Design, synthesis, and application of a chiral sulfinamide phosphine catalyst for the enantioselective intramolecular rauhut-currier reaction

Article abstract of DOI:10.1002/anie.201500907

A novel class of chiral sulfinamide phosphine catalysts (Xiao-Phos) are reported, which can be easily prepared from inexpensive commercially available starting materials. The Xiao-Phos catalysts showed good performance in enantioselective intramolecular R

Full text of DOI:10.1002/anie.201500907

Angewandte
Chemie
International Edition: DOI: 10.1002/anie.201500907
German Edition: DOI: 10.1002/ange.201500907
Organocatalysis
Design, Synthesis, and Application of a Chiral Sulfinamide Phosphine
Catalyst for the Enantioselective Intramolecular Rauhut–Currier
Reaction**
Xiao Su, Wei Zhou, Yangyan Li, and Junliang Zhang*
Abstract: A novel class of chiral sulfinamide phosphine
catalysts (Xiao-Phos) are reported, which can be easily
prepared from inexpensive commercially available starting
materials. The Xiao-Phos catalysts showed good performance
in enantioselective intramolecular Rauhut–Currier reactions,
generating a-methylene-g-butyrolactones in high yields with
up to 99% ee under mild conditions. Moreover, kinetic
resolution and parallel kinetic resolution were also observed
with the use of two different substituted racemic precursors.
asymmetric transition-metal catalysis and the sulfinamide
plays a second role in stereoselectivity control.[5] With a series
of chiral Ming-Phos ligands in hand and as a part of our
program for developing chiral-phosphine-catalyzed enantio-
selctive transformations,[6] we wished to expand the applica-
tions of Ming-Phos variants from transition-metal catalysis to
nucleophilic phosphine catalysis. In this context, recent
elegant work by Sasai and co-workers[7] attracted our
attention. They successfully accomplished a chiral-phos-
phine-catalyzed enantioselective intramolecular Rauhut–
Currier (RC) reaction,[8] efficiently furnishing synthetically
valuable a-methylene-g-butyrolactones.[9] However, the per-
formance of the Ming-Phos variants was disappointing; in
most cases, the reaction did not give high conversions because
of the low nucleophilic catalyst activity. We then envisaged
that a new type of chiral sulfinamide phosphines, called Xiao-
Phos, should have better nucleophilic activity than the Ming-
Phos variants. With two stereocenters, an H-bonding site, and
tunable side chains, the Xiao-Phos series may be applicable to
asymmetric nucleophilic catalysis for organic transformations
such as RC reactions (Figure 1). Herein, we report our efforts
toward the stereodivergent synthesis of these new chiral
phosphines and their application in enantioselective intra-
molecular RC reaction.
After many attempts, we were pleased to find that Xiao-
Phos variants could be easily prepared from commercially
available Ph2PCH3, tert-butylsulfinamide, and aldehyde
(Scheme 1).[10] Treatment of Ph2PCH3 with BuLi in the
presence of TMEDA at room temperature produced a solu-
tion of Ph2PCH2Li in THF according to the reported
procedure,[11] which then undergoes nucleophilic addition to
chiral (Rs)-sulfinimines, thereby furnishing the corresponding
phosphines X1–X7 in good yield with moderate to high
diastereoselectivity. Notably, X8 was obtained from the
corresponding o-hydroxyl-substituted sulfinimines. X9–X12
were made through the silylation of X8 under mild conditions.
(see the Supporting Information). The absolute configura-
Over the past decade, asymmetric nucleophilic catalysis
with chiral phosphines has emerged as a powerful approach to
structurally diverse and synthetically valuable optically active
organic building blocks.[1] Among the many types of chiral
phosphines, chiral b-aminephosphines represent one of the
most attractive and have been utilized as nucleophilic
catalysts[2] or chiral ligands[3] in a broad spectrum of useful
organic transformations. Compared to the intensive attention
focused on the utility of chiral b-aminephosphines in organic
synthesis, only a handful of methods have been reported so far
for their synthesis. Among these, the approach from readily
available natural or unnatural chiral amino acids is the most
attractive.[4] Despite the fact that much progress has been
made in the construction of chiral phosphine catalysts, the
development/design of highly efficient new types of chiral
phosphines, especially from inexpensive, commercially avail-
able chiral resources, remains a considerable challenge.
Recently, our group developed a new type of chiral
sulfinamide phosphine (Ming-Phos ligands), which could be
easily prepared in good yields from inexpensive commercially
available chiral tert-butylsulfinamide in two steps. Gratify-
ingly, Ming-Phos ligands have shown good performance in
[*] X. Su,[+] W. Zhou,[+] Y. Li, Prof. Dr. J. Zhang
Shanghai Key Laboratory of Green Chemistry and Chemical
Processes, School of Chemistry and Molecular Engineering
East China Normal University, Shanghai, 200062 (P.R. China)
E-mail: jlzhang@chem.ecnu.edu.cn
Homepage: http://faculty.ecnu.edu.cn/s/1811/main.jspy
Prof. Dr. J. Zhang
State Key Laboratory of Organometallic Chemistry
Shanghai Institute of Organic Chemistry, CAS
345 Lingling Road, Shanghai, 200032 (P.R. China)
[+] These authors contributed equally to this work.
[**] We are grateful to 973 Programs (2011CB808600), the National
Natural Science Foundation of China (21372084, 21425205), and
Changjiang Scholars and Innovative Research Team in University
(PCSIRT) for financial supports.
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/anie.201500907.
Figure 1. The design of novel chiral sufinamide phosphines.
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Scheme 1. Concise synthetic approach to Xiao-Phos variants. TME-
DA=N,N,N’,N’-tetramethylethylenediamine, THF=tetrahydrofuran.
tions of (S,RS)-X4 and (R,RS)-X8 were established by single-
crystal X-ray diffraction.[12]
With the chiral phosphine catalysts in hand, we concen-
trated our investigation on their performance in the enantio-
selective
intramolecular
Rauhut–Currier
reaction
(Scheme 2). The desired product (À)-2a was obtained in
good yield and with moderate enantioselectivity when Xiao-
Phos catalysts derived from aliphatic sulfinimines, such as
(S,RS)-X1 and (S,RS)-X2, were employed. (S,RS)-X3, which
bears a bulky adamantanyl substituent, exhibited lower
enantioselectivity. For higher reactivity and enantioselectiv-
ity, a survey of Xiao-Phos catalysts derived from aromatic
sulfinimines was then conducted. Although the reaction
proceeded with good yield, the ee values decreased slightly
to 50% with the use of (S,RS)-X4 and (S,RS)-X5. A positive
effect on the enantioselectivity was observed when three
methoxyl moieties were introduced to the phenyl ring,
however, the yield was reduced slightly to 42%. The bulkier
phosphine (S,RS)-X7, which has three isopropyl groups in the
phenyl ring, was clearly inferior in terms of reactivity and
enantioselectivity when compared with (S,RS)-X4 and (S,RS)-
X5. Further improvements in reactivity and enantioselectivity
were achieved when (R,RS)-X8 was employed, which led to
the production of (+)-2a in 91% yield and 81% ee, whereas
its diastereomer (S,RS)-X8 gave very low enantioselectivity.
This remarkable difference between (R,RS)-X8 and (S,RS)-X8
revealed that the carbon stereocenter might also play a crucial
role in realizing good enantioselectivity. Inspired by this
interesting result, catalysts X9, X10, X11, and X12, which bear
different silyl protecting groups, were next examined in the
RC reaction. Unfortunately, phosphine catalysts containing
the TES group, such as (R,RS)-X9 and (S,RS)-X9, did not show
any improvement in performance. To our delight, with the
employment of (R,RS)-X10 as the catalyst, dramatic improve-
ments in reactivity and enantioselectivity were achieved and
the desired (+)-2a was produced in 94% yield and 98% ee.
The absolute configuration of (+)-2a was established by
single-crystal X-ray diffraction.[12] Ikegami[13] and co-workers
showed that the addition of phenol facilitates the Baylis–
Hillman reaction and significantly improves the reaction
Scheme 2. Screening Xiao-Phos catalysts in the enantioselective intra-
molecular Rauhut–Currier reaction. [a] 50 mol% PhOH was added,
12 h. TES=triethylsilyl, TIPS=triisopropylsilyl, TBDMS=tert-butyldi-
methylsilyl, TBDPS=tert-butyldiphenylsilyl.
yield. In our case, with the addition of 50 mol% of phenol, the
catalyst loading could be reduced to 10 mol% and the
reaction could be completed within 12 h without loss of
efficiency and enantiopselectivity. By contrast, the phenol has
a slightly negative effect on the reactivity in the work of Sasai
and co-workers.[7] The TBDMS- and TBDPS-derived Xiao-
Phos catalysts (R,RS)-X11 and (R,RS)-X12 delivered high
reactivity and enantioselectivity. Notably, (À)-2a could be
obtained in 76–90% yield and 46–81% ee in the presence of
(S,RS)-X10, (S,RS)-X11, and (S,RS)-X12. No better results
were obtained after the screening of various solvents and
variation of reaction temperature (see Section S3 in the
Supporting Information). Based on the results, the optimal
reaction conditions were identified: 10 mol% (R,RS)-X10 as
the catalyst, 50 mol% phenol as an additive and CHCl3 as the
reaction medium at 258C.
The substrate scope of this enantioselective intramolecu-
lar RC reaction was investigated under the optimized reaction
conditions (Scheme 3). Variation of the alkyl substituent on
the starting materials from methyl to n-butyl was tolerated
and the corresponding cyclized products (+)-2a–d were
obtained in good yield with 98–99% ee. Substrates 1e and
1 f, which contain ester side chains, also worked well and the
desired products (+)-2e and (+)-2 f were isolated in 76–84%
yield with 98% ee. To further investigate the substrate scope,
a set of aryl-substituted substrates were synthesized and
investigated under optimal reaction conditions. Phenyl-sub-
stituted 1g underwent clean cyclization to produce (+)-2g in
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Scheme 3. The scope of the X10-catalyzed enantioselective intramolec-
ular Rauhut–Currier reaction. [a] 18 h. [b] (R,RS)-X10 (20 mol%), with-
out phenol, 72 h. [c] (S,RS)-X10 (20 mol%), without phenol, 72 h.
[d] (S,RS)-X10 (20 mol%), without phenol, 36 h. [e] (S,RS)-X10
(20 mol%), without phenol, 24 h.
Scheme 4. Kinetic resolution of rac-1l, parallel kinetic resolution of rac-
1m, and proposed transition states.
with 90% ee. Notably, an exciting parallel kinetic resolution
of rac-1m was realized and enantioenriched (+)-2m and
(+)-2n could be obtained in satisfied yield and with high
enantioselectivity. It is noteworthy that these two types of
kinetic resolution were run without the addition of phenol. As
far as we know, this is the first successful example of parallel
kinetic resolution for the RC reactions. To account for the
observed stereochemistry in the parallel kinetic resolution
reactions, two possible transition states were propos-
ed.[2a,b,7,8l,r,18] The zwitterion intermediate is formed through
nucleophilic addition of (R,RS)-X10 to the acrylate chain of
rac-1m, which is stabilized by the vital hydrogen-bonding
interaction between sulfinamide and the enolate. The bulky
TIPS group blocks the front site of the enolate. The steric
repulsion between the TIPS group and the methyl group
makes addition to the methyl-substituted olefin much slower
than addition to the other olefin, thereby leading to parallel
kinetic resolution.
In conclusion, we have developed a highly concise and
efficient strategy for the construction of a new type of chiral
sulfinamide phosphine catalyst from commercially available
inexpensive starting materials. The Xiao-Phos catalyst (R,RS)-
X10 has shown excellent performance in the enantioselective
intramolecular RC reactions, leading to a-methylene-g-butyr-
olactones in high yields and up to 99% ee under mild
conditions. Moreover, kinetic resolution and parallel kinetic
resolution were also realized with the use of two different
substituted racemic precursors, both of which worked nicely
with a very high s factor. As far as we know, this is the first
successful example of a parallel kinetic resolution in the
Rauhut-Currier reaction. Further applications of Xiao-Phos
variants as organocatalysts or chiral ligands for transition
metals in asymmetric reactions and as a precursor to other
chiral phosphines[19] are currently underway in our laboratory
and will be reported in due course.
95% yield with 96% ee. The enantioselective cyclization
reactions of 1h–j, which contain F, Br, or three Fatoms on the
phenyl ring, respectively, were all converted to the corre-
sponding products in good yield with excellent enantioselec-
tivity. Notably, substrate 1k, which is derived from 3,4,5-
trimethylphenol, offers an opportunity to evaluate the
performance of (R,RS)-X10 in the construction of scaffolds
with two contiguous quaternary carbon centers. Under
slightly modified reaction conditions (20 mol% catalyst
loading, longer reaction time, and without phenol), the
valuable product (+)-2k was successfully obtained in 82%
yield with 98% ee.
We next turned our investigation to the performance of
(S,RS)-X10 in the intramolecular Rauhut–Currier reaction. To
our delight, the enantiomer (À)-2a was obtained in 91% yield
and 81% ee from the corresponding substrate 1a. Addition-
ally, the substrates 1e and aryl-substituted 1g and 1h were
also converted to the desired enantiomers (À)-2e, (À)-2g,
and (À)-2h in good yield and with acceptable enantioselec-
tivity. These results indicate that the performance of (S,RS)-
X10 is much more sensitive to the structure of the substrate
than its diastereomer (R,RS)-X10.
Despite the dramatic progress that has been made in the
field of enantioselective RC reactions during the past
decades, kinetic resolution (KR)[14,15] and parallel kinetic
resolution (PKR)[16] of racemic precursors through asymmet-
ric RC process have been less studied. Given the fact that the
reaction of 1k with methyl groups on the dienone moiety is
much slower than that of 1a, we envisaged that the kinetic
resolution of racemic precursors might be realized under the
catalysis of Xiao-Phos. Rac-1l and rac-1m were then synthe-
sized and subjected to the reaction with (R,RS)-X10
(Scheme 4). To our delight, a nice kinetic resolution process
with a high s factor (s = 95)[17] was indeed observed in the
reaction of rac-1l, furnishing the desired (+)-2l in 46% yield
with 96% ee and the (S)-1l could be recovered in 51% yield
Keywords: chiral phosphines · enantioselectivity ·
kinetic resolution · organocatalysis · Rauhut–Currier reaction
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Luis, K. Agapiou, H.-Y. Jang, M. J. Krische, J. Am. Chem. Soc.
2002, 124, 2402; f) S. A. Frank, D. J. Mergott, W. R. Roush, J.
Am. Chem. Soc. 2002, 124, 2404; g) B. G. Jellerichs, J.-R. Kong,
M. J. Krische, J. Am. Chem. Soc. 2003, 125, 7758; h) C. A. Evans,
S. J. Miller, J. Am. Chem. Soc. 2003, 125, 12394; i) R. K. Thalji,
W. R. Roush, J. Am. Chem. Soc. 2005, 127, 16778; j) M. E.
Krafft, T. F. N. Haxell, J. Am. Chem. Soc. 2005, 127, 10168;
k) M. E. Krafft, T. F. N. Haxell, K. A. Seibert, K. A. Abboud, J.
Am. Chem. Soc. 2006, 128, 4174; l) C. E. Aroyan, S. J. Miller, J.
Am. Chem. Soc. 2007, 129, 256; m) F. O. Seidel, J. A. Gladysz,
Adv. Synth. Catal. 2008, 350, 2443; n) T. E. Reynolds, M. S.
Binkley, K. A. Scheidt, Org. Lett. 2008, 10, 2449; o) P. S. Selig,
S. J. Miller, Tetrahedron Lett. 2011, 52, 2148; p) Q.-Y. Zhao, C.-
K. Pei, X.-Y. Guan, M. Shi, Adv. Synth. Catal. 2011, 353, 1973;
q) S. Osuna, A. Dermenci, S. J. Miller, K. N. Houk, Chem. Eur. J.
2013, 19, 14245; r) X. Dong, L. Liang, E. Li, Y. Huang, Angew.
Chem. Int. Ed. 2015, 54, 1621; Angew. Chem. 2015, 127, 1641 and
references cited therein.
[1] Selected reviews related to nucleophilic catalysis with chiral
phosphines: a) J. L. Methot, W. R. Roush, Adv. Synth. Catal.
2004, 346, 1035; b) L.-W. Ye, J. Zhou, Y. Tang, Chem. Soc. Rev.
2008, 37, 1140; c) Y. Wei, M. Shi, Acc. Chem. Res. 2010, 43, 1005;
d) A. Marinetti, A. Voituriez, Synlett 2010, 174; e) S.-X. Wang,
X. Han, F. Zhong, Y. Wang, Y. Lu, Synlett 2011, 2766; f) Q.-Y.
Zhao, Z. Lian, Y. Wei, M. Shi, Chem. Commun. 2012, 48, 1724;
g) L.-W. Xu, ChemCatChem 2013, 5, 2775; h) Y. Wei, M. Shi,
Chem. Rev. 2013, 113, 6659; i) Y. C. Fan, O. Kwon, Chem.
Commun. 2013, 49, 11588; j) Z. Wang, X. Xu, O. Kwon, Chem.
Soc. Rev. 2014, 43, 2927; k) Y. Wei, M. Shi, Chem. Asian J. 2014,
9, 2720.
[2] Selected leading examples of chiral b-aminephosphines utilized
as nucleophilic catalysts: a) X. Han, Y. Wang, F. Zhong, Y. Lu, J.
Am. Chem. Soc. 2011, 133, 1726; b) F. Zhong, X. Han, Y. Wang,
Y. Lu, Angew. Chem. Int. Ed. 2011, 50, 7837; Angew. Chem. 2011,
123, 7983; c) X. Han, F. Zhong, Y. Wang, Y. Lu, Angew. Chem.
Int. Ed. 2012, 51, 767; Angew. Chem. 2012, 124, 791; d) F. Zhong,
J. Luo, G.-Y. Chen, X. Dou, Y. Lu, J. Am. Chem. Soc. 2012, 134,
10222; e) F. Zhong, X. Dou, X. Han, W. Yao, Q. Zhu, Y. Meng, Y.
Lu, Angew. Chem. Int. Ed. 2013, 52, 943; Angew. Chem. 2013,
125, 977; f) T. Wang, W. Yao, F. Zhong, G. H. Pang, Y. Lu,
Angew. Chem. Int. Ed. 2014, 53, 2964; Angew. Chem. 2014, 126,
3008; g) X. Han, W. Yao, T. Wang, Y. R. Tan, Z. Yan, J.
Kwiatkowski, Y. Lu, Angew. Chem. Int. Ed. 2014, 53, 5643;
Angew. Chem. 2014, 126, 5749; h) C. E. Henry, Q. Xu, Y. C. Fan,
T. J. Martin, L. Belding, T. Dudding, O. Kwon, J. Am. Chem. Soc.
2014, 136, 11890; i) Y.-Q. Fang, P. M. Tadross, E. N. Jacobsen, J.
Am. Chem. Soc. 2014, 136, 17966; j) W. Yao, X. Dou, Y. Lu, J.
Am. Chem. Soc. 2015, 137, 54; k) H.-Y. Wang, K. Zhang, C.-W.
Zheng, Z. Chai, D.-D. Cao, J.-X. Zhang, G. Zhao, Angew. Chem.
Int. Ed. 2015, 54, 1775; Angew. Chem. 2015, 127, 1795.
[3] Selected examples of chiral b-aminephosphines utilized as
ligands for transition metal complexes: a) W. Zuo, A. J. Lough,
Y. F. Li, R. H. Morris, Science 2013, 342, 1080; b) S. Werkmeis-
ter, K. Junge, B. Wendt, E. Alberico, H. Jiao, W. Baumann, H.
Junge, F. Gallou, M. Beller, Angew. Chem. Int. Ed. 2014, 53,
8722; Angew. Chem. 2014, 126, 8867; c) P. O. Lagaditis, P. E.
Sues, J. F. Sonnenberg, K. Y. Wan, A. J. Lough, R. H. Morris, J.
Am. Chem. Soc. 2014, 136, 1367.
[4] Selected strategies for the synthesis of chiral aminephosphines:
a) A. Saitoh, T. Morimoto, K. Achiwa, Tetrahedron: Asymmetry
1997, 8, 3567; b) A. M. Porte, W. A. van der Donk, K. Burgess, J.
Org. Chem. 1998, 63, 5262; c) A. Saitoh, T. Uda, T. Morimoto,
Tetrahedron: Asymmetry 1999, 10, 4501; d) I. J. Krauss, J. L.
Leighton, Org. Lett. 2003, 5, 3201; e) M. Ito, A. Osaku, C.
Kobayashi, A. Shiibashi, T. Ikariya, Organometallics 2009, 28,
390; f) R. Guo, S. Lu, X. Chen, C.-W. Tsang, W. Jia, C. Sui-Seng,
D. Amoroso, K. Abdur-Rashid, J. Org. Chem. 2010, 75, 937.
[5] Z.-M. Zhang, P. Chen, W. Li, Y. Niu, X.-L. Zhao, J. Zhang,
Angew. Chem. Int. Ed. 2014, 53, 4350; Angew. Chem. 2014, 126,
4439.
[6] Y. Li, X. Su, W. Zhou, W. Li, J. Zhang, Chem. Eur. J. 2015, 21,
4224.
[7] S. Takizawa, T. M.-N. Nguyen, A. Grossmann, D. Enders, H.
Sasai, Angew. Chem. Int. Ed. 2012, 51, 5423; Angew. Chem. 2012,
124, 5519.
[9] Selected reviews and examples related to a-alkylidene-g-butyro-
lactones: a) R. R. A. Kitson, A. Millemaggi, R. J. K. Taylor,
Angew. Chem. Int. Ed. 2009, 48, 9426; Angew. Chem. 2009, 121,
9590; b) P. V. Ramachandran, M. Yip-Schneider, C. M. Schmidt,
Future Med. Chem. 2009, 1, 179; c) C. Muthiah, M. A. Arai, T.
Shinohara, T. Arai, S. Takizawa, H. Sasai, Tetrahedron Lett. 2003,
44, 5201.
[10] Chiral tert-butanesulfinamide (4500 RMBKgÀ1) and methyldi-
phenylphos-phine (9000 RMBKgÀ1) were bought from Shanghai
Darui Finechemical Co., Ltd. and Shanghai Macklin Biochem-
ical Co., Ltd, respectively.
[11] J.-M. Camus, J. Andrieu, P. Richard, R. Poli, Eur. J. Inorg. Chem.
2004, 1081.
[12] See the Supporting Information for X-ray structures.
CCDC 1045425 ((S,Rs)-X4), 1045426 ((R,Rs)-X8) and 1052333
((+)-2a) 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.
[13] Y. M. A. Yamada, S. Ikegami, Tetrahedron Lett. 2000, 41, 2165.
[14] An example of the kinetic resolution of intramolecular Rauhut-
Currier reaction: S. Takizawa, T. M.-N. Nguyen, A. Grossmann,
M. Suzuki, D. Enders, H. Sasai, Tetrahedron 2013, 69, 1202.
[15] Selected examples of other kinetic resolution reactions catalyzed
by chiral phosphines: a) E. Vedejs, O. Daugulis, J. Am. Chem.
Soc. 1999, 121, 5813; b) E. Vedejs, J. A. MacKay, Org. Lett. 2001,
3, 535; c) E. Vedejs, O. Daugulis, J. Am. Chem. Soc. 2003, 125,
4166.
[16] Examples of other parallel kinetic resolution reactions catalyzed
by chiral phosphines: a) E. Vedejs, E. Rozners, J. Am. Chem.
Soc. 2001, 123, 2428; b) T. A. Duffey, J. A. MacKay, E. Vedejs, J.
Org. Chem. 2010, 75, 4674.
[17] S = [ln(1-c)(1-ee)]/ln[(1-c)(1 + ee)]; c refers to the conversion of
(rac)-1l (1-(yield of recovered (R)-1l)).
[18] Selected reports related to transition states in the reactions
catalyzed by b-aminephosphines: a) M. Shi, L.-H. Chen, C.-Q.
Li, J. Am. Chem. Soc. 2005, 127, 3790; b) Y. Xia, Y. Liang, Y.
Chen, M. Wang, L. Jiao, F. Huang, S. Liu, Y. Li, Z.-X. Yu, J. Am.
Chem. Soc. 2007, 129, 3470.
[19] The tert-butylsulfinyl group could easily be removed under acid
conditions: a) G. Liu, D. A. Cogan, J. A. Ellman, J. Am. Chem.
Soc. 1997, 119, 9913; for reviews of chiral sulfinamide in organic
synthesis, please see: b) M. T. Robak, M. A. Herbage, J. A.
Ellman, Chem. Rev. 2010, 110, 3600; c) F. Ferreira, C. Botuha, F.
Chemla, A. Pꢀrez-Luna, Chem. Soc. Rev. 2009, 38, 1162.
[8] Selected general reviews related to RC reactions: a) C. E.
Aroyan, A. Dermenci, S. J. Miller, Tetrahedron 2009, 65, 4069;
b) P. Xie, Y. Huang, Eur. J. Org. Chem. 2013, 6213; for earlier
examples, please see: c) M. M. Rauhut, H. Currier, U.S. Patent,
3074999, 1963; M. M. Rauhut, H. Currier, Chem. Abstr. 1963, 58,
11224a; d) K. Morita, T. Kobayashi, Bull. Chem. Soc. Jpn. 1969,
42, 2732; for selected leading progress, see: e) L.-C. Wang, A. L.
Received: January 30, 2015
Revised: March 6, 2015
Published online: && &&, &&&&
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Organocatalysis
X. Su, W. Zhou, Y. Li,
J. Zhang*
&&&& — &&&&
Design, Synthesis, and Application of
a Chiral Sulfinamide Phosphine Catalyst
for the Enantioselective Intramolecular
Rauhut–Currier Reaction
Xiao-Phos: A new class of chiral sulfina-
mide phosphine catalyst was developed.
These Xiao-Phos catalysts can be pre-
pared from inexpensive commercially
available starting materials and show
good performance in the enantioselective
intramolecular Rauhut–Currier reaction
under mild conditions. Moreover, kinetic
resolution was also observed with the use
of two different substituted racemic pre-
cursors.
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