Optically active 10,10′-spirobi[10H-phenoxasilin]-1,1′-diol: Synthesis, structure, and application of its phosphoramidite derivative to palladium-catalyzed asymmetric allylic amination

Article abstract of DOI:10.1246/CL.200070

Optically active (S)-(+)- and (R)-(-)-10,10′-spirobi[10H-phenoxasilin]-1,1′-diols were synthesized by the transesterification of their optically active di-p-toluoyl derivatives resolved by chiral HPLC. The absolute configurations of the optically active s

Full text of DOI:10.1246/CL.200070

Advance Publication Cover Page
Optically Active 10,10’-spirobi[10H-phenoxasilin]-1,1’-diol:
Synthesis, Structure, and Application of its Phosphoramidite Derivative
to Palladium-catalyzed Asymmetric Allylic Amination
Kazumasa Kajiyama,* Takane Nishi, Seina Noda, Saki Horiuchi, and Hidetaka Yuge
Advance Publication on the web March 5, 2020
doi:10.1246/cl.200070
©
2020 The Chemical Society of Japan
Advance Publication is a service for online publication of manuscripts prior to releasing fully edited, printed versions. Entire
manuscripts and a portion of the graphical abstract can be released on the web as soon as the submission is accepted. Note that the
Chemical Society of Japan bears no responsibility for issues resulting from the use of information taken from unedited, Advance
Publication manuscripts.

1
Optically Active 10,10’-spirobi[10H-phenoxasilin]-1,1’-diol:
Synthesis, Structure, and Application of its Phosphoramidite Derivative
to Palladium-catalyzed Asymmetric Allylic Amination
Kazumasa Kajiyama,* Takane Nishi, Seina Noda, Saki Horiuchi, and Hidetaka Yuge
Department of Chemistry, School of Science, Kitasato University, 1-15-1 Kitasato, Minami-ku, Sagamihara, Kanagawa 252-0373, Japan
E-mail: kajiyama@sci.kitasato-u.ac.jp
1
2
3
4
5
6
7
8
9
0
Optically active (S)-(+)- and (R)-(–)-10,10’-
RO
spirobi[10H-phenoxasilin]-1,1’-diols were synthesized by
SiCl4 (0.5 equiv)
the transesterification of their optically active di-p-toluoyl
O
Si
O
derivatives resolved by chiral HPLC. The absolute
configurations of the optically active spirosilanes were
elucidated by single-crystal X-ray structural analysis.
Phosphoramidite derivatives of the optically active diols
were applied to Pd-catalyzed asymmetric allylic amination
using 1,3-diphenylallyl acetate and benzylamine with
moderate enantioselectivity.
THF, –78 °C to rt
0%
5
OR
n-BuLi (2.5 equiv)
(
±)-2; R = MOM
(±)-3; R = H
(±)-4; R = p-MeBz
TMEDA (2.5 equiv)
a
O
b
THF, –30 °C to rt
OMOM
1
1
SiCl2Ph2 (1 equiv)
THF, –78 °C to rt
Ph
1
1
1
2
Keywords: Optically active spirocyclic diol |
Spirosilane | Phosphoramidite
O
Si
Ph
50%
OMOM
5
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
Optically active C
carbon spiro center which possess axial chirality have
attracted much attention because they are potentially useful
2
symmetric spiro compounds with
50
5
5
5
5
5
5
1
2
3
4
5
6
Scheme 1. Syntheses of spirosilanes (±)-2–4 and
monocyclic silane 5. p-TsOH·H (2.1 equiv),
acetone/EtOH (1:1), reflux 27%. b NaH (2 equiv), THF,
then p-toluoyl chloride (2 equiv) 84%.
a
2
O
as chiral ligand scaffolds for transition metal catalyzed
1
asymmetric reactions.
spirosilanes with C
Meanwhile, optically active
2
symmetry are still rare, which have
been mainly obtained by rhodium-catalyzed intramolecular
2
enantioselective hydrosilylation and dehydrogenative
3
silylation of dihydrosilane precursors. However, although a
number of spirosilanes with C
2
symmetry have been
4
synthesized, to the best of our knowledge, there is only one
report on the optical resolution of the racemate of
5
spirosilane by chiral HPLC.
Optically active spiro diols with C
1,1’-spirobiindane-7,7’-diol (SPINOL)
spirobixanthene-1,1’-diol (SBIXOL), are of interest as
precursors for monodentate spiro phosphorus ligands in
2
symmetry, such as
6
and
9,9’-
7
metal catalyzed ,7a,8asymmetric reactions with high
1
enantioselectivity.
However, in the syntheses of the
5
7
diols, several synthetic steps and chiral resolving agents are
necessary for the construction of the spiro framework and
the optical resolution of the racemic diols, respectively. In
contrast, the construction of spirosilane is more readily than
that of spiro compounds with carbon spiro center. For
instance, 10,10’-spirobi[10H-phenoxasilin] has been
58
1
59 Figure 1. H NMR (400 MHz) spectrum of 2 in CDCl .
3
6
,7
60
61 with benzylamine.
62
The racemate of 1,1’-bis(methoxymethoxy)-10,10’-
63 spirobi[10H-phenoxasilin] (±)-2 could be synthesized in
64 moderate yield (50%) by the reaction of SiCl with the
65 dianion generated from 3-(methoxymethoxy)phenyl phenyl
66 ether 1 and n-BuLi (Scheme 1). In this synthesis, TMEDA
67 was used as an additive to activate all organolithium species
68 on the reaction pathway because it has been reported that
69 the reaction of SiCl with 2,2’-dilithiodiaryl ethers bearing
70 an electron-donating group did not afford the corresponding
71 spirosilanes. The H NMR spectrum showed a single
72 resonance for the methyl groups and seven signals in the
73 aromatic region indicative of C symmetry (Figure 1). Endo
74 configuration was demonstrated by spectroscopically non-
75 equivalent methylene protons due to the restriction of
synthesized by the reaction of SiCl
4
with 2,2’-
4
dilithiodiphenyl ether generated from diphenyl ether and n-
9
BuLi. Thus, we envisioned that the spiro framework of
silicon analogue of SBIXOL could also be readily
constructed. Herein, we report on the synthesis and
structural characterization of optically active dihydroxy
spirosilanes, (S)-(+)- and (R)-(–)-10,10’-spirobi[10H-
phenoxasilin]-1,1’-diol [(S)-(+)-3 and (R)-(–)-3], and their
di-p-toluoyl derivatives (S)-(+)-4 and (R)-(–)-4. Also
presented are the application of their phosphoramidite
derivatives (S)-(–)-6 and (R)-(+)-6 to palladium-catalyzed
asymmetric allylic amination of 1,3-diphenylallyl acetate
4
1
0
1
2

2
(
S)-(+)-4
(S)-(+)-3 (92%)
or
NaOMe (2 equiv)
MeOH/THF, rt
or
(
R)-(–)-4
(R)-(–)-3 (87%)
4
4
2
3
4
4
4
4
5
6
Scheme 2. Transesterification reactions of (S)-(+)-4 and
(R)-(–)-4.
1
2
3
4
2 2
Figure 2. UV-vis spectra (in CH Cl ) of 2 and 5.
4
4
7
8
4
5
5
5
5
9
0
1
2
3
Figure 4. The ORTEP drawing of (+)-3 showing the
thermal ellipsoids at the 50% probability level. All
hydrogens are omitted for clarity.
1
4
be S and R, respectively, by means of refinement of the
1
5
5
6
54 Flack parameter.
55 Optically active dihydroxy spirosilanes (+)-3 and (–)-3
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
Figure 3. The ORTEP drawing of (+)-4 showing the
thermal ellipsoids at the 50% probability level. All
hydrogens are omitted for clarity.
56 could be obtained by the transesterification reactions of the
57 di-p-toluoyl ester (S)-(+)-4 and (R)-(–)-4, respectively, with
58 NaOMe in MeOH/THF (Scheme 2). The high enantiomeric
59 purity of the products indicate that there was no
60 racemization of spirosilanes in the reaction through
61 nucleophilic attack of the methoxide anion at silicon spiro
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
rotation about C–OMOM bond and the absence of an
aromatic proton signal without vicinal coupling constants.
The spiro structure of (±)-2 could also be supported by
UV-vis spectroscopic analysis (Figure 2). In the UV-vis
spectrum of the spirosilane (±)-2, although the spectral
shape and λmax were similar to those of monocyclic
diphenylsilane 5 synthesized as a reference compound
(Scheme 1), the molar extinction coefficient of λmax was
approximately 1.5 to 2 times as large as that of 5. However,
because the weak absorption maximum at longer-
wavelength (> 300 nm) resulted from HOMO–LUMO
transition was not observed, the influence of spiro-
3
b
62 center. The Lewis acidity at silicon in 1,1’-dioxy-10,10’-
63 spirobi[10H-phenoxasilin] framework must be decreased
64 owing to π-electron donation from oxygens. The single-
65 crystal X-ray diffraction analyses of (+)-3 (Figure 4) and (–
1
6
66 )-3 revealed that the absolute configurations were also
1
4
67 assigned to be S and R, respectively, by means of
1
5
68 refinement of the Flack parameter. The bond lengths and
69 angles around the silicon atoms of 3 and 4 were comparable
70 with those of the reported six-membered π-conjugated
9
b,11c,17
71 spirosilanes,
and the spiro rings of them assumed
1
1
conjugation and interaction between σ* orbital of the Si–C
72 slightly distorted planar structures. Meanwhile, the
73 tetrahedral geometry around the silicon spiro center was
74 distorted with small endocyclic C–Si–C angles of around
75 100° in contrast to nearly ideal tetrahedral geometry around
1
2
bond on silicon and π* orbital of two biaryl ether units
leading to the narrowing of HOMO–LUMO energy gap
could not be evaluated.
Removal of methoxymethyl (MOM) groups from (±)-2
2
by TsOH·H O under reflux conditions in a mixture of
acetone/EtOH 1/1 (v/v) could afford dihydroxy spirosilane
(±)-3 even in low yields (Scheme 1), although unidentifiable
decomposition products were mainly obtained. Chiral high-
performance liquid chromatography (HPLC) separation of
(±)-3 was not practical because of its low solubility in
organic solvents. Thus, the diol (±)-3 was converted to di-p-
toluoyl ester (±)-4 (Scheme 1) followed by the chiral HPLC
separation of (±)-4 performed on recycling preparative
HPLC equipped with a CHIRALPAK IA column using a
7
b
76 the carbon spiro center of SBIXOL probably due to long
77 Si–C bonds compared with C–C bonds. Additionally, the C–
78 O–C bond angles of around 125° in six-membered spiro
79 rings for the spirosilanes were significantly larger than those
7
b
80 of around 119° for SBIXOL, which would result from the
81 distortion around the silicon spiro center. The low and good
7
82 yields of the spiro diols (±)-3 and (±)-SBIXOL in the
83 deprotection reactions with protic acids under reflux
84 conditions should be influenced by the presence and
85 absence of the significant distortion around spiro center,
86 respectively.
mixture of n-hexane/CHCl
3
2/1 (v/v) as the eluent. The
87
To ascertain that the spiro diol 3 can be the chiral
crystal structures of (+)-4 (Figure 3) and (–)-4 have been
88 ligand scaffold for transition metal catalyzed asymmetric
89 reactions, monodentate phosphoramidite ligand 6 was
90 synthesized for the asymmetric allylic amination. According
determined by the single-crystal X-ray diffraction
1
3
analyses, and the absolute configurations were assigned to

3
1
2
3
4
5
6
7
to the synthetic procedure for the phosphoramidite ligands
50 Supporting
51 http://dx.doi.org/10.1246/cl.******.
Information
is
available
on
7
a,8
from SBIXOL, the optically active ligands (S)-(–)-6 and
(R)-(+)-6 were obtained by the reactions of (S)-(+)-3 and
(R)-(–)-3, respectively, with hexamethylphosphorus
triamide (HMPT) in refluxing toluene (Scheme 3). It is
worth noting that the reaction time (3 h) and yield were
shorter and higher, respectively, than those (72 h and 35%)
5
2 References and Notes
53
1
For selected review articles, see: a) J.-H. Xie, Q.-L. Zhou, Acc.
Chem. Res. 2008, 41, 581. b) K. Ding, Z. Han, Z. Wang, Chem.
Asian J. 2009, 4, 32. c) G. B. Bajracharya, M. A. Arai, P. S.
Koranne, T. Suzuki, S. Takizawa, H. Sasai, Bull. Chem. Soc. Jpn.
2009, 82, 285. d) G. B. Bajracharya, J. Nepal. Chem. 2011, 28, 1.
e) Q.-L. Zhou, J.-H. Xie, Top. Organomet. Chem. 2011, 36, 1.
K. Tamao, K. Nakamura, H. Ishii, S. Yamaguchi, M. Shiro, J.
Am. Chem. Soc. 1996, 118, 12469.
a) Y. Kuninobu, K. Yamauchi, N. Tamura, T. Seiki, K. Takai,
Angew. Chem. Int. Ed. 2013, 52, 1520. b) M. Murai, Y. Takeuchi,
K. Yamauchi, Y. Kuninobu, K. Takai, Chem. Eur. J. 2016, 22,
6048. c) L. J. P. van der Boon, S.-i. Fuku-en, J. C. Slootweg, K.
Lammertsma, A. W. Ehlers, Top. Catal. 2018, 61, 674.
a) V. Déjean, H. Gornitzka, G. Oba, M. Koenig, G. Manuel,
Organometallics 2000, 19, 711. b) B. Wrackmeyer, E. Khan, R.
Kempe, Appl. Organomet. Chem. 2008, 22, 383. c) E. Khan, B.
Wrackmeyer, R. Kempe, Eur. J. Inorg. Chem. 2008, 5367. d) H.
Lenormand, J.-P. Goddard, L. Fensterbank, Org. Lett. 2013, 15,
748. e) E. Khan, B. Wrackmeyer, C. Döring, R. Kempe, Eur. J.
Inorg. Chem. 2014, 3411. f) Lenormand, V. Corcé, G. Sorin, C.
Chhun, L.-M. Chamoreau, L. Krim, E.-L. Zins, J.-P. Goddard, L.
Fensterbank, J. Org. Chem. 2015, 80, 3280.
L. J. P. van der Boon, L. van Gelderen, T. R. de Groot, M. Lutz,
J. C. Slootweg, A. W. Ehlers, K. Lammertsma, Inorg. Chem.
2018, 57, 12697.
a) V. B. Birman, A. L. Rheingold, K.-C. Lam, Tetrahedron:
Asymmetry 1999, 10, 125. b) J.-H. Zhang, J. Liao, X. Cui, K.-B.
Yu, J. Zhu, J.-G. Deng, S.-F. Zhu, L.-X. Wang, Q.-L. Zhou, L. W.
Chung, T. Ye, Tetrahedron: Asymmetry 2002, 13, 1363. c) Z. Li,
X. Liang, F. Wu, B. Wan, Tetrahedron: Asymmetry 2004, 15,
665.
a) S. Wu, W. Zhang, Z. Zhang, X. Zhang, Org. Lett. 2004, 6,
3565. b) W. Zhang, S. Wu, Z. Zhang, H. Yennawar, X. Zhang,
Org. Biomol. Chem. 2006, 4, 4474.
W. Zhang, C.-J. Wang, W. Gao, X. Zhang, Tetrahedron Lett.
2005, 46, 6087.
a) K. Oita, H. Gilman, J. Am. Chem. Soc. 1957, 79, 339. b) J. T.
Mague, M. S. Balakrishna, R. Venkateswaran, Acta Cryst. 2007,
E63, o4429.
C. H. S. Hitchcock, F. G. Mann, A. Vanterpool, J. Chem. Soc.
1957, 4537.
a) H. Dürr, R. Gleiter, Angew. Chem. 1978, 17, 559. b) A. Ito, M.
Urabe, K. Tanaka, Angew. Chem. Int. Ed. 2003, 42, 921. c) A. Ito,
K. Hata, K. Kawamoto, Y. Hirao, K. Tanaka, M. Shiro, K.
Furukawa, T. Kato, Chem. Eur. J. 2010, 16, 10866.
a) J. Ohshita, K.-H. Lee, D. Hamamoto, Y. Kunugi, J. Ikadai, Y.-
W. Kwak, A. Kunai, Chem. Lett. 2004, 33, 892. b) S. Furukawa,
J. Kobayashi, T. Kawashima, Dalton. Trans. 2010, 39, 9329.
Crystallographic data have been deposited with Cambridge
Crystallographic Data Centre as supplementary publication nos.
CCDC-1980056 for (+)-4 and CCDC-1980057 for (–)-4. Copies
of the data can be obtained free of charge via CCDC Website.
5
5
5
5
5
5
4
5
6
7
8
9
(
S)-(+)-3
(S)-(–)-6 (65%)
or
P(NMe
2
)
3
(1 equiv)
O
Si
O
O
2
3
or
PNMe
2
Toluene reflux
60
(
R)-(–)-3
(R)-(+)-6 (76%)
O
6
6
6
6
6
6
6
1
2
3
4
5
6
7
8
9
0
1
2
1
1
1
Scheme 3. Syntheses of optically active phosphoramidite
ligands (S)-(–)-6 and (R)-(+)-6.
4
3
[
Pd(η -C
3
H
5
)Cl]
2
(1 mol%)
68
69
70
OAc
Ph
L (4 mol%)
NHBn
*
BnNH
2
(3 equiv)
2
, rt, 3 h
Ph
Ph
Ph
7
7
7
1
2
3
CH
2
Cl
L = (S)-(–)-6
L = (R)-(+)-6
y. > 99%, 71% ee (S)
y. > 99%, 69% ee (R)
1
1
3
4
74
75
76
5
6
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
Scheme 4. Pd(II)/(S)-(–)-6- and Pd(II)/(R)-(+)-6-catalyzed
asymmetric allylic amination reaction of rac-(2E)-1,3-
diphenyl-2-propenyl acetate with benzylamine.
7
7
7
8
7
8
9
0
7
a
1
13
for the reaction of SBIXOL.
H
and
C
NMR
81
82
spectroscopic analyses of the ligands 6 revealed that the two
diaryl ether moieties were spectroscopically unequivalent
based on the pyramidal geometry at phosphorus while the
NMR spectra of the spirosilanes 2–4 were consistent with
8
8
8
8
3
4
5
6
7
C
2
symmetric structures. The optically active ligands 6
87
88
8
9
could be applied to Pd-catalyzed asymmetric allylic
amination reaction of rac-(2E)-1,3-diphenylallyl acetate
with benzylamine affording the chiral allylic amine in
nearly quantitative yield with moderate enantiomeric excess
(Scheme 4). It is noteworthy that the complete conversion of
the substrate was achieved in a short reaction time of 3 h
compared to the reactions (12–36 h) with other monodentate
8
9
9
9
9
0
1
2
10
93
94 11
9
5
1
8
96
phosphoramidite ligands under similar reaction conditions.
In summary, first optically active C symmetric spiro
diols with silicon spiro center, (S)-(+)- and (R)-(–)-10,10’-
spirobi[10H-phenoxasilin]-1,1’-diols [(S)-(+)-3 and (R)-(–)- 100
9
7
8
2
9
12
99
1
1
1
1
01 13
02
03
04
3], were synthesized by the transesterification of their
optically active di-p-toluoyl derivatives 4 resolved by chiral
HPLC. The absolute configurations of the optically active
spirosilanes 3 and 4 were elucidated by single-crystal X-ray 105 14 E. L. Eliel, S. H. Wilen, in Stereochemistry of Organic
structural analysis. Phosphoramidite derivatives 6 of the 106
optically active diols 3 were synthesized and applied to Pd-
catalyzed asymmetric allylic amination reaction of 1,3-
diphenylallyl acetate with benzylamine affording the chiral
allylic amine in nearly quantitative yield with moderate 111
enantioselectivity. Improved method for the removal of 112
MOM groups from the spirosilane 2 and applications of the
optically active ligands 6 to other transition metal-catalyzed
asymmetric reactions are under investigations.
Compounds, John Wiley & Sons, New York, 1994, pp. 1138–
1142.
H. D. Flack, Acta Cryst. A 1983, 39, 876.
Crystallographic data have been deposited with Cambridge
Crystallographic Data Centre as supplementary publication nos.
CCDC-1980058 for (+)-3 and CCDC-1980059 for (–)-3. Copies
of the data can be obtained free of charge via CCDC Website.
X.-Y. Liu, X. Tang, Y. Zhao, D. Zhao, J. Fan, L.-S. Liao, J.
Mater. Chem. C 2018, 6, 1023.
1
1
1
1
07
08 15
09 16
10
1
1
1
1
13 17
14
15 18
16
117
a) K. N. Gavrilov, E. B. Benetsky, V. E. Boyko, E. A.
Rastorguev, V. A. Davankov, B. Schäfener, A. Börner, Chirality
2010, 22, 844. b) Z. Liu, Z. Cao, H. Du, Org. Biomol. Chem.

4
1
2
2011, 9, 5369. c) C. Schmitz, W. Leitner, G. Franciò, Eur. J. Org.
Chem. 2015, 6205.