Access to P- and Axially Chiral Biaryl Phosphine Oxides by Enantioselective CpxIrIII-Catalyzed C?H Arylations

Article abstract of DOI:10.1002/anie.201807749

An enantioselective C?H arylation of phosphine oxides with o-quinone diazides catalyzed by an iridium(III) complex bearing an atropchiral cyclopentadienyl (Cp^x) ligand and phthaloyl tert-leucine as co-catalyst is reported. The method allows access to a) P-chiral biaryl phosphine oxides, b) atropo-enantioselective construction of sterically demanding biaryl backbones, and also c) selective assembly of axial and P-chiral compounds in excellent yields and diastereo- and enantioselectivities. Enantiospecific reductions provide monodentate chiral phosphorus(III) compounds having structures and biaryl backbones with proven importance as ligands in asymmetric catalysis.

Full text of DOI:10.1002/anie.201807749

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Accepted Article
Title: Access to P- and Axially-Chiral Biaryl Phosphine Oxides by
Enantioselective CpxIrIII-Catalyzed C-H Arylations
Authors: Nicolai Cramer, Yun-Suk Jang, Lukasz Wozniak, and Julia
Pedroni
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To be cited as: Angew. Chem. Int. Ed. 10.1002/anie.201807749
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10.1002/anie.201807749
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COMMUNICATION
Access to P- and Axially-Chiral Biaryl Phosphine Oxides by
Enantioselective CpxIrIII-Catalyzed C-H Arylations
Yun-Suk Jang,[a] Łukasz Woźniak,[a] Julia Pedroni[a] and Nicolai Cramer*[a]
Abstract: An enantioselective C-H arylation of phosphine oxides
with o-quinone diazides catalyzed by an iridium(III) complex bearing
an atropchiral cyclopentadienyl (Cpx) ligand and phthaloyl tert-
leucine as co-catalyst is reported. The method allows access to (a)
P-chiral biaryl phosphine oxides, (b) atropo-enantioselective
construction of sterically demanding biaryl backbones as well as (c)
selective assembly of axial and P-chiral compounds in excellent
Figure 1. Typical chiral biaryl monophosphines with different chiral elements.
yields, diastereo- and enantioselectivities. Enantiospecific reductions
provide monodentate chiral phosphorus(III) compounds having
The asymmetric phosphine oxide C-H arylation offers a unifying
structures and biaryl backbones with proven importance as ligands
efficient approach to construct a variety of different chiral
in asymmetric catalysis.
elements (Scheme 1). First, an enantioselective C-H activation
of II desymmetrizes the phosphorus atom (III) yielding P-
chirality.[13] Subsequent trapping of the iridacycle with an o-
quinone diazide forges the biaryl axis (V). Usage of a bulky o-
Chiral biaryl phosphines are a critically important cornerstone of
asymmetric transition-metal catalysis.[1] Besides classical
chelating diphosphines,[2] chiral monodentate biaryl phosphines
quinone diazides result in stable atropisomers with a locked
chiral axis (3)[14f, 17, 12g, 18] that is either formed directly or by point-
have gained tremendous importance as ligands for a very broad
range of different enantioselective transformations (Figure 1).[3]
The most exploited chiral element of these ligands is a very
stable chiral axis of the binaphthyl backbone.[4] Archetypical
to-axial chirality transfer[19] upon aromatization (VI).
members
are
the
MOP[5] and
Kenphos
ligands.[6]
Complementary elements of chirality proved to be highly
valuable as well. For instance, ligands having a C2-symmetric
point chiral phospholane unit such as Sagephos[7] or P-chiral
center as found in the BI-DIME ligand have been introduced.[8]
For an increasing number of catalytic applications, combinations
of the different chiral elements have proven advantageous.[9] For
instance, ligand A, featuring a chiral axis and a P-chiral
phosphorus atom.[9a] However, accessing these ligands requires
10]
elaborate synthetic routes.[9,
Despite their utility, these
shortcomings hamper full exploitation of their application
potential. Hence, the development of modular and straight-
forward catalytic enantioselective procedures, providing access
to these structural motifs is a highly desirable goal.
Scheme 1. Different possible stereo-determining steps of the enantioselective
phosphine oxide C-H arylation.
Over the past years, the phosphorous(V) compounds have
emerged as a competent directing group[11] for enantioselective
Initially, the different catalysts and reaction parameters were
evaluated with diphenylcyclohexylphosphine oxide (1a) and
quinone diazide 2a. A small set of IrIII-catalysts bearing our most
common chiral Cpx ligands, were tested in combination with tert-
leucine derived acid (S)-A1 (table 1, entries 1-4). Ir1 bearing the
MeO-substituted Cpx ligand,[14d] performed best in terms of
reactivity and enantioselectivity, giving desired P-chiral product
3aa in 73 % isolated yield and 95:5 er (entry 1). Bulkier Cpx
ligands were less reactive and selective. The opposite
enantiomer (R)-A1 caused a drop in enantioselectivity, while the
overall reactivity was maintained (entry 5). Valine-derived acid
(S)-A2 provided a slightly lower enantiomeric ratio of 3aa (entry
6). A reaction using (R)-A2 confirmed the observed matched/
mismatched trend (entry 7). Achiral 2,4,6-trimethylbenzoic acid
13]
C-H functionalizations.[12,
We recently disclosed an Ir(III)-
catalyzed enantioselective C-H amidation of phosphine
oxides,[12h] capitalizing on synergistic effects of
chiral
a
cyclopentadienyl (CpX) ligand[14] and a chiral carboxylic acid.
Herein, we report highly selective C-H arylations of phosphine
oxides with o-quinone diazides providing access to highly
sought-after P- and atrop-chiral biaryl phosphine oxides. Recent
report by Yang et al.[15] indicated the suitability of trapping an
iridacycle with quinone diazides.[16]
[a]
Y.-S. Jang, Dr. Ł. Woźniak, Dr. J. Pedroni, Prof. Dr. N. Cramer
Laboratory of Asymmetric Catalysis and Synthesis
EPFL SB ISIC LCSA, BCH 4305
CH-1015 Lausanne (Switzerland)
E-mail: nicolai.cramer@epfl.ch
Homepage: http://isic.epfl.ch/lcsa
Supporting information for this article is given via a link at the end of
the document.
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10.1002/anie.201807749
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COMMUNICATION
Table 2. Scope of the enantioselective phosphine oxide arylation.[a]
resulted in poor conversion and low enantioselectivity (entry 8).
Control experiments confirmed the importance of each
ingredient of the reaction protocol. Omitting the carboxylic acid
additive shut down the reaction completely (entry 9). Along the
same lines, no reaction occurred without AgSbF6, confirming the
requirement of an intermediate cationic IrIII species (entry 10).
Finally, the combination of achiral Cp*IrIII with (S)-A1 gave 3aa in
a very poor yield and negligible enantioselectivity (entry 11).
Entry
1
3xy
3ba
3ca
3da
3ea
3fa
R1
R2
Yield [%][b]
er[c]
Table 1. Optimization of the enantiotopic C-H arylation.[a]
tBu
tBu
tBu
tBu
tBu
tBu
tBu
Ad
H
98
85
96
92
60
89
69
94
96
74
69
97.5:2.5
98:2
2
4-Me
3-Me
4-MeO
3-MeO
4-NMe2
4-Cl
H
3
94.5:5.5
98.5:1.5
94.5:5.5
97.5:2.5
95.5:4.5
98:2
4
5
6
3ga
3ha
3ia
7
8
Entry
Ir
Acid
(S)-A1
Yield [%][b]
er[c]
95:5
iPr
9
3ja
H
94.5:5.5
68.5:31.5
85.5:14.5
73 (79)[d]
1
Ir1
Me
10
11
3ka
3la
H
(S)-A1
46
30
0
92.5:7.5
87.5:12.5
-
2
Ir2
N(iPr)2
H
(S)-A1
3
Ir3
[a] Conditions: 0.2 mmol 1x, 0.1 mmol of 2a, 3.0ꢀµmol Ir1, 12ꢀµmol AgSbF6,
15ꢀµmol (S)-A1, 0.1 M in dioxane, 15 °C for 18 h; [b] Isolated yield; [c]
determined by chiral HPLC.
(S)-A1
4
Ir4
(R)-A1
77
88
67
12
0
83.5:16.5
91:9
5
Ir1
Furthermore, a range of diazo components 2y was studied in
the transformation (Scheme 2). o-Quinone diazides having just a
4-methyl (2d), a 5-tBu (2f) or a 5-Br substituent (2g) proved to
be sufficiently stable and underwent smooth transformation. In
addition, 2-naphthyl derived quinone diazides such as 2b and 2c
performed equally well. A uniformly high enantioselectivity of
98:2 er was achieved as quinone diazides intersect the catalytic
cycle after the enantiodetermining step and trapping occurs
faster than erosion of the selectivity of iridacycle III.
(S)-A2
6
Ir1
(R)-A2
70.5:29.5
38:62
0
7
Ir1
2,4,6-Me-C6H2CO2H
-
8
Ir1
9
Ir1
(S)-A1
0
0
10
11
Ir1 (no AgSbF6)
[Cp*IrCl2]2
(S)-A1
<5
45.5:54.5
[a] Conditions: 0.1 mmol 1a, 0.05 mmol of 2a, 1.5ꢀµmol Ir, 6.0ꢀµmol AgSbF6,
7.5ꢀµmol acid, 0.1 M in dioxane, 15 °C for 12 h; [b] NMR yield with internal
standard; [c] determined by chiral HPLC; [d] Isolated yield on doubled scale.
With the aforementioned optimized conditions, we evaluated
a range of phosphine oxides 1x (Table 2). A variety of different
substituents R1 on different positions on the aryl groups were
found to have little influence on the reaction outcome. Very good
yields and enantioselectivities of C-H arylation products 3xa
were obtained.[20] Variation of R2 revealed that in particular,
bulky groups such as tert-butyl or adamantyl, which are of high
value for later applications as phosphine ligands were well
suited (entries 1-9). Nevertheless, smaller (entry 10) or hetero-
atom substituents R2 (entry 11) were tolerated and provided the
arylation product 3ka and 3la in good yields, albeit with reduced
enantioselectivities. X-Ray crystal structure analysis of 3ba
allowed for the determination of the absolute configuration of the
arylation products.[21]
Scheme 2. Scope of the C-H arylation with different diazo compounds 2.
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10.1002/anie.201807749
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Diazo reactants with increased bulk in the ortho position
such as 1-diazonaphthalen-2(1H)-one 2h, generated a stable
chiral axis in addition to the point chirality at the phosphorus
atom (Scheme 3). Single diastereomers and an excellent er of
99:1 to 99.5:0.5 were observed for bulky phosphine oxides 1b,
1e, 1i and 1m. Smaller groups R1 lead to lower dr values, but
still maintain high enantioselectivities for the major
diastereomers. Isolated diastereoisomers did not undergo
isomerization even at elevated temperature, indicating a high
rotational barrier of the biaryl axis (See SI). This feature, in
addition to the arrangement of the modifiable hydroxyl group
makes these structures attractive precursors for the
corresponding phosphine ligands.
Scheme 4. Scope for the atropo-enantioselective C-H arylation. [a] with 5
mol% Ir1, 20 mol% AgSbF6, 25 mol% (S)-A1.
Subsequently, reductions of representative members for all
three phosphine oxide classes to the corresponding desired
phosphine ligands were performed (Scheme 5). Alkylation of the
free hydroxyl group with MeI gave the corresponding products 4
in excellent yields. Reduction using Imamoto’s method[22]
provided PIII-chiral phosphine 5bc and 5bh with complete
enantiospecificity. 4nh could be reduced under classical
conditions with trichlorosilane to 5nh without erosion of
enantiopurity.
Scheme 3. Scope of the C-H arylation for the axial and P-chiral phosphine
oxides 3xy. [a] reaction at 25 °C. Ar1=PMP, Ar2=3,5-MeO-C6H3.
The observation that the chiral Cpx ligand enables enantiotopic
C-H activation, but also has a bearing on the formation of the
atropchiral biaryl axis, prompted us to further investigate this
intriguing aspect. We exploited our methodology for the
synthesis of purely axial chiral phosphine oxides possesing the
basis structural feature of the MOP ligand. In this respect, tris-
3,5-dimethoxy-phenylphosphine oxide 1n was used as
a
substrate (Scheme 4). Smooth arylations with different
napthoquinone diazides occurred in dichloroethane and formed
products 3nh, 3ni and 3nj in high enantioselectivities. To
underscore the application potential, the transformation was
perfomered at gram-scale giving 3nh in 94 % yield and 96:4 er.
Trituration with iPrOH/hexane increased the optical purity to
>99.5:0.5 er (87 % yield). The superior reactivity of the 3,5-
dimethoxyphenyl allowed the highly selective preparation of
products 3oh, 3ph and 3qh featuring sterically and electronically
different triaryl phosphines. No activation of other possible
Caryl-H bonds was observed.
Scheme 5. Enantiospecific reduction to the corresponding phosphines: a) MeI,
K2CO3, acetone, 60 °C.
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54, 6265; Angew.Chem. 2015, 127, 6363; c) L. Liu, A.-A. Zhang, Y.
Wang, F. Zhang, Z. Zuo, W.-X. Zhao, C.-L. Feng, W. Ma, Org. Lett.,
2015, 17, 2046; d) G. Xu, M. Li, S. Wang, W. Tang, Org. Chem. Front.,
2015, 2, 1342; e) Z.-J. Du, J. Guan, G.-J. Wu, P. Xu, L.-X. Gao, F.-S.
Han, J. Am. Chem. Soc., 2015, 137, 632; f) Y. Sun, N. Cramer, Angew.
Chem., Int. Ed., 2017, 56, 364; Angew. Chem. 2017, 129, 370; g) S.-X.
Li, Y.-N. Ma, S.-D. Yang, Org. Lett. 2017, 19, 1842; h) Y.-S. Jang, M.
Dieckmann, N. Cramer, Angew. Chem. Int. Ed., 2017, 56, 15088; Angew.
Chem. 2017, 129 ,15284; i) Y.-M. Cui, Y. Lin, L.-W. Xu, Coord. Chem.
Rev. 2017, 330, 37; j) Z. Wang T. Hayashi Angew. Chem. Int. Ed. 2018,
57, 1702; Angew. Chem. 2018, 130, 1718; k) Y. Sun, N. Cramer, Chem.
Sci., 2018, 9, 2981.
In summary, we disclosed efficient and highly enantioselective
C-H arylations of phosphine oxides with o-quinone diazides
enabled by chiral CpxIrIII complexes in cooperation with phthaloyl
tert-leucine as co-catalyst. This technology is suitable to access
biaryl phosphine oxides with point chirality at phosphorus as well
as to construct axial chirality of sterically demanding biaryl
backbones. Moreover, compounds containing both axial and P-
chirality, which are otherwise cumbersome to obtain, are
synthesized in highly enantioselective and diastereoselective
fashion. Enantiospecific reductions complete access to
monodentate chiral phosphorus(III) compounds with proven
biaryl ligand backbones in asymmetric catalysis.
[13] Recent reviews on enantioselective C-H functionalizations: a) R. Giri, B.-
F. Shi, K. M. Engle, N. Maugel, J.-Q. Yu, Chem. Soc. Rev. 2009, 38,
3242; b) J. Wencel-Delord, F. Colobert, Chem. Eur. J. 2013, 19, 14010;
c) C. Zheng, S.-L. You, RSC Adv. 2014, 4, 6173; d) D.-W. Gao, J. Zheng,
K.-Y. Ye, C. Zheng, S.-L. You, in Asymmetric Functionalization of C–H
Bonds (Ed.: S.-L. You), Royal Society of Chemistry: Cambridge, U.K.,
2015, p. 141; e) C. G. Newton, S.-G. Wang, C. C. Oliveira, N. Cramer,
Chem. Rev. 2017, 117, 8908; f) T. G. Saint-Denis, R.-Y. Zhu, G. Chen,
Q.-F. Wu, J.-Q. Yu, Science 2018, 359, 759.
Acknowledgements
This work is supported by the Swiss National Science
Foundation (no 157741). We thank Dr. R. Scopelliti and Dr. F.
Fadaei Tirani for X-ray crystallographic analysis of compound
3ba, 3bj, and 3nh.
[14] For reviews see: a) B. Ye, N. Cramer, Acc. Chem. Res. 2015, 48, 1308;
b) C. G. Newton, D. Kossler, N. Cramer, J. Am. Chem. Soc. 2016, 138,
3935; seminal reports detailing the ligand synthesis: c) B. Ye, N. Cramer,
Science 2012, 338, 504; d) B. Ye, N. Cramer, J. Am. Chem. Soc. 2013,
135, 636; e) J. Zheng, W.-J. Cui, C. Zheng, S.-L. You, J. Am. Chem. Soc.
2016, 138, 5242; f) Z.-J. Jia, C. Merten, R. Gontla, C. G. Daniliuc, A. P.
Antonchick, H. Waldmann, Angew. Chem. Int. Ed. 2017, 56, 2429;
Angew. Chem. 2017, 129, 2469; g) S. Wang, S. Hwan Park, N. Cramer,
Angew. Chem. Int. Ed. 2018, 57, 5459; h) E. A. Trifonova, N. M.
Ankudinov, A. A. Mikhaylov, D. A. Chusov, Y. V. Nelyubina, D. S.
Perekalin, Angew. Chem. Int. Ed. 2018, 57, 7714.
Keywords: Asymmetric Catalysis • C‒H Activation • Iridium •
Chiral Cp Ligand • P-Chirality
[1] a) Privileged Chiral Ligands and Catalysts (Eds.: Q‐L. Zhou), Wiley‐VCH
Verlag, Weinheim, 2011. b) Hartwig, J. Organotransition Metal
Chemistry: From Bonding to Catalysis; University Science Books:
Sausalito, CA, 2010.
[2] Phosphorus(III) Ligands in Homogeneous Catalysis: Design and
Synthesis, (Eds. P. C. J. Kamer, P. W. N. M. v. Leeuwen), Wiley,
Hoboken, 2012.
[15] Z. Liu, J.-Q. Wu, S.-D. Yang, Org. Lett. 2017, 19, 5434.
[16] S.-S. Zhang, C.-Y. Jiang, J.-Q. Wu, X.-G. Liu, Q. Li, Z.-S. Huang, D. Li,
H. Wang, Chem. Commun. 2015, 51, 10240.
[3] F. Lagasse, H. B. Kagan, Chem Pharm. Bull. 2000, 48, 315; b)
Phosphorus Ligands in Asymmetric Catalysis: Synthesis and
Applications, Volumes. 1-3 (Ed.: A. Börner), Wiley-VCH, Weinheim,
2008; c) J. Pedroni, N. Cramer, Chem. Commun. 2015, 51, 17647; d) W.
Fu, W. Tang, ACS Catal. 2016, 6, 4814.
[17] C-H functionalization forges the chiral axis: a) K. Yamaguchi, J.
Yamaguchi, A. Studer, K. Itami, Chem. Sci. 2012, 3, 2165. b) K.
Yamaguchi, H. Kondo, J. Yamaguchi, K. Itami, Chem. Sci. 2013, 4,
3753; c) Y. Nishimoto, H. Kondo, K. Yamaguchi, D. Yokogawa, J.,
Yamaguchi, K. Itami, S. Irle, J. Org. Chem., 2017, 82, C. G. Newton, E.
Braconi, J. Kuziola, M. D. Wodrich, N. Cramer, Angew. Chem. Int. Ed.
10.1002/anie.201806527.
[4] R. Noyori, Acc. Chem. Res. 1990, 23, 345.
[5] T. Hayashi, Acc. Chem. Res., 2000, 33, 354.
[6] J. Yin, S. L. Buchwald, J. Am. Chem. Soc. 2000, 122, 12051.
[7] T.Saget, S. J. Lemouzy, N. Cramer, Angew. Chem. Int. Ed. 2012, 51,
2238.
[18] C-H functionalization locks an existing axis: a) C. He, M. Hou, Z. Zhu, Z.
Gu, ACS Catal. 2017, 7, 5316; b) Q.-J. Yao, S. Zhang, B.-B. Zhan, B.-F.
Shi, Angew. Chem. Int. Ed. 2017, 56, 6617; c) G. Liao, Q.‐J. Yao, Z.‐
Z. Zhang, Y.‐J. Wu, D.‐Y. Huang, B.‐F. Shi, Angew. Chem. Int. Ed.
2018, 57, 3665; d) F. Kakiuchi, P. Le Gendre, A. Yamada, H. Ohtaki, S.
Murai, Tetrahedron: Asymmetry 2000, 11, 2647; e) J. Zheng, S.-L. You,
Angew. Chem. Int. Ed. 2014, 53, 13244. f) J. Zheng, W.-J. Cui, C. Zheng,
S.-L. You, J. Am. Chem. Soc. 2016, 138, 5242.
[8] W. Tang, X. Wei, W. Li, A. White, N. D. Patel, J. Savoie, J. J. Gao, S.
Rodriguez, B. Qu, N. Haddad, B. Z. Lu, D. Krishnamurthy, N. K. Yee, C.
H. Senanayake, Angew. Chem. Int. Ed. 2010, 49, 5879.
[9] a) T. Hamada, S. L. Buchwald, Org. Lett, 2002, 4, 999; b) B. Saha, T. V.
RajanBabu, J. Org. Chem. 2007, 72, 2357; c) A. M. Taylor, R. A. Altman,
S. L. Buchwald, J. Am. Chem. Soc., 2009, 131, 9900; d) S. Rousseaux,
J. García-Fortanet, M. A. Del Aguila Sanchez, S. L. Buchwald, J. Am.
Chem. Soc. 2011, 133, 9282; e) S. Lühr, J. Holz, Armin Börner,
ChemCatChem 2011, 3, 1708; f) M. M. Pereira, M. J. F. Calvete, R. M. B.
Carrilhoa, A. R. Abreu Chem. Soc. Rev. 2013, 42, 6990; g) D. Grosheva,
N. Cramer, ACS Catal. 2017, 7, 7417.
[19] a) G. Bringmann, A. J. P. Mortimer, P. A. K., M. J. Gresser, J. Garner, M.
Breuning, Angew. Chem. Int. Ed. 2005, 44, 5384; Angew. Chem. 2018,
130, 7254; b) P. Loxq, E. Manoury, R. Poli, E. Deydier, A. Labande,
Coord. Chem. Rev. 2016, 308, 131; c) B. Zilate, A. Castrogiovanni, C.
Sparr, ACS Catal. 2018, 8, 2981; d) A. Link, C. Sparr, Chem. Soc. Rev.,
2018, 47, 3804.
[10] a) B. L. Feringa, Acc. Chem. Res. 2000, 33, 346; b) I. A. Shuklov, N. V.
Dubrovina,H. Jiao, A. Spannenberg, A. Börner, Eur. J. Org. Chem. 2010,
1669; c) E. Raluy, O. Pamies, M. Dieguez Adv. Synth. Catal. 2009, 351,
1648; d) K. N. Gavrilov, S. V. Zheglov, E. A. Rastorguev, N. N. Groshkin,
M. G. Maksimova, E. B. Benetsky, V. A. Davankov, M. T. Reetz Adv.
Synth. Catal. 2010, 352, 2599.
[20] Compounds 3aa-3la and 3ba-3bg appear as a set of rotamers by NMR
spectroscopy.
[21] CCDC 1854285, 1854287 and 1854288 contain the supplementary
crystallographic data for this paper. These data can be obtained free of
charge from The Cambridge Crystallographic Data Centre via
www.ccdc.cam.ac.uk/data_request/cif.
[11] a) Y.-N. Ma, S.-X. Li, S.-D. Yang, Acc. Chem. Res. 2017, 50, 1480; b) Z.
Zhang, P. H. Dixneuf, J.-F. Soule, Chem. Commun. 2018, 54, 7265.
[12] a) D. Gwon, S. Park, S. Chang, Tetrahedron, 2015, 71, 4504; b) Z.-Q.
Lin, W.-Z. Wang, S.-B. Yan, W.-L. Duan, Angew. Chem. Int. Ed., 2015,
[22] T. Imamoto, S.-I. Kikuchi, T. Miura, Y. Wada, Org. Lett. 2001, 3, 87.
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Entry for the Table of Contents
COMMUNICATION
Yun-Suk Jang, Łukasz Woźniak, Julia
Pedroni and Nicolai Cramer
Page No. – Page No.
Access to P- and Axially-Chiral Biaryl
Phosphine Oxides by
Enantioselective CpxIrIII-Catalyzed C-
H Arylations
An enantioselective C-H arylation of phosphine oxides with o-quinone diazides is
catalyzed by a CpxIr(III) complex and chiral carboxylic acid co-catalyst. It provides a
unifying access to P-chiral phosphine oxides, atropo-enantioselective construction
of sterically demanding biaryl backbones and a selective assembly of axial and P-
chiral compounds in excellent yields, diastereo- and enantioselectivities.
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