Planar chiral hydroxy derivatives of [2.2]paracyclophane as auxiliaries for asymmetric allylboration

Article abstract of DOI:10.1007/s11172-007-0348-x

Allylboronic esters with various structures were synthesized for the first time based on [2.2]paracyclophane derivatives containing one or two hydroxy groups. It was demonstrated that these esters can be used as chiral inductors in the asymmetric allylboration of benzaldehyde. The highest enantiomeric excess of 1-phenylbut-3-en-1-ol (60%) was achieved in the reactions with acyclic bis-O,O-(paracyclophanyl) allylboronates based on (S)-4-hydroxy-and (S)-12-bromo-4-hydroxy[2.2]paracyclophanes. (S)-4-Hydroxy[2.2]paracyclophane was studied by X-ray diffraction.

Full text of DOI:10.1007/s11172-007-0348-x

Russian Chemical Bulletin, International Edition, Vol. 56, No. 11, pp. 2225—2231, November, 2007
2225
Planar chiral hydroxy derivatives of [2.2]paracyclophane
as auxiliaries for asymmetric allylboration

N. V. Vorontsova, R. P. Zhuravsky, E. V. Sergeeva, E. V. Vorontsov, Z. A. Starikova, and V. I. Rozenberg
A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences,
28 ul. Vavilova, 119991 Moscow, Russian Federation.
Fax: +7 (499) 135 5085. Eꢀmail: ineosꢀghkl@yandex.ru
Allylboronic esters with various structures were synthesized for the first time based on
[2.2]paracyclophane derivatives containing one or two hydroxy groups. It was demonstrated
that these esters can be used as chiral inductors in the asymmetric allylboration of benzaldeꢀ
hyde. The highest enantiomeric excess of 1ꢀphenylbutꢀ3ꢀenꢀ1ꢀol (60%) was achieved in the
reactions with acyclic bisꢀO,O´ꢀ(paracyclophanyl) allylboronates based on (S)ꢀ4ꢀhydroxyꢀ and
(S)ꢀ12ꢀbromoꢀ4ꢀhydroxy[2.2]paracyclophanes. (S)ꢀ4ꢀHydroxy[2.2]paracyclophane was studied
by Xꢀray diffraction.
Key words: [2.2]paracyclophanes, allylboration, asymmetric synthesis, planar chirality,
chiral auxiliaries, homoallylic alcohols, Xꢀray diffraction study.
The allylboration of aldehydes is one of the most widely
used approaches to the stereoselective C—C bond formaꢀ
tion.1—4 Generally, enantiomerically pure compounds
(diols, diamines, sulfamides, and amino alcohols) posꢀ
sessing central4 or (more rarely) axial chirality5 are used
for the design of reagents for the asymmetric allylboration.
Earlier,6,7 we have demonstrated for the first time
that planar chiral [2.2]paracyclophane derivatives can be
used in this reaction. For example, diastereomerically
is that they contain only one (planar) chirality center,
which eliminates the question about the possible coopꢀ
erative effect of the planar and central chirality in the
asymmetric process.
pure diallylborinate 2 was synthesized starting from
4ꢀacetyl[2.2]paracyclophane (1)8,9 (Scheme 1).
Compound 2 was used in the allylboration of 4ꢀforꢀ
myl[2.2]paracyclophane (4) (de of relꢀ(Rp,R)ꢀ4ꢀ(1ꢀhydrꢀ
oxybutꢀ3ꢀenyl)[2.2]paracyclophane (5) 50%) and benzꢀ
aldehyde (6) (ee of 1ꢀphenylbutꢀ3ꢀenꢀ1ꢀol (7) was 18%).
Homoallylic alcohol 3 produced in the reaction is a reꢀ
cyclable auxiliary because it again gives ester 2 in the
reaction with triallylborane (see Scheme 1).
In alcohol 3, the hydroxy group is two bonds from the
paracyclophane moiety. In the present study, we investiꢀ
gated the influence of the distance between the functional
group and the paracyclophane moiety on the stereochemiꢀ
cal result of asymmetric allylboration of benzaldehyde.
For this purpose, we examined for the first time the possiꢀ
bility of designing reagents for the asymmetric allylꢀ
boration based on chiral phenols, viz., (S)ꢀ4ꢀhydrꢀ
oxy[2.2]paracyclophane (8) and (S)ꢀ12ꢀbromoꢀ4ꢀhydrꢀ
oxy[2.2]paracyclophane (9), in which the hydroxy group
is directly fixed in the aromatic ring of [2.2]paracycloꢀ
phane.
Results and Discussion
Synthesis of starting phenols 8 and 9. Racemic phenol
8 was synthesized according to a known procedure.10 To
synthesize its enantiomers, we have developed11—14 a proꢀ
cedure for the resolution of racꢀ8 into enantiomers through
esters with (1S)ꢀ(–)ꢀcamphanic acid 10 (Scheme 2).15,16
Diastereomeric esters 10 were separated by fractional
crystallization15 followed by the preparative separation of
the mother liquor by silica gel column chromatography.16
In the present study, we improved the procedure for
the isolation of enantiomers of phenol 8 from diastereoꢀ
merically pure esters by using the hydrolysis with KOH in
an aqueous methanolic mixture (see Scheme 2) instead of
the reduction of esters 10 with a large excess of LiAlH4 in
anhydrous THF (the yield of 8 was 93%).15 In this case,
the refluxing of individual diastereomers of 10 in a Soxhlet
apparatus during a long period of time (6—12 h) is not
An important feature, which distinguishes phenols 8
and 9 from alcohol 3 containing two stereogenic centers,
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2149—2155, November, 2007.
1066ꢀ5285/07/5611ꢀ2225 © 2007 Springer Science+Business Media, Inc.

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Russ.Chem.Bull., Int.Ed., Vol. 56, No. 11, November, 2007
Vorontsova et al.
Scheme 1
Reagents and conditions: i. CH2Cl2, 40 °C, 5 h. ii. relꢀ(Rp,R)ꢀ2 and 4, CH2Cl2, –70 °C; 0.5 h, ~20 °C; then MeOH and NaOH in H2O,
the yield of relꢀ(Rp,R)ꢀ3 was 96%, the yield of 5 was 92%. iii. (Sp,S)ꢀ2 and 6, THF, –70 °C, 17 h; then NaBH4 in EtOH, 1 h; then
MeOH and NaOH in H2O, ~20 °C, the yield of (Sp,S)ꢀ3 was 86%, the yield of 7 was 97%.
required; the hydrolysis is completed in 2 h at room temꢀ
perature and gives enantiomers of phenol 8 in almost
quantitative yield.
The geometric parameters of molecules 8A and 8B are
given in Table 1. As can be seen from this table, the
independent molecules are structurally identical.
The crystal structure consists of isolated hydrogenꢀ
bonded tetrameric associates (Fig. 2).
Allylborating agents based on phenol 8. With the aim of
synthesizing allylborating agents starting from phenol 8,
we studied the reaction of the latter with triallylborane
(Scheme 3).
The formation of allylboronic esters 11—13 was moniꢀ
tored by 11B NMR spectroscopy because the chemical
shifts of boranes and boronic esters with one, two, or
three B—O bonds are substantially different.20 When pheꢀ
nol 8 and All3B were used in a ratio of 1 : 1.1 (CH2Cl2,
~20 °C, 2 h), the 11B NMR spectrum (CH2Cl2) of the
reaction mixture measured after distillation of excess All3B
showed only one signal at δ 51 corresponding to diallylꢀ
borinate 11. The yield of ester 11 (>99%) was determined
based on the yield of 1ꢀphenylbutꢀ3ꢀenꢀ1ꢀol (7), which
Earlier, we have synthesized17 racemic bromo phenol 9
in high yield by the selective monolithiation of 4,12ꢀdiꢀ
bromo[2.2]paracyclophane with BuLi in THF followed
by the replacement of the Li atom by the B atom in the
reaction of the Li intermediate with B(OMe)3 and the
oxidation of boronic ester with the H2O2/NaOH sysꢀ
tem.17—19 The procedure, which we have developed earꢀ
lier18,19 for the resolution of bromophenol 9 into enantiꢀ
omers, also involves the synthesis and chromatographic
separation of its esters with (1S)ꢀ(–)ꢀcamphanic acid folꢀ
lowed by hydrolysis of individual diastereomers.
The (R)ꢀenantiomer of 8 was studied by Xꢀray diffracꢀ
tion. The structure of 8 contains two crystallographically
independent molecules (8A and 8B). In one molecule
(8A), the hydrogen atom of the OH group is disordered
over two positions (Fig. 1).

[2.2]Paracyclophanes in allylboration
Russ.Chem.Bull., Int.Ed., Vol. 56, No. 11, November, 2007 2227
Scheme 2
Table 1. Bond lengths (d) and selected bond angles (ω) in comꢀ
pound 8
Parameter
8A
8B
Bond
d/Å
С(4)—О(1)
С(4)—С(5)
С(7)—С(8)
С(12)—С(13)
С(15)—С(16)
C(3)—C(4)
C(3)—C(8)
C(6)—C(5)
C(6)—C(7)
C(11)—C(12)
C(11)—C(16)
C(14)—C(13)
C(14)—C(15)
С(2)—С(3)
С(6)—С(9)
С(1)—С(14)
С(10)—С(11)
С(1)—С(2)
С(9)—С(10)
1.386(2)
1.387(3)
1.379(3)
1.382(3)
1.386(3)
1.396(3)
1.400(3)
1.392(3)
1.396(3)
1.396(3)
1.395(3)
1.391(3)
1.404(3)
1.510(3)
1.511(3)
1.517(3)
1.511(3)
1.583(3)
1.580(3)
1.377(3)
1.384(3)
1.382(3)
1.389(3)
1.385(3)
1.398(3)
1.401(3)
1.384(3)
1.402(3)
1.398(3)
1.393(3)
1.396(3)
1.393(3)
1.512(3)
1.508(3)
1.512(3)
1.510(3)
1.587(3)
1.589(3)
Reagents and conditions: i. (1S)ꢀ(–)ꢀCamphanoyl chloride, Py,
~20 °C, 6 h, the yield of 10 was 95%. ii. Crystallization (AcOEt)
and silica gel chromatography, the yields of (Sp,Sc)ꢀ10 and
(Rp,Sc)ꢀ10 were up to 40%. iii. KOH, MeOH, ~20 °C, 2 h,
the yields of (Sp)ꢀ8 or (Rp)ꢀ8 were 95%.
Angle
О(1)—С(4)—С(3)
О(1)—С(4)—С(5)
ω/deg
120.5(2)
117.3(2)
120.5(2)
117.6(2)
was prepared by the subsequent reaction with benzaldeꢀ
hyde (see below). To synthesize allylboronate 12, the raꢀ
tio of 8 to All3B was increased to 2.2 : 1, which required
more drastic conditions (2 h, toluene, 110 °C). In this
case, the 11B NMR spectrum (toluene) shows the main
signal at δ 27 corresponding to allylboronate 12 and
a minor signal at δ 15 assigned to borate 13. The yield of
ester 12 was 80%. When the 8 : All3B ratio was increased
to 3 : 1 and the protolysis time was increased to 5 h
(toluene, 110 °C), triparacyclophanyl borate 13 was obꢀ
C(10)
C(9)
O(1´A)
C(11)
O(1A)
H(10B)
O(1´B)
H(20A)
H(10A)
C(6)
H(10)
O(1)
H(10C)
C(12)
H(20)
C(16)
C(5)
C(7)
C(13)
C(15)
C(4)
H(2O)
C(8)
C(14)
C(3)
O(1)
H(1O)
Fig. 2. Tetrameric associate in the crystal structure of 8. The
hydrogen bond parameters for the O(1)—H(10)...O(1´A)
(–x + 2, y + 1, –z + 1), O(1)—H(20)...O(1A) (–x + 2, y, –z + 1),
and O(1´A)—H(10A)...O(1) bonds: the O...O and O...H disꢀ
tances are 2.796(2), 2.801(3), 2.796(2) Å and 1.98, 1.99, 2.00 Å,
respectively, the O—H—O angles are 159, 160, and 156°, reꢀ
spectively.
C(1)
C(2)
Fig. 1. Molecular structure of (R)ꢀ4ꢀhydroxy[2.2]paracycloꢀ
phane (8A).

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Vorontsova et al.
Scheme 3
Scheme 4
Reagents and conditions: i. All3B (1.1 equiv. of 8), CH2Cl2,
~20 °C, 2 h, the yield of 11 was >99%. ii. All3B (2.2 equiv. of 8),
toluene, 110 °C, 2 h, the yield of 12 was 80%. iii. All3B (3 equiv.
of 8), toluene, 110 °C, 5 h, the yield of 13 was 70%.
X = H (8, 11, 12), Br (9, 14); n = 2 (11), 1 (12, 14)
Reagents and conditions: i. (S)ꢀ11, (S)ꢀ12 or (S)ꢀ14, –78 °C,
40 h; then NaBH4/EtOH and NaOH/H2O.
tained as the major product (according to the 11B NMR
spectrum, the yield was 70%).
Diallylborinate (S)ꢀ11 and allylboronate (S)ꢀ12 were
tested in the asymmetric allylboration of benzaldehyde 6
(Scheme 4, Table 2, runs 1—4).
stable. Thus, it is recovered from the reaction mixture in
quantitative yield and the same enantiomeric purity,
whereas homoallylic alcohol (Sp,S)ꢀ3 (see Scheme 1) is
unstable.
Allylborating agents based on phenol 9. The introducꢀ
tion of substituents at different positions of the threeꢀ
dimensional paracyclophanyl moiety allows the design of
related ligands by varying the chiral environment and
The reactions were carried out with 1 equiv. of aldeꢀ
hyde 6 at –78 °C for 40 h in toluene or THF. The yield of
product 7 was estimated from the intensity ratio of the
signals for the protons of 7 and the protons of phenol 8 in
the 1H NMR spectra of the reaction mixtures. The
enantioselectivity of the reaction with diallylborinate
(S)ꢀ11 was 23 (toluene) and 30% (THF) (see Table 2,
runs 1 and 2). In the reaction with allylboronate (S)ꢀ12,
the enantiomeric excess of the reaction product substanꢀ
tially depends on the nature of the solvent. For example,
the enantiomeric excess of alcohol (R)ꢀ7 in the reaction
in toluene was 24%, whereas it was as high as 60% in THF
(see Table 2, runs 3 and 4).
These experiments showed that phenols of the
[2.2]paracyclophane series can be used as auxiliaries for
the asymmetric allylboration. For example, the use of
phenol (S)ꢀ8 instead of the previously used alcohol
(Sp,S)ꢀ3 leads to an increase in the enantiomeric excess of
the reaction product from 18 to 60%. A substantial advanꢀ
tage of phenol (S)ꢀ8 as the reagent is that it is chemically
Table 2. Asymmetric allylboration of benzaldehyde 6
Run
Agent
Solvent Yield of 7
ee 7*
Configuꢀ
ration of 7**
%
1
2
3
4
5
(S)ꢀ11
(S)ꢀ11
(S)ꢀ12
(S)ꢀ12
(S)ꢀ14
Toluene
THF
Toluene
THF
80
75
99
24
50
23
30
24
60
59
R
R
R
R
R
THF
* The enantiomeric excess was determined by enantioselecꢀ
tive HPLC.
** The configuration of the alcohol was determined by comparꢀ
ing the sign of the observed angle of rotation with the published
23
data: [α]D –44.92 (c 7.38, benzene) for (S)ꢀ7 (ee 96%).21

[2.2]Paracyclophanes in allylboration
Russ.Chem.Bull., Int.Ed., Vol. 56, No. 11, November, 2007 2229
steric crowding of the reaction center. Hence, we chose
bromoꢀsubstituted phenol 9,17—19 which is an analog of
phenol 8 and contains the bulky substituent in the
pseudoꢀortho position, as the model compound.
bifunctional paracyclophane derivatives with ortho and
pseudoꢀortho structures serve as efficient inductors of variꢀ
ous reactions in the asymmetric synthesis and catalyꢀ
sis.22—24 Hence, we examined the possibility of the use of
bifunctional hydroxy derivatives of [2.2]paracyclophane
in the allylboration reaction. In the test reactions with
benzaldehyde, we used biphenols with the ortho and
pseudoꢀortho arrangement of the hydroxy groups ((S)ꢀ16
(see Refs 18 and 19) and (R)ꢀ17,25 respectively), diꢀ
hydroxyarylparacyclophane (S)ꢀ18,18,19 and hydroxyꢀ
aldehyde (R)ꢀ19 (see Ref. 26) as the auxiliaries.
Since the best result in the allylboration reaction with
the use of reagents based on phenol (S)ꢀ8 was obtained
for allylboronate (S)ꢀ12, we decided to synthesize the
structurally similar allylborating agent based on broꢀ
mophenol 9. For this purpose, the reaction of bromopheꢀ
nol (S)ꢀ9 with triallylborane was carried out under the
conditions analogous to those used for the transformation
(S)ꢀ8 → (S)ꢀ12 (the reagent ratio (S)ꢀ9 : All3B = 2.2 : 1,
toluene, 110 °C). However, after 2 h the 11B NMR specꢀ
trum showed, along with a signal at δ 32 corresponding to
allylboronate (S)ꢀ14, a signal at δ 53 belonging to diꢀ
allylborinate (S)ꢀ15 (Scheme 5). The ratio of products 14
to 15 was 4 : 1.
Scheme 5
Allylboronic esters based on dihydroxy derivatives are
cyclic compounds.4,5,20 Hence, allylborating agents based
on bifunctional [2.2]paracyclophane derivatives 16—19
were synthesized with the use of an equimolar amount
of All3B. The cyclic structures of esters were suggested
based on the almost quantitative yield of the final allylboꢀ
ration product 7. In the case of compound (R)ꢀ19, the forꢀ
mation of cyclic allylboronate (Rp,S)ꢀ20 has been confirꢀ
med earlier7 by 11B NMR spectroscopic data (Scheme 6).
Reagents and conditions: i. All3B, toluene, ~20 °C, 2 h, the yield
of (S)ꢀ14 was 95%; (S)ꢀ15, 5%.
Scheme 6
Product 14 was selectively synthesized by the reaction
performed at room temperature. It appeared that the forꢀ
mation of almost pure allylboronate (S)ꢀ14 was observed
even in the reaction with the use of equimolar amounts of
the reagents.
As demonstrated above, the highest enantioselectivity
of the allylboration of benzaldehyde with allylboronate
(S)ꢀ12 was achieved at –78 °C in THF. Under the same
conditions, the enantiomeric excess of the product in the
reaction with reagent (S)ꢀ14 remained unchanged (59%),
whereas the yield of alcohol (R)ꢀ7 increased from 24
to 50% (see Table 2, run 5).
Allylboration with the involvement of diols 16—19.
Chiral aliphatic diols are known4,20 to be highly efficient
as auxiliaries in the asymmetric allylboration. In addition,
Reagents and conditions: i. All3B, CH2Cl2, ~20 °C, 0.5 h, >99%.
The allylboration of benzaldehyde was carried out in
THF at –78 °C. Unexpectedly, the enantioselectivity in

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Vorontsova et al.
Na2SO4, and the solvent was removed under reduced pressure.
The solid residue was passed through a layer of silica gel using
benzene as the eluent. The yield of (R)ꢀ(+)ꢀ8 was 0.713 g (99%),
ee >99% (according to the GLC data, ts = 80.17, tr = 88.21),
m.p. 229—230 °C (cf. lit. data12: m.p. 232—234 °C).
(S)ꢀ(–)ꢀ4ꢀHydroxy[2.2]paracyclophane ((S)ꢀ(–)ꢀ8) was synꢀ
thesized analogously from camphanic ester (Sp,S)ꢀ10 in 99%
yield, ee >99%.
(S)ꢀ([2.2]Paracyclophanꢀ4ꢀyl) diallylborinate ((S)ꢀ11).
A 0.3 M All3B solution in CH2Cl2 (1.8 mL, 0.515 mmol) was
added with stirring to a solution of phenol (S)ꢀ8 (ee >98%)
(0.115 g, 0.513 mmol) in CH2Cl2 (5 mL). The reaction mixture
was stirred for 2 h. Then excess All3B and the solvent were
distilled off in vacuo. 11B NMR (128.378 MHz, CH2Cl2), δ: 51.
The yield was >99% (determined from the reaction of (S)ꢀ11
with benzaldehyde).
the reactions with compounds 16—19 appeared to be low
(ee of alcohol 7 was 9, 15, and 3% for (S)ꢀ16, (R)ꢀ17, and
(R)ꢀ19, respectively) and depend only slightly on the muꢀ
tual arrangement of the functional groups. In this series,
the best result (ee of alcohol 7 was 23%) was achieved for
aryl[2.2]paracyclophanyl biphenol (S)ꢀ18, which is conꢀ
formationally labile with respect to the CAr—CAr bond
and in which one hydroxy group is present in the paraꢀ
cyclophanyl moiety and another hydroxy group is present
in the aryl fragment.
To summarize, we characterized a new class of allylꢀ
borating agents based on planar chiral phenols of the
[2.2]paracyclophane series and their derivatives. The
protolysis of triallylborane with 4ꢀhydroxyꢀ and 12ꢀbromoꢀ
4ꢀhydroxy[2.2]paracyclophanes was studied for the first
time. The conditions for the preparation of individual
diallylborinate 11, allylboronates 12 and 14, and borate
13 were found. Allylboronic esters based on enantioꢀ
merically pure compounds 8, 9, and 16—19 were tested in
the asymmetric allylboration of benzaldehyde. The best
results (ee of alcohol 7 was 60%) were achieved in the
reactions with allylboronates (Sp,Sp)ꢀ12 and (Sp,Sp)ꢀ14
containing two paracyclophanyl fragments, which were
synthesized from phenols (S)ꢀ8 and (S)ꢀ9, respectively.
In the future, we plan to examine the possibility of
performing the asymmetric allylboration with other reꢀ
agents based on paracyclophane derivatives, in which the
allylboron groups are attached directly to the paracycloꢀ
phanyl moiety (diallylparacyclophanylꢀ and allyldiparaꢀ
cyclophanylboranes).
BisꢀO,O´ꢀ{(S)ꢀ[2.2]paracyclophanꢀ4ꢀyl}
allylboronate
((S)ꢀ12). A 0.3 M All3B solution in toluene (1.1 mL, 0.314 mmol)
was added with stirring to a solution of phenol (S)ꢀ8 (0.155 g,
0.692 mmol) (ee >98%) in toluene (6 mL). The reaction mixture
was refluxed for 2 h, and the solvent was distilled off in vacuo.
11B NMR (128.378 MHz, CH2Cl2), δ: 27. The yield was 80%
(determined from the reaction of (S)ꢀ12 with benzaldehyde).
Allylborating agents based on compounds 16—19 were synꢀ
thesized analogously to compound (S)ꢀ12 using CH2Cl2 as the
solvent.
BisꢀO,O´ꢀ{(S)ꢀ12ꢀbromo[2.2]paracyclophanꢀ4ꢀyl} allylboꢀ
ronate ((S)ꢀ14). A 0.3 M All3B solution in toluene (0.8 mL,
0.233 mmol) was added with stirring to a solution of phenol
(S)ꢀ9 (ee >96%) (0.188 g, 0.513 mmol) in toluene (5 mL). The
reaction mixture was stirred at ~20 °C for 2 h. 11B NMR
(128.378 MHz, toluene), δ: 32.
Allylboration of benzaldehyde (general procedure). Allylꢀ
boronic ester, which was synthesized from compound 8
(9 or 16—19), was dissolved in THF (0.04 mol L–1). The reacꢀ
tion mixture was cooled to –78 °C, and 1 molꢀequiv. of freshly
distilled benzaldehyde was added with stirring. After 40 h, the
reaction mixture was treated with a 0.5 M NaBH4 solution in
EtOH, stirred for 1 h, and allowed to warm to ~20 °C. Then
MeOH and a 0.5 M NaOH solution in H2O were successively
added. The reaction mixture was stirred for 30 min and then
concentrated. The residue was extracted with diethyl ether
(3×15 mL), washed with H2O, and dried with Na2SO4. Alcoꢀ
hol 7 was isolated by either vacuum distillation or extraction
from the reaction mixture with pentane. The enantiomeric exꢀ
cess of 7 was determined by HPLC.
Xꢀray diffraction study of compound (R)ꢀ8. Colorless prisꢀ
matic crystals of C16H16O (R)ꢀ8 (M = 224.29) are monoclinic,
at 110 K a = 26.327(3) Å, b = 7.7134(8) Å, c = 11.477(1) Å,
β = 105.917(2)°, V = 2241.2(4) Å3, space group C2, Z = 8,
dcalc = 1.329 g cm–3. The intensities of 7267 reflections were
measured on a Bruker SMART CCD Area Detector diffractoꢀ
Experimental
All reactions were carried out under argon in anhydrous
solvents. The 1H and 11B NMR spectra were recorded on a
Bruker AMXꢀ400 instrument (400.13 and 128.378 MHz, reꢀ
spectively) in CDCl3, CH2Cl2, and toluene with the use of the
residual signals for the protons of the solvents as the interꢀ
nal standard (δ 7.27 for CDCl3 and 0 for BF3•Et2O). The
TLC analysis was performed on Sorbfil PTSKhꢀAFꢀAꢀUF
(Sorbpolimer, Russia) and Silufol UVꢀ254 (Chemapol) plates.
The enantioselective HPLC was carried out on a (R,R)ꢀWhelkꢀ01
column (25 cm × 4.6 mm) using a 100 : 1 heptane—PriOH
mixture as the eluent (the elution rate was 1 mL min–1) and an
UV detector (254 nm). The enantioselective GLC was carried
out on a ChiraldexꢀβꢀDM column (30 m × 0.25 mm), T =
180 °C, helium as the carrier gas, 103.41 kPa, the split ratio
was 75/1, a flame ionization detector.
(R)ꢀ(+)ꢀ4ꢀHydroxy[2.2]paracyclophane ((R)ꢀ(+)ꢀ8). Potasꢀ
sium hydroxide (0.764 g, 13.64 mmol) was added to a suspenꢀ
sion of camphanic ester (Rp,S)ꢀ10 (see Refs 15 and 16) (1.300 g,
3.22 mmol) in MeOH (120 mL). The reaction mixture was
stirred at ~20 °C for 2 h. Then a saturated aqueous NaCl soluꢀ
tion (120 mL) and benzene (60 mL) were added, and the mixꢀ
ture was vigorously stirred for 0.5 h. The organic layer was
separated, and the aqueous layer was extracted with benzene
(2×50 mL). The combined organic phases were dried with
meter at 110 K (MoꢀKα radiation, 2θ
= 54°) from a single
max
crystal with dimensions 0.8×0.4×0.2 mm. After merging of the
equivalent reflections, 4343 independent reflections were obꢀ
tained (Rint = 0.0177), which were used for the structure soluꢀ
tion and refinement. Absorption (µ = 0.081 mm–1) was ignored;
the transmission coefficients Tmax and Tmin determined with the
use of the SADABS program27 were 0.985 and 0.945, respecꢀ
tively. The structure was solved by direct methods. All nonꢀ
hydrogen atoms were located in difference electron density maps

[2.2]Paracyclophanes in allylboration
Russ.Chem.Bull., Int.Ed., Vol. 56, No. 11, November, 2007 2231
and refined anisotropically based on F2hkl. All hydrogen atoms
(except for the H atoms of the OH group, which were located in
difference electron density maps) were positioned geometrically.
All hydrogen atoms were refined using a riding model with
U(H) = 1.2U(C), where U(C) are the equivalent thermal paramꢀ
eters of the parent atoms. The final R factors were R1 = 0.0460
(based on Fhkl for 3937 reflections with I > 2σ(I )), wR2 = 0.1002
11. A. Cipiciani, F. Fringuelli, V. Mancini, O. Piermatti, and
F. Pizzo, J. Org. Chem., 1997, 62, 3744.
12. A. Cipiciani, F. Fringuelli, V. Mancini, O. Piermatti, A. M.
Scappini, and R. Ruzziconi, Tetrahedron, 1997, 53, 11853.
13. D. Pamperin, B. Ohse, H. Hopf, and M. Pietzsch, J. Mol.
Catal. B: Enzym., 1998, 5, 317.
14. D. Pamperin, C. Schulz, H. Hopf, C. Syldatk, and
M. Pietzsch, Eur. J. Org. Chem., 1998, 1441.
(based on F 2 for all 4343 reflections), GOOF 0.996, 307 paꢀ
hkl
rameters were refined. All calculations were carried out using
the SHELXTL PLUS 5 program package.28
15. V. Rozenberg, T. Danilova, E. Sergeeva, E. Vorontsov,
Z. Starikova, A. Korlyukov, and H. Hopf, Eur. J. Org. Chem.,
2002, 468.
We thank S. Yu. Erdyakov for providing triallylborane
and M. M. Il´in for performing the enantiomeric analysis.
This study was financially supported by the Russian
Foundation for Basic Research (Project No. 06ꢀ03ꢀ33086)
and the Division of Chemistry and Materials Science of
the Russian Academy of Sciences (Program No. 1).
16. N. V. Vorontsova, Ph. D. (Chem.) Thesis, A. N. Nesmeyanov
Institute of Organoelement Compounds, Russian Academy
of Sciences, Moscow, 2002, 113 pp. (in Russian).
17. R. P. Zhuravsky, V. I. Rozenberg, D. Yu. Antonov, E. V.
Vorontsov, and Z. A. Starikova, Modern Trends in Organoꢀ
element and Polymer Chemistry, Moscow, 2004, P166.
18. T. Focken, J. Rudolph, and C. Bolm, Synthesis, 2005, 3, 429.
19. V. I. Rozenberg, R. P. Zhuravsky, and E. V. Sergeeva,
Chirality, 2006, 18(2), 95.
References
20. Comprehensive Organic Chemistry, Eds D. Barton and W. D.
Ollis, Pergamon Press, Oxford, 1982, vol. 6.
21. H. C. Brown and P. K. Jadhav, J. Am. Chem. Soc., 1983,
105, 2092.
22. V. I. Rozenberg, E. V. Sergeeva, and H. Hopf, in Modern
Cyclophane Chemistry, Eds R. Gleiter and H. Hopf,
Wiley—VCH, Weinheim, 2004, 435.
23. S. E. Gibson and J. D. Knight, Org. Biomol. Chem.,
2003, 1256.
24. S. Bräse, S. Dahmen, S. Höfener, F. Lauterwasser, M. Kreis,
and R. E. Ziegert, Synlett, 2004, 2647.
25. D. C. Braddok, I. D. MacGilp, and B. G. Perry, J. Org.
Chem., 2002, 67, 8679.
1. Y. Bubnov, in Science of Synthesis: HoubenꢀWeyl Methods of
Molecular Transformation. Category 1: Organometallics. Vol. 6:
Boron Compounds, Eds D. E. Kaufmann and D. S. Matteson,
Thieme, Stuttgart—New York, 2005, Ch. 6.1.35, 945.
2. S. Lou, P. N. Moquist, and S. E. Schaus, J. Am. Chem. Soc.,
2006, 128, 12660.
3. N. Miyaura and Y. Yamamoto, in Comprehensive Organoꢀ
metallic Chemistry III. Vol 9: Boron, Ed. P. Knochel, Elsevier,
Amsterdam, 2007, Ch. 9.05.3.3, 194.
4. Y. Yamamoto and N. Asao, Chem. Rev., 1993, 93, 2222.
5. S. Thormeier, B. Carboni, and D. Kaufmann, J. Organomet.
Chem., 2002, 657, 136.
26. D. Yu. Antonov, Y. N. Belokon´, N. S. Ikonnikov, S. A.
Orlova, A. P. Pisarevsky, N. I. Raevski, V. I. Rozenberg,
E. V. Sergeeva, Yu. T. Struchkov, V. I. Tararov, and E. V.
Vorontsov, J. Chem. Soc., Perkin Trans. 1, 1995, 1873.
27. G. M. Sheldrick, SADABS, Bruker AXS Inc., Madison
(WIꢀ53719, USA), 1997.
6. N. V. Vorontsova, V. I. Rozenberg, O. L. Tok, and Yu. N.
Bubnov, Izv. Akad. Nauk, Ser. Khim., 1997, 2271 [Russ.
Chem. Bull., 1997, 46, 2152 (Engl. Transl.)].
7. N. V. Vorontsova, V. I. Rozenberg, E. V. Vorontsov, O. L.
Tok, and Yu. N. Bubnov, Izv. Akad. Nauk, Ser. Khim., 2000,
914 [Russ. Chem. Bull., Int. Ed., 2000, 49, 912].
8. V. Rozenberg, N. Dubrovina, E. Vorontsov, E. Sergeeva,
and Yu. Belokon´, Tetrahedron: Asymmetry, 1999, 10, 511.
9. H. Falk, P. ReichꢀRohrwig, and K. Schlogl, Tetrahedron,
1970, 26, 511.
28. G. M. Sheldrick, SHELXTLꢀ97, Version 5.10, Bruker AXS
Inc., Madison (WIꢀ53719, USA), 1997.
10. K. Krohn, H. Rieger, H. Hopf, D. Barrett, P. G. Jones, and
D. Doring, Chem. Ber., 1990, 123, 1729.
Received February 5, 2007;
in revised form April 16, 2007