(000) 1648. Data collection: colourless
plate 0.50 · 0.20 · 0.10 mm from n-hexane, Kuma KM4-
CCD diffractometer. Measured reflections 30011 (hmax
(2 · s, C7H, C7 H), 31.58, 31.68 (2 · s, C5H, C50 H), 34.23
0
(s, C4H2, C4 H2), 43.24, 43.86 (2 · s, C6H2, C6 H2), 48.69

1004
P. Bałczewski et al. / Journal of Organometallic Chemistry 692 (2007) 997–1009
0
3
2
(2 · d, JC–P = 5.81 Hz, C2H, C2 H), 77.27 (2 · d, JC–P
=
5.6 mmol; 50% dispersion in oil) was added at room tem-
perature under argon atmosphere. Then the resulting mix-
ture was stirred for 1 h at 50 ꢁC and ethyl iodide (467 mg,
240 lL, 3 mmol) was added after cooling the mixture to
room temperature. After 24 h, aqueous solution of NH4Cl
was added, the solvent was evaporated and the residue was
partitioned between chloroform and water. The chloro-
form layer was dried with anhydrous MgSO4, filtered and
evaporated to give the crude product which was purified
using column chromatography (eluent: petroleum ether/
acetone in a gradient).
0
6.12 Hz, C1H, C1 H).
31P NMR (81 MHz, CDCl3): d = 5.90 ppm.
IR (film): 2928, 2870, 2421, 1456, 1257, 1013, 963.
MS [CI (isobutane)]: m/z (%) = 359 (M++1, 100).
HRMS [CI (isobutane)]: m/z calcd. for C20H40O3P
359.2719; found: 359.2731.
3.3.2. (ꢀ)-Dimenthyl methylphosphonate (2)
To a stirred solution of (ꢀ)-dimenthyl phosphite 1
(31.99 g, 0.092 mol) in dry THF (300 mL), sodium hydride
(4.46 g, 0.2 mol; 50% dispersion in oil) was added in one
portion at room temperature under argon atmosphere.
The resulting solution was refluxed for approximately 1 h
until sodium hydride dissolved completely (the vigorous
evolution of hydrogen occurred at 50 ꢁC). After cooling
to room temperature, methyl iodide (15.67 g, 6.87 mL,
0.11 mol) was added dropwise and the resulting solution
was stirred overnight under argon atmosphere. After evap-
oration of the solvent, the residue was partitioned between
chloroform (200 mL) and water (150 mL). The chloroform
solution was washed again with water (100 mL) then dried
over MgSO4, filtered and evaporated to give a residue which
was distilled (b.p. = 140 ꢁC/0.03 Torr) to give 27.7 g (81%
reproducible yield) of 2 as a liquid (n2D3 1:4705Þ, which solid-
20
Yield: 75%; light yellow oil; ½aꢂD ꢀ94:8 (c = 2.0,
acetone).
3.3.4. (ꢀ)-Dimenthyl ethylphosphonate 3 (from 2)
To a stirred solution of (ꢀ)-dimenthyl methylphospho-
nate 2 (1 g, 2.7 mmol) in dry THF (100 mL), n-BuLi
(1.8 mL, 2.7 mmol, 1.6 M solution in n-hexane) was added
under argon atmosphere at ꢀ78 ꢁC. The dry ice/acetone
bath was removed and when temperature reached 30 ꢁC,
methyl iodide was added (383 mg, 168 lL, 2.7 mmol). Then
the reaction mixture was allowed to warm to room temper-
ature and left for 1hr at this temperature. Then aqueous
solution of NH4Cl was added, solvents were evaporated
and the residue was partitioned between water and chloro-
form. The chloroform layer was dried with anhydrous
MgSO4, filtered and evaporated to give the crude product
which was purified with column chromatography (eluent:
petroleum ether/acetone in a gradient).
20
ified in the fridge (m.p. = 33–38 ꢁC); ½aꢂD ꢀ95:2 (c = 2.0,
acetone).
1H NMR (500 MHz, CDCl3): d = 0.80, 0.81 (2 · d, 6H,
0
JH–H = 6,92 Hz, C10H3, C10 H3), 0.86–0.90 (m, 2H, C4H,
3
0
0
C4 H), 0.93 (d, 12H, JH–H = 6,76 Hz, C8H3, C8 H3, C9H3,
Yield: 92%; light yellow oil.
3
0
0
C9 H3), 0.98–1.05 (m, 2H, C3H, C3 H), 1.10–1.20 (m, 2H,
1H NMR (500 MHz, CDCl3): d = 0.77 (d, 6H, JH–H
=
0
3
0
0
0
C6H, C6 H), 1.25–1.35 (m, 2H, C2H, C2 H), 1.40–1-44 (m,
6.97 Hz, C10H3, C10 H3), 0.79–0.85 (m, 2H, C4H, C4 H),
0
0
2
3
2H, C5H, C5 H), 1.48 (d, 3H, JH–P = 17.35 Hz, C11H3),
0.87 (d, 12H, JH–H = 6.86 Hz, C8H3, C8 H3, C9H3,
0
0
0
0
1.64, 1.66 (2 · s-br, 4H, , 0C3H, C3 H, C4H, C4 H), 2.00–
C9 H3), 0.92–1.01 (m, 2H, C3H, C3 H), 1.05–1.10 (m, 2H,
0
2.18 (2m, 2H, C7H, C7 H), 2.20–2.28 (m, 2H, C6H,
C6H, C6 H), 1.12 (2 · t, 3H, JH–H = 7.60 Hz, JH–P
=
3
3
0
0
0
C6 H), 4.10–4.20 (m, 2H, C1H, C1 H).
19.66 Hz, C18H3), 1.21–1.30 (m, 2H, C2H, C2 H), 1.37–
0
13C NMR (125 MHz, CDCl3): d = 13.09 (d, JP–C
=
1.45 (m, 2H, C5H, C5 H), 1.60, 1.63 (2 · s-br, 4H, C3H,
1
0
0
0
145.95 Hz, C11H3), 15.60, 15.78 (2 · s, C9H3, C9 H3),
C3 H, C4H, C4 H), 1.67 (2 · q, 2H, JH–H = 7.75 Hz, JH–P
3
2
0
0
20.93 (s, C8H3, C8 H3), 21.81, 21.85 (2 · s, C10H3,
= 25.74 Hz, C11H2), 2.05–2.18 (2 · m, 2H, C7H, C7 H),
0
0
0
C
10 H3), 22.69, 22.78 (2 · s, C3H2, C3 H2), 25.31, 25.57
2.20–2.27 (m, 2H, C6H, C6 H), 4.08–4.18 (m, 2H, C1H,
0
0
0
(2 · s, C7H, C7 H), 31.37, 31.44 (2 · s, C5H, C50 H), 34.01
C1 H).
0
(s, C4H2, C4 H2), 42.99, 43.55 (2 · s, C6H2, C6 H2), 48.46
13C NMR (125 MHz, CDCl3): d = 6.98 (d, JP–C
=
2
0
0
(2 · d, JC–P = 6.84 Hz, C2H, C2 H), 76.78 (2 · d, JC–P
=
7.27 Hz, C18H3), 15.56, 15.78 (2 · s, C9H3, C9 H3), 20.66
3
2
0
0
7.57 Hz, C1H, C1 H).
(d, JP–C = 144.35 Hz, C11H2), 21.01 (s, C8H3, C8 H3),
1
0
31P NMR (81 MHz, CDCl3): d = 29.00 ppm.
21.89, 21.92 (2 · s, C10H3, C10 H3), 22.69, 22.75 (2 · s,
0
0
IR (film): 2954, 2927, 2869, 1456, 1370, 1307, 1248,
1029, 1009, 987, 943.
C3H2, C3 H2), 25.25, 25.45 (2 · s, C7H, C7 H), 31.40,
0
0
31.48 (2 · s, C5H, C5 H), 34.07 (s, C4H2, C4 H2), 43.07,
0
MS [CI (isobutane)]: m/z (%) 373 (M++1, 100), 235
(M++1-menthene, 52), 97 (M++1-2· menthene, 30).
HRMS [CI (isobutane)]: m/z calcd. for C21H42O3P:
373.2862; found: 373.2871.
43.70 (2 · s, C6H2, C6 H2), 48.56, 48.59 (2 · d, JC–P
=
3
0
6.19 Hz, C2H, C2 H), 76.57, 76.63 (2 · d, JC–P = 7.08 Hz,
2
0
C1H, C1 H).
31P NMR (81 MHz, CDCl3): d = 33.40 ppm.
IR (film): 2953, 2926, 2868, 1456, 1239, 1034, 1008, 989,
965.
Anal. Calc. for C21H41O3P (372.53); C, 67.71; H, 11.09;
P, 8.31. Found: C, 67.64; H, 11.28; P, 8.40%.
MS [CI (isobutane)]: m/z (%) 387 (M++1, 100), 249
(M++1-menthene, 48), 125 (M++1-2 · menthene, 55).
HRMS [CI (isobutane)]: m/z calcd. for C22H44O3P:
387.3000; found: 387.3028.
3.3.3. (ꢀ)-Dimenthyl ethylphosphonate 3 (from 1)
To a stirred solution of (ꢀ)-dimenthyl phosphite 1 (1 g,
2.8 mmol) in dry THF (60 mL), sodium hydride (140 mg,

P. Bałczewski et al. / Journal of Organometallic Chemistry 692 (2007) 997–1009
1005
3.3.5. (ꢀ)-Dimenthyl isopropylphosphonate (4)
3.9 mmol, 1.6 M solution in n-hexane) was added at
ꢀ78 ꢁC under argon atmosphere. After 20 min a solution
of iodine (60 mg, 5.2 mmol) in THF (10 mL) was added
and the resulting mixture was allowed to warm to room
temperature. Stirring was continued for 1 h at this temper-
ature and aqueous solution of NH4Cl was added. Solvents
were evaporated and the residue was extracted with chloro-
form. The organic layer was washed with water and 10%
aqueous solution of Na2S2O3, dried over anhydrous
MgSO4, filtered and evaporated to give the crude product
6 which was purified with column chromatography over sil-
ica gel (eluent: petroleum ether/acetone in a gradient).
Yield: 30%.
3.3.5.1. Procedure A (with TMEDA). To a stirred solu-
tion of (ꢀ)-dimenthyl ethylphosphonate 3 (1 g, 2 mmol)
and N,N,N0,N0-tetramethylethylenediamine (TMEDA;
0.6 g, 0.8 mL, 5.2 mmol) in dry THF (180 mL), n-BuLi
(3.2 mL, 5.2 mmol, 1.6 M solution in n-hexane) was added
at ꢀ78 ꢁC under argon atmosphere. After 3 min methyl
iodide (0.37 g, 0.16 mL, 2.6 mmol) was added and the
resulting mixture was allowed to warm to room tempera-
ture. Stirring was continued for additional 1 h at this
temperature and aqueous solution of NH4Cl was added,
solvents were evaporated and the residue was extracted with
chloroform. The organic layer was dried over anhydrous
MgSO4, then filtered and evaporated to give a crude prod-
uct which was purified with column chromatography over
silica gel (eluent:petroleum ether/acetone in a gradient).
Yield: 70%.
3.3.7. Procedure B (a modification of the Savignac’s
protocol [34])
To a stirred solution of (ꢀ)-dimenthyl ethylphosphonate
3 (1 g, 2.6 mmol) in dry THF (180 mL), the following
reagents were added in the given order at ꢀ78 ꢁC, under
argon atmosphere and in 20 min intervals: n-BuLi
(2.4 mL, 3.9 mmol, 1.6 M solution in n-hexane), Me3SiCl
(330 lL, 28 mg, 2.6 mmol), n-BuLi (2.4 mL, 3.9 mmol),
iodine (60 mg, 5.2 mmol). The resulting mixture was
allowed to warm to room temperature and a solution of
EtONa in EtOH (60 mg, 2.6 mmol of Na in 2 mL of EtOH)
was added. Stirring was continued for a few hours at this
temperature to completion (31P NMR) and aqueous solu-
tion of NH4Cl was added. Solvents were evaporated and
the residue was extracted with chloroform. The chloroform
layer was washed with water and 10% aqueous solution of
Na2S2O3 and water, dried over anhydrous MgSO4, filtered
and evaporated to give the crude product 6 which was puri-
fied with column chromatography over silica gel (eluent:
petroleum ether/acetone in a gradient).
3.3.5.2. Procedure B (without TMEDA). To a stirred
solution of 3 (1 g, 2.6 mmol) in dry THF (180 mL), n-BuLi
(3.2 mL, 5.2 mmol, 1.6 M solution in n-hexane) was added
at ꢀ78 ꢁC under argon atmosphere. After 20 min methyl
iodide (0.37 g, 0.16 mL, 2.6 mmol) was added and the
product was workuped as in Section 3.3.5.1.
Yield: 78%, yellow oil.
20
½aꢂD ꢀ100:90 (c = 2.0, acetone).
3
1H NMR (500 MHz, CDCl3): d = 0.75 (d, 6H, JH–H
=
0
0
6.98 Hz, C10H3, C10 H3), 0.77–0.82 (m, 2H, C4H, C4 H),
0
3
0.87 (d, 12H, JH–H = 6.86 Hz, C8H3, C8 H3, C9H3,
0
0
C9 H3), 0.92–0.97 (m, 2H, C3H, C3 H), 1.03–1.07 (m, 2H,
0
3
3
C6H, C6 H), 1.11 (4 · d, 6H, JH–H = 7.18 Hz, JH–P
=
0
18.23 Hz, C12H3, C18H3), 1.20–1.30 (m, 2H, C2H, C2 H),
0
1.34–1.42 (m, 2H, C5H, C5 H), 1.59, 1.61 (2 · s-br, 4H,
30
40
C3H, C H, C4H, C H), 1.76–1.87 (2 · m, 1H, J2H–P
=
0
25.56 Hz, C11H), 1.99–2.16 (m, 2H, C6H, C6 H), 2.18–
Yield: 87%, yellow oil.
0
0
20
2.25 (m, 2H, C7H, C7 H), 4.05–4.15 (m, 2H, C1H, C1 H).
13C NMR (125 MHz, CDCl3): d = 15.45, 15.75 (2 · s,
½aꢂD ꢀ75:35 (c = 2.3, acetone).
3
1H NMR (500 MHz CDCl3): d = 0.80 (d, 6H, JH–H
=
0
0
C9H3, C9 H3), 16.45, 16.50 (d, JP–C = 5.99 Hz, C12H3,
6.90 Hz, C10H3, C10 H3), 0 0.90 (d, 12H, JH–H = 6.40 Hz,
2
3
0
0
C18H3), 21.01 (s, C8H3, C8 H3), 21.89, 21.92 (2 · s,
C8H3, C8 H3, C9H3, C9 H3), 0.93–0.98 (m, 2H, C4H,
0
0
0
0
C10H3, C10 H3), 22.61 (s, C3H2, C3 H2), 25.12, 25.24
C4 H), 1.00–1.08 (m, 02H, C3H, C3 H), 1.12–1.28 (m, 4H,
0
0
0
(2 · s, C7H, C7 H), 27.36 (d, JP–C = 144.34 Hz, C11H),
C6H, C6 H, C2H, C2 H), 1.30–1.400 (m, 2H, C5H, C5 H),
1
0
0
0
31.38, 31.44 (2 · s, C5H, C5 H), 34.05 (s, C4H2, C4 H2),
1.65, 1.68 (2 · s-br, 4H, C3H, C3 H, C4H, C4 H), 1.99
0
3
3
43.07, 43.77 (2 · s, C6H2, C6 H2), 48.61, 48.67 (2 · d,
(2 · d, 3H, JH–H = 7.41 Hz, JH–P = 16.70 Hz, C18H3),
0
0
3JC–P = 7.59 Hz, C2H, C2 H), 76.36, 76.51 (2 · d, JC–P
=
2.15–2.25 (2 · m, 2H, C7H, C7 H), 2.28–2.35 (m, 2H,
2
0
0
7.67 Hz, C1H, C1 H).
C6H, C6 H), 3.75–3.85 (2 · q, 1H, JH–H = 7.44 JH–P
=
3
2
0
31P NMR (81 MHz, CDCl3): d = 33.92 ppm.
24.10 Hz, C11H), 4.18–4.28 (m, 2H, C1H, C1 H).
IR (film): 2955, 2928, 2870, 1456, 1229, 1025, 1008, 986,
13C NMR (125 MHz, CDCl3): d = 8.63, 9.30 (2 · d,
965, 890.
1JP–C = 156.01 Hz, C11H), 15.69, 15.76,0 15.80, 15.88
0
MS [CI (isobutane)]: m/z (%) 401 (M++1, 100), 263
(M++1-menthene, 64), 125 (M++1-2 · menthene, 76).
HRMS [CI (isobutane)]: m/z calcd. for C23H46O3P:
401.3167; found: 401.3184.
(4 · s, C9H3, C9 H3), 21.07 (s, C8H3, C8 H3), 21.96 (s,
0
C10H3, C10 H3), 22.31, 22.35 (2 · d, JP–C = 5.97 Hz,
2
0
C18H3), 22.65, 22.68, 22.70, 22.73 (4 · s, C3H2, C3 H2),
0
25.22, 25.25, 25.30, 25.39 (4 · s, C7H, C7 H), 31.50, 31.58
0
0
(2 · s, C5H, C5 H), 33.90, 34.02 (2 · s, C4H2, C4 H2),
0
3.3.6. (ꢀ)-Dimenthyl 1-iodoethylphosphonate (6)
42.76, 42.99, 43.50, 43.67 (4 · s, C6H2, C6 H2), 48.51,
0
3
3.3.6.1. Procedure A (by a direct iodination). To a stirred
48.58, 48.64, 48.73 (2 · d, JC–P = 7.39 Hz, C2H, C2 H),
2
solution of (ꢀ)-dimenthyl ethylphosphonate
3
(1 g,
78.27, 78.40, 78.77, 79.03 (2 · d, JC–P = 7.69 Hz, C1H,
0
2.6 mmol) in dry THF (180 mL), n-BuLi (2.4 mL,
C1 H).

1006
P. Bałczewski et al. / Journal of Organometallic Chemistry 692 (2007) 997–1009
31P NMR (81 MHz, CDCl3): d = 21.59, 21.96 ppm.
IR (film): 2952, 2926, 1456, 1372, 1232, 1029, 1011, 991,
7.05 Hz, C14H3CH2OP); 1.63, 1.68 (2 · s-br, 2H, C3H,
C4H), 2.00 (2 · d, 3H, 3JH–H = 7.45 Hz, 3JH–P
=
912.
16.94 Hz, C12H3), 2.10–2.35 (m, 2H, C7H, C6H), 3.75–
3.93 (m, 1H, C11H), 4.05–4.35 (m, 3H, CH3C13H2OP,
C1H,).
MS [CI (isobutane)]: m/z (%) 513 (M++1, 100).
HRMS [CI (isobutane)]: m/z calcd. for C22H43O3PI:
513.1975; found: 513.1994.
13C NMR (50 MHz, CDCl3): d = 6.22, 6.77, 9.34, 9.88
1
(4 · d, JP–C = 156.96 Hz, C11H), 15.54, (4 · s, C9H3),
3
3.3.8. Ethyl (ꢀ)-menthyl ethylphosphonate (8)
16.35 (d, JC–P = 5.98 Hz, C14H3CH2OP); 20.07 (s,
2
To a stirred solution of menthol (1 g, 6.4 mmol) in dry
THF (50 mL), n-BuLi (4.0 mL, 6.4 mmol, 1.6 M solution
in n-hexane) was added at 0 ꢁC under argon atmosphere.
After 10 min a solution of diethyl ethylphosphonate 7
(0.53 g, 3.2 mmol) in THF (20 mL) was added. The result-
ing mixture was warmed to room temperature and left
overnight. Then aqueous solution of NH4Cl was added,
solvents were evaporated and the residue was extracted
with ethyl acetate. The organic layer was dried over anhy-
drous MgSO4, filtered and evaporated to give the crude
product 8 which was purified with column chromatography
over silica gel (eluent: petroleum ether/ acetone in a
gradient).
C8H3), 20.87 (s, C10H3), 21.87 (d, JP–C = 4.07 Hz,
C12H3), 22.69 (s, C3H2), 25.36 (s, C7H), 31.41 (s, C5H),
3
33.90, (s, C4H2), 43.07 (2 · s, C6H2), 48.42 (d, JC–P
=
6.37 Hz, C2H), 64.03 (d, JC–P = 6.58 Hz, CH3C13H2OP);
2
2
78.27, (d, JC–P = 7.96 Hz, C1H).
31P NMR (81 MHz, CDCl3): d = 21.65, 21.77, 21.89,
22.02 ppm (1.00:1.15:1.60:1.30).
IR (film): 2955, 2927, 2869, 1454, 1241, 1047, 1010, 993,
966.
MS [CI (isobutane)]: m/z (%) 403 (M++1, 45), 264
(M++1-menthene, 100).
HRMS [CI (isobutane)]: m/z calcd. for C14H29O3PI:
403.0906; found: 403.0899.
Yield: 94%, yellow oil.
20
½aꢂD ꢀ48:73 (c = 2.3, acetone).
3.3.10. (ꢀ)-Dimenthyl 3-iodo-1-methyl-n-
1H NMR (500 MHz, CDCl3): d = 0.80 (d, 3H, JH–H
=
heptylphosphonate (10)
3
6.92 Hz, C10H3), 0.85–0.95 (m, 2H, C4H, C3H, and d, 6H,
3JH–H = 6.80 Hz, C8H3, C9H3), 1.05–1.10 (m, 1H, C6H),
A stirred solution of (ꢀ)-dimenthyl 1-iodoethylphosph-
onate 6 (1 g, 1.95 mmol) and AIBN (320 mg, 1.95 mmol)
in 1-hexene (50 mL) was refluxed for 24 h under argon
atmosphere. After 16 h a new portion of AIBN (320 mg,
1.95 mmol) was added. After complexion of the reaction,
the excess of 1-hexene was evaporated and the product
containing four diastereomers in a 1.6:1:1:0.4 ratio was
separated into two pairs using column chromatography
over silica gel (eluent: petroleum ether/ acetone in a
gradient).
1.12 (t, 3H, JH–H = 7.60 Hz, JH–P = 19.66 Hz, C12H3),
3
3
1.21–1.28 (m, 1H, C2H), 1.30 (t, 3H, JH–H = 7.1 Hz,
3
C14H3CH2OP); 1.37–1.45 (m, 1H, C5H), 1.60, 1.63 (2 ·
s-br, 2H, C3H, C4H), 1.67 (2 · q, 2H, JH–H = 7.75 Hz
3
2JH–P = 25.74 Hz, C11H2), 2.05–2.27 (m, 2H, C6H, C7H),
3.95–4.30 (m, 3H, CH3C13H2OP C1H).
13C NMR (50 MHz, CDCl3): d = 6.71 (d, JP–C
=
=
2
6.99 Hz, C12H3), 15.57 (s, C9H3), 16.41 (d, JC–P
3
6.01 Hz, C14H3CH2OP) 19.98 (d, JP–C = 143.57 Hz,
C11H2), 20.92 (s, C8H3), 21.87 (s, C10H3), 22.73 (s, C3H2),
25.37 (s, C7H), 31.40 (s, C5H), 34.02 (s, C4H2), 43.40 (s,
Yield: 40%, yellow oils.
1
First pair of diastereomers:
20
½aꢂD ꢀ55:35 (c = 1.5, acetone).
C6H2), 48.46 (d, JC–P = 6.24 Hz, C2H), 61.32 (d, JC–P
=
1H NMR (500 MHz, CDCl3): d = 0.82 (d, 6H, JH–H
=
0
3
2
3
0
6.38 Hz, CH3C13H2OP); 76.71 (d, JC–P = 7.41 Hz, C1H).
31P NMR (81 MHz, CDCl3): d = 32.75, 32.98 ppm
(1.8:1).
6.67 Hz, C10H3, C10 H3), 0.82–0.87 (m, 2H, C4H, C4 H),
2
0
3
0.87 (d, 12H, JH–H = 6.27 Hz, C8H3, C8 H3, C9H3,
0
0
C9 H3), 0.92–0.97 (m, 5H, C3H, C3 H, C17H3), 1.03–1.10
0
3
IR (film): 2955, 2928, 2870, 1457, 1251, 1226, 1055,
1008, 994, 791.
(m, 2H, C6H, C6 H), 1.17 (2 · d, 3H, JH–H = 7.23 Hz,
0
3JH–P = 18.49 Hz, C18H3), 1.20–1.30 (m, 2H, C2H, C2 H),
0
MS [CI (isobutane)]: m/z (%) 277 (M++1, 30); 139
(menthene, 100).
1.35–1.45 (m, 4H, C5H, C5 H, C16H2), 1.50–1.54 (m, 2H,
0
0
C14H2), 1.59, 1.62 (2 · s-br, 4H, C3H, C3 H, C4H, C4 H),
HRMS [CI (isobutane)]: m/z calcd. for C14H30O3P:
277.1925; found: 277.1932.
1.65–1.75 (m, 2H, C15H2); 1.90–1.96 (m, 1H, C11H),
60
2.05–2.15 (m, 4H, C6H, C H,C12H2), 2.20–2.31 (2 · m,
0
0
2H, C7H, C7 H), 4.05–4.15 (m, 2H, C1H, C1 H), 4.35–
4.45 (m, 1H, C13H-I).
3.3.9. Ethyl (ꢀ)-menthyl 1-iodoethylphosphonate (9)
This compound was obtained in the same way as 6 (Pro-
cedure B).
13C NMR (125 MHz, CDCl3) d = 13.38, 13.42 (2 · d,
2JP–C = 5.52 Hz, C18H3), 13.91, 13.94 (2 · s, C17H3),
0
Yield: 85%, yellow oil.
15.50, 15.55, 15.76, 15.81 (4 · s, C9H3, C9 H3), 21.10 (s,
0
0
20
½aꢂD ꢀ38:75 (c = 2.5, acetone).
C8H3, C8 H3), 21.96 (s, C10H3,C10 H3), 22.350 (s, C16H2),
1H NMR (200 MHz, CDCl3): d = 0.80 (d, 3H, JH–H
=
22.45, 22.55 22.65, 22.68 (4 · s, C3H2, C3 H2), 25.14,
3
0
6.89 Hz, C10H3), 0.91 (d, 6H, JH–H = 6.77 Hz, C8H3,
25.18, 25.27, 25.32 (4 · s, C7H, C7 H), 29.71, 29.86 (2 · s,
3
0
C9H3), 0.93–1.08 (m, 2H, C4H, C3H), 1.12–1.28 (m, 2H,
C15H2), 31.44, 31.50 (2 · s, C5H, C5 H), 32.45 (d, JC–P
=
1
0
C6H, C2H), 1.30–1.50 (m, 1H, C5H, 3H, JH–H
=
141.35 Hz, C11H), 33.96, 34.10 (2 · s, C4H2, C4 H2), 36.18
3

P. Bałczewski et al. / Journal of Organometallic Chemistry 692 (2007) 997–1009
1007
3
(d, JC–P = 18.54 Hz, C13H-I), 40.93, 41.05 (2 · s, C12H2,
solution was stirred at this temperature for 2 h. Then the
temperature was raised to 25 ꢁC and the solvent was evap-
orated. The crude product was purified four times using
column chromatography (CC) over silica gel (eluent: petro-
leum ether/acetone in a gradient), however the final mate-
rial still contained ca. 10% of impurities based on 1H NMR
(although it was pure based on 31P NMR).
0
C14H2); 43.10, 43.24, 43.82, 43.93 (4 · s, C6H2, C6 H2),
48.66, 48.68, 48.71, 48.75 (2 · d, JC–P = 6.10 Hz, C2H,
3
0
C2 H), 76.38, 76.44, 76.56, 76.62 (2 · d, JC–P = 7.79 Hz,
2
0
C1H, C1 H).
31P NMR (81 MHz, CDCl3): d = 31.42, 31.49 ppm.
IR (film): 2956, 2928, 2869, 1456, 1260, 1146, 1006,
1023, 978, 965, 802.
Yield: ca. 48% after first CC, oil.
MS [CI (isobutane)]: m/z (%) 597 (M++1, 100), 469
(M++1-HI, 28); 459 (M++1-menthene, 14), 331 (M++
1-HI-menthene, 16), 321 (M++1ꢀ2· menthene, 7), 193
(M++1-HIꢀ2· menthene, 16).
1H NMR (200 MHz, CDCl3) d = 0.80 (d, 12H, JH–
3
0
H = 6.90 Hz, C10H3, C10 H3), 0.90 (d, 24H, JH–H
=
3
0
0
6.73 Hz, 0 C8H3, C8 H3, C9H3, C9 H3), 0.92–0.97 (m, 8H,
0
0
C4H, C4 H, C3H, C3 H), 1.03–1.10 (m, 8H, C6H, C6 H),
0
HRMS [CI (isobutane)]: m/z calcd. for C28H55O3PI:
597.2916; found: 597.2933.
1.17 (2 · m, 6H, C18H3), 1.20–1.30 (m, 4H, C2H, C2 H),
0
1.35–1.45 (m, 4H, C5H, C5 H), 1.59, 1.62 (2 · s-br, 8H,
0
0
Second pair of diastereomers:
C4H, C4 H, C3H, C3 H), 1.90–1.96 (m, 2H, C11H), 2.05–
0
20
½aꢂD ꢀ52:17 (c = 1.5, acetone).
2.20 (2 · m, 4H, C7H, C7 H), 4.05–4.35 (2·m, 4H, C1H,
0
1H NMR (500 MHz, CDCl3): d = 0.81 (d, 6H, JH–H
=
0
C1 H).
3
0
6.94 Hz, C10H3, C10 H3), 0.81–0.86 (m, 2H, C4H, C4 H),
13C NMR (125 MHz, CDCl3) d = 15.66, 15.86 (2 · s,
0
0
0.91 (d, 12H, JHꢀH = 6.31 Hz, C8H3, C8 H3,C9H3,
C9H3, C9 H3), 15.91, 15.97 (2 · s, C18H3), 21.05, 21.07
3
0
0
0
0
C9 H3), 0.92–0.98 (m, 5H, C3H, C3 H, C17H3), 1.05–1.13
(2 · s, C8H3, C8 H3), 21.91, 21.95 (2 · s, C10H3,C10 H3),
0
0
(m, 2H, C6H, C6 H), 1.17 (2 · d, 3H, JH–H = 7.23 Hz,
22.89, 23.05 (2 · s, C3H2, C3 H2), 25.34, 25.54 (2 · s,
3
0
0
3JH–P = 17.56 Hz, C18H3), 1.24–1.30 (m, 2H, C2H, C2 H),
C7H, C7 H), 27.23, 27.29 (2 · s,C11H), 30.60, 31.50 (2 · s,
0
0
0
1.32–1.37 (m, 4H, C5H, C5 H, C16H2), 1.40–1.46 (m, 2H,
C5H, C5 H), 34.00, 34.17 (2 · s, C4H2, C4 H2), 43.21,
0
0
0
C14H2), 1.66, 1.66 (2 · s-br, 4H, C3H, C3 H, C4H, C4 H),
43.42 (2 · s, C6H2, C6 H2), 48.57, 48.70 (2 · s, C2H,
0
0
1.72–1.82 (m, 2H, C15H2); 1.85–1.96 (m, 1H, C11H),
C2 H), 76.36, 76.60 (2 · s, C1H, C1 H).
0
2.10–2.20 (m, 4H, C6H, C6 H, C12H2), 2.23–2.33 (2 · m,
31P NMR (81 MHz, CDCl3): d = 31.81, 32.06 ppm.
IR (film): 2924, 1456, 1378, 1224, 987, 888, 730.
MS [CI (isobutane)]: m/z (%) 771 (M++1, 26), 385(100),
247(56), 111(63).
0
0
2H, C7H, C7 H), 4.15–4.25 (m, 2H, C1H, C1 H), 4.51–
4.57 (m, 1H, C13H-I).
13C NMR (125 MHz, CDCl3): d = 13.43, 13.55 (2 · d,
2JP–C = 5.35 Hz, C18H3), 14.01, 14.14 (2 · s, C17H3),
5-Chloro-1-trimethylsilylpent-1-yne (13) and 5-Iodo-1-
trimethylsilylpent-1-yne (14) were obtained based on the
procedure by Koft et al. [41] in 92% and 87% yields,
respectively.
0
15.43, 15.52, 15.64, 15.75 (4 · s, C9H3, C9 H3), 21.17 (s-
0
0
br, C8H3, C8 H3), 22.06 (s, C10H3,C10 H3), 22.98 (s,
0
C16H2), 23.15, 23.23 23.39, 23.45 (4 · s, C3H2, C3 H2),
0
25.13, 25.19, 25.28, 25.34 (4 · s, C7H, C7 H), 29.86, 29.94
0
(2 · s, C15H2), 31.44, 31.52 (2 · s, C5H, C5 H), 32.48 (d,
1JC–P = 141.35 Hz, C11H), 33.82, 34.01 (2 · s, C4H2,
3.3.12. (ꢀ)-Dimenthyl 1-methyl-6-trimethylsilyl-n-hex-5-
ynylphophonate (15)
0
C4 H2), 36.12 (d, JC–P = 17.99 Hz, C13H-I), 40.90, 41.02
To a stirred solution of (ꢀ)-dimenthyl ethylphosphonate
3 (1 g, 2.6 mmol) in dry THF (180 mL), n-BuLi (2.2 mL,
5.2 mmol, 2.4 M solution in n-hexane) was added at
ꢀ78 ꢁC under argon atmosphere. After 20 min the iodide
14 (60 mg, 2.8 mmol) was added. The reaction mixture
was warmed to room temperature and left for 2 h at this
temperature. Then aqueous solution of NH4Cl was added
and solvents were evaporated. The residue was extracted
with chloroform and the organic layer was dried over anhy-
drous MgSO4, filtered and evaporated to give the crude
product which was purified with column chromatography
over silica gel (eluent: petroleum ether/ acetone in a
gradient).
3
(2 · s, C12H2, C14H2); 43.10, 43.21, 43.78, 43.91 (4 · s,
0
C6H2, C6 H2), 47.63, 47.68, 47.72, 47.77 (2 · d, JC–P
=
3
0
6.25 Hz, C2H, C2 H), 76.32, 76.36, 76.48, 76.52 (2 · d,
0
2JC–P = 7.92 Hz, C1H, C1 H).
31P NMR (81 MHz, CDCl3): d = 32.26, 32.62 ppm.
IR (film): 2958, 2929, 2863, 1456, 1263, 1039, 1003, 965,
804.
MS [CI (isobutane)]: m/z (%) 597 (M++1, 100), 469
(M++1-HI, 28); 459 (M++1-menthene, 14), 331 (M++1-
HI-menthene, 16), 321 (M++1ꢀ2· menthene, 7), 193
(M++1-HIꢀ2· menthene, 16).
HRMS [CI (isobutane)]: m/z calcd. for C28H55O3PI:
597.2916; found: 597.2929.
Yield: 60%, yellow oil.
20
½aꢂD ꢀ46:84 (c = 2.4, acetone).
3.3.11. (ꢀ)-Tetramenthyl 1,10-dimethylethylene-
bisphosphonate (11)
To a stirred solution of (ꢀ)-dimenthyl 1-iodoethyl-
phosphonate 6 (1 g, 1.95 mmol) and 1-hexene (1.64 g,
2.44 mL, 19.5 mmol) in toluene, Et3B (1.95 mL, 1.95 mmol,
1 M solution in n-hexane) was added at ꢀ78 ꢁC and the
1H NMR (500 MHz CDCl3): d = 0.140 (s, 9H, Si(CH3)3),
0.80 (d, 6H, 3JH–H = 6.87 Hz, C10H3, C10 H3), 0.90 (d, 12H,
0
0
3JH–H = 6.73 Hz, 0 C8H3, C8 H3, C9H3, C9 H3), 0.93–0.98
0
(m0, 4H, C4H, C4 H, C3H, C3 H), 1.02–1.09 (m, 2H, C6H,
C6 H), 1.12–1.20 (m, 2H, C13H2) 1.23–1.35 (m, 4H, C20H,
0
0
C2 H, C5H, C5 H), 1.64, 1.67 (2 · s-br, 4H, C3H, C3 H,

1008
P. Bałczewski et al. / Journal of Organometallic Chemistry 692 (2007) 997–1009
0
0
0
2
C4H, C4 H), 1.70–1.80 (2 · m, 1H, JH–P = 23.15 Hz,
C4H2, C4 H2), 44.14, 44.18 (2 · s, C6H2, C6 H2), 49.49,
0
C11H), 1.83–1.89 (m, 2H, C12H2), 2.20 (2 · d, 3 H, JH–H
49.55 (20· s, C2H, C2 H), 78.60, 78.67, 78.86, 79.93 (4 · s,
3
= 6.72 Hz, JH–P = 16.12 Hz, C18H3), 2.22–2.31 (2 · m,
C1H, C1 H), 85.31 (s, C15), 106.95 (s, C16).
3
0
2H, C7H, C7 H), 2.30–2.37 (m, 2H, C14H2) 2.40–2.48 (m,
31P NMR (81 MHz, CDCl3): d = 20.19, 20.58 ppm.
IR (film): 2957, 2929, 2869, 2174, 1456, 1243, 1375,
1225, 1026, 978, 965, 842.
0
0
2H, C6H, C6 H), 4.12–4.20 (m, 2H, C1H, C1 H).
13C NMR (125 MHz, CDCl3): d = 0.17 (s,0 Si(CH3)3),
13.42, 13.57, 15.54, 15.61 (4 · s, C9H3, C9 H3, C8H3,
MS [CI (isobutane)]: m/z (%) 651 (M++1, 100), 523
(M++1-HI, 62); 513 (M++1-menthene, 38), 385 (M++1-
HI-menthene, 32), 375 (M++1ꢀ2· menthene, 46), 247
(M+ +1- HI – 2 · menthene, 33).
0
0
C8 H3), 15.85, 15.92 (s, C10H3, C10 H3), 21.15, 22.00 (2 · s,
30
C13H2; C14H2), 22.59, 22.70 (2 · s, C3H2, C H2), 25.21,
0
25.34 (2 · s, C7H, C7 H), 26.85, 26.97 (2 · s, C12H3), 29.68,
0
29.75 (2 · s, C18H3), 31.48, 31.55 (2 · s, C5H, C5 H), 33.03
HRMS [CI (isobutane)]: m/z calcd. for C30H57O3PISi:
651.2862; found: 651.2859.
0
(d, JPꢀC = 142.35, C11H), 34.13 (s, C4H2, C4 H2), 43.15,
2
0
0
43.24 (2 · s, C6H2, C6 H2), 48.73 (s, C2H, C2 H), 78.15,
0
78.22, 78.36, 79.42 (4 · s, C1H, C1 H), 82.31 (s, C15),
4. Supplementary material
107.13 (s, C16).
31P NMR (81 MHz, CDCl3): d = 31.91, 32.64 ppm.
IR (film): 2955, 2927, 2869, 2174, 1456, 1370, 1223,
1026, 986, 978, 842, 755.
CCDC 296401 contains contains the supplementary
crystallographic data for this paper. These data can be
obtained free of charge via http://www.ccdc.cam.ac.uk/
conts/retrieving.html, or from the Cambridge Crystallo-
graphic Data Centre, 12 Union Road, Cambridge CB2
1EZ, UK; fax: (+44) 1223 336 033; or e-mail: deposit@
ccdc.ac.uk.
MS [CI (isobutane)]: m/z (%) 525 (M++1, 100), 387
(M++1-menthene, 36), 249 (M++1ꢀ2· menthene, 46).
HRMS [CI (isobutane)]: m/z calcd. for C30H58O3PSi:
525.3898; found: 525.3892.
3.3.13. (ꢀ)-Dimenthyl 1-iodo-1-methyl-6-trimethylsilyl-n-
hex-5-ynylphosphate (16)
References
To a stirred solution of the phosphonate 15 (100 mg,
0.19 mmol) in dry THF (50 mL), n-BuLi (0.16 mL,
0.38 mmol, 2.4 M solution in n-hexane) was added at
ꢀ78 ꢁC under argon atmosphere. After 20 min iodine
(96 mg, 0.38 mmol) was added and the resulting mixture
was warmed to room temperature. After additional 1 h,
an aqueous solution of NH4Cl was added. Solvents were
evaporated and the residue was extracted with chloroform.
The chloroform layer was washed with water and 10%
aqueous solution of Na2S2O3, dried over anhydrous
MgSO4, filtered and evaporated to give the crude product
which was purified with column chromatography over sil-
ica gel (eluent: petroleum ether/acetone in a gradient).
Yield: 34%, yellow oil.
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20
½aꢂD ꢀ 40:65 (c = 2.3, acetone).
1H NMR (500 MHz CDCl3): d = 0.150 (s, 9H, Si(CH3)3),
0.83 (d, 6H, 3JH–H = 6.96 Hz, C10H3, C10 H3), 0.87 (d, 12H,
0
0
3JH–H = 6.68 Hz, C8H3, C8 H3, C9H3, C9 H3), 0.90–1.08
40
30
60
(m, 6H, C4H, C H, C3H, C H, C6H, C H), 1.12–1.20
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(m0, 2H, C13H2) 1.26–1.39 (m, 4H, C20H, C2 H, C5H,
0
C5 H), 1.63, 1.66 (2 · s-br, 4H, C3H, C3 H, C4H, C4 H),
1.73–1.82 (m, 2H, C12H2), 2.03 (2 · d, 3H, JH–H = 6.41
3
Hz, JH–P = 15.48 Hz, C18H3), 2.15–2.25 (2 · m, 2H,
3
0
0
C7H, C7 H), 2.29–2.45 (m, 4H, C14H2, C6H, C6 H), 4.20–
0
4.30 (m, 2H, C1H, C1 H).
13C NMR (125 MHz, CDCl3): d = 0.54 (s, Si(CH ) ),
0 3 3
12.63, 13.30 (2 · s. C11), 14.32, 14.49, (2 · s, C9H3, C9 H3),
0
0
16.38, 16.44 (2 · s, C8H3, C8 H3), 16.64 (s, C10H3,C10 H3),
20.01, 20.05 (2 · s, C14H2) 21.57, 21.60 (2 · s, C13H2),
0
23.05, 23.17 (2 · s, C3H2, C3 H2), 25.43, 25.63 (2 · s, C7H,
0
C7 H), 27.38, 27.45 (2 · s, C12H ), 29.72, 29.78 (2 · s,
3 0
C18H3), 31.88, 31.92 (2 · s, C5H, C5 H), 33.08 33.16 (2 · s,

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