In situ dearomatisation/alkylation of arylphosphane derivatives

Article abstract of DOI:10.1002/ejoc.201200096

The dearomatisation of aryldialkylphosphane-boranes and aryldialkylphosphane oxides under Birch reduction conditions, followed by treatment with reactive alkyl halides, provides the corresponding α-functionalised (cyclohexa-1,4-dien-3-yl)phosphane derivatives. This reaction offers a method of choice for the synthesis of bulky (cyclohexadienyl)phosphanes.

Full text of DOI:10.1002/ejoc.201200096

FULL PAPER
DOI: 10.1002/ejoc.201200096
In Situ Dearomatisation/Alkylation of Arylphosphane Derivatives
[a]
[a]
[a]
ˇ
´
Marek Stankevic,* Karolina Wójcik, Magdalena Jaklinska, and
K. Michał Pietrusiewicz[a]
Keywords: Phosphanes / Boranes / Reduction / Alkylation
The dearomatisation of aryldialkylphosphane–boranes and
aryldialkylphosphane oxides under Birch reduction condi-
tions, followed by treatment with reactive alkyl halides, pro-
vides the corresponding α-functionalised (cyclohexa-1,4-
dien-3-yl)phosphane derivatives. This reaction offers a
method of choice for the synthesis of bulky (cyclohexa-
dienyl)phosphanes.
Introduction
method is in practice limited to the (very important) intro-
duction of sulfonyl groups.[8] Directed ortho-metallation re-
actions, very popular methods for the functionalisation of
arenes in classical organic chemistry,[9] have to date found
little use in organophosphorus chemistry.[10]
Many research groups have devoted intense attention to
the synthesis of phosphanes because of their importance in
organic synthesis and as ligands in transition-metal-cata-
lysed transformations. Standard synthetic methods include
1) nucleophilic substitutions at electrophilic phosphorus
atoms,[1] 2) nucleophilic substitutions with phosphorus nu-
cleophiles,[2] 3) transition-metal-catalysed coupling reac-
tions,[3] 4) addition of organophosphorus reagents to mul-
tiple bonds,[4] or 5) reduction of the corresponding phos-
phane oxides.[5] The common feature of these methods is
their focus on the phosphorus centre as the source of reac-
tivity, and quite strict constraints are imposed upon the
synthetic pathway in order to allow the phosphane to be
the final product. This means that any preparation of a
modified phosphane by an analogous pathway is likely to
be tedious, because the synthesis usually has to be repro-
duced in its totality. In cases in which the structural differ-
ences between two desired product phosphanes are small,
as will often be the case in optimisation of a catalytic pro-
cess, this problem would ideally be resolved by post-syn-
thetic modification of the phosphane itself. Such an ap-
proach, which treats phosphanes as the starting point in the
synthetic pathway, can obviously provide a step-economical
synthesis of new compounds through a wide range of trans-
formations. Any phosphanes already possessing a range of
classical functional groups can obviously be modified
through functional group interconversions (FGIs),[6] but
those that lack functional groups require modification of
the carbon skeleton.[7] For arylphosphanes and their deriva-
tives, modification of the arene fragment can be achieved
through electrophilic aromatic substitution, although this
One particular arene group modification stands out
through its very specific transformation of the aryl frag-
ment. Birch reduction can be used to convert an aryl unit
into the corresponding cyclohexa-1,4-dienyl fragment
through the action of solutions of alkali metals in liquid
ammonia (Scheme 1)[11] and is of general applicability.
Many aromatic compounds such as unsubstituted arenes,[12]
aryl ethers[13] or arenecarboxylic acid derivatives[14] are suc-
cessfully dearomatised under Birch reduction conditions.
This transformation has also been found to be useful in
dearomatisations of heteroaromatic compounds such as
furans,[15] indoles,[16] pyrroles[17] or pyridines[18] into the
corresponding non-aromatic unsaturated heterocycles.
Scheme 1. Birch reduction of an arylamide.
The Birch reduction of an arene proceeds through the
formation of a carbanionic intermediate, and this raises the
possibility of coupling an initial Birch reduction step to an
in situ reaction with an electrophile to generate a substi-
tuted cyclohexa-1,4-diene (Scheme 2).[19]
[a] Department of Organic Chemistry, Faculty of Chemistry,
Maria Curie-Skłodowska University,
Gliniana 33, 20-614 Lublin, Poland
Fax: +48-81-524-22-51 ext. 136
E-mail: marek.stankevic@poczta.umcs.lublin.pl
Supporting information for this article is available on the
WWW under http://dx.doi.org/10.1002/ejoc.201200096.
Scheme 2. In situ reduction/alkylation of an arene.
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M. Stankevicˇ, K. Wójcik, M. Jaklin´ska, K. M. Pietrusiewicz
The outcome is that treatment of substrates with alkali
FULL PAPER
Given that the both functionalised arenes and electro-
philes are, in principle, likely to be tolerated, such a Birch metals in liquid ammonia and subsequent addition of elec-
reduction/alkylation might be usable to create very reactive trophiles generally provides the corresponding α-alkylated
structures well-adapted to further modification. More clas- (cyclohexa-1,4-dien-3-yl)phosphane–boranes in modest to
sical Birch reduction products have found use in syntheses good yields. When methyl iodide was used, the correspond-
of, for example, bicyclic[20] and polycyclic compounds,[21] as ing α-alkylated phosphane–borane products shown in
well as of natural products.[22]
Table 1 were isolated in 21–91% yields (Table 1, Entries 1,
Unlike in classic organic chemistry, where it is ubiqui- 2, 4, and 5), except in the case of the diarylalkylphosphane–
tous, the use of Birch reduction in organophosphorus borane 5. This underwent phenyl group cleavage and subse-
chemistry has little precedent. The first report of Birch re- quent alkylation of the intermediate phosphane–borane
ductions of a few very electron-rich arylphosphanes ap- anion rather than Birch reduction/alkylation (Table 1, En-
peared towards the end of the last century,[23] and as part try 6). It was found that phosphane–borane 2 is quite sus-
of this research project, directed towards the application of ceptible to benzyl group cleavage when sodium is used
Birch reductions in organophosphorus chemistry, we have (Table 1, Entry 2) and that this process dominates massively
already reported the efficient dearomatisations of the much when sodium is replaced by potassium (Table 1, Entry 3).
more classical aryldialkylphosphane–boranes[24] and aryldi- Similar trends were observed when benzyl chloride replaced
alkylphosphane oxides.[25] More recently, the area has also methyl iodide as the electrophile (Table 1, Entries 7–11).
been explored by Verdaguer et al., through the dearomati- The corresponding α-alkylated Birch reduction products
sation of tert-butylphenylphosphinous acid–borane were obtained in good yields except in the case of 5, which
amide.[26]
again predominantly underwent phenyl group cleavage and
This very easy access to (cyclohexadienyl)phosphane de- subsequent benzylation (Table 1, Entry 11). The unantici-
rivatives that the Birch reduction provides has led us to pated product 2b was obtained in the system in which benz-
publish a preliminary investigation of their utility in organic ylphosphane–borane 2 was used with benzyl chloride as the
synthesis and it is already clear that these compounds can electrophile (Table 1, Entry 8); it was probably formed
be used in Michael-type additions with secondary phos- through a reaction sequence involving debenzylation in the
phane oxides to give diphosphane dioxides containing cy- first step followed by alkylation, then deprotonation at the
clohexenyl or cyclohexyl linkers;[27] similar reactivity has benzylic position and further benzylation. This assumption
also recently been observed by Salem and colleagues.[28]
Here we wish to demonstrate the utility of Birch re- yielded mainly 1 under the reaction conditions.
duction reactions in the synthesis of structurally new α-sub- When the electrophile was the more hindered cyclohexyl
was based on the reaction between 2 and MeI, which
stituted (cyclohexa-1,4-dien-3-yl)phosphane derivatives bromide, the desired α-alkylated Birch reduction products
through in situ Birch reduction/alkylation of aryldialkyl- were not obtained (Table 1, Entries 12–16). In these cases,
phosphane derivatives.
the main products isolated from the reaction mixtures were
either non-alkylated Birch reduction products (for 2–4) or
secondary phosphane–boranes resulting from P–Ph bond
cleavage (for 2 and 5). This lack of reactivity with the sec-
ondary alkyl halide can reasonably be ascribed to the small
Results and Discussion
For the first set of in situ Birch reduction/alkylation ex- volume of unoccupied space about the contiguous quater-
periments we chose five model arylphosphane–boranes nary centres; this obviously precludes the approach of the
(Scheme 3). Four of them – namely tert-butylmethylphenyl- bulkier electrophile.
phosphane–borane (1), benzyl-tert-butylphenylphosphane–
When performing the preliminary dearomatization/alk-
borane (2), dimethylphenylphosphane–borane (3) and 1- ylation experiments we observed an interesting feature in
phenylphospholane–borane (4) – possessed two alkyl sub- dialkylphenylphosphane–boranes 3 and 4; these formed sig-
stituents on their phosphorus atoms, whereas methyldi- nificant amounts of trialkylphosphane–boranes 3bЈ–5bЈ
phenylphosphane–borane (5) had only one. All model (Table 1, Entries 5, 9 and 10). These products could only
phosphane–boranes were treated with the appropriate have been formed if the phenyl-phosphorus bond had been
amount of alkali metal dissolved in liquid ammonia at cleaved prior to alkylation. The difference between these
–78 °C followed by treatment with an excess of an alkyl phosphane–boranes and 1 is that they each have two small
halide. The results of the screening are presented below.
alkyl substituents at phosphorus, so it seems that the natu-
Scheme 3. Products obtained upon in situ Birch reduction/alkylation of model phosphane–boranes.
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In Situ Dearomatisation/Alkylation of Arylphosphanes
Table 1. Screening of in situ Birch reduction/alkylation of model phosphane–boranes.
Entry
Substrate
R
Electrophile (equiv.)
Yields of the products[a]
RЈ
1[b]
2
1
2
2
3
4
5
1
2
3
4
5
1
2
3
4
5
1
1
1
1
1
1
1
1
1
tBu
tBu
tBu
Me
Me
MeI (a, 2.5)
1a (91%)
2a (21%)[c]
1 (86%)
3a (49%)
4a (42%)
3 (86%)
PhCH2
PhCH2
Me
MeI (a, 2.5)
1 (45%)[c]
4aЈ (46%)
3[b]
4
MeI (a, 2.5)
MeI (a, 2.5)
5
–(CH2)4–
MeI (a) (2.5)
6
Ph
Me
Me
PhCH2
Me
MeI (a, 2.5)
7[b]
8
tBu
tBu
Me
PhCH2Cl (b, 2)
1b (74%)
2b (51%)
3b (67%)
4b (62%)
5b (25%)[e]
no reaction
2c (21%)
3c (51%)
4c (47%)
5c (45%)[c]
1d (67%)
1e (75%)
1f (75%)[d]
1g (56%)
1h (35%)[d]
1i (57%)
1j (38%)
1k (48%)
1l (72%)
PhCH2Cl (b, 2)
9
10
PhCH2Cl (b, 2)
3bЈ (30%)[d]
4bЈ (30%)[d]
5bЈ (60%)[e]
–(CH2)4–
PhCH2Cl (b) (2)
PhCH2Cl (b, 2)
11
Ph
Me
Me
PhCH2
Me
12[b]
13
tBu
tBu
Me
cHexBr (c, 2)
cHexBr (c, 2)
2cЈ (35%)
14
15
16
cHexBr (c, 2)
–(CH2)4–
cHexBr (c, 2)
Ph
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
cHexBr (c, 2)
17[b]
18[b]
19[b]
20[b]
21[b]
22[b]
23[b]
24[b]
25[b]
tBu
tBu
tBu
tBu
tBu
tBu
tBu
tBu
tBu
chloroacetonitrile (d, 2)
2-phenylethyl bromide (e, 2)
propargyl bromide (f, 2)
ethyl bromoacetate (g, 2)
allyl chloride (h, 2)
4-bromobut-1-ene (i, 2)
2-bromobenzyl bromide (j, 2)
1,2-dibromoethane (k, 4)
1,3-dibromopropane (l, 2)
[a] Yields of pure compounds, unless otherwise noted. [b] The reaction was performed with potassium (2.5 equiv.). [c] Yields based on
the NMR spectra of the mixture of 2a and 1. [d] Yields based on the NMR spectra of the mixtures with substrate. [e] Yields based on
the NMR spectra of the mixture of 5b and 5bЈ.
res of the alkyl substituents might strongly influence the quence with a series of phosphorus-containing alkyl halides
course of the reaction through an as yet unknown mecha- (Table 2 and Scheme 4).
nism.
Table 2. Birch reduction/alkylation with phosphorus-containing
alkyl halides.
Given that the in situ Birch reduction/alkylation ap-
peared to work for the reactions between most of the phen-
Entry
Substrate
Alkylated products
ylphosphane–boranes tested and simple primary alkyl hal-
ides, we were curious to see whether or not other activated
halides possessing additional functionalities could react
similarly under the reaction conditions. Irrespective of the
functionalised alkyl halides under investigation (all of them
primary or benzylic), we observed the formation of the cor-
responding α-alkylated Birch reduction products of 1 in
reasonable yields (Table 1, Entries 17–25). Functionalities
such as double or triple bonds and cyano or carboxy groups
are compatible with the reaction conditions. Even dihaloalk-
anes such as 1,2-dibromoethane and 1,3-dibromopropane
(Table 1, Entries 24 and 25) can be used to generate mono-
substituted products in good yields, although this was not
the case for dihalomethanes, which failed to give the corre-
sponding (α-halomethyl)cyclohexadienylphosphane–bor-
anes (data not shown).
1
2
3
4
5
6
Ph2P(O)CH2I (6)
no alkylated product
no alkylated product
no alkylated product
Ph2P(BH3)CH2CH2Cl (7)
(EtO)2P(O)CH2CH2Br (8)
Ph2P(BH3)(CH2)3Br (9)
Ph2P(BH3)(CH2)4Br (10)
12 (47%)
15 (23%)
16 (16%)
13 (39%)
tBuPhP(BH3)(CH2)4Br (11) 14 (31%)[a]
[a] A mixture of two diastereoisomers.
Scheme 4. Birch reduction/alkylation with phosphorus-containing
alkyl halides.
The successful use of functionalised haloalkanes to intro-
duce an additional reactive centre such as cyano or carb-
The outcomes of such in situ alkylations of the interme-
oxylate one carbon atom away remote from the cyclohexa- diate carbanion of 1 with phosphorus-containing alkyl hal-
dienyl fragment gives a green light for the introduction of ides seemed to be quite sensitive to the structures of the
a second phosphorus group into the molecule by means of electrophiles. Functionalised alkyl halides with short linkers
a phosphorus-functionalised halide. The phosphane–bor- between the two functionalities, as in 6–8, failed to react
ane 1 was therefore subjected to the studied reaction se- with the carbanion formed in situ (Table 2, Entries 1–3) but
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M. Stankevicˇ, K. Wójcik, M. Jaklin´ska, K. M. Pietrusiewicz
FULL PAPER
Scheme 5. Double alkylation of carbanions formed in situ .
those with longer linkers such as 9–11 afforded the desired ment by an alkyl group, which was successfully applied by
products in fair yields (Table 2, Entries 4–6). In view of the another research group in the case of diarylalkylphos-
crowded nature of the intermediate tertiary carbanion, the phane–boranes.[29] The replacement of the phenyl substitu-
lack of the reactivity of 6–8 is probably again associated ents in phenyldialkylphosphane–boranes in the presence of
with strong steric interactions with the incoming proximal large excesses of alkali metal was thus attempted
quaternary phosphorus centre. In the cases of 9 and 10 we (Scheme 6).
also observed the formation of the side products 15 and 16
(Table 2, Entries 4 and 5), which are formally the alkylation
products of the corresponding secondary phosphane–bor-
ane anion. This indicates that cleavage of the phosphorus-
phenyl bond in 1 can also occur to some extent under the
reaction conditions.
Because in situ alkylation of the intermediate carbanion
with an excess of a dihaloalkane provides an α-alkylated
Birch reduction product possessing an easily substituted
halide group in the side chain, adjustment of the amount
of dihaloalkane might give rise to a double alkylation pro-
cess and thus to new diphosphane derivatives containing
very special linkers (Scheme 5).
We anticipated that use of 1,3-dibromopropane
(0.5 equiv.) should drive the reaction towards double alkyl-
ation, but obtained the monoalkylation product 1l in 32%
yield together with the desired bis-alkylation product 17 in
Scheme 6. In situ P–Ph bond cleavage/alkylation of 1, 3 and 4.
38% yield (Scheme 5). However, o-bis(bromomethyl)benz-
ene underwent reaction with 1 under Birch reduction condi-
This treatment of model phosphane–boranes 1, 3 and 4
tions to give the disubstituted compound 18 as the only with large excesses of alkali metal, although preferentially
observable product, isolated in 29% yield (see Scheme 5). at –33 °C, indeed caused phosphorus-phenyl bond cleavage
The sterically less demanding organophosphorus substrate in the phenyldialkylphosphane–boranes. Treatment of the
3 gave an increased yield (43%) of the bis(phosphane)– obtained secondary phosphane–borane anions with methyl
bis(borane) 19, which again emphasises the influence of the iodide or benzyl chloride in situ yielded the corresponding
steric crowding in the substrate on the reaction yield.
trialkylphosphane–boranes in moderate to good yields. The
Above we discussed the formation of compounds 4aЈ, phosphane–borane anions derived from 3 and 4 afforded
3bЈ, 4bЈ, 15 and 16 during the Birch reduction/alkylation of chain homologated products 24 and 25 upon treatment with
1. It is postulated that these products arise through initial benzyl chloride. Again, the initial products seem to undergo
phosphorus-phenyl bond cleavage and formation of the sec- benzyl group deprotonation under the reaction conditions
ondary phosphane–borane anion, which subsequently un- and subsequent alkylation with excess benzyl chloride.
dergoes alkylation with an added electrophile. It seemed When ammonium chloride was used as the electrophile, the
reasonable to assume that this methodology might repre- corresponding secondary phosphane–boranes 20 and 23
sent a valuable method for replacing a phosphane aryl frag- were formed.
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In Situ Dearomatisation/Alkylation of Arylphosphanes
Given that dearomatization/alkylation of the phenyl sub-
stituent in phenyldialkylphosphane–boranes appears to
have quite general utility, we also attempted similar Birch
reduction/alkylation sequences with the corresponding
phosphane oxides (Scheme 7).
Experimental Section
General: All the reactions were performed under argon by Schlenk
techniques. Only dry solvents were used and the glassware was
heated under vacuum prior to use. All chemicals were used as re-
ceived unless otherwise noted. Solvents for chromatography and
crystallisation were distilled once before use and the solvents for
extraction were used as received. Ammonia was passed through
solid NaOH before condensation.
The NMR spectra were recorded with Bruker Ascend (500 MHz),
Varian Mercury 400BB or Bruker Avance (300 MHz) spectrome-
ters in CDCl3 as a solvent at room temperature unless otherwise
noted. Chemical shifts (δ) are reported in ppm relative to residual
solvent peak. Mass spectra were recorded with a Shimadzu GC-
MSQP2010S spectrometer in electron ionisation (EI) mode and a
Phenomenex Zebron ZB-35HT INFERNO column [pressure
97.9 kPa, total flow 19.5 mLmin–1, column flow 1.5 mLmin–1, lin-
ear velocity 44.9 cmsec–1, split 10, temperature program (70 °C,
hold 3 min, 70–340 °C/12 °Cmin–1, hold 9.5 min, total 35 min)] or
Phenomenex Zebron ZB-5MSi column [pressure 65 kPa, total flow
23.9 mLmin–1, column flow 1.2 mLmin–1, linear velocity
36.8 cmsec–1, split 20, temperature program (80 °C, hold 3 min, 80–
250 °C/20 °Cmin–1, hold 5 min, 250–300 °C/10 °Cmin–1, hold
30.5 min total 50 min)]. Thin-layer chromatography (TLC) was per-
formed with precoated silica gel plates and visualised with UV light
or KMnO4 solution. The reaction mixtures were purified by col-
umn chromatography over silica gel (60–240 mesh).
tert-Butylmethylphenylphosphane–borane (1),[30] benzyl-tert-but-
ylphenylphosphane–borane (2),[31] dimethylphenylphosphane–bor-
ane (3),[27] diphenyl(iodomethyl)phosphane oxide (6),[32] diethyl 2-
bromoethylphosphonate (8),[33] tert-butylmethylphenylphosphane
oxide (26)[34] and dimethylphenylphosphane oxide (27)[26] were pre-
pared as reported in the literature.
Scheme 7. In situ Birch reduction/alkylation of phosphane oxides
26–28.
It appears that phenyldialkylphosphane oxides cleanly
undergo analogous reaction sequences under the same con-
ditions to yield the corresponding α-alkylated (cyclohexadi-
enyl)phosphane oxides in fair to excellent yields. The only
exception here was the reaction between 1-phenylphos-
pholane oxide (28) and benzyl chloride, which afforded a
mixture of 34 and benzylphospholane oxide (35).
1-Phenylphospholane–Borane (4): A solution of 1-phenylphos-
pholane oxide[35] (1.246 g, 7.0 mmol) in methanol (15 mL) was
placed in a flame-dried Schlenk tube (100 mL). Pd/C (10%,
0.125 g) was then added, the reaction vessel was evacuated three
times and filled with hydrogen, and the reaction mixture was stirred
under hydrogen (1 atm) at room temperature for 24 h. The reaction
mixture was then filtered through Celite, which was washed with
CH2Cl2 (2ϫ20 mL), and the organic phase was evaporated under
reduced pressure to yield chemically and spectroscopically pure 1-
phenylphospholane oxide (28, 1.26 g, 100%) as a colourless liquid.
RF = 0.59 (EtOAc/MeOH 20:1). 1H NMR (300 MHz, CDCl3): δ =
1.78–2.23 (m, 8 H), 7.39–7.51 (m, 3 H), 7.63–7.72 (m, 2 H) ppm.
Conclusions
The application of Birch reduction methodology to or-
ganophosphorus chemistry is still in its infancy, but the re-
sults obtained so far show the potential of this reaction as
a tool for transforming the relatively stable P-phenyl sub- 13C NMR (75 MHz, CDCl3): δ = 25.23 (d, JP,C = 8.3 Hz), 29.58
(d, JP,C = 67.5 Hz), 128.58 (d, JP,C = 11.2 Hz), 129.81 (d, JP,C
=
stituent into a reactive cyclohexadienyl fragment without
affecting the phosphorus functionality. The formation of an
intermediate cyclohexadienyl carbanion during the dearo-
matisation process allows the preparation of new organo-
phosphorus compounds featuring bulky cyclohexadienyl P-
substituents by simple alkylation of this carbanion with re-
active primary alkyl halides. The presence of other func-
tionalities in alkyl halides is tolerated in this reaction, which
means that it can be applied to the synthesis of diphospho-
rus compounds containing complex carbon linkers. The
flexibility of the chemistry available with phosphane–bor-
ane complexes is nicely illustrated by the easy shift of the
reaction outcome from Birch reduction/alkylation to P–Ph
bond cleavage/alkylation through a simple change in the
quantity of the alkali metal.
9.5 Hz), 131.56 (d, JP,C = 2.9 Hz), 134.20 (d, JP,C = 90.2 Hz) ppm.
31P NMR (121.5 MHz, CDCl3): δ = 60.98 ppm. GC (Phenomenex
Zebron ZB-5MSi): RT = 12.92 min. GC-MS (EI, 70 eV): m/z (%)
= 180 (100) [M]·+, 179 (65), 152 (65), 151 (24), 134 (42), 125 (21),
124 (32), 105 (73), 91 (26), 79 (17), 78 (13), 77 (68). C10H13OP
(180.18): calcd. C 66.66, H 7.27; found C 66.80, H 7.32.
A solution of 1-phenylphospholane oxide (1.26 g, 7.0 mmol) was
dissolved in toluene (10 mL) and trichlorosilane (2.10 mL,
21 mmol) was added, followed by triethylamine (2.92 mL,
21 mmol). The reaction mixture was heated to 100 °C for 24 h and,
after cooling, BH3·THF (10.5 mL, 1 m in THF, 10.5 mmol) was
added and the stirring was continued for 2 h at room temperature.
The reaction mixture was quenched by slow addition of NaOH
solution (5m, 10 mL), water (10 mL) was then added, and the reac-
tion mixture was extracted with CHCl3 (5ϫ20 mL). The organic
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FULL PAPER
phase was washed with water (2ϫ10 mL), dried with MgSO4 and
concentrated to dryness. The residue was purified by column
chromatography on silica gel with hexane/EtOAc (6:1) to yield 1-
phenylphospholane–borane (4, 0.90 g, 72%). The analytical data
are in accordance with those reported in the literature.[36]
(162 MHz, CDCl3): δ = 15.92 ppm. GC (Phenomenex Zebron ZB-
35HT INFERNO): RT = 20.28 min. GC-MS (EI, 70 eV): m/z (%)
= 307 (14), 305 (15), 280 (12), 279 (28), 278 (11), 277 (28), 227 (13),
226 (16), 204 (15), 202 (17), 200 (18), 199 (100), 185 (26), 184 (13),
183 (91), 152 (18), 123 (18), 121 (49), 109 (18), 108 (23), 107 (39),
78 (16), 77 (24), 54 (91). C15H19BBrP (321.00): calcd. C 56.12, H
5.97; found C 56.33, H 6.29.
Methyldiphenylphosphane–Borane (5): A solution of diphenylphos-
phane–borane[37] (1.00 g, 4.95 mmol) in THF (10 mL) was placed
in a flame-dried Schlenk vessel (100 mL) under argon. The solution
was cooled to –78 °C and n-butyllithium (3.41 mL, 1.6 m in hex-
anes, 5.44 mmol) was added over 5 min. After the mixture had been
kept for 30 min at –78 °C, methyl iodide (0.46 mL, 7.42 mmol) was
added in one portion and the reaction mixture was allowed to
warm to room temperature over 2 h. Saturated NH4Cl solution
(5 mL) was then added, the mixture was extracted with CH2Cl2
(3ϫ15 mL), and collected organic fractions were dried with
MgSO4 and concentrated under reduced pressure. The residue was
purified with column chromatography on silica gel with hexane/
EtOAc (6:1) as eluent to yield 5 as a colourless pasty solid (0.96 g,
90%). The spectroscopic data are in accordance with those re-
ported in the literature.[38]
(4-Bromobutyl)diphenylphosphane–Borane (10): This compound
was prepared as described for compound 7 with triphenylphos-
phane–borane (2.76 g, 10 mmol), sodium (0.506, 22 mmol) and 1,4-
dibromobutane (1.195 mL, 10 mmol). Yield 1.809 g (54%). White
oily solid. RF = 0.42 (hexane/EtOAc 6:1). 1H NMR (400 MHz,
CDCl3): δ = 0.21–1.42 (m, 3 H), 1.61–1.77 (m, 2 H), 1.87–2.01 (m,
2 H), 2.16–2.29 (m, 2 H), 3.36 (t, JH,H = 6.68 Hz, 2 H) 7.39–7.52
(m, 6 H), 7.62–7.72 (m, 4 H) ppm. 13C NMR (100 MHz, CDCl3):
δ = 21.69, 24.80 (d, JP,C = 40.0 Hz), 32.43, 33.62 (d, JP,C = 13.7 Hz),
128.81 (d, JP,C = 9.8 Hz), 131.19, 132.01 (d, JP,C = 9.3 Hz) ppm.
31P NMR (162 MHz, CDCl3): δ = 16.30 ppm. GC (Phenomenex
Zebron ZB-35HT INFERNO): RT = 16.26 min. GC-MS (EI,
70 eV): m/z (%) = 242 (21), 200 (36), 199 (100), 183 (36), 120 (10),
109 (14), 108 (35), 107 (18), 91 (22). C16H21BBrP (335.03): calcd.
C 57.36, H 6.32; found C 57.33, H 6.55.
(2-Chloroethyl)diphenylphosphane–Borane (7): Triphenylphos-
phane–borane (2.76 g, 10 mmol) in THF (10 mL) was placed under
(4-Bromobutyl)-tert-butylphenylphosphane–Borane (11): tert-Butyl-
phenylphosphane–borane (1.80 g, 10 mmol) in THF (10 mL) was
placed under argon in a flame-dried three-necked flask (100 mL)
and the mixture was cooled to –70 °C. nBuLi (6.88 mL, 1.6 m in
hexanes, 11 mmol) was added dropwise by syringe over 5 min and
the mixture was stirred at –78 °C for 30 min. 1,4-Dibromobutane
(1.195 mL, 10 mmol) was added in one portion and the mixture
was allowed to warm to room temperature over 5 h. The reaction
was quenched by addition of aqueous HCl (1 m, 5 mL), the mixture
was extracted with dichloromethane (3ϫ20 mL), the collected or-
ganic fraction was dried with MgSO4, the solvent was evaporated
under reduced pressure, and the residue was purified by column
chromatography with hexane/ethyl acetate (6:1) as eluent to yield
11 (2.394 g, 76%). Pale yellow solid; m.p. 65.3–66.4 °C. RF = 0.77
argon in
a flame-dried two-necked flask (100 mL). Sodium
(0.506 g, 22 mmol) was then added in several pieces and the reac-
tion mixture was allowed to stir at room temperature for 24 h. Dur-
ing the reaction time, the colour of the reaction mixture changed
from colourless to deep maroon. After 24 h, excess sodium was
removed, tert-butyl chloride (1.196 mL, 11 mmol) was added, and
the reaction mixture was stirred for another hour. The reaction
mixture was cooled to –70 °C, 1,2-dichloroethane (0.788 mL,
10 mmol) was added, and the reaction mixture was allowed to
warm to room temperature over 3 h. The reaction was quenched
by addition of aqueous HCl (1 m, 5 mL), the mixture was extracted
with dichloromethane (3ϫ20 mL), the collected organic fraction
was dried with MgSO4, the solvent was evaporated under reduced
pressure, and the residue was purified by column chromatography
with hexane/ethyl acetate (6:1) as eluent to yield 7 (1.103 g, 42%)
as a white solid; m.p. 68.8–69.6 °C. RF = 0.70 (hexane/EtOAc 6:1).
1H NMR (400 MHz, CDCl3): δ = 0.39–1.58 (m, 3 H), 2.69–2.82
(m, 2 H), 3.62–3.72 (m, 2 H), 7.39–7.63 (m, 6 H), 7.64–7.74 (m, 4
1
(hexane/EtOAc 6:1). H NMR (400 MHz, CDCl3): δ = 0.21–1.12
(br. m, 3 H), 1.09 (d, JP,H = 13.6 Hz, 9 H), 1.72–1.86 (m, 2 H),
1.87–1.99 (m, 2 H), 1.99–2.07 (m, 1 H), 2.09–2.23 (m, 1 H), 3.30–
3.41 (m, 2 H), 7.43–7.54 (m, 3 H), 7.66–7.72 (m, 2 H) ppm. 13C
NMR (75 MHz, CDCl3): δ = 17.92 (d, JP,C = 33.6 Hz), 21.88, 25.43
H) ppm. 13C NMR (100 MHz, CDCl3): δ = 23.14 (d, JP,C
39.0 Hz), 45.51 (d, JP,C = 16.1 Hz), 128.84 (d, JP,C = 55.6 Hz),
128.89 (d, JP,C = 9.8 Hz), 131.33, 132.04 (d, JP,C = 9.3 Hz) ppm.
13C NMR (125 MHz, CDCl3): δ = 29.99 (d, JP,C = 32.7 Hz), 38.51
(d, JP,C = 8.2 Hz), 128.03 (d, JP,C = 55.4 Hz), 129.07 (d, JP,C
10.0 Hz), 131.67 (d, JP,C 2.7 Hz), 131.99 [d, J(P,C)
=
(d, JP,C = 2.6 Hz), 29.05 (d, JP,C = 33.1 Hz), 30.93, 34.13 (d, JP,C
=
12.4 Hz), 125.78 (d, JP,C = 48.0 Hz), 128.35 (d, JP,C = 9.8 Hz),
131.18 (d, JP,C = 2.6 Hz), 133.35 (d, JP,C = 8.3 Hz) ppm. 31P NMR
(162 MHz, CDCl3): δ = 30.90 ppm. C14H25BBrP (315.04): calcd. C
53.37, H 8.00; found C 53.30, H 7.88.
=
=
=
10.0 Hz] ppm. 31P NMR (162 MHz, CDCl3): δ = 13.83 ppm. GC
(Phenomenex Zebron ZB-35HT INFERNO): RT = 19.01 min. GC-
MS (EI, 70 eV): m/z (%) = 262 (16) [M]+·, 233 (11), 200 (25), 199
(100), 183 (52), 158 (15), 121 (15), 107 (22), 91 (31). C14H17BClP
(262.52): calcd. C 64.05, H 6.53; found C 65.30, H 6.35.
General Procedure for in situ Birch Reduction/Alkylation of Aryl-
phosphane-Boranes: Gaseous ammonia was passed through a
flame-dried three-necked flask (100 mL) fitted with inert gas inlet,
dry-ice condenser and cooling bath (–78 °C) until 15 mL of it was
condensed. The alkali metal (2.5 equiv.) was added and the mixture
was stirred for 15 min. The phosphane–borane (1 equiv.) was then
added, followed after 5 min by the electrophile (2–2.5 equiv.), and
the mixture was allowed to stir at –78 °C for 30 min. The reaction
was quenched by addition of solid NH4Cl (0.5 g), ammonia was
evaporated off, the residue was filtered, the solid was washed with
CH2Cl2 (3ϫ15 mL), and the collected organic phases were concen-
trated under reduced pressure. The residue was purified by column
chromatography on silica gel with hexane/EtOAc (6:1) as an eluent.
(3-Bromopropyl)diphenylphosphane–Borane (9): This compound
was prepared as described for compound 7 with triphenylphos-
phane–borane (2.76 g, 10 mmol), sodium (0.506, 22 mmol) and 1,3-
dibromopropane (1.614 mL, 10 mmol). Yield 1.573 g (49%). Pale
orange pasty solid. RF = 0.40 (hexane/EtOAc 6:1). 1H NMR
(400 MHz, CDCl3): δ = 0.39–1.63 (m, 3 H), 1.98–2.19 (m, 2 H),
2.33–2.47 (m, 2 H), 3.46 (t, JH,H = 6.22 Hz, 2 H) 7.41–7.54 (m, 6
H), 7.67–7.76 (m, 4 H) ppm. 13C NMR (125 MHz, CDCl3): δ =
24.42 (d, JP,C = 37.5 Hz), 26.28 (d, JP,C = 1.8 Hz), 34.27 (d, JP,C
=
tert-Butylmethyl(3-methylcyclohexa-1,4-dien-3-yl)phosphane–
Borane (1a): This compound was prepared by the General Pro-
cedure from 1 (0.097 g, 0.5 mmol), potassium (0.049 g, 1.25 mmol)
15.4 Hz), 128.85 (d, JP,C = 55.4 Hz), 128.90 (d, JP,C = 10.0 Hz),
131.34 (d, JP,C = 2.7 Hz), 132.05 (d, JP,C = 9.1 Hz) ppm. 31P NMR
2526
www.eurjoc.org
© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2012, 2521–2534

In Situ Dearomatisation/Alkylation of Arylphosphanes
and methyl iodide (0.078 mL, 1.25 mmol). Yield 0.096 g (91 %). 5.58–5.67 (m, 2 H), 5.84–5.93 (m, 2 H) ppm. 13C NMR (75 MHz,
Colourless oil. RF = 0.65 (hexane/EtOAc 6:1). 1H NMR (300 MHz,
CDCl3): δ = 21.49 (d, JP,C = 33.3 Hz), 23.97 (d, JP,C = 3.7 Hz),
CDCl3): δ = –0.15 to 0.93 (br. m, 3 H, BH3), 1.18 (d, JP,H = 8.3 Hz, 26.51 (d, JP,C = 4.3 Hz), 27.33, 35.01 (d, JP,C = 28.2 Hz), 126.15 (d,
3 H), 1.21 (d, JP,H = 13.0 Hz, 9 H), 1.39 (d, JP,H = 13.9 Hz, 3 H), JP,C = 7.5 Hz), 127.40 (d, JP,C = 3.7 Hz) ppm. 31P NMR (202 MHz,
2.54–2.65 (m, 2 H), 5.62–5.83 (m, 4 H) ppm. 13C NMR (75 MHz,
CDCl3): δ = 51.20 ppm. GC (Phenomenex Zebron ZB-35 HT In-
CDCl3): δ = 3.05 (d, JP,C = 33.9 Hz), 26.07 (d, JP,C = 3.7 Hz), 26.24 ferno): RT = 10.63 min. GC-MS (EI, 70 eV): m/z (%) = 93 (100),
(d, JP,C = 2.3 Hz), 127.13 (d, JP, C = 1.2 Hz), 31.21 (d, JP, C
26.7 Hz), 37.28 (d, JP,C = 28.7 Hz), 124.69 (d, JP,C = 7.8 Hz), 124.79
(d, JP,C = 6.6 Hz), 129.00 (d, JP,C = 3.7 Hz), 129.04 (d, JP, C
=
92 (23), 91 (91), 89 (22), 88 (94), 87 (15). C11H20BP (194.06): calcd.
C 68.08, H 10.39; found C 67.84, H 10.10.
=
1-Methylphospholane–Borane (4aЈ): This compound was prepared
by the General Procedure from 4 (0.089 g, 0.5 mmol), sodium
(0.029 g, 1.25 mmol) and methyl iodide (0.078 mL, 1.25 mmol).
Yield 0.027 g (46%). Colourless oil. RF = 0.54 (hexane/EtOAc 6:1).
1H NMR (500 MHz, CDCl3): δ = 0.23–0.92 (br. m, 3 H), 1.33 (d,
JP,H = 10.7 Hz), 1.64–1.77 (m, 2 H), 1.79–1.95 (m, 6 H) ppm. 13C
NMR (125 MHz, CDCl3): δ = 11.75 (d, JP,C = 31.8 Hz), 25.60 (d,
JP,C = 36.3 Hz), 26.81 ppm. 31P NMR (202 MHz, CDCl3): δ =
5.8 Hz) ppm. 31P NMR (121.5 MHz, CDCl3): δ = 39.86 ppm. GC
(Phenomenex Zebron ZB-35 HT Inferno): RT = 7.07 min. GC-MS
(EI, 70 eV): m/z (%) = 104 (31), 93 (73), 92 (14), 91 (52), 77 (30), 65
(10), 57 (100). C12H24BP (210.10): calcd. C 68.60, H 11.51; found C
68.84, H 11.80.
Benzyl-tert-butyl-(3-methylcyclohexa-1,4-dien-3-yl)phosphane–
Borane (2a): This compound was prepared by the General Pro-
cedure from 2 (0.135 g, 0.5 mmol), sodium (0.029 g, 1.25 mmol)
and methyl iodide (0.078 mL, 1.25 mmol). It was isolated as a mix-
23.56 ppm. GC (Phenomenex Zebron ZB-35 HT Inferno): RT
=
8.07 min. GC-MS (EI, 70 eV): m/z (%) = 115 (17) [M], 113 (16),
ture with 1, yield 21% (based on NMR). RF = 0.67 (hexane/EtOAc
6:1). H NMR (500 MHz, CDCl3): δ = –0.16 to 1.21 (br. m, 3 H), 51.79, H 12.17; found C 51.94, H 12.00.
1.20 (d, JP,H = 12.5 Hz, 9 H), 1.37 (d, JP,H = 13.6 Hz), 2.65–2.76
102 (100), 101 (30), 99 (21), 85 (10). C5H14BP (115.95): calcd. C
1
Dimethylphenylphosphane–Borane (3): This compound was pre-
(m, 2 H), 2.99–3.10 (m, 1 H), 3.23–3.37 (m, 1 H), 5.78–5.96 (m, 4
pared by the General Procedure from 5 (0.107 g, 0.5 mmol), sodium
(0.029 g, 1.25 mmol) and methyl iodide (0.078 mL, 1.25 mmol).
Yield 0.065 g (86%). The analytical data are in accordance with
those reported in the literature.[27]
H), 7.20–7.30 (m, 3 H), 7.39–7.45 (m, 2 H) ppm. 13C NMR
(125 MHz, CDCl3): δ = 26.27 (d, JP,C = 1.8 Hz), 26.95 (d, JP,C
=
1.8 Hz), 27.93, 29.94 (d, JP,C = 30.9 Hz), 33.16 (d, JP,C = 22.7 Hz),
39.05 (d, JP,C = 26.3 Hz), 124.63 (d, JP,C = 7.3 Hz), 125.00 (d, JP,C
= 6.4 Hz), 126.53 (d, JP,C = 1.8 Hz), 128.04 (d, JP,C = 1.8 Hz),
129.53 (d, JP,C = 3.6 Hz), 129.58 (d, JP,C = 3.6 Hz), 130.60 (d, JP,C
= 3.6 Hz), 132.97 (d, JP,C = 5.5 Hz) ppm. 31P NMR (202 MHz,
CDCl3): δ = 46.94 ppm. GC (Phenomenex Zebron ZB-35 HT In-
ferno): RT = 14.15 min. GC-MS (EI, 70 eV): m/z (%) = 272 (11)
[M – BH3], 258 (3), 216 (4), 215 (4), 125 (49), 123 (12), 122 (12),
109 (8), 105 (9), 93 (34), 92 (10), 91 (100).
(3-Benzylcyclohexa-1,4-dien-3-yl)-tert-butylmethylphosphane–
Borane (1b): This compound was prepared by the General Pro-
cedure from 1 (0.097 g, 0.5 mmol), potassium (0.049 g, 1.25 mmol)
and benzyl chloride (0.126 mL, 1 mmol). Yield 0.106 g (74%).
Colourless pasty solid. RF = 0.54 (hexane/EtOAc 6:1). 1H NMR
(300 MHz, CDCl3): δ = –0.19 to 0.89 (br. m, 3 H), 1.20 (d, JP,H
=
12.9 Hz, 9 H), 1.21 (d, JP,H = 10.1 Hz, 3 H), 2.00–2.43 (m, 2 H),
2.86–3.17 (dd, JH,H = 5.8 Hz, JP,H = 13.0 Hz, 2 H), 5.60–5.69 (m,
3 H), 5.77–5.85 (m, 1 H), 7.06–7.14 (m, 3 H), 7.15–7.26 (m, 2
H) ppm. 13C NMR (75 MHz, CDCl3): δ = 3.28 (d, JP,C = 33.9 Hz),
tert-Butylmethylphenylphosphane–Borane (1): This compound was
prepared by the General Procedure from 2 (0.135 g, 0.5 mmol), so-
dium (0.029 g, 1.25 mmol) and methyl iodide (0.078 mL,
1.25 mmol). It was isolated as a mixture with 2a, yield 45% (based
on NMR). The analytical data are in accordance with those re-
ported in the literature.[30]
25.83 (d, JP,C = 4.6 Hz), 27.35 (d, JP,C = 1.7 Hz), 31.70 (d, JP,C
=
26.4 Hz), 42.39 (d, JP,C = 5.2 Hz), 42.80 (d, JP,C = 27.6 Hz), 126.56,
126.66 (d, JP,C = 6.9 Hz), 126.91 (d, JP,C = 7.5 Hz), 128.16 (d, JP,C
= 9.8 Hz), 128.27 (d, JP,C = 2.3 Hz), 129.97 (d, JP,C = 4.0 Hz),
Dimethyl(3-methylcyclohexa-1,4-dien-3-yl)phosphane–Borane (3a): 132.76 (d, JP,C = 8.6 Hz), 132.89 (d, JP,C = 5.2 Hz) ppm. 31P NMR
This compound was prepared by the General Procedure from 3
(0.076 g, 0.5 mmol), sodium (0.029 g, 1.25 mmol) and methyl iod-
ide (0.078 mL, 1.25 mmol). Yield 0.041 g (49%). Colourless solid;
m.p. 48.8–50.1 °C. RF = 0.60 (hexane/EtOAc 6:1). 1H NMR
(161.5 MHz, CDCl3): δ = 40.28 ppm. GC (Phenomenex Zebron
ZB-35 HT Inferno): RT = 11.74 min. GC-MS (EI, 70 eV): m/z (%)
= 169 (13), 168 (97), 167 (100), 153 (28), 152 (28), 141 (4), 139 (4),
128 (4), 115 (8), 91 (28), 89 (10), 83 (14), 65 (16), 63 (11). C18H28BP
(286.20): calcd. C 75.54, H 9.86; found C 75.50, H 9.99.
(300 MHz, CDCl3): δ = –0.12 to 1.06 (br. m, 3 H), 1.12 (d, JP,H
=
9.9 Hz, 6 H), 1.26 (d, JP,H = 15.6 Hz, 3 H), 2.51–2.72 (m, 2 H),
5.48–5.57 (m, 2 H), 5.79–5.88 (m, 2 H) ppm. 13C NMR (125 MHz,
CDCl3): δ = 7.04 (d, JP,C = 36.3 Hz), 22.84 (d, JP,C = 3.6 Hz), 26.40
tert-Butyl(1,2-diphenylethyl)phenylphosphane–Borane (2b): This
compound was prepared by the General Procedure from 2 (0.135 g,
0.5 mmol), sodium (0.029 g, 1.25 mmol) and benzyl chloride
(0.126 mL, 1 mmol). Yield 0.092 g (51%). White solid; m.p. 109.4–
110.8 °C. RF = 0.86 (hexane/EtOAc 6:1). 1H NMR (500 MHz,
CDCl3): δ = 0.33–1.05 (m, 3 H), 0.87 (d, JP,H = 13.6 Hz, 9 H),
2.76–2.83 (m, 1 H), 3.12–3.19 (m, 1 H), 3.79–3.87 (m, 1 H), 6.64–
6.68 (m, 2 H), 7.05–7.09 (m, 3 H), 7.10–7.38 (m, 5 H), 7.58–7.62
(m, 3 H), 8.06–8.11 (m, 2 H) ppm. 13C NMR (CDCl3, 125 MHz):
δ = 26.01 (d, JP,C = 1.8 Hz), 30.96 (d, JP,C = 28.2 Hz), 39.21 (d,
(d, JP,C = 4.5 Hz), 34.83 (d, JP, C = 34.5 Hz), 126.45 (d, JP, C
=
7.3 Hz), 126.85 (d, JP,C = 3.6 Hz) ppm. 31P NMR (202 MHz,
CDCl3): δ = 22.48 ppm. GC (Phenomenex Zebron ZB-35 HT In-
ferno): RT = 10.63 min. GC-MS (EI, 70 eV): m/z (%) = 167 (2)
[M – 1], 153 (5), 140 (7), 139 (8), 126 (4), 93 (100), 92 (30), 91 (78),
89 (15). C9H18BP (168.02): calcd. C 64.33, H 10.80; found C 64.44,
H 10.64.
1-(3-Methylcyclohexa-1,4-dien-3-yl)phospholane–Borane (4a): This
compound was prepared by the General Procedure from 4 (0.089 g,
JP,C = 4.5 Hz), 42.31 (d, JP,C = 26.3 Hz), 126.08, 127.42 (d, JP,C
9.2 Hz), 127.43 (d, JP,C = 1.7 Hz), 127.50 (d, JP, C = 46.6 Hz),
=
0.5 mmol), sodium (0.029 g, 1.25 mmol) and methyl iodide 127.97, 128.10 (d, JP,C = 9.5 Hz), 128.55 (d, JP,C = 9.2 Hz), 128.56,
(0.078 mL, 1.25 mmol). Yield 0.041 g (42%). Colourless solid; m.p.
41.4–42.2 °C. RF = 0.58 (hexane/EtOAc 6:1). 1H NMR (300 MHz,
CDCl3): δ = –0.10 to 1.10 (br. m, 3 H), 1.29 (d, JH,P = 15.4 Hz, 3
H), 1.71–1.89 (m, 4 H), 1.96–2.16 (m, 4 H), 2.66–2.78 (m, 2 H),
131.29 (d, JP,C = 2.9 Hz), 136.86, 139.40 (d, JP,C = 12.9 Hz) ppm.
31P NMR (161.5 MHz, CDCl3): δ = 39.73 ppm. GC (Phenomenex
Zebron ZB-35 HT Inferno): RT = 12.55 min. GC-MS (EI, 70 eV):
m/z (%) = 346 (12) [M – BH3], 345 (10), 290 (6), 255 (7), 199 (13),
Eur. J. Org. Chem. 2012, 2521–2534
© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
2527

M. Stankevicˇ, K. Wójcik, M. Jaklin´ska, K. M. Pietrusiewicz
FULL PAPER
182 (15), 181 (100), 180 (24), 179 (11), 167 (17), 166 (32), 165 (25),
(3-Benzylcyclohexa-1,4-dien-3-yl)methylphenylphosphane–Borane
121 (17), 110 (14), 109 (29), 103 (34), 91 (24). C24H30BP (360.28): (5b): This compound was prepared by the General Procedure from
calcd. C 80.01, H 8.39; found C 79.75, H 8.50.
5 (0.107 g, 0.5 mmol), sodium (0.029 g, 1.25 mmol) and benzyl
chloride (0.126 mL, 1 mmol). It was isolated as a mixture with 5bЈ,
yield 25% (based on NMR). RF = 0.61 (hexane/EtOAc 6:1). 1H
NMR (300 MHz, CDCl3): δ = 0.23–1.41 (br. m, 3 H), 1.60 (d, JP,H
= 9.5 Hz, 3 H), 2.23–2.34 (m, 2 H), 3.18–3.29 (m, 2 H), 5.31–5.40
(m, 1 H), 5.77–5.86 (m, 3 H), 6.96–7. 03 (m, 2 H), 7.12–7.19 (m, 3
H), 7.42–7.59 (m, 3 H), 7.74–7.82 (m, 2 H) ppm. 13C NMR
(3-Benzylcyclohexa-1,4-dien-3-yl)dimethylphosphane–Borane (3b):
This compound was prepared by the General Procedure from 3
(0.076 g, 0.5 mmol), sodium (0.029 g, 1.25 mmol) and benzyl chlor-
ide (0.126 mL, 1 mmol). Yield 0.082 g (67%). Colourless solid; m.p.
83.9–85.5 °C. RF = 0.43 (hexane/EtOAc 6:1). 1H NMR (300 MHz,
CDCl3): δ = –0.03 to 1.21 (br. m, 3 H), 1.29 (d, JP,H = 9.5 Hz, 6
H), 2.91 (d, JP,H = 7.6 Hz, 2 H), 5.52–5.61 (m, 1 H), 5.71–5.80
(m, 1 H), 7.01–7.12 (m, 3 H), 7.15–7.26 (m, 3 H) ppm. 13C NMR
(75 MHz, CDCl3): δ = 5.84 (d, JP,C = 40.2 Hz), 26.14 (d, JP,C
=
4.9 Hz), 35.90 (d, JP,C = 31.0 Hz), 40.85 (d, JP,C = 6.6 Hz), 125.32
(d, JP,C = 8.6 Hz), 125.36 (d, JP,C = 4.3 Hz), 126.16, 126.71 (d, JP,C
(125 MHz, CDCl3): δ = 7.42 (d, JP,C = 36.3 Hz), 26.21 (d, JP,C
=
= 48.0 Hz), 127.50, 128.16 (d, JP,C = 9.5 Hz), 129.69 (d, JP,C
4.3 Hz), 130.23, 131.79 (d, JP,C = 2.6 Hz), 133.40 (d, JP, C
8.1 Hz) ppm. 31P NMR (161.5 MHz, CDCl3): δ = 25.52 ppm.
=
=
4.5 Hz), 40.23 (d, JP,C = 33.6 Hz), 40.69 (d, JP,C = 5.5 Hz), 124.95
(d, JP,C = 3.6 Hz), 126.28, 127.60, 128.04 (d, JP,C = 8.2 Hz), 130.28,
136.92 (d, JP,C = 12.7 Hz) ppm. 31P NMR (161.5 MHz, CDCl3): δ
Benzylmethylphenylphosphane–Borane (5bЈ): This compound was
prepared by the General Procedure from 5 (0.107 g, 0.5 mmol), so-
dium (0.029 g, 1.25 mmol) and benzyl chloride (0.126 mL,
1 mmol). It was isolated as a mixture with 5b, yield 60% (based on
NMR). RF = 0.55 (hexane/EtOAc 6:1). 1H NMR (300 MHz,
CDCl3): δ = 0.23–1.41 (br. m, 3 H), 1.52 (d, JP,H = 9.8 Hz, 3 H),
2.59–2.68 (m, 2 H), 6.90–6.95 (m, 2 H), 7.21–7.26 (m, 3 H), 7.39–
7.60 (m, 5 H) ppm. 13C NMR (75 MHz, CDCl3): δ = 8.89 (d, JP,C
= 39.1 Hz), 41.99 (d, JP,C = 31.0 Hz), 126.55 (d, JP,C = 2.9 Hz),
128.19 (d, JP,C = 8.9 Hz), 128.24 (d, JP,C = 2.0 Hz), 128.32 (d, JP,C
= 4.9 Hz), 128.55 (d, JP,C = 10.1 Hz), 131.34 (d, JP,C = 2.6 Hz),
131.74 (d, JP,C = 9.2 Hz), 131.95 (d, JP,C = 46.3 Hz) ppm. 31P NMR
(161.5 MHz, CDCl3): δ = 10.69 ppm. GC (Phenomenex Zebron
ZB-5MSI): RT = 8.85 min. GC-MS (EI, 70 eV): m/z (%) = 214 (26)
[M – BH3], 213 (30), 167 (4), 123 (37), 121 (34), 107 (9), 91 (100),
79 (11), 77 (21).
= 22.94 ppm. GC (Phenomenex Zebron ZB-35 HT Inferno): RT
=
8.78 min. GC-MS (EI, 70 eV): m/z (%) = 168 (10), 167 (12), 153
(5), 152 (5), 91 (100), 65 (17). C15H22BP (244.12): calcd. C 73.80,
H 9.08; found C 73.52, H 8.81.
Benzyldimethylphosphane–Borane (3bЈ): This compound was pre-
pared by the General Procedure from 3 (0.076 g, 0.5 mmol), sodium
(0.029 g, 1.25 mmol) and benzyl chloride (0.126 mL, 1 mmol). It
was isolated as a mixture with 3, yield 30% (based on NMR). RF
= 0.47 (hexane/EtOAc 6:1). 1H NMR (300 MHz, CDCl3): δ = –0.11
to 1.06 (br. m, 3 H), 1.13 (d, JP,H = 10.4 Hz, 6 H), 2.95 (d, JP,H
=
10.5 Hz, 2 H), 7.03–7.10 (m, 2 H), 7.15–7.29 (m, 3 H) ppm. 13C
NMR (75 MHz, CDCl3): δ = 10.14 (d, JP,C = 37.6 Hz), 34.29 (d,
JP,C = 31.0 Hz), 126.99 (d, JP,C = 2.9 Hz), 128.59 (d, JP,C = 2.6 Hz),
129.38 (d, JP,C = 4.0 Hz), 132.51 (d, JP,C = 8.1 Hz) ppm. 31P NMR
(121 MHz, CDCl3): δ = 5.86 ppm. GC (Phenomenex Zebron ZB-
35 HT Inferno): RT = 11.74 min. GC-MS (EI, 70 eV): m/z (%) =
152 (25) [M – BH3], 109 (5), 91 (100), 65 (20).
Benzyl-tert-butyl(cyclohexa-1,4-dien-3-yl)phosphane–Borane (2c):
This compound was prepared by the General Procedure from 2
(0.135 g, 0.5 mmol), sodium (0.029 g, 1.25 mmol) and cyclohexyl
bromide (0.123 mL, 1 mmol). Yield 0.029 g (21%). The data are in
accordance with those reported in the literature.[25]
1-(3-Benzylcyclohexa-1,4-dien-3-yl)phospholane–Borane (4b): This
compound was prepared by the General Procedure from 4 (0.089 g,
0.5 mmol), sodium (0.029 g, 1.25 mmol) and benzyl chloride
(0.126 mL, 1 mmol). Yield 0.124 g (92%). Colourless solid; m.p.
87.4–88.7 °C. RF = 0.67 (hexane/EtOAc 6:1). 1H NMR (300 MHz,
CDCl3): δ = 0.03–1.24 (br. m, 3 H), 1.54–1.82 (m, 6 H), 1.87–2.07
(m, 2 H), 2.31–2.58 (m, 2 H), 2.97 (d, JP,H = 9.1 Hz, 2 H), 5.56–
5.63 (m, 2 H), 5.71–5.79 (m, 2 H), 7.04–7.19 (m, 5 H) ppm. 13C
tert-Butylphenylphosphane–Borane (2cЈ): This compound was pre-
pared by the General Procedure from 2 (0.135 g, 0.5 mmol), sodium
(0.029 g, 1.25 mmol) and cyclohexyl bromide (0.123 mL, 1 mmol).
Yield 0.032 g (35%). The data are in accordance with those re-
ported in the literature.[39]
NMR (75 MHz, CDCl3): δ = 21.88 (d, JP,C = 33.3 Hz), 26.32 (d, (Cyclohexa-1,4-dien-3-yl)dimethylphosphane–Borane (3c): This
JP,C = 4.6 Hz), 27.21 (d, JP,C = 0.9 Hz), 40.43 (d, JP,C = 26.4 Hz), compound was prepared by the General Procedure from 3 (0.076 g,
42.20 (d, JP,C = 5.8 Hz), 125.55 (d, JP,C = 4.3 Hz), 126.33, 127.51
0.5 mmol), sodium (0.029 g, 1.25 mmol) and cyclohexyl bromide
(0.123 mL, 1 mmol). Yield 0.039 g (51%). The data are in accord-
(d, JP,C = 7.8 Hz), 127.64, 130.35, 136.70 (d, JP,C = 11.2 Hz) ppm.
31P NMR (161.5 MHz, CDCl3): δ = 51.15 ppm. C17H24BP ance with those reported in the literature.[25]
(270.16): calcd. C 75.58, H 8.95; found C 75.75, H 8.96.
1-(Cyclohexa-1,4-dien-3-yl)phospholane–Borane (4c): This com-
pound was prepared by the General Procedure from 4 (0.089 g,
0.5 mmol), sodium (0.029 g, 1.25 mmol) and cyclohexyl bromide
(0.123 mL, 1 mmol). Yield 0.042 g (47%). The data are in accord-
ance with those reported in the literature.[25]
1-Benzylphospholane–Borane (4bЈ): This compound was prepared
by the General Procedure from 4 (0.089 g, 0.5 mmol), sodium
(0.029 g, 1.25 mmol) and benzyl chloride (0.126 mL, 1 mmol). It
was isolated as a mixture with starting material, yield 30% (based
on NMR). RF = 0.60 (hexane/EtOAc 6:1). 1H NMR (300 MHz,
CDCl3): δ = –0.03 to 1.21 (br. m, 3 H), 1.55–1.84 (m, 8 H), 3.00
(d, JP,H = 10.70 Hz, 2 H), 7.04–7.14 (m, 3 H), 7.23–7.32 (m, 2
Methylphenylphosphane–Borane (5c): This compound was prepared
by the General Procedure from 5 (0.107 g, 0.5 mmol), sodium
(0.029 g, 1.25 mmol) and cyclohexyl bromide (0.123 mL, 1 mmol).
It was isolated as a mixture with starting material, yield 45 %
(based on NMR). RF = 0.65 (hexane/EtOAc 6:1). 1H NMR
H) ppm. 13C NMR (75 MHz, CDCl3): δ = 23.20 (d, JP, C
37.4 Hz), 27.49 (d, JP,C = 1.4 Hz), 33.06 (d, JP,C = 24.7 Hz), 126.95
(d, JP,C = 2.9 Hz), 128.65 (d, JP,C = 2.6 Hz), 129.38 (d, JP, C
=
=
(300 MHz, CDCl3): δ = 0.15–1.29 (br. m, 3 H), 1.53 (dd, JH,H =
4.0 Hz), 131.33 (d, JP,C = 8.9 Hz) ppm. 31P NMR (121 MHz,
CDCl3): δ = 32.92 ppm. GC (Phenomenex Zebron ZB-35HT IN-
FERNO): RT = 7.25 min. GC-MS (EI, 70 eV): m/z (%) = 178 (18)
[M – BH3], 150 (16), 92 (11), 91 (100), 65 (23).
6.0 Hz, JP,H = 11.2 Hz), 5.48 (dm, JP,H = 371.3 Hz, 1 H), 7.31–7.48
(m, 3 H), 7.55–7.67 (m, 2 H) ppm. 13C NMR (75 MHz, CDCl3): δ
= 8.03 (d, JP,C = 38.8 Hz), 126.29 (d, JP,C = 56.9 Hz), 128.90 (d,
JP,C = 10.4 Hz), 131.51 (d, JP,C = 2.9 Hz), 132.13 (d, JP, C
=
2528
www.eurjoc.org
© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2012, 2521–2534

In Situ Dearomatisation/Alkylation of Arylphosphanes
9.2 Hz) ppm. 31P NMR (121.5 MHz, CDCl3): δ = –15.47 ppm. GC
(Phenomenex Zebron ZB-35HT INFERNO): RT = 5.99 min. GC-
MS (EI, 70 eV): m/z (%) = 124 (100) [M – BH3], 121 (12), 109 (80),
108 (59), 107 (31), 91 (9), 83 (12), 81 (10.).
0.079 g (56%). Colourless oil. RF = 0.31 (hexane/EtOAc 6:1). 1H
NMR (400 MHz, CDCl3): δ = 0.02–1.05 (m, 3 H), 1.18 (t, JH,H
7.0 Hz, 3 H), 1.21 (d, JP,H = 9.1 Hz, 3 H), 1.24 (d, JP,H = 13.1 Hz,
9 H), 2.61–2.75 (m, 2 H), 2.77–2.82 (m, 2 H), 4.05 (q, JH,H
=
=
7.0 Hz, 3 H), 5.75–5.81 (m, 1 H), 5.88–5.96 (m, 3 H) ppm. 13C
NMR (75 MHz, CDCl3): δ = 3.22 (d, JP,C = 34.8 Hz), 14.21, 26.27
(d, JP,C = 4.6 Hz), 27.37 (d, JP,C = 1.4 Hz), 31.82 (d, JP,C = 24.7 Hz),
40.71 (d, JP,C = 27.9 Hz), 42.16 (d, JP,C = 6.0 Hz), 60.34, 126.11 (d,
JP,C = 4.6 Hz), 126.17 (d, JP,C = 4.3 Hz), 126.74 (d, JP,C = 7.2 Hz),
127.09 (d, JP,C = 7.5 Hz), 169.84 (d, JP,C = 18.1 Hz) ppm. 31P NMR
(162 MHz, CDCl3): δ = 42.67 ppm. C15H28BO2P (282.17): calcd. C
63.85, H 10.00; found C 63.75, H 9.82.
tert-Butyl(3-cyanomethyl-cyclohexa-1,4-dien-3-yl)methylphosphane–
Borane (1d): This compound was prepared by the General Pro-
cedure from 1 (0.097 g, 0.5 mmol), potassium (0.049 g, 1.25 mmol)
and chloroacetonitrile (0.063 mL, 1 mmol). Yield 0.079 g (67%).
White solid; m.p. 93–94 °C. RF = 0.27 (hexane/EtOAc 6:1). 1H
NMR (400 MHz, CDCl3): δ = –0.04 to 0.89 (br. m, 3 H), 1.21 (d,
JP,H = 13.7 Hz, 9 H), 1.25 (d, JP,H = 9.0 Hz, 3 H), 2.62–2.72 (m, 1
H), 2.74–2.81 (m, 1 H), 2.84–2.90 (m, 1 H), 2.91–2.98 (m, 1 H),
5.66–5.72 (m, 1 H), 5.79–5.85 (m, 1 H), 6.07–6.14 (m, 1 H) ppm.
13C NMR (75 MHz, CDCl3): δ = 3.39 (d, JP,C = 33.9 Hz), 26.29
(d, JP,C = 3.2 Hz), 26.94 (d, JP,C = 1.4 Hz), 28.35 (d, JP,C = 10.4 Hz),
31.59 (d, JP,C = 27.0 Hz), 38.98 (d, JP,C = 28.5 Hz), 116.51 (d, JP,C
= 16.4 Hz), 124.07 (d, JP,C = 4.6 Hz), 124.26 (d, JP,C = 2.3 Hz),
129.11 (d, JP,C = 7.2 Hz), 129.58 (d, JP,C = 6.0 Hz) ppm. 31P NMR
(162 MHz, CDCl3): δ = 41.13 ppm. GC (Phenomenex Zebron ZB-
35HT INFERNO): RT = 9.43 min. GC-MS (EI, 70 eV): m/z (%) =
117 (100), 116 (42), 90 (58), 89 (32), 63 (15), 51 (17). C13H23BNP
(235.11): calcd. C 66.41, H 9.86; found C 66.53, H 9.91.
tert-Butylmethyl[3-(prop-2-enyl)cyclohexa-1,4-dien-3-yl]phos-
phane–Borane (1h): This compound was prepared by the General
Procedure from 1 (0.097 g, 0.5 mmol), potassium (0.049 g,
1.25 mmol) and allyl chloride (0.082 mL, 1 mmol). It was isolated
as a mixture with starting material, yield 35% (based on NMR).
1
RF = 0.65 (hexane/EtOAc 6:1). H NMR (300 MHz, CDCl3): δ =
–0.16 to 0.92 (br. m, BH3), 1.17 (d, J = 12.9 Hz, 9 H), 1.25 (d, JP,H
= 9.7 Hz, 3 H), 1.88–2.03 (m, 2 H), 2.04–2.27 (m, 2 H), 4.99–5.03
(m, 2 H), 5.47–6.05 (m, 5 H) ppm. 13C NMR (75 MHz, CDCl3): δ
= 3.24 (d, JP,C = 34.5 Hz), 25.50 (d, JP,C = 2.7 Hz), 26.35 (d, JP,C
= 3.6 Hz), 31.64 (d, JP,C = 26.3 Hz), 33.79 (d, JP,C = 10.0 Hz), 41.50
(d, JP,C = 28.2 Hz), 117.01, 123.21 (d, JP,C = 5.5 Hz), 123.65 (d,
JP,C = 8.2 Hz), 126.54 (d, JP,C = 8.2 Hz), 126.71 (d, JP,C = 4.5 Hz),
133.93 (d, JP,C = 11.8 Hz) ppm. 31P NMR (121.5 MHz, CDCl3): δ
= 40.12 ppm. GC (Phenomenex Zebron ZB-5MSI): RT = 8.44 min.
GC-MS (EI, 70 eV): m/z (%) = 222 (8) [M – BH3], 221 (7), 125
(42), 123 (10), 109 (14), 103 (100), 91 (10), 79 (13), 77 (12).
tert-Butylmethyl[3-(2-phenylethyl)cyclohexa-1,4-dien-3-yl]phos-
phane–Borane (1e): This compound was prepared by the General
Procedure from 1 (0.097 g, 0.5 mmol), potassium (0.049 g,
1.25 mmol) and 2-phenylethyl bromide (0.137 mL, 1 mmol). Yield
0.113 g (75%). Colourless oil. RF = 0.75 (hexane/EtOAc 6:1). 1H
NMR (400 MHz, CDCl3): δ = 0.06–1.03 (br. m, 3 H), 1.20 (d, JP,H
= 9.3 Hz, 3 H), 1.23 (d, JP,H = 12.8 Hz, 9 H), 1.93–2.03 (m, 1 H),
2.12–2.22 (m, 1 H), 2.43–2.56 (m, 2 H), 2.68–2.81 (m, 2 H), 5.68–
5.74 (m, 1 H), 5.80–5.86 (m, 1 H), 5.95–6.01 (m, 2 H), 7.13–7.18
(m, 3 H), 7.18–7.25 (m, 2 H) ppm. 13C NMR (100 MHz, CDCl3):
δ = 3.14 (d, JP,C = 34.0 Hz), 26.41 (d, JP,C = 4.2 Hz), 27.36, 31.19
(d, JP,C = 8.8 Hz), 31.63 (d, JP,C = 26.3 Hz), 37.60 (d, JP,C = 3.4 Hz),
41.85 (d, JP,C = 28.2 Hz), 125.75, 127.04 (d, JP,C = 3.1 Hz), 127.13,
127.20 (d, JP,C = 8.0 Hz), 128.31, 128.38 ppm. 31P NMR (162 MHz,
CDCl3): δ = 38.93 ppm. GC (Phenomenex Zebron ZB-5MSI): RT
= 11.13 min. GC-MS (EI, 70 eV): m/z (%) = 182 (15), 165 (15), 91
(100). C19H30BP (300.23): calcd. C 76.01, H 10.07; found C 76.12,
H 9.98.
tert-Butylmethyl[3-(but-3-enyl)-cyclohexa-1,4-dien-3-yl]phos-
phane–Borane (1i): This compound was prepared by the General
Procedure from 1 (0.097 g, 0.5 mmol), potassium (0.049 g,
1.25 mmol) and 4-bromobut-1-ene (0.051 mL, 1 mmol). Yield
0.072 g (57%). Colourless oil. RF = 0.79 (hexane/EtOAc 6:1). 1H
NMR (500 MHz, CDCl3): δ = 0.09–0.82 (br. m, 3 H), 1.19 (d, JP,H
= 9.1 Hz, 3 H), 1.22 (d, JP,H = 12.9 Hz, 9 H), 1.72–1.80 (m, 1 H),
188–1.97 (m, 3 H), 2.64–2.73 (m, 2 H), 4.91–5.01 (m, 2 H), 5.59–
5.63 (m, 1 H), 5.71–5.75 (m, 1 H), 5.77–5.84 (m, 1 H), 5.87–5.94
(m, 2 H) ppm. 13C NMR (125 MHz, CDCl3): δ = 3.13 (d, JP,C
34.5 Hz), 26.34 (d, JP,C = 4.5 Hz), 27.37 (d, JP,C = 1.8 Hz), 29.18
(d, JP,C = 10.0 Hz), 31.59 (d, JP,C = 25.4 Hz), 34.99 (d, JP, C
=
=
tert-Butylmethyl[3-(prop-2-ynyl)cyclohexa-1,4-dien-3-yl]phos-
phane–Borane (1f): This compound was prepared by the General
Procedure from 1 (0.097 g, 0.5 mmol), potassium (0.049 g,
1.25 mmol) and propargyl bromide (0.108 mL, 80 % in toluene,
1 mmol). It was isolated as a mixture with starting material, yield
3.6 Hz), 41.69 (d, JP,C = 28.2 Hz), 114.59, 126.93 (d, JP,C = 8.2 Hz),
127.03 (d, JP,C = 1.8 Hz), 138.35 ppm. 31P NMR (202 MHz,
CDCl3): δ = 39.35 ppm. C15H28BP (250.17): calcd. C 72.02, H
11.28; found C 72.30, H 11.50.
1
75% (based on NMR). RF = 0.63 (hexane/EtOAc 6:1). H NMR
{3-[(2-Bromophenyl)methyl]cyclohexa-1,4-dien-3-yl}-tert-butyl-
methylphosphane–Borane (1j): This compound was prepared by the
General Procedure from 1 (0.097 g, 0.5 mmol), potassium (0.049 g,
1.25 mmol) and 2-bromobenzyl bromide (0.250 g, 1 mmol). Yield
(400 MHz, CDCl3): δ = –0.14–1.01 (br. m, 3 H), 1.21 (d, JP,H
=
13.3 Hz, 9 H), 1.23 (d, JP,H = 9.1 Hz, 3 H), 1.95 (t, JH,H = 2.7 Hz,
1 H), 2.28–2.33 (m, 2 H), 2.70–2.75 (m, 2 H), 5.66–5.73 (m, 1 H),
5.74–5.81 (m, 1 H), 5.94–6.01 (m, 2 H) ppm. 13C NMR (125 MHz,
CDCl3): δ = 3.53 (d, JP,C = 33.6 Hz), 26.30 (d, JP,C = 3.6 Hz), 27.12
(d, JP,C = 1.8 Hz), 28.44 (d, JP,C = 8.2 Hz), 31.52 (d, JP,C = 27.3 Hz),
1
0.069 g (38%). Colourless crystals; m.p. 95.3–97.0 °C. H NMR
(400 MHz, CDCl3): δ = 0.10–1.03 (br. m, 3 H), 1.28 (d, JP,H
=
12.9 Hz, 9 H), 1.35 (d, JP,H = 9.1 Hz, 3 H), 2.08–2.21 (m, 1 H),
2.35–2.49 (m, 1 H), 3.24–3.37 (m, 2 H), 5.64–5.70 (m, 1 H), 5.74–
5.81 (m, 1 H), 5.86–5.93 (m, 1 H), 6.01–6.08 (m, 1 H), 6.99–7.04
(m, 1 H), 7.09–7.17 (m, 2 H), 7.44–7.49 (m, 1 H) ppm. 13C NMR
40.56 (d, JP,C = 28.2 Hz), 70.88 (d, JP,C = 2.7 Hz), 80.22 (d, JP,C
=
15.4 Hz), 125.89 (d, JP,C = 4.5 Hz), 127.34 (d, JP,C = 7.3 Hz) ppm.
31P NMR (162 MHz, CDCl3): δ = 41.26 ppm. GC (Phenomenex
Zebron ZB-5MSI): RT = 7.59 min. GC-MS (EI, 70 eV): m/z (%) =
220 (30) [M – BH3], 219 (6), 164 (42), 163 (52), 162 (12), 149 (17),
147 (17), 133 (13), 124 (10), 117 (37), 116 (61), 115 (100), 91 (37).
(75 MHz, CDCl3): δ = 3.31 (d, JP,C = 33.9 Hz), 25.78 (d, JP,C
4.0 Hz), 27.32 (d, JP,C = 1.2 Hz), 31.78 (d, JP,C = 26.4 Hz), 41.32
(d, JP,C = 6.3 Hz), 43.57 (d, JP, C = 28.2 Hz), 125.80 (d, JP, C
=
=
tert-Butyl[3-(ethoxycarbonylmethyl)cyclohexa-1,4-dien-3-yl]-
methylphosphane–Borane (1g): This compound was prepared by the
General Procedure from 1 (0.097 g, 0.5 mmol), potassium (0.049 g,
1.25 mmol) and ethyl bromoacetate (0.111 mL, 1 mmol). Yield
5.2 Hz), 126.18, 126.40 (d, JP,C = 2.9 Hz), 127.00 (d, JP,C = 2.3 Hz),
127.11 (d, JP,C = 1.2 Hz), 127.84, 128.19 (d, JP,C = 9.2 Hz), 132.39,
132.63, 136.26 ppm. 31P NMR (202 MHz, CDCl3): δ = 40.13 ppm.
GC (Phenomenex Zebron ZB-35HT INFERNO): RT = 14.59 min.
Eur. J. Org. Chem. 2012, 2521–2534
© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
2529

M. Stankevicˇ, K. Wójcik, M. Jaklin´ska, K. M. Pietrusiewicz
FULL PAPER
GC-MS (EI, 70 eV): m/z (%) = 228 (25), 227 (100), 197 (8), 196
(5), 166 (5), 165 (19), 133 (5), 113 (6), 91 (14). C18H27BBrP
(365.10): calcd. C 59.22, H 7.45; found C 59.40, H 7.70.
tert-Butyl{3-[4-(diphenylboranatophosphanyl)butyl]cyclohexa-1,4-
dien-3-yl}methylphosphane–Borane (13): This compound was pre-
pared by the General Procedure from 1 (0.097 g, 0.5 mmol), potas-
sium (0.049 g, 1.25 mmol) and 4-bromobutyldiphenylphosphane–
borane (10, 0.168 g, 0.5 mmol). Yield 0.092 g (39%). White waxy
solid. RF = 0.40 (hexane/EtOAc 6:1). 1H NMR (400 MHz, CDCl3):
δ = 0.00–1.00 (br. m, 6 H), 1.15 (d, JP,H = 8.8 Hz, 3 H), 1.19 (d,
JP,H = 12.9 Hz, 9 H), 1.46–1.50 (m, 2 H), 1.50–1.59 (m, 2 H), 1.60–
1.66 (m, 1 H), 1.73–1.83 (m, 1 H), 2.13–2.21 (m, 2 H), 2.59–2.67
(m, 2 H), 5.50–5.55 (m, 1 H), 5.63–5.67 (m, 1 H), 5.83–5.87 (m, 2
H), 7.40–7.50 (m, 6 H), 7.61–7.67 (m, 4 H) ppm. 13C NMR
(75 MHz, CDCl3): δ = 3.10 (d, JP,C = 35.1 Hz), 23.21, 25.73 (d, JP,C
= 37.1 Hz), 26.29 (d, JP,C = 4.3 Hz), 26.35 (d, JP,C = 9.2 Hz), 27.34
(d, JP,C = 1.2 Hz), 31.58 (d, JP,C = 26.2 Hz), 35.17 (d, JP,C = 3.5 Hz),
41.67 (d, JP,C = 28.2 Hz), 126.76 (d, JP,C = 8.1 Hz), 126.86 (d, JP,C
= 7.5 Hz), 127.03 (d, JP,C = 4.6 Hz), 127.08 (d, JP,C = 3.5 Hz),
128.75 (d, JP,C = 10.1 Hz), 127.47 (d, JP,C = 54.9 Hz), 129.52 (d,
JP,C = 54.9 Hz), 131.06 (d, JP,C = 2.3 Hz), 132.06 (d, JP,C = 8.9 Hz),
132.07 (d, JP,C = 9.2 Hz) ppm. 31P NMR (121.5 MHz, CDCl3): δ =
25.00, 38.60 ppm. GC (Phenomenex Zebron ZB-35HT IN-
FERNO): RT = 13.78 min. GC-MS (EI, 70 eV): m/z (%) = 318 (13),
289 (24), 262 (8), 213 (12), 200 (16), 199 (46), 187 (9), 186 (67),
183 (34), 152 (8), 121 (14), 109 (16), 108 (100), 107 (20), 91 (47).
C27H42B2P2 (450.19): calcd. C 72.03, H 9.40; found C 72.22, H
9.72.
[3-(2-Bromoethyl)cyclohexa-1,4-dien-3-yl]-tert-butylmethylphos-
phane–Borane (1k): This compound was prepared by the General
Procedure from 1 (0.097 g, 0.5 mmol), potassium (0.049 g,
1.25 mmol) and 1,2-dibromoethane (0.172 mL, 2 mmol). Yield
0.073 g (48%). Colourless oil. RF = 0.56 (hexane/EtOAc 6:1). 1H
NMR (400 MHz, CDCl3): δ = –0.16 to 0.90 (br. m, 3 H), 1.19 (d,
JP,H = 9.0 Hz, 3 H), 1.22 (d, JP,H = 13.2 Hz, 9 H), 2.8–2.31 (m, 1
H), 2.35–2.48 (m, 1 H), 2.62–2.73 (m, 2 H), 3.19–3.26 (m, 2 H),
5.59–5.61 (m, 1 H), 5.72–5.80 (m, 1 H), 5.91–6.00 (m, 2 H) ppm.
13C NMR (75 MHz, CDCl3): δ = 5.69 (d, JP,C = 37.9 Hz), 26.76
(d, JP,C = 4.6 Hz), 27.78 (d, JP,C = 1.4 Hz), 29.17 (d, JP,C = 11.8 Hz),
32.21 (d, JP,C = 25.9 Hz), 39.48 (d, JP,C = 5.2 Hz), 42.74 (d, JP,C
=
27.3 Hz), 126.23 (d, JP,C = 4.3 Hz), 126.28 (d, JP,C = 3.2 Hz), 128.24
(d, JP,C = 7.8 Hz), 128.40 (d, JP,C = 7.2 Hz) ppm. 31P NMR
(162 MHz, CDCl3): δ = 40.85 ppm. C13H25BBrP (303.03): calcd. C
51.53, H 8.32; found C 51.74, H 8.65.
[3-(3-Bromopropyl)cyclohexa-1,4-dien-3-yl]-tert-butylmethylphos-
phane–Borane (1l): This compound was prepared by the General
Procedure from 1 (0.097 g, 0.5 mmol), potassium (0.049 g,
1.25 mmol) and 1,3-dibromopropane (0.102 mL, 1 mmol). Yield
0.114 g (72%). Colourless solid; m.p. 57.6–59.1 °C. RF = 0.59 (hex-
ane/EtOAc 6:1). 1H NMR (400 MHz, CDCl3): δ = –0.12 to 0.54
(br. m, 3 H), 1.13 (d, JP,H = 8.8 Hz, 3 H), 1.16 (d, JP,H = 12.9 Hz,
9 H), 1.64–1.98 (m, 4 H), 2.57–2.68 (m, 2 H), 3.32 (t, JH,H = 6.5 Hz,
2 H), 5.50–5.59 (m, 1 H), 5.62–5.70 (m, 1 H), 5.80–5.90 (m, 2
H) ppm. 13C NMR (75 MHz, CDCl3): δ = 3.15 (d, JP,C = 34.5 Hz),
tert-Butyl{3-[4-(tert-butylphenylboranatophosphanyl)butyl]cyclo-
hexa-1,4-dien-3-yl}methylphosphane–Borane (14): This compound
was prepared as a mixture of diastereoisomers by the General Pro-
cedure from 1 (0.097 g, 0.5 mmol), potassium (0.049 g, 1.25 mmol)
and tert-butyl(4-bromobutyl)phenylphosphane–borane (11,
0.158 g, 0.5 mmol). It was isolated as a mixture of diastereoisomers,
yield 0.067 g (31%). Colourless oil. RF = 0.44 (hexane/EtOAc 6:1).
Major diastereoisomer: 1H NMR (500 MHz, CDCl3): δ = 0.01–
26.29 (d, JP,C = 4.0 Hz), 27.36 (d, JP,C = 1.4 Hz), 28.44 (d, JP,C
=
9.5 Hz), 31.60 (d, JP,C = 25.9 Hz), 33.78, 34.33 (d, JP,C = 4.0 Hz),
41.40 (d, JP,C = 28.4 Hz), 126.80 (d, JP,C = 4.3 Hz), 126.82 (d, JP,C
= 3.4 Hz), 127.18 (d, JP,C = 7.5 Hz), 127.28 (d, JP,C = 7.2 Hz) ppm.
31P NMR (162 MHz, CDCl3): δ = 40.07 ppm. GC (Phenomenex
Zebron ZB-5MSI): RT = 7.57 min. GC-MS (EI, 70 eV): m/z (%) =
222 (8), 221 (6), 180 (14), 166 (39), 165 (10), 138 (41), 124 (20), 118
(73), 117 (19), 115 (13), 103 (11), 91 (100). C14H27BBrP (317.05):
calcd. C 53.04, H 8.58; found C 53.30, H 8.80.
1.01 (br. m, 6 H), 1.06 (d, JP,H = 13.6 Hz, 9 H), 1.14 (d, JP,H
=
9.1 Hz, 3 H), 1.18 (d, JP,H = 12.9 Hz, 9 H), 1.19–1.29 (m, 2 H),
1.53–1.70 (m, 2 H), 1.71–1.83 (m, 3 H), 2.04–2.15 (m, 1 H), 2.59–
2.68 (m, 2 H), 5.50–5.59 (m, 1 H), 5.61–5.71 (m, 1 H), 5.82–5.90
(m, 2 H), 7.42–7.52 (m, 3 H), 7.63–7.69 (m, 2 H) ppm. 13C NMR
(125 MHz, CDCl3): δ = 3.11 (d, JP,C = 34.5 Hz), 18.70 (d, JP,C
=
tert-Butyl{3-[3-(diphenylboranatophosphanyl)propyl]cyclohexa-1,4-
dien-3-yl}methylphosphane–Borane (12): This compound was pre-
pared by the General Procedure from 1 (0.097 g, 0.5 mmol), potas-
sium (0.049 g, 1.25 mmol) and 3-bromopropyldiphenylphosphane–
borane (9, 0.161 g, 0.5 mmol). Yield 0.103 g (47%). Colourless oil.
33.6 Hz), 23.26, 25.36 (d, JP,C = 1.8 Hz), 26.26 (d, JP,C = 4.5 Hz),
26.65 (dd, JP,C = 9.1, JP,C = 13.6 Hz), 27.25 (d, JP,C = 1.8 Hz), 28.90
(d, JP,C = 32.7 Hz), 31.52 (d, JP,C = 25.4 Hz), 35.22 (d, JP, C
2.7 Hz), 41.45 (d, JP,C = 28.2 Hz), 125.94 (d, JP,C = 48.1 Hz), 126.61
(d, JP,C = 8.2 Hz), 126.78 (d, JP,C = 7.3 Hz), 126.96 (d, JP, C
4.5 Hz), 127.07 (d, JP,C = 2.7 Hz), 128.22 (d, JP,C = 9.1 Hz), 130.98
=
=
1
RF = 0.40 (hexane/EtOAc 6:1). H NMR (400 MHz, CDCl3): δ =
–0.06 to 1.81 (br. m, 6 H), 1.11 (d, JP,H = 9.2 Hz, 3 H), 1.16 (d, (d, JP,C = 3.6 Hz), 133.27 (d, JP,C = 8.2 Hz) ppm. 31P NMR
JP,H = 13.0 Hz, 9 H), 1.44–1.55 (m, 2 H), 1.66–1.76 (m, 1 H), 1.82–
1.92 (m, 1 H), 2,17–2.26 (m, 2 H), 2.55–2.63 (m, 2 H), 5.46–5.54
(m, 1 H), 5.61–5.68 (m, 1 H), 5.79–5.88 (m, 2 H), 7.39–7.51 (m, 6
H), 7.59–7.67 (m, 4 H) ppm. 13C NMR (75 MHz, CDCl3): δ = 3.07
(121.5 MHz, CDCl3): δ = 31.17, 39.10 ppm. Minor diastereoiso-
mer: 1H NMR (500 MHz, CDCl3): δ = 0.01–1.01 (br. m, 6 H), 1.06
(d, JP,H = 13.6 Hz, 9 H), 1.14 (d, JP,H = 9.1 Hz, 3 H), 1.18 (d, JP,H
= 12.9 Hz, 9 H), 1.19–1.29 (m, 2 H), 1.53–1.70 (m, 2 H), 1.71–1.83
(m, 3 H), 2.04–2.15 (m, 1 H), 2.59–2.68 (m, 2 H), 5.50–5.59 (m, 1
H), 5.61–5.71 (m, 1 H), 5.82–5.90 (m, 2 H), 7.42–7.52 (m, 3 H),
7.63–7.69 (m, 2 H) ppm. 13C NMR (125 MHz, CDCl3): δ = 2.97
(d, JP,C = 33.6 Hz), 18.56 (d, JP,C = 33.6 Hz), 23.33, 25.36 (d, JP,C
(d, JP,C = 34.5 Hz), 18.64 (d, JP,C = 10.1 Hz), 25.72 (d, JP, C
36.8 Hz), 26.25 (d, JP,C = 4.0 Hz), 27.33 (d, JP,C = 1.4 Hz), 29.43
(d, JP,C = 37.1 Hz), 31.57 (d, JP,C = 25.9 Hz), 36.86 (d, JP, C
3.5 Hz), 126.53 (d, JP,C = 4.6 Hz), 126.58 (d, JP,C = 3.7 Hz), 127.21
(d, JP,C = 7.8 Hz), 127.36 (d, JP,C = 7.5 Hz), 128.77 (d, JP, C
=
=
=
= 1.8 Hz), 26.23 (d, JP,C = 4.5 Hz), 26.90 (dd, JP,C = 10.0, JP,C =
9.8 Hz), 129.61 (d, JP,C = 54.6 Hz), 129.69 (d, JP, C = 54.9 Hz),
131.08 (d, JP,C = 2.6 Hz), 132.03 (d, JP,C = 8.9 Hz), 132.04 (d, JP,C
= 8.9 Hz) ppm. 31P NMR (121.5 MHz, CDCl3): δ = 15.20,
38.68 ppm. GC (Phenomenex Zebron ZB-35HT INFERNO): RT
= 13.07 min. GC-MS (EI, 70 eV): m/z (%) = 304 (12), 303 (20), 275
12.7 Hz), 27.37, 28.90 (d, JP,C = 32.7 Hz), 31.52 (d, JP,C = 25.4 Hz),
35.19 (d, JP,C = 4.5 Hz), 41.90 (d, JP,C = 28.2 Hz), 125.92 (d, JP,C
= 48.1 Hz), 126.90 (d, JP,C = 8.2 Hz), 127.07 (d, JP,C = 2.7 Hz),
127.11 (d, JP,C = 7.3 Hz), 127.12 (d, JP,C = 4.5 Hz), 128.23 (d, JP,C
= 9.1 Hz), 130.98 (d, JP,C = 3.6 H), 133.27 (d, JP,C = 8.2 Hz) ppm.
(8), 262 (6), 200 (38), 199 (100), 185 (8), 183 (36), 152 (8), 121 (8), 31P NMR (121.5 MHz, CDCl3): δ = 31.17, 39.10 ppm. GC (Phe-
108 (15), 107 (14), 91 (44). C26H40B2P2 (436.17): calcd. C 71.60, H
9.24; found C 71.91, H 9.50.
nomenex Zebron ZB-5MSI): RT = 16.78 min. GC-MS (EI, 70 eV):
m/z (%) = 298 (17), 200 (15), 199 (26), 166 (39), 124 (100), 110 (76),
2530
www.eurjoc.org
© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2012, 2521–2534

In Situ Dearomatisation/Alkylation of Arylphosphanes
109 (58), 108 (24), 91 (57). C25H46B2P2 (430.20): calcd. C 69.80, H
10.78; found C 70.03, H 11.03.
General Procedure from 1 (0.097 g, 0.5 mmol), potassium (0.049 g,
1.25 mmol) and o-bis(bromomethyl)benzene (0.066 g, 0.25 mmol)
as a mixture of two diastereoisomers. Yield 0.036 g (29%). White
solid; m.p. 159.7–160.8 °C. RF = 0.58 (hexane/EtOAc 6:1). 1H
NMR (400 MHz, CDCl3): δ = 0.14–1.41 (br. m, 6 H), 1.23 (d, JP,H
= 12.8 Hz, 18 H), 1.43 (d, JP,H = 9.1 Hz, 6 H), 1.81–1.94 (m, 2 H),
2.23–2.36 (m, 2 H), 2.82–2.90 (m, 2 H), 3.28–3.36 (m, 2 H), 5.58–
5.66 (m, 4 H), 5.72–5.80 (m, 2 H), 5.88–5.95 (m, 2 H), 6.89–6.99
tert-Butyl[3-(diphenylboranatophosphanyl)propyl]methylphos-
phane–Borane (15): This compound was prepared by the General
Procedure from 1 (0.097 g, 0.5 mmol), potassium (0.049 g,
1.25 mmol) and 3-bromopropyldiphenylphosphane–borane (9,
0.161 g, 0.5 mmol). Yield 0.048 g (23%). Pasty white solid. RF
0.23 (hexane/EtOAc 6:1). H NMR (400 MHz, CDCl3): δ = –0.09
to 0.80 (br. m, 6 H), 1.08 (d, JP,H = 13.5 Hz, 9 H), 1.11 (d, JP,H
=
1
(m, 4 H) ppm. 13C NMR (75 MHz, CDCl3): δ = 3.34 (d, JP,C
33.6 Hz), 25.79 (d, JP,C = 4.3 Hz), 27.32 (d, JP,C = 1.4 Hz), 31.78
=
=
9.4 Hz, 3 H), 1.55–1.72 (m, 2 H), 1.74–1.94 (m, 2 H), 2.22–2.34 (m,
2 H), 2.42–2.54 (m, 2 H), 7.41–7.53 (m, 6 H), 7.65–7.73 (m, 4
H) ppm. 13C NMR (75 MHz, CDCl3): δ = 4.97 (d, JP,C = 34.5 Hz),
17.56 (d, JP,C = 1.2 Hz), 22.27 (dd, JP,C = 10.9 Hz, JP,C = 31.0 Hz),
24.92 (d, JP,C = 2.3 Hz), 27.06 (dd, JP,C = 10.9 Hz, JP,C = 36.2 Hz),
27.24 (d, JP,C = 34.5 Hz), 128.75 (d, JP,C = 55.2 Hz), 128.86 (d, JP,C
= 9.8 Hz), 128.91 (d, JP,C = 10.4 Hz), 129.48 (d, JP,C = 55.2 Hz),
131.26 (d, JP,C = 2.3 Hz), 131.35 (d, JP,C = 2.3 Hz), 132.02 (d, JP,C
= 9.2 Hz), 132.18 (d, JP,C = 9.2 Hz) ppm. 31P NMR (162 MHz,
CDCl3): δ = 14.96, 25.24 ppm. GC (Phenomenex Zebron ZB-35HT
INFERNO): RT = 18.11 min. GC-MS (EI, 70 eV): m/z (%) = 274
(17), 273 (100), 258 (5), 185 (6), 183 (13), 139 (5), 121 (8), 91 (5), 57
(12). C20H34B2P2 (358.05): calcd. C 67.09, H 9.57; found C 67.01, H
9.90.
(d, JP,C = 26.2 Hz), 41.31 (d, JP, C = 6.3 Hz), 43.59 (d, JP, C
27.9 Hz), 125.79 (d, JP,C = 5.2 Hz), 126.18, 126.40 (d, JP, C
=
=
2.9 Hz), 127.00 (d, JP,C = 2.3 Hz), 127.11 (d, JP,C = 1.2 Hz), 127.84,
128.20 (d, JP,C = 9.2 Hz), 132.39, 132.63, 136.26 ppm. 31P NMR
(202 MHz, CDCl3): δ = 38.48 ppm. GC (Phenomenex Zebron ZB-
35HT INFERNO): RT = 16.79 min. GC-MS (EI, 70 eV): m/z (%)
= 259 (6), 258 (29), 181 (14), 180 (100), 179 (88), 178 (32); 168 (6),
167 (47), 166 (14), 165 (59), 152 (24), 115 (10), 91 (19), 89 (13).
1,2-Bis{[3-(dimethylboranatophosphanyl)cyclohexa-1,4-dien-3-
yl]methyl}benzene (19): This compound was prepared by the Gene-
ral Procedure from 3 (0.076 g, 0.5 mmol), sodium (0.029 g,
1.25 mmol) and o-bis(bromomethyl)benzene (0.066 g, 0.25 mmol).
Yield 0.044 g (43%). Colourless oil. RF = 0.27 (hexane/EtOAc 6:1).
1H NMR (500 MHz, CDCl3): δ = 0.19–0.93 (br. m, 6 H), 1.31 (d,
JP,H = 9.5 Hz, 12 H), 2.22–2.33 (m, 2 H), 2.38–2.49 (m, 2 H), 3.10
(d, JP,H = 7.3 Hz, 4 H), 5.66–5.71 (m, 4 H), 5.79–5.85 (m, 4 H),
7.01–7.05 (m, 2 H), 7.05–7.09 (m, 2 H) ppm. 13C NMR (125 MHz,
CDCl3): δ = 7.62 (d, JP,C = 36.2 Hz), 26.05 (d, JP,C = 4.5 Hz), 36.96
tert-Butyl[4-(diphenylboranatophosphanyl)butyl]methylphosphane–
Borane (16): This compound was prepared by the General Pro-
cedure from 1 (0.097 g, 0.5 mmol), potassium (0.049 g, 1.25 mmol)
and 4-bromobutyldiphenylphosphane–borane (10, 0.161 g,
0.5 mmol). Yield 0.035 g (16%). White solid; m.p. 126.7–128.3 °C.
(d, JP,C = 7.3 Hz), 40.92 (d, JP, C = 33.6 Hz), 124.66 (d, JP, C
4.5 Hz), 125.49, 128.23 (d, JP,C = 9.1 Hz), 131.35, 135.77 (d, JP,C
=
=
1
RF = 0.37 (hexane/EtOAc 6:1). H NMR (500 MHz, CDCl3): δ =
0.09–1.09 (br. m, 6 H), 1.13 (d, JP,H = 13.5 Hz, 9 H), 1.14 (d, JP,H
= 9.7 Hz, 3 H), 1.43–1.78 (m, 6 H), 2.11–2.35 (m, 2 H), 7.14–7.51
(m, 6 H), 7.61–7.70 (m, 4 H) ppm. 13C NMR (125 MHz, CDCl3):
δ = 5.09 (d, JP,C = 33.6 Hz), 20.93 (d, JP,C = 32.7 Hz), 24.94 (d,
JP,C = 6.4 Hz), 25.01 (d, JP,C = 1.8 Hz), 25.05 (d, JP,C = 4.5 Hz),
25.43 (dd, JP,C = 5.5 Hz, JP,C = 36.3 Hz), 27.21 (d, JP,C = 34.5 Hz),
128.83 (d, JP,C = 10.0 Hz), 128.87 (d, JP,C = 10.0 Hz), 129.19 (d,
13.6 Hz) ppm. 31P NMR (202 MHz, CDCl3): δ = 22.59 ppm.
C24H38B2P2 (410.26): calcd. C 70.28, H 9.34; found C 70.60, H
9.55.
General Procedure for in situ P–Ph Bond Cleavage/Alkylation of
Arylphosphane-Boranes: Gaseous ammonia was passed through a
flame-dried three-necked flask (100 mL) fitted with inert gas inlet,
dry-ice condenser and cooling bath (–78 °C) until 15 mL of it was
condensed. Potassium (6 equiv.) was added and the mixture was
stirred for 15 min. Phosphane–borane (1 equiv.) was then added,
followed after 1 h at –33 °C by tBuCl (4 equiv.) and the mixture
was cooled again and allowed to stir at –78 °C for 15 min. An elec-
trophile (2 equiv.) was added and the mixture was stirred at the
same temperature for 30 min. The reaction was quenched by ad-
dition of solid NH4Cl (0.5 g), ammonia was evaporated, the residue
was filtered, the solid was washed with CH2Cl2 (3ϫ15 mL), and
the collected organic phases were concentrated under reduced pres-
sure. The residue was purified by column chromatography on silica
gel with hexane/EtOAc (6:1) as an eluent.
JP,C = 55.2 Hz), 129.42 (d, JP, C = 55.2 Hz), 131.21 (d, JP, C
=
2.7 Hz), 131.26 (d, JP,C = 2.7 Hz), 132.00 (d, JP,C = 8.1 Hz), 132.12
(d, JP,C = 7.8 Hz) ppm. 31P NMR (202 MHz, CDCl3): δ = 15.54,
25.74 ppm. GC (Phenomenex Zebron ZB-35HT INFERNO): RT
= 13.10 min. GC-MS (EI, 70 eV): m/z (%) = 288 (18), 287 (100),
185 (7), 183 (15), 121 (5), 108 (11). C21H36B2P2 (372.08): calcd. C
67.79, H 9.75; found C 67.85, H 9.90.
1,3-Bis[3-(tert-butylmethylboranatophosphanyl)cyclohexa-1,4-dien-
3-yl]propane (17): This compound was prepared by the General
Procedure from 1 (0.097 g, 0.5 mmol), potassium (0.049 g,
1.25 mmol) and 1,3-dibromopropane (0.025 mL, 0.25 mmol) as a
mixture of two diastereoisomers. Yield 0.041 g (38%). Colourless
tert-Butylmethylphosphane–Borane (20): This compound was pre-
pared by the General Procedure from 1 (0.097 g, 0.5 mmol), potas-
sium (0.117 g, 3 mmol), tert-butyl chloride (0.217 mL, 2 mmol) and
ammonium chloride (0.5 g). Yield 0.034 g (57%). Colourless oil.
1
oil. RF = 0.78 (hexane/EtOAc 6:1). H NMR (500 MHz, CDCl3):
δ = 0.08–0.76 (br. m, 6 H), 1.16 (d, JP,H = 9.1 Hz, 6 H), 1.20 (d,
JP,H = 12.9 Hz 18 H), 1.24–1.32 (m 2 H), 1.61–1.73 (m, 2 H), 1.74–
1.86 (m, 2 H), 2.59–2.68 (m, 4 H), 5.52–5.59 (m, 2 H), 5.64–5.71
(m, 2 H), 5.83–5.90 (m, 4 H) ppm. 13C NMR (125 MHz, CDCl3):
δ = 3.07 (d, JP,C = 33.6 Hz), 3.09 (d, JP,C = 34.5 Hz), 20.17 (q, JP,C
= 9.1 Hz), 26.31 (d, JP,C = 5.5 Hz), 27.37 (d, JP,C = 1.8 Hz), 31.58
(d, JP,C = 26.3 Hz), 35.56 (d, JP,C = 3.6 Hz), 35.58 (d, JP,C = 3.5 Hz),
41.94 (d, JP,C = 28.2 Hz), 42.00 (d, JP,C = 28.2 Hz), 126.58 (d, JP,C
= 8.2 Hz), 126.61 (d, JP,C = 8.2 Hz), 126.69 (d, JP,C = 9.1 Hz),
127.16 (d, JP,C = 4.5 Hz), 127.22 (d, JP,C = 3.6 Hz), 127.26 (d, JP,C
= 3.6 Hz) ppm. 31P NMR (202 MHz, CDCl3): δ = 39.09 ppm.
1
RF = 0.73 (hexane/EtOAc 6:1). H NMR (300 MHz, CDCl3): δ =
–0.09 to 1.03 (br. m, 3 H), 1.19 (d, JP,H = 14.6 Hz, 9 H), 1.30 (dd,
JH,H = 6.1 Hz, JP,H = 10.8 Hz, 3 H), 4.39 (dm, JP,H = 355.1 Hz, 1
H) ppm. 13C NMR (75 MHz, CDCl3): δ = 2.13 (d, JP,C = 35.1 Hz),
25.96 (d, JP,C = 35.1 Hz), 26.21 (d, JP,C = 2.9 Hz) ppm. 31P NMR
(121.5 MHz, CDCl3): δ = 11.89 ppm. GC (Phenomenex Zebron
ZB-35HT INFERNO): RT = 8.12 min. GC-MS (EI, 70 eV): m/z
(%) = 117 (7) [M – 1], 105 (7), 104 (100), 89 (13). C5H16BP (117.97):
calcd. C 50.91, H 13.67; found C 51.22, H 14.01.
1,2-Bis{[3-(tert-butylmethylboranatophosphanyl)cyclohexa-1,4-
dien-3-yl]methyl}benzene (18): This compound was prepared by the
tert-Butyldimethylphosphane–Borane (21): This compound was pre-
pared by the General Procedure from 1 (0.097 g, 0.5 mmol), potas-
Eur. J. Org. Chem. 2012, 2521–2534
© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
2531

M. Stankevicˇ, K. Wójcik, M. Jaklin´ska, K. M. Pietrusiewicz
FULL PAPER
sium (0.117 g, 3 mmol), tert-butyl chloride (0.217 mL, 2 mmol) and
methyl iodide (0.062 mL, 1 mmol). Yield 0.021 g (31%). Colourless
solid; m.p. 74.5–77.1 °C (subl.). RF = 0.84 (hexane/EtOAc 6:1). 1H
(67%). White solid; m.p. 126.3–128.0 °C. RF = 0.55 (hexane/EtOAc
6:1). H NMR (300 MHz, CDCl3): δ = –0.03 to 1.21 (br. m, 3 H),
1.02 (d, JP,H = 10.0 Hz, 3 H), 1.10 (d, JP,H = 10.1 Hz, 3 H), 3.00–
1
NMR (500 MHz, CDCl3): δ = –0.11–0.77 (br. m, 3 H), 1.16 (d, 3.15 (m, 2 H), 3.27–3.40 (m, 1 H), 6.99–7.11 (m, 6 H), 7.12–7.23
JP,H = 13.6 Hz, 9 H), 1.23 (d, JP,H = 9.8 Hz, 6 H) ppm. 13C NMR (m, 4 H) ppm. 13C NMR (75 MHz, CDCl3): δ = 9.08 (d, JP,C
(125 MHz, CDCl3): δ = 7.32 (d, JP,C = 35.4 Hz), 24.78 (d, JP,C 36.2 Hz), 11.21 (d, JP,C = 37.1 Hz), 35.63 (d, JP,C = 5.2 Hz), 45.95
(d, JP,C = 29.3 Hz), 126.23, 128.19, 128.64, 127.29 (d, JP, C
=
=
2.7 Hz), 26.67 (d, JP,C = 35.4 Hz) ppm. 31P NMR (202 MHz,
CDCl3): δ = 20.25 ppm. GC (Phenomenex Zebron ZB-35HT IN-
FERNO): RT = 4.11 min. GC-MS (EI, 70 eV): m/z (%) = 118 (79)
[M – BH3], 88 (16), 74 (23), 73 (13), 63 (17), 62 (100), 61 (14), 59
(15), 57 (78). C6H18BP (131.99): calcd. C 54.60, H 13.75; found C
54.92, H 13.77.
=
2.0 Hz), 128.47 (d, JP,C = 1.7 Hz), 128.80 (d, JP,C = 4.3 Hz), 136.15
(d, JP,C = 4.9 Hz), 139.13 (d, JP,C = 12.6 Hz) ppm. 31P NMR
(121.5 MHz, CDCl3): δ = 13.41 ppm. GC (Phenomenex Zebron
ZB-35HT INFERNO): RT = 9.18 min. GC-MS (EI, 70 eV): m/z
(%) = 242 (27) [M – BH3], 241 (87), 182 (10), 181 (69), 180 (45),
179 (38), 178 (28), 167 (10), 166 (56), 165 (58), 153 (12), 152 (21),
151 (84), 139 (12), 138 (100), 123 (26), 121 (10), 115 (11), 109 (38),
104 (15), 103 (93), 102 (13), 91 (81), 89 (10). C16H22BP (256.13):
calcd. C 75.03, H 8.66; found C 75.32, H 8.70.
Benzyl-tert-butylmethylphosphane–Borane (22): This compound
was prepared by the General Procedure from 1 (0.097 g, 0.5 mmol),
potassium (0.117 g, 3 mmol), tert-butyl chloride (0.217 mL,
2 mmol) and benzyl chloride (0.126 mL, 1 mmol). Yield 0.056 g
(54 %). Colourless solid; m.p. 83.1–84.7 °C. RF = 0.79 (hexane/
EtOAc 6:1). 1H NMR (300 MHz, CDCl3): δ = –0.22 to 0.98 (br.
m, 3 H), 0.95 (d, JP,H = 9.4 Hz, 3 H), 1.13 (d, JP,H = 13.7 Hz, 9 H),
2.82–3.04 (m, 2 H), 7.11–7.27 (m, 5 H) ppm. 13C NMR (75 MHz,
CDCl3): δ = 4.58 (d, JP,C = 35.3 Hz), 25.16 (d, JP,C = 2.0 Hz), 27.75
General Procedure for in situ Birch Reduction/Alkylation of Aryl-
phosphane Oxides: Gaseous ammonia was passed through a flame-
dried three-necked flask (100 mL) fitted with inert gas inlet, dry-
ice condenser and cooling bath (–78 °C) until 15 mL of it was con-
densed. Sodium (2.5 equiv.) was added and the mixture was stirred
for 15 min. Phosphane oxide (1 equiv.) was then added, followed
after 5 min by an electrophile (2–2.5 equiv.), and the mixture was
allowed to stir at –78 °C for 15 min. The reaction was quenched by
addition of solid NH4Cl (0.5 g), ammonia was evaporated off, the
residue was filtered, the solid was washed with CH2Cl2 (3ϫ15 mL),
and the collected organic phases were concentrated under reduced
pressure. The residue was purified by column chromatography on
silica gel with CHCl3/MeOH (15:1) as an eluent.
(d, JP,C = 31.9 Hz), 28.96 (d, JP,C = 28.2 Hz), 126.81 (d, JP,C
=
2.9 Hz), 128.56 (d, JP,C = 2.6 Hz), 130.00 (d, JP,C = 3.7 Hz), 132.93
(d, JP,C = 5.5 Hz) ppm. 31P NMR (121.5 MHz, CDCl3): δ =
27.94 ppm. GC (Phenomenex Zebron ZB-35HT INFERNO): RT
= 11.02 min. GC-MS (EI, 70 eV): m/z (%) = 194 (15) [M – BH3],
138 (33), 91 (100), 57 (33). C12H22BP (208.09): calcd. C 69.26, H
10.66; found C 69.55, H 10.99.
Phospholane–Borane (23): This compound was prepared by the Ge-
neral Procedure from 4 (0.089 g, 0.5 mmol), potassium (0.117 g,
3 mmol), tert-butyl chloride (0.217 mL, 2 mmol) and ammonium
chloride (0.5 g). Yield 0.030 g (58 %). Colourless oil. RF = 0.42
(hexane/EtOAc 6:1). 1H NMR (300 MHz, CDCl3): δ = –0.01 to
1.23 (br. m, 3 H), 1.56–1.94 (m, 6 H), 1.98–2.17 (m, 2 H), 4.72 (dm,
JP,C = 353.4 Hz, 1 H) ppm. 13C NMR (75 MHz, CDCl3): δ = 20.88
(d, JP,C = 36.8 Hz), 27.44 ppm. 31P NMR (121.5 MHz, CDCl3): δ
= –3.84 ppm. GC (Phenomenex Zebron ZB-35HT INFERNO): RT
= 3.25 min. GC-MS (EI, 70 eV): m/z (%) = 88 (100) [M – BH3], 87
(26). C4H12BP (101.92): calcd. C 47.14, H 11.87; found C 47.50, H
12.20.
tert-Butylmethyl(3-methylcyclohexa-1,4-dien-3-yl)phosphane Oxide
(29): This compound was prepared by the General Procedure from
26 (0.098 g, 0.5 mmol), sodium (0.029 g, 1.25 mmol) and methyl
iodide (0.078 mL, 1.25 mmol). It was isolated as a mixture with
starting material, yield 59% (based on NMR). RF = 0.36 (EtOAc/
MeOH 20:1). 1H NMR (500 MHz, CDCl3): δ = 1.16 (d, JP,H
=
13.8 Hz, 9 H), 1.31 (d, JP,H = 10.9 Hz, 3 H), 1.37 (d, JP,H = 13.1 Hz,
3 H), 2.58–2.71 (m, 2 H), 5.55–5.61 (m, 1 H), 5.67–5.82 (m, 3
H) ppm. 13C NMR (125 MHz, CDCl3): δ = 7.49 (d, JP, C
60.0 Hz), 24.17, 24.83 (d, JP,C = 4.5 Hz), 26.20, 35.33 (d, JP,C
=
=
60.9 Hz), 42.15 (d, JP,C = 60.9 Hz), 124.40 (d, JP,C = 8.2 Hz), 124.99
(d, JP,C = 9.1 Hz), 128.66 (d, JP,C = 3.6 Hz), 128.96 (d, JP, C
=
1-(1,2-Diphenylethyl)phospholane–Borane (24): This compound was
prepared by the General Procedure from 4 (0.089 g, 0.5 mmol), po-
tassium (0.117 g, 3 mmol), tert-butyl chloride (0.217 mL, 2 mmol)
and benzyl chloride (0.126 mL, 1 mmol). Yield 0.120 g (85%).
3.6 Hz) ppm. 31P NMR (202 MHz, CDCl3): δ = 58.22 ppm. GC
(Phenomenex Zebron ZB-35HT INFERNO): RT = 12.79 min. GC-
MS (EI, 70 eV): m/z (%) = 211 (1) [M – 1], 121 (7), 120 (100), 93
(47), 92 (27), 91 (83).
1
White solid; m.p. 91.9–93.5 °C. RF = 0.54 (hexane/EtOAc 6:1). H
NMR (300 MHz, CDCl3): δ = 0.08–1.23 (br. m, 3 H), 1.35–1.61
(m, 6 H), 1.61–1.78 (m, 2 H), 2.98–3.23 (m, 2 H), 3.26–3.37 (m, 1
H), 6.94–7.02 (m, 2 H), 7.02–7.10 (m, 3 H), 7.10–7.26 (m, 5
(3-Benzylcyclohexa-1,4-dien-3-yl)-tert-butyl-methylphosphane Ox-
ide (30): This compound was prepared by the General Procedure
from 26 (0.098 g, 0.5 mmol), sodium (0.029 g, 1.25 mmol) and
benzyl chloride (0.126 mL, 1 mmol). Yield 0.144 g (100%). White
solid; m.p. 102.6–103.3 °C. RF = 0.74 (CHCl3/MeOH 15:1). 1H
NMR (500 MHz, CDCl3): δ = 1.29 (d, JP,H = 13.6 Hz, 9 H), 1.45
(d, JP,H = 11.0 Hz), 2.18–2.30 (m, 1 H), 2.38–2.52 (m, 1 H), 3.05–
3.13 (m, 1 H), 3.23–3.31 (m, 1 H), 5.63–5.78 (m, 3 H), 5.88–5.95
(m, 1 H), 7.07–7.12 (m, 2 H), 7.13–7.24 (m, 3 H) ppm. 13C NMR
H) ppm. 13C NMR (75 MHz, CDCl3): δ = 23.36 (d, JP, C
35.3 Hz), 25.06 (d, JP,C = 34.2 Hz), 26.49, 26.86, 37.10 (d, JP,C
=
=
5.2 Hz), 45.29 (d, JP,C = 23.6 Hz), 126.31, 127.27 (d, JP,C = 2.0 Hz),
128.23, 128.50 (d, JP,C = 1.7 Hz), 128.73, 128.86 (d, JP,C = 4.3 Hz),
136.96 (d, JP,C = 3.5 Hz), 139.07 (d, JP,C = 11.2 Hz) ppm. 31P NMR
(121.5 MHz, CDCl3): δ = 41.19 ppm. GC (Phenomenex Zebron
ZB-35HT INFERNO): RT = 18.61 min. GC-MS (EI, 70 eV): m/z
(%) = 268 (27) [M – BH3], 267 (72), 181 (100), 180 (61), 177 (41),
166 (46), 165 (67), 141 (9), 115 (14), 103 (94), 77 (66). C18H24BP
(282.17): calcd. C 76.62, H 8.57; found C 76.70, H 8.90.
(125 MHz, CDCl3): δ = 7.83 (d, JP,C = 60.0 Hz), 25.95 (d, JP,C
=
4.5 Hz), 26.41, 35.85 (d, JP,C = 60.9 Hz), 41.11 (d, JP,C = 1.9 Hz),
47.71 (d, JP,C = 60.0 Hz), 126.07, 126.44 (d, JP,C = 9.1 Hz), 126.56
(d, JP,C = 6.4 Hz), 126.57 (d, JP,C = 5.5 Hz), 127.21 (d, JP, C
=
(1,2-Diphenylethyl)dimethylphosphane–Borane (25): This compound
was prepared by the General Procedure from 3 (0.076 g, 0.5 mmol),
potassium (0.117 g, 3 mmol), tert-butyl chloride (0.217 mL,
2 mmol) and benzyl chloride (0.126 mL, 1 mmol). Yield 0.086 g
9.1 Hz), 127.31, 130.89, 136.69 (d, JP,C = 11.8 Hz) ppm. 31P NMR
(202 MHz, CDCl3): δ = 57.42 ppm. GC (Phenomenex Zebron ZB-
35HT INFERNO): RT = 17.30 min. GC-MS (EI, 70 eV): m/z (%)
= 288 (17) [M], 287 (20), 231 (10), 197 (58), 167 (14), 165 (12), 152
2532
www.eurjoc.org
© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2012, 2521–2534

In Situ Dearomatisation/Alkylation of Arylphosphanes
(10), 141 (83), 140 (30), 125 (13), 120 (13), 119 (25), 92 (20), 91
JP,C = 10.0 Hz) ppm. 31P NMR (202 MHz, CDCl3): δ = 78.72 ppm.
(100), 57 (72). C18H25OP (288.36): calcd. C 74.97, H 8.74; found C GC (Phenomenex Zebron ZB-35HT INFERNO): RT = 18.12 min.
75.15, H 8.89.
GC-MS (EI, 70 eV): m/z (%) = 271 (2) [M – 1], 181 (9), 168 (10),
167 (14), 165 (8), 153 (6), 152 (7), 105 (25), 104 (100), 103 (27), 91
(81).
Dimethyl(3-methylcyclohexa-1,4-dien-3-yl)phosphane Oxide (31):
This compound was prepared by the General Procedure from 27
(0.077 g, 0.5 mmol), sodium (0.029 g, 1.25 mmol) and methyl iod-
ide (0.078 mL, 1.25 mmol). It was isolated as a mixture with start-
ing material, yield 47 % (based on NMR). RF = 0.56 (EtOAc/
1-Benzylphospholane Oxide (35): This compound was prepared by
the General Procedure from 28 (0.090 g, 0.5 mmol), sodium
(0.029 g, 1.25 mmol) and benzyl chloride (0.126 mL, 1 mmol). It
was isolated as a mixture with 34, yield 38% (based on NMR). RF
= 0.64 (CHCl3/MeOH 15:1). 1H NMR (500 MHz, CDCl3): δ =
1.68–1.78 (m, 4 H), 1.86–1.98 (m, 4 H), 3.26 (d, JP,H = 14.8 Hz, 2
H), 7.17–7.28 (m, 3 H), 7.30–7.34 (m, 2 H) ppm. 13C NMR
MeOH 20:1). 1H NMR (500 MHz, CDCl3): δ = 1.37 (d, JP,H
=
12.3 Hz, 6 H), 1.70 (d, JP,H = 13.2 Hz, 3 H), 2.53–2.80 (m, 2 H),
5.55–5.61 (m, 2 H), 5.83–5.88 (m, 2 H) ppm. 13C NMR (125 MHz,
CDCl3): δ = 11.72 (d, JP,C = 67.2 Hz), 21.25 (d, JP,C = 3.6 Hz),
26.27 (d, JP,C = 5.5 Hz), 40.65 (d, JP,C = 69.0 Hz), 126.36 (d, JP,C
= 9.1 Hz), 127.19 (d, JP,C = 4.5 Hz) ppm. 31P NMR (202 MHz,
CDCl3): δ = 51.40 ppm. GC (Phenomenex Zebron ZB-35HT IN-
FERNO): RT = 17.30 min. GC-MS (EI, 70 eV): m/z (%) = 169 (1)
[M – 1], 93 (57), 92 (19), 91 (100).
(125 MHz, CDCl3): δ = 24.31 (d, JP,C = 8.2 Hz), 24.81 (d, JP,C
74.5 Hz), 46.02 (d, JP,C = 59.9 Hz), 125.54 (d, JP,C = 3.6 Hz), 126.91
(d, JP,C = 2.7 Hz), 128.82 (d, JP,C = 2.7 Hz), 132.19 (d, JP, C
=
=
7.3 Hz) ppm. 31P NMR (202 MHz, CDCl3): δ = 69.40 ppm. GC
(Phenomenex Zebron ZB-35HT INFERNO): RT = 15.06 min. GC-
MS (EI, 70 eV): m/z (%) = 194 (31) [M], 193 (19), 166 (10), 148
(7), 117 (20), 103 (19), 92 (13), 91 (100), 85 (14).
(3-Benzylcyclohexa-1,4-dien-3-yl)dimethylphosphane Oxide (32):
This compound was prepared by the General Procedure from 27
(0.077 g, 0.5 mmol), sodium (0.029 g, 1.25 mmol) and benzyl chlor-
ide (0.126 mL, 1 mmol). Yield 0.117 g (95%). Colourless solid; m.p.
76.6–78.1 °C. RF = 0.56 (CHCl3/MeOH 15:1). 1H NMR (500 MHz,
CDCl3): δ = 1.45 (d, JP,H = 12.0 Hz, 6 H), 2.35–2.55 (m, 2 H), 3.10
(d, JP,H = 6.9 Hz, 2 H), 5.62–5.69 (m, 2 H), 5.76–5.84 (m, 2 H),
7.08–7.13 (m, 2 H), 7.13–7.23 (m, 3 H) ppm. 13C NMR (125 MHz,
CDCl3): δ = 12.15 (d, JP,C = 67.2 Hz), 26.05 (d, JP,C = 5.5 Hz),
38.93 (d, JP,C = 2.7 Hz), 46.08 (d, JP,C = 68.1 Hz), 125.33 (d, JP,C
= 5.5 Hz), 126.16, 127.53, 127.88 (d, JP,C = 10.0 Hz), 130.24, 136.79
(d, JP,C = 12.7 Hz) ppm. 31P NMR (202 MHz, CDCl3): δ =
50.86 ppm. GC (Phenomenex Zebron ZB-35HT INFERNO): RT
= 16.41 min. GC-MS (EI, 70 eV): m/z (%) = 246 (2) [M], 245 (3),
168 (10), 167 (14), 165 (9), 155 (19), 153 (6), 152 (7), 92 (11), 91
(100). C15H19OP (246.28): calcd. C 73.15, H 7.78; found C 73.10,
H 8.11.
Supporting Information (see footnote on the first page of this arti-
1
cle): H, 13C, 31P and GC-MSof compounds.
Acknowledgments
Financial support from the Polish Ministry of Science and Higher
Education (grant number N204 2328 34) is gratefully acknowl-
edged. The authors are grateful to Dr. Duncan Carmichael for his
guidance during the preparation of manuscript.
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compound was prepared by the General Procedure from 28
(0.090 g, 0.5 mmol), sodium (0.029 g, 1.25 mmol) and methyl iod-
ide (0.078 mL, 1.25 mmol). Yield 0.098 g (100%). Colourless solid;
m.p. 81.4–83.1 °C. RF = 0.60 (CHCl3/MeOH 15:1). 1H NMR
(500 MHz, CDCl3): δ = 1.41 (d, JP,H = 13.9 Hz, 3 H), 1.54–1.72
(m, 4 H), 1.73–1.85 (m, 2 H), 1.88–2.01 (m, 2 H), 2.59–2.82 (m, 2
H), 5.56–5.63 (m, 2 H), 5.80–5.88 (m, 2 H) ppm. 13C NMR
(125 MHz, CDCl3): δ = 22.11 (d, JP,C = 3.6 Hz), 24.11 (d, JP,C
62.7 Hz), 25.12 (d, JP,C = 7.3 Hz), 26.39 (d, JP,C = 5.5 Hz), 40.54
(d, JP,C = 60.9 Hz), 126.31 (d, JP,C = 9.1 Hz), 127.19 (d, JP,C
=
=
4.5 Hz) ppm. 31P NMR (202 MHz, CDCl3): δ = 79.87 ppm. GC
(Phenomenex Zebron ZB-35HT INFERNO): RT = 13.90 min. GC-
MS (EI, 70 eV): m/z (%) = 195 (0.25) [M – 1], 105 (10), 104 (100),
103 (34), 93 (30), 92 (11), 91 (44). C11H17OP (196.23): calcd. C
67.33, H 8.73; found C 67.34, H 8.95.
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1
36% (based on NMR). RF = 0.73 (CHCl3/MeOH 15:1). H NMR
(500 MHz, CDCl3): δ = 1.44–1.56 (m, 2 H), 1.57–1.68 (m, 4 H),
1.78–1.87 (m,2 H), 2.52–2.61 (m, 2 H), 3.16 (d, JP,H = 8.8 Hz, 2
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6.4 Hz), 26.05 (d, JP,C = 65.4 Hz), 26.33 (d, JP,C = 5.5 Hz), 38.55
(d, JP,C = 55.4 Hz), 40.58 (d, JP,C = 2.7 Hz), 126.36, 127.65 (d, JP,C
= 10.0 Hz), 127.72, 129.41 (d, JP,C = 5.5 Hz), 130.48, 136.67 (d,
Eur. J. Org. Chem. 2012, 2521–2534
© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
2533

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Received: January 27, 2012
Published Online: March 27, 2012
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Eur. J. Org. Chem. 2012, 2521–2534