C1-Symmetric Binap Derivative Featuring Single Diferrocenylphosphino-Donor Moiety

Article abstract of DOI:10.1021/acs.organomet.1c00132

A C1-symmetric chiral bisphosphine, FcPh-Binap (1), which possesses a single diferrocenylphosphino moiety together with a conventional Ph2P-substituent, was prepared in enantiomerically pure forms. Ligand 1 is sterically less demanding than Fc-Segphos (A)

Full text of DOI:10.1021/acs.organomet.1c00132

pubs.acs.org/Organometallics
Communication
C1‑Symmetric Binap Derivative Featuring Single
Diferrocenylphosphino-Donor Moiety
Yuuki Enomoto, Hiroki Ichiryu, Hao Hu, Yasuyuki Ura, and Masamichi Ogasawara*
Cite This: Organometallics 2021, 40, 1020−1024
Read Online
sı
*
Metrics & More
Article Recommendations
Supporting Information
ACCESS
ABSTRACT: A C1-symmetric chiral bisphosphine, FcPh-Binap (1), which possesses a single
diferrocenylphosphino moiety together with a conventional Ph2P-substituent, was prepared in
enantiomerically pure forms. Ligand 1 is sterically less demanding than Fc-Segphos (A), which
has two diferrocenylphosphino groups, and showed higher activity than A in the rhodium-
catalyzed asymmetric conjugate addition of phenylboronic acid to 2-cyclohexenone. Ligand 1 was
applied in the two palladium-catalyzed asymmetric reactions, namely the synthesis of axially chiral
allenes and the intermolecular Heck reaction, and displayed higher enantioselectivity than parent
Binap. The Pd/(R)-1 species showed up to 47% ee enhancement over the Pd/(R)-Binap catalyst
in the former reaction and up to 39% ee enhancement in the latter.
hiral phosphines are arguably the most common chiral
auxiliaries in asymmetric metal catalysis.1 Accordingly,
the electronic impacts of the ferrocenyl group in a series of
organophosphines.7 The electronic properties of the ferrocenyl
group in organophosphines were estimated to be similar to
those of primary alkyl groups. The steric influences of the
ferrocenyl group are larger than those of typical bulky
substituents, such as tert-butyl and o-tolyl groups, and
comparable to those of the mesityl group.
In 2020, we reported a novel chiral bisphosphine ligand, Fc-
Segphos A, in which the diphenylphosphino-substituents in
parent Segphos B were replaced with the diferrocenylphos-
phino-groups (Figure 2).8,9 Fc-Segphos was applied in the
C
the design of novel chiral phosphines has been a central subject
in the development of metal-catalyzed asymmetric trans-
formations. In a metal catalyst coordinated with chiral
phosphine(s), phosphorus-bound substituents are primal
elements to create the chiral environment at the metal center
in many cases. For example, upon the coordination of Binap to
a metal atom, the orientation of the four phenyl groups are
regulated by the chiral binaphthyl backbone to generate the
effective chiral pocket around the metal (Figure 1).2,3 Steric
Figure 2. Structures of ferrocenyl group, (R)-Fc-Segphos A, and
parent (R)-Segphos B.
Figure 1. Structure of (S)-Binap and its 3D representation in a metal
complex.
and electronic decorations of the phenyl groups are conven-
tional strategies to improve the properties of chiral phosphines.
Modified aryl groups, such as 3,5-dimethylphenyl (Xyl), 3,5-di-
tert-butyl-4-methoxyphenyl (DTBM), 3,5-bis(trifluoromethyl)-
phenyl, and so on, have been frequently used for these
purposes.4
palladium-catalyzed asymmetric synthesis of axially chiral
allenes achieving higher enantioselectivity than B. In contrast,
A was not effective in the rhodium-catalyzed asymmetric
conjugate addition of phenylboronic acid to cyclohexenone.
The catalytic inactivity of the Rh/A species could be
We have been interested in utilizing ferrocenyl (Fc) groups
as components of ancillary phosphine ligands in metal
catalysts. While ferrocene displays an aromatic character,5 its
steric properties are significantly different from those of
benzenoid aromatics because of the cylindrical structure.
Furthermore, the ferrocenyl group is highly electron-donating
for an aryl substituent.6 We recently quantified the steric and
Received: March 5, 2021
Published: April 9, 2021
https://doi.org/10.1021/acs.organomet.1c00132
© 2021 American Chemical Society
Organometallics 2021, 40, 1020−1024
1020

Organometallics
pubs.acs.org/Organometallics
Communication
rationalized as the overcrowding at the rhodium center due to
the presence of the four bulky ferrocenyl substituents in A.
Since the positive influences of the ferrocenyl substituents in
A were proven in the palladium-catalyzed reaction, we
intended to adjust its structure for wider applicability. In this
Communication, the synthesis and applications of a C1-
symmetric Binap derivative having a single diferrocenylphos-
phino moiety (FcPh-Binap; 1) are reported.
A major drawback of A is the overcrowding at the
coordinating metal center. Our strategy to solve this problem
is introducing one diferrocenylphosphino group in a chiral
bisphosphine ligand instead of two in A, and C1-symmetric
FcPh-Binap (1) was designed. An axially chiral binaphthyl
framework was employed in 1 instead of the bi(benzodioxolyl)
skeleton in A, since the starting compound, (S)-/(R)-
binaphthol, was commercially available. The synthesis of 1 is
outlined in Scheme 1. Diphenylphosphino/triflate 2 (prepared
Scheme 1. Preparation of FcPh-Binap 1
Figure 3. Ball-and-stick drawing of the X-ray structure of PdCl2[(S)-
FcPh-Binap] ((S)-3) with selected atom numbering. Cocrystallized
solvent molecules are omitted for clarity. Selected bond lengths (Å)
and angles (deg): Pd1−P1 = 2.252(1), Pd1−P2 = 2.287(2), Pd1−Cl1
= 2.347(2), Pd1−Cl2 = 2.333(2), C2−C12 = 1.508(8); P1−Pd1−P2
= 92.20(6), Cl1−Pd1−P2 = 86.61(7), Cl1−Pd1−Cl2 = 89.13(7),
Cl2−Pd1−P1 = 92.54(6), dihedral angles between the two Cp planes
in a Fc substituent = 6.41 (in Fc1) and 4.81 (in Fc2); nonbonding
distances: H6−H26 = 2.382, H6−H30 = 2.438, H17−H22 = 2.325.
ferrocenyl substituents leading to the distortion of the
ferrocenyl units. However, the distortion in 3 is smaller than
that in PdCl2(Fc-Segphos), which indicates that the over-
crowding in A is somewhat reduced in 1. The dihedral angle
between the P1Pd1P2 plane and the Cl1Pd1Cl2 plane is 9.21°.
The distortion at Pd1 is marginal, and the sum of the four
angles at Pd1 involving Cl1, Cl2, P1, and P2 is 360.48. The
bite angle, P1−Pd1−P2, in 3 is 92.20(6)°, which is comparable
to that in PdCl2(Binap) (92.69(8)°).3 Likewise, the dihedral
angle between the two naphthyl planes in 3 (71.64°) is only
slightly larger than that in PdCl2(Binap) (71.30°).
(R)-FcPh-Binap 1 was tested in several metal-catalyzed
asymmetric reactions, and its performance was compared with
that of parent Binap. The first reaction examined was the
palladium-catalyzed asymmetric synthesis of axially chiral
allenes (Table 1).13 While the Pd/(R)-Binap catalyst provided
allene (R)-6ax of 34% ee in 85% yield for the reaction of 4a
with malonate 5x (entry 1), the enantioselectivity was
improved to 81% ee by the use of Pd/(R)-1 under the
otherwise identical conditions (entry 2). Similarly, (R)-1
showed higher enantioselectivity than (R)-Binap for the
reaction of 4a or 4b with malonate 5y to give (R)-6ay (82%
ee vs 86% ee; entries 3 and 4) or (R)-6by (54% ee vs 88% ee;
entries 5 and 6). The reaction with bissulfone 5z also showed
advantage of (R)-1 over (R)-Binap. Allene (R)-6cz of 46% ee
was obtained in 94% yield using Binap (entry 7). In
comparison, the Pd/(R)-1 catalyst afforded (R)-6cz of 86%
ee in 94% yield (entry 8).
from (R)-binaphthol)10 was reacted with diferrocenylphos-
phine11 in the presence of DABCO and catalytic NiCl2(dppe)
in DMF. The reaction proceeded slowly, and 1 was obtained in
52% in 60 h. Similar conditions were used in the preparation of
unsymmetric Binap derivatives,12 and the coupling reactions
proceeded with retention of the stereochemistry in 2.
However, the partial racemization was detected in the present
reaction, and (R)-1 was isolated in 48% ee. The enantiomeric
purification of scalemic (R)-1 was achieved by the preparative
chiral HPLC on Daicel Chiralpak IA, and (R)- and (S)-1 were
obtained as pure enantiomers. Alternatively, enantiomerically
pure (R)-1 was isolated by recrystallization of scalemic (R)-1
(48% ee) from chloroform/pentane. The X-ray crystallography
of (R)-(+)-1 confirmed its structure and the absolute
configuration (see Supporting Information). Bisphosphine 1
is air-stable, and the 31P NMR analysis of crystalline 1, which
had been stored under air for a few months, showed no
oxidation.
A reaction of an equimolar mixture of (S)-1 and PdCl2(cod)
in chloroform gave PdCl2[(S)-FcPh-Binap] ((S)-3) quantita-
tively. The 31P NMR signals of unligated (S)-1, detected at δP
−35.0 and −14.0, shifted downfield to δP 14.4 and 26.1 upon
the coordination to Pd(II). The single-crystals of (S)-3 were
grown as deep-red prisms by recrystallization from chloro-
form/hexane, and the crystal structure is shown in Figure 3
(see Supporting Information for details). The skewed seven-
membered chelate and the alternating face-edge orientation of
the phosphorus-bound Fc and Ph groups are similar to those in
PdCl2(Binap).3 As observed in PdCl2(Fc-Segphos),8 both
FeCp fragments are located away from Pd1 to avoid the steric
congestion around Pd1. The nonbonding interactions are
observed between Fc2 and H6 as well as between the two
Whereas FcPh-Binap 1 was more effective than Binap in the
reaction in Table 1, the validity of 1 was examined in the
intermolecular asymmetric Heck reaction of aryl triflates 8 with
2,3-dihydrofuran 7 (Table 2).3,15 The initial product in the
reaction is 10, which subsequently undergoes the isomerization
to 9 under the palladium catalysis. The isomerization is also
1021
https://doi.org/10.1021/acs.organomet.1c00132
Organometallics 2021, 40, 1020−1024

Organometallics
pubs.acs.org/Organometallics
Communication
Binap were (S)-enriched, the Pd/(R)-1 catalyst provided (R)-
enriched 10. This is because the enantioselectivity of Pd/(R)-1
was quite high at the initial carbon−carbon bond formation,
and thus, remaining 10 were (R)-enriched even after the
kinetic resolution/isomerization.
Table 1. Palladium-Catalyzed Asymmetric Synthesis of
Axially Chiral Allenes
a
FcPh-Binap 1 showed decent performance in the rhodium-
catalyzed asymmetric conjugate addition (Scheme 2).16 For
Scheme 2. Rhodium-Catalyzed Asymmetric 1,4-Addition of
Phenylboronic Acid to 2-Cyclohexenone
b
c d
,
entry
4
5
base
CsOtBu
L*
Binap
FcPh-Binap
Binap
FcPh-Binap
Binap
FcPh-Binap
Binap
yield (%)
% ee
1
2
3
4
5
6
7
8
4a
5x
85 (6ax)
88 (6ax)
90 (6ay)
88 (6ay)
81 (6by)
85 (6by)
94 (6cz)
94 (6cz)
34 (R)
81 (R)
82 (R)
86 (R)
54 (R)
88 (R)
46 (R)
86 (R)
4a
4b
4c
5y
5y
5z
CsOtBu
CsOtBu
Me3SiCH2Li
FcPh-Binap
a
All the reactions were carried out with 4 (0.20 mmol), 5 (0.23
mmol), and base (0.25 mmol) in THF (2.0 mL) for 24 h in the
presence of a Pd catalyst (5 mol %) generated from Pd(dba)2 and the
the reaction between 2-cyclohexenone and phenylboronic acid,
the Rh/(R)-1 catalyst gave (R)-3-phenylcyclohexanone in 87%
ee and 84% yield. Although the enantioselectivity was lower
than that of the Rh/(R)-Binap catalyst (99% ee), the result is
in striking contrast to the sluggishness of the Rh/(R)-A
catalyst.8 The catalytic inactivity of the Rh/(R)-A species could
be attributed to the excessive congestion at the Rh center due
to the presence of the four bulky Fc-substituents in A.
Apparently, the rational design of (R)-1, reducing the number
of ferrocenyl substituents to two, widens the available space
around the Rh center and increases the catalytic activity of the
Rh/(R)-1 species.
In summary, a novel axially chiral C1-symmetric bi-
sphosphine ligand, FcPh-Binap 1, was prepared. Ligand 1
possesses a single bulky and electron-donating Fc2P-group
instead of the two Fc2P-groups in A. Because of the reduced
steric congestion in 1, the Rh complex of 1 showed better
catalytic activity than that of A in the conjugate addition of
phenylboronic acid to 2-cyclohexenone. Meanwhile, 1
displayed better enantioselectivity than Binap in the palla-
dium-catalyzed asymmetric synthesis of axially chiral allenes as
well as in the intermolecular asymmetric Heck reaction
showing up to 47% ee and 39% ee enhancement, respectively,
b
chiral phosphine. Isolated yield by chromatography on alumina.
c
d
Determined by HPLC on a chiral stationary phase. The absolute
configurations were deduced by the Lowe−Brewster rule [ref 14].
enantioselective, and major enantiomer (R)-10 isomerizes
faster than (S)-10 with Pd/(R)-Binap. This kinetic resolution
process enhances the enantiomeric purity of (R)-9 by the
selective concentration of the (S)-enantiomer in remaining 10.
Accordingly, the product ratios between 9 and 10 show strong
influence on %ee of 9 and 10. Under the conditions we
employed, the yields of 10 were marginal, 7% at most. For the
comparison of 1 with Binap at the carbon−carbon bond
formation step, the mixtures of 9 and 10 were hydrogenated
using the Wilkinson’s catalyst, and the enantiomeric purities of
2-aryl-THFs 11 were determined by the chiral HPLC analysis.
The reactions using the Pd/(R)-Binap catalyst provided 11 in
modest enantioselectivity of ranging from 55 to 64% ee
(entries 1, 3, and 5). On the other hand, the enantiomeric
purities of 11 obtained by Pd/(R)-1 were 91−95% ee (entries
2, 4, and 6). While minor products 10 obtained by Pd/(R)-
a
Table 2. Palladium-Catalyzed Intermolecular Heck Reactions of 2,3-Dihydrofuran with Aryl Triflates
b
c
d
d
b
d
entry
8
L*
yield of 9 + 10 (%)
9/10 ratio
% ee of 9
% ee of 10
yield of 11 (%)
% ee of 11
1
2
3
4
5
6
8a
Binap
FcPh-Binap (1)
Binap
FcPh-Binap (1)
Binap
FcPh-Binap (1)
>95 (9a + 10a)
>95 (9a + 10a)
78 (9b + 10b)
67 (9b+ 10b)
>95 (9c + 10c)
>95 (9c + 10c)
95/5
>99/<1
93/7
95/5
96/4
98/2
70 (R)
95 (R)
70 (R)
92 (R)
55 (R)
94 (R)
46 (S)
----
41 (S)
72 (R)
25 (S)
57 (R)
83 (11a)
90 (11a)
60 (11b)
71 (11b)
84 (11c)
83 (11c)
64 (R)
95 (R)
58 (R)
91 (R)
55 (R)
94 (R)
8b
8c
a
All the reactions were carried out with 7 (2.5 mmol), 8 (0.50 mmol), and iPr2NEt (3.0 mmol) in benzene (2.0 mL) for 72 h in the presence of a
b
c
Pd catalyst generated from Pd(OAc)2 (3.0 mol %) and the chiral phosphine (6.5 mol %). Isolated yield by silica gel chromatography. Determined
by the H NMR analysis of the crude reaction mixture. Determined by HPLC on a chiral stationary phase.
d
1
1022
https://doi.org/10.1021/acs.organomet.1c00132
Organometallics 2021, 40, 1020−1024

Organometallics
pubs.acs.org/Organometallics
Communication
over the palladium catalysts derived from parent Binap.
Application of 1 in other transition-metal-catalyzed asymmetric
reactions will be examined in due course.
REFERENCES
■
(1) Börner, A., Ed. Phosphorus Ligands in Asymmetric Catalysis:
Synthesis and Applications; Wiley-VCH: Weinheim, 2008.
(2) (a) Miyashita, A.; Yasuda, A.; Takaya, H.; Toriumi, K.; Ito, T.;
Souchi, T.; Noyori, R. Synthesis of 2,2’-Bis(diphenylphosphino)-1,1’-
binaphthyl (BINAP), as Atropisomeric Chiral Bis(triaryl)phosphine,
and Its Use in the Rhodium(I)-Catalyzed Asymmetric Hydrogenation
of α-(Acylamino)acrylic Acids. J. Am. Chem. Soc. 1980, 102, 7932−
7934. (b) Ohkuma, T.; Kurono, N. BINAP. In Privileged Chiral
Ligands and Catalysts; Zhou, Q.-L., Ed.; Wiley-VCH: Weinheim,
2011; Chapter 1, pp 1−53.
(3) Ozawa, F.; Kubo, A.; Matsumoto, Y.; Hayashi, T.; Nishioka, E.;
Yanagi, K.; Moriguchi, K. Palladium-Catalyzed Asymmetric Arylation
of 2,3-Dihydrofuran with Phenyl Triflate. A Novel Asymmetric
Catalysis Involving a Kinetic Resolution Process. Organometallics
1993, 12, 4188−4196.
ASSOCIATED CONTENT
■
sı
* Supporting Information
The Supporting Information is available free of charge at
https://pubs.acs.org/doi/10.1021/acs.organomet.1c00132.
Full experimental procedures, NMR spectra (1H, 13C,
and 31P) for all the new compounds, and chiral HPLC
chromatograms (PDF)
Accession Codes
CCDC 2060069 and 2060082 contain the supplementary
crystallographic data for this paper. These data can be obtained
free of charge via www.ccdc.cam.ac.uk/data_request/cif, or by
emailing data_request@ccdc.cam.ac.uk, or by contacting The
Cambridge Crystallographic Data Centre, 12 Union Road,
Cambridge CB2 1EZ, UK; fax: +44 1223 336033.
(4) (a) Berthod, M.; Mignani, G.; Woodward, G.; Lemaire, M. The
Modified BINAP: The How and the Why. Chem. Rev. 2005, 105,
1801−1836. (b) Pereira, M. M.; Calvete, M. J. F.; Carrilho, R. M. B.;
Abreu, A. R. Synthesis of Binaphthyl Based Phosphine and Phosphite
Ligands. Chem. Soc. Rev. 2013, 42, 6990−7027.
(5) (a) Kealy, T. J.; Pauson, P. L. A New Type of Organo-Iron
Compound. Nature 1951, 168, 1039−1040. (b) Wilkinson, G.;
Rosenblum, M.; Whiting, M. C.; Woodward, R. B. The Structure of
Iron Bis-cyclopentadienyl. J. Am. Chem. Soc. 1952, 74, 2125−2126.
(c) Fischer, E. O.; Pfab, W. Zur Kristallstruktur der Di-cyclo-
pentadienyl-verbindungen des Zwiwertigen Eisens, Kobalts, und
Nickels. Z. Naturforsch., B: J. Chem. Sci. 1952, 7, 377−379. (d) Dunitz,
J.; Orgel, L.; Rich, A. The Crystal Structure of Ferrocene. Acta
Crystallogr. 1956, 9, 373−375.
(6) Floris, B.; Illuminati, G.; Jones, P. E.; Ortaggi, G. The Electron-
Donor Properties of Ferrocene. Coord. Chem. Rev. 1972, 8, 39−43.
(7) Hu, H.; Ichiryu, H.; Nakajima, K.; Ogasawara, M. Estimating
Effective Steric and Electronic Impacts of Ferrocenyl Group in
Organophosphines. ACS Omega 2021, 6, 5981−5989.
(8) Hu, H.; Ichiryu, H.; Seki, N.; Nakajima, K.; Ohki, Y.; Ogasawara,
M. Synthesis, Characterization, and Application of Segphos Derivative
Having Diferrocenylphosphino-Donor Moieties. Organometallics
2020, 39, 788−792.
(9) A Diop derivative with Fc2P-donor moieties was reported, see:
Guillaneux, D.; Martiny, L.; Kagan, H. B. Diferrocenylphosphine: A
Facile Synthesis and Its Use to Prepare Chiral Phosphines. Collect.
Czech. Chem. Commun. 2000, 65, 717−728.
AUTHOR INFORMATION
■
Corresponding Author
Masamichi Ogasawara − Department of Natural Science,
Graduate School of Science and Technology, Tokushima
International Science Institute, and Research Cluster on
“Innovative Chemical Sensing”, Tokushima University,
Tokushima 770-8506, Japan; orcid.org/0000-0002-
1893-3306; Email: ogasawar@tokushima-u.ac.jp
Authors
Yuuki Enomoto − Department of Natural Science, Graduate
School of Science and Technology, Tokushima International
Science Institute, and Research Cluster on “Innovative
Chemical Sensing”, Tokushima University, Tokushima 770-
8506, Japan
Hiroki Ichiryu − Department of Natural Science, Graduate
School of Science and Technology, Tokushima International
Science Institute, and Research Cluster on “Innovative
Chemical Sensing”, Tokushima University, Tokushima 770-
8506, Japan
Hao Hu − Department of Natural Science, Graduate School of
Science and Technology, Tokushima International Science
Institute, and Research Cluster on “Innovative Chemical
Sensing”, Tokushima University, Tokushima 770-8506,
Japan; Graduate School of Life Science, Hokkaido University,
Sapporo 001-0021, Japan
Yasuyuki Ura − Department of Chemistry, Biology, and
Environmental Science, Faculty of Science, Nara Women’s
University, Nara 630-8506, Japan; orcid.org/0000-0003-
0484-1299
(10) (a) Kurz, L.; Lee, G.; Morgans, D., Jr.; Waldyke, M. J.; Ward, T.
Stereospecific Functionalization of (R)-(−)-1,1’-Bi-2-naphthol Tri-
flate. Tetrahedron Lett. 1990, 31, 6321−6324. (b) Uozumi, Y.;
Hayashi, T. Catalytic Asymmetric Synthesis of Optically Active 2-
Alkanols via Hydrosilylation of 1-Alkenes with a Chiral Mono-
phosphine-Palladium Catalyst. J. Am. Chem. Soc. 1991, 113, 9887−
9888. (c) Uozumi, Y.; Tanahashi, A.; Lee, S.-Y.; Hayashi, T. Synthesis
of Optically Active 2-(Diarylphosphino)-1,1’-binaphthyls, Efficient
Chiral Monodentate Phosphine Ligands. J. Org. Chem. 1993, 58,
1945−1948.
(11) Baxter, S. G.; Collins, R. L.; Cowley, A. H.; Sena, S. F.
Ferrocenyl-Substituted Phosphenium Cations and Phosphide Anions.
Inorg. Chem. 1983, 22, 3475−3479.
(12) (a) Gladiali, S.; Dore, A.; Fabbri, D.; Medici, S.; Pirri, G.;
Pulacchini, S. Synthesis of P,P’-Heterotopic Binaphthyldiphosphanes
(BINAPP’) Devoid of C2 Symmetry from 2,2’-Binaphthol. Eur. J. Org.
Chem. 2000, 2000, 2861−2865. (b) Cho, S. Y.; Shibasaki, M.
Synthesis and Evaluation of a New Chiral Ligand: 2Diphenylarsino-2’-
diphenylphosphino-1,1’-binaphthyl (BINAPAs). Tetrahedron Lett.
1998, 39, 1773−1776. (c) Sayo, N.; Zhang, X.; Omoto, T.;
Yokozawa, T.; Yamasaki, T.; Kumobayashi, H. (Takasago Interna-
tional Corp.). European Patent Appl. EP 0754696, 1997.
(13) (a) Ogasawara, M.; Ikeda, H.; Nagano, T.; Hayashi, T.
Palladium-Catalyzed Asymmetric Synthesis of Axially Chiral Allenes:
A Synergistic Effect of Dibenzalacetone on High Enantioselectivity. J.
Am. Chem. Soc. 2001, 123, 2089−2090. (b) Ogasawara, M.; Nagano,
Complete contact information is available at:
https://pubs.acs.org/10.1021/acs.organomet.1c00132
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
This work was supported by a Grant-in-Aid for Scientific
Research (B) to M.O. (Grant No. 18H01979) from MEXT,
Japan. This paper is dedicated to Prof. Tamotsu Takahashi on
the occasion of his retirement.
1023
https://doi.org/10.1021/acs.organomet.1c00132
Organometallics 2021, 40, 1020−1024

Organometallics
pubs.acs.org/Organometallics
Communication
T.; Hayashi, T. A New Route to Methyl (R,E)-(−)-Tetradeca-2,4,5-
trienoate (Pheromone of Acanthoscelides obtectus) Utilizing a
Palladium-Catalyzed Asymmetric Allene Formation Reaction. J. Org.
Chem. 2005, 70, 5764−5767. (c) Ogasawara, M.; Okada, A.;
Subbarayan, V.; Sörgel, S.; Takahashi, T. Palladium-Catalyzed
Asymmetric Synthesis of Axially Chiral Allenylsilanes and Their
Application to SE2’ Chirality Transfer Reactions. Org. Lett. 2010, 12,
5736−5739.
(14) (a) Lowe, G. The Absolute Configuration of Allenes. Chem.
Commun. 1965, 411−413. (b) Brewster, J. H. Helix Models of Optical
Activity. Top. Stereochem. 2007, 2, 1−72.
(15) Ozawa, F.; Kubo, A.; Hayashi, T. Catalytic Asymmetric
Arylation of 2,3-Dihydrofuran with Aryl Triflates. J. Am. Chem. Soc.
1991, 113, 1417−1419.
(16) (a) Takaya, Y.; Ogasawara, M.; Hayashi, T.; Sakai, M.; Miyaura,
N. Rhodium-Catalyzed Asymmetric 1,4-Addition of Aryl- and
Alkenylboronic Acids to Enones. J. Am. Chem. Soc. 1998, 120,
5579−5580. (b) Hayashi, T.; Takahashi, M.; Takaya, Y.; Ogasawara,
M. Catalytic Cycle of Rhodium-Catalyzed Asymmetric 1,4-Addition
of Organoboronic Acids. Arylrhodium, Oxa-π-allylrhodium, and
Hydroxorhodium Intermediates. J. Am. Chem. Soc. 2002, 124,
5052−5058.
1024
https://doi.org/10.1021/acs.organomet.1c00132
Organometallics 2021, 40, 1020−1024