Preparation of Optically Active cis-Cyclopropane Carboxylates: Cyclopropanation of α-Silyl Stryenes with Aryldiazoacetates and Desilylation of the Resulting Silyl Cyclopropanes

Article abstract of DOI:10.1021/acs.orglett.6b02117

Optically active cis-cyclopropane carboxylates are prepared via the Rh₂(S-PTAD)₄-catalyzed cyclopropanation of α-silyl styrenes with aryl diazoacetates followed by desilylation of the resulting silyl cyclopropane carboxylates. The co

Full text of DOI:10.1021/acs.orglett.6b02117

Letter
pubs.acs.org/OrgLett
Preparation of Optically Active cis-Cyclopropane Carboxylates:
Cyclopropanation of α‑Silyl Stryenes with Aryldiazoacetates and
Desilylation of the Resulting Silyl Cyclopropanes
Yan Su,†,‡ Qing-Fang Li,† Yu-Ming Zhao,‡,§ and Peiming Gu*,†
†School of Chemistry & Chemical Engineering, Key Laboratory of Energy Sources & Engineering, and Ningxia Engineering and
Research Center for Natural Medicines, Ningxia University, Yinchuan 750021, China
‡Department of Chemistry, Lanzhou University, Lanzhou 730000, China
§School of Chemistry & Chemical Engineering, Shaanxi Normal University, Xi’an 710119, China
S
* Supporting Information
ABSTRACT: Optically active cis-cyclopropane carboxylates are prepared via the Rh2(S-PTAD)4-catalyzed cyclopropanation of
α-silyl styrenes with aryl diazoacetates followed by desilylation of the resulting silyl cyclopropane carboxylates. The conjugation
of the aryl ring with CC bond and π stacking are proposed for the stereoselectivity of cyclopropanation, and configuration
inversion is observed with the desilylation process.
Scheme 1. Stereochemistry of the Cyclopropane Carboxylates
nantioenriched cyclopropane carboxylates are very impor-
E
tant molecules that are generally prepared through the trans-
selective cyclopropanation of an alkene with a diazo ester
(Scheme 1).1,2 Though considerable efforts have been made
toward the cis-selective cyclopropanation of alkenes by the Rh,
Cu, Ir, and other metal catalysts,3 much is left to be desired. To
date, the best result on the topics was reported by Katsuki’s group
with the Ir−salen complexes,4 where only the diazoacetates were
used. Asymmetric cyclopropanation of stryenes with Rh−
carbenoids from aryl diazoacetates is always trans-selective,
affording the (E)-1,2-diarylcyclopropane carboxylates.5 The (Z)-
analogues had been efficiently obtained as the racemates via the
carbozincation of cyclopropenes.6 In this paper, we reported the
enantio- and diastereoselective cyclopropanation of α-silyl
stryenes with aryl diazoacetates and desilylation of the resulting
cyclopropanes for preparation of the optically active cis-
cyclopropane carboxylates.
was explored with the dirhodium catalysts (Table 1). The
cyclopropanation reactions using dirhodium carboxylates all
afforded 3aa with absolute control of diastereoselectivity (entries
1−7), and Rh2(S-PTAD)4 was efficient for the conversion.
Opposite enantioselectivity was observed when Rh2(S-DOSP)4
was employed for the cyclopropanation reaction,14,16 and Doyle
dirhodium carboxamidates afforded low conversions (entries 8−
10).
The optimal conditions (in bold, Table 1) were used for
investigation of the aryl diazoacetates (Scheme 2). First,
cyclopropanation of 2a with 1a was re-examined at ∼0.5 mmol
scale, where the yield of 3aa was improved to 99%, and the
enantio- and diastereoselectivity were retainable. Other aryl
diazoacetates 1b−n were all cyclopropanated with 2a, and the
Incorporation of a silyl group onto the cyclopropane ring and
application of these silylcyclopropanes has attracted considerable
interest.7−13 A range of methods to optically active silyl
cyclopropanes were reported,9−13 but only few catalytic
approaches demonstrated their efficiencies in control of enantio-
and diastereoselectivities, producing some bifunctional cyclo-
propanes.10 Other methods suffered poor to moderate
enantioselectivity with significant limitation of substrates. Cyclo-
propanation of the silylalkenes with diazo compounds had been
explored by Ru and Cu catalysts, and only the vinylsilane and
diazoacetates were examined.13
Following our interest in the β-functionalized cyclopropane
carboxylates with restricted conformation,14,15 the asymmetric
cyclopropanation of phenyldiazoacetate 1a and α-silyl styrene 2a
Received: July 19, 2016
© XXXX American Chemical Society
A
DOI: 10.1021/acs.orglett.6b02117
Org. Lett. XXXX, XXX, XXX−XXX

Organic Letters
Letter
a
Table 1. Asymmetric Cyclopropanation of α-Silyl Styrene 1a
with Phenyldiazoacetate 2a
Scheme 3. Scope of the α-Silyl Styrenes
a
b
c
d
entry
catalyst
time (min) yield (%)
dr
ee
1
Rh2(S-DOSP)4
Rh2(R-TBSP)4
30
43
46
>99:1
>99:1
>99:1
>99:1
>99:1
>99:1
>99:1
−34
38
2
60
3
4
Rh2(S-PTAD)4
Rh2(S-PTPA)4
30
92
98
99
30
77
5
Rh2(S-PTTL)4
30
85
98
6
Rh2(S-TCPTTL)4
Rh2(S-TFPTTL)4
Rh2(4S-MPPIM)4
Rh2(4S-MEOX)4
Rh2(5R-MEPY)4
30
65
73
a
Cyclopropanation of α-silyl styrenes 2y (1.5 mmol) with aryl
diazoacetates 1x (0.5 mmol) in hexane (0.5 mL) with Rh2(S-PTAD)4
(1.6 mg, 0.001 mmol) at ∼15 °C for 30 min.
7
30
42
85
8
16 h
16 h
16 h
trace
trace
trace
9
10
directing group in the Rh-catalyzed cyclopropanation of alkenes.5
To our great surprise, the ester group here faced to the same
direction of the silyl group according to the single-crystal X-ray
crystallography of 3da,17 which was different from the expected
structure.
A similar intriguing stereocontrol had been reported with the
cyclopropanation reaction of 1,1-diarylethylenes by the Davies
group, and good diastereoselectivity was observed even when two
aryl rings substituted with the alkene were very similar in size.18
The better conjugation of electron-rich aryl ring with the CC
bond was proposed to support their good diastereoselectivity.
Here, the conjugation effect should also contribute to the
diastereocontrol of the cyclopropanation of α-silyl styrenes.
Considering the excellent diastereoselectivity in this paper, we
thought that the two aromatic rings, one from the α-silyl styrene
and the other from the aryl diazoacetate, might had some tight
interaction.
a
Cyclopropanation of 1a (52.8 mg, 0.3 mmol) and 2a (19.0 mg, 0.1
mmol) with Rh catalyst (0.0002 mmol) in hexane (0.1 mL) at ∼15 °C.
b
c
Isolated yield after purification. Determined by 1H NMR of the
d
crude reaction mixture. Determined by chiral HPLC.
a
Scheme 2. Scope of the Aryl Diazoacetates
Two more experiments, cyclopropanation of vinylsilane 2g
with 1a and cyclopropanation of 2a with ethyl diazoacetate 1o,
were carried out to see if the diastereoselectivity would be kept
when one of the aryl rings was removed from the system (Scheme
4). Both reactions gave the silyl cyclopropane carboxylates 3ag
a
Cyclopropanation of α-silyl styrene 2a (1.5 mmol) with aryl
diazoacetate 1x (0.5 mmol) in hexane (0.5 mL) with Rh2(S-PTAD)4
(1.6 mg, 0.001 mmol) at ∼15 °C for 30 min.
Scheme 4. Diastereoselectivity in the Cyclopropanation of 1a
with 2g and 1o with 2a
conversion was nearly immune to the substituents on the aryl
group of the aryl diazoacetates. The silyl cyclopropane
carboxylates 3aa−na except 3ma were obtained in excellent
yields, diastereoselecitivity (dr >99:1), and enantioselectivity
(98%−99% ee). The enantioselectivity for 3ma (88% ee)
indicated the reaction was sensitive to the size of the ester group.
The α-silyl styrenes were next explored, and the results are
summarized in Scheme 3. All of the corresponding cyclopropane
carboxylates were obtained with excellent diastereoselectivity (dr
>99:1). It indicated that introduction of an electron-donating
group at the phenyl ring of α-silyl styrene would slightly decrease
the enantioselectivity. If a methyl group was attached at the ortho-
position of the phenyl ring, the cyclopropanation reaction
completely failed (not shown in Scheme 3), while its analogues
3ab and 3ac with the methyl group at the para- and meta-position
of phenyl ring were produced with excellent yields. Furthermore,
cyclopropanation of α-silyl para-methylstyrene and α-silyl para-
chlorostyrene, with aryl diazoacetates 1c and 1h, respectively,
afforded four β-silyl cyclopropanecarboxylates with excellent
enantio- and diastereoselectivity.
and 3oa with poor stereocontrol and poor yields, which indicated
that the π stacking interaction19 between the two aromatic rings
could possibly exist.
Rh2(S-PTAD)4 and Rh2(S-PTTL)4 are both derived from N-
phthaloylamino acids, and the differences between the two
catalysts are the substituents at the α-carbon of leucine. The two
catalysts had demonstrated their efficiencies with the cyclo-
propanation reaction (Table 1, entries 3 and 5). Several groups
reported that a “chiral crown” conformation of Rh2(S-PTTL)4
was observed with its X-ray crystal structure,20 where an
approximate C2-symmetric chiral cavity with Rh catalyst face
was generated. Four phthalimido groups were oriented on the
same face, but they were not equal in space. A similar cavity of
We were very glad that the asymmetric cyclopropanation of α-
silyl styrene herein addressed both excellent enantio- and
diastereoselectivity. The ester group was regarded as a trans-
B
DOI: 10.1021/acs.orglett.6b02117
Org. Lett. XXXX, XXX, XXX−XXX

Organic Letters
Letter
for 4aa). Then a range of silylcyclopropanes were desilylated
undertheconditions, andonlythe(Z)-cyclopropanecarboxylates
were observed and separated. In some cases, the yields were
slightly moderate, which was thought be due to part
saponification of the ester group under the strong basic
conditions. It should be noted that the (E)-4aa could be
hydrolyzed to the corresponding (E)-cyclopropane carboxylic
acid, and then it would be lost in the basic aqueous phase. Further
careful treatment of 3aa (0.40 mmol) with the optimized
conditions gave (Z)-4aa in 82% yield and a mixture of
cyclopropane carboxylic acid diastereomers (E/Z < 1/7) in
13% yield, which indicated that the diastereoselectivity of the
desilylation reaction was very excellent (dr >98:2). Finally, the
structure of 4hd was unambiguously confirmed by X-ray
crystallography.
The possible desilylation process was proposed through the
following two stages: (1) desilylation of the silyl cyclopropane
carboxylate 3 would generate a planar carbanion stabilized by the
cyclopropyl ring21 and a benzyl group, where the planar
conformation would strengthen the conjugation of the carbanion
and Ar2 ring;22 (2) protonation of the carbanion might proceed
from the above side of the cyclopropane ring, affording the (Z)-
1,2-diarylcyclopropane carboxylate with configuration retention,
and the down side should be blocked by the carbonyl group or the
alkoxyl group of the ester (Scheme 6).
Figure 1. Possible induction model for cyclopropanation of α-silyl
styrene with aryl diazoacetates.
Rh2(S-PTAD)4 was proposed for illustration of the stereo-
selectivity (Figure 1). With the catalyst face, quadrants I and III
arelessstericallyencumberedthanquadrantsIIandIV.According
to Fox’s research,20a the carbene would be aligned with the X-axis,
and then approach of the α-silyl styrene to the Rh−carbenoid
would proceed through an end-on model5a from quadrant I. The
bulky silyl group might point to the vertical phthalimido group in
quadrant II, and then the Ar2 ring and the CC bond could
possess a coplanar conformation, resulting in better conjugation.
On the contrary, if the Ar2 ring closer to quadrant II was applied,
therequiredorthogonalconformationofAr2 ringandCCbond
would destroy the conjugation. Furthermore, with the coplanar
conformation, the possible Pi stacking of Ar1 ring and Ar2 ring
could come into being, and it might stabilize the transition states.
The conjugation effect and Pi stacking interaction would
dominate the product with two aromatic rings pointing in the
same direction.
Scheme 6. Possible Mechanism of Desilylation of the Silyl
Cyclopropane Carboxylate
Desilylation of the α-silyl α-alkyl cyclopropanes had been
reported by the group of Inomata and Ukaji,9g affording a mixture
of diastereomers of cyclopropane carboxylates. The major isomer
was assigned as the corresponding cyclopropane with config-
urationretention. Treatmentof3aawithTBAFinTHFaffordeda
mixture of cis/trans cyclopropane carboxylate (89:11) in 98%
yield, and the major isomer (Z)-4aa was obtained with
configuration inversion. Further desilylation of 3aa (0.20
mmol) with KOtBu/18-crown-6 in DMSO delivered (Z)-4aa as
the only isomer in 75% yield (Scheme 5). The enantiomeric
excess for 4aa was expected to be excellent as only one of the two
stereocenters of 3aa was involved in the desilylation process, and
the precognition was confirmed by chiral HPLC analysis (98% ee
In summary, we have demonstrated the asymmetric cyclo-
propanation of α-silyl styrenes with aryl diazoacetates and
desilylation of the resulting silylcyclopropanes with configuration
inversion. This strategy might be very useful for preparation of
chiral (Z)-1,2-diarylcyclopropane carboxylates, which was very
difficult to address previously.
a
Scheme 5. Desilylation of β-Silyl Cyclopropanes 3
ASSOCIATED CONTENT
* Supporting Information
■
S
TheSupportingInformationisavailablefreeofchargeontheACS
Publications website at DOI: 10.1021/acs.orglett.6b02117.
Experimental procedures and spectroscopic data and
copies of NMR spectra for all new compounds (PDF)
X-ray crystallographic data for compound 3da (CIF)
X-ray crystallographic data for compound 4hd (CIF)
AUTHOR INFORMATION
Corresponding Author
■
a
Desilylation of 3 (0.20 mmol) with t-BuOK (26.9 mg, 0.24 mmol)
*E-mail: gupm@nxu.edu.cn.
Notes
and 18-crown-6 (15.8 mg, 0.06 mmol) in DMSO (1.0 mL) at ∼15 °C
b
c
for 10 min. Desilylation for 1 min. Desilylation of 3hd at 0.27 mmol
scale.
The authors declare no competing financial interest.
C
DOI: 10.1021/acs.orglett.6b02117
Org. Lett. XXXX, XXX, XXX−XXX

Organic Letters
Letter
G. J. Am. Chem. Soc. 2000, 122, 4464−4470. (i) Mizojiri, R.; Urabe, H.;
Sato, F. J. Org. Chem. 2000, 65, 6217−6222.
ACKNOWLEDGMENTS
■
This work was supported by the National Natural Science
Foundation of China (Nos. 21262024 and 21202074), the
Program for New Century Excellent Talents in University
(NCET-13-0874), and the Research Starting Funds for Imported
Talents of Ningxia University (BQD2015001).
(9) For preparation of chiral silyl cyclopropanes via stoichiometric
́
chiral reagents, see: (a) Begis, G.; Cladingboel, D. E.; Jerome, L.;
Motherwell, W. B.; Sheppard, T. D. Eur. J. Org. Chem. 2009, 2009, 1532−
1548. (b) Liu, X.; Fox, J. M. J. Am. Chem. Soc. 2006, 128, 5600−5601.
(c) Krysiak, J.; Lyon, C.; Baceiredo, A.; Gornitzka, H.; Mikolajczyk, M.;
Bertrand, G. Chem. - Eur. J. 2004, 10, 1982−1986. (d) Barluenga, J.;
́
Fananas, F. J.; Sanz, R.; Marcos, C. Org. Lett. 2002, 4, 2225−2229.
̃
REFERENCES
(e) Krysiak, J.; Kato, T.; Gornitzka, H.; Baceiredo, A.; Mikolajczyk, M.;
Bertrand, G. J. Org. Chem. 2001, 66, 8240−8242. (f) Adams, D.;
Simpkins, N. Chem. Commun. 1998, 1605−1606. (g) Ukaji, Y.; Sada, K.;
Inomata, K. Chem. Lett. 1993, 22, 1227−1230.
■
(1) For reviews on preparation of cyclopropane carboxylates, see:
(a) Lebel, H.; Marcoux, J.-F.; Molinaro, C.; Charette, A. B. Chem. Rev.
2003, 103, 977−1050. (b) Davies, H. M. L.; Beckwith, R. E. J. Chem. Rev.
2003, 103, 2861−2903. (c) Li, A.-H.; Dai, L. X.; Aggarwal, V. K. Chem.
Rev. 1997, 97, 2341−2372. (d) Maas, G. Chem. Soc. Rev. 2004, 33, 183.
(10) For catalytic enantioselective preparations of chiral silyl bifunc-
tional cyclopropanes, see: (a) Ito, H.; Kosaka, Y.; Nonoyama, K.; Sasaki,
Y.; Sawamura, M. Angew. Chem., Int. Ed. 2008, 47, 7424−7427.
(b) Rubina, M.; Rubin, M.; Gevorgyan, V. J. Am. Chem. Soc. 2004, 126,
3688−3689. (c) Rubina, M.; Rubin, M.; Gevorgyan, V. J. Am. Chem. Soc.
2003, 125, 7198−7199.
(e) Muller, P. Acc. Chem. Res. 2004, 37, 243. (f) Davies, H. M. L.;
̈
Antoulinakis, E. Org. React. 2001, 57, 1. (g) Chen, D. Y.-K.; Pouwer, R.
H.; Richard, J.-A. Chem. Soc. Rev. 2012, 41, 4631. (h) Rubin, M.; Rubina,
M.; Gevorgyan, V. Chem. Rev. 2007, 107, 3117.
(11) For catalytic preparation of chiral silyl cyclopropanes via
Simmons−Smith reaction, see: (a) Miura, T.; Itoh, K.; Yasaku, Y.;
Koyata, N.; Murakami, Y.; Imai, N. Tetrahedron Lett. 2008, 49, 5813−
5815. (b) Imai, N.; Sakamoto, K.; Maeda, M.; Kouge, K.; Yoshizane, K.;
Nokami, J. Tetrahedron Lett. 1997, 38, 1423−1426. (c) Imai, N.;
Sakamoto, K.; Takahashi, H.; Kobayashi, S. Tetrahedron Lett. 1994, 35,
7045−7048.
(2) For reviews on reaction of cyclopropane carboxylates, see:
(a) Carson, C. A.; Kerr, M. A. Chem. Soc. Rev. 2009, 38, 3051−3060.
(b) Reissig, H.-U.; Zimmer, R. Chem. Rev. 2003, 103, 1151−1196.
(c)Gnad, F.;Reiser, O. Chem. Rev. 2003, 103, 1603−1624. (d) Cavitt, M.
A.;Phun, L. H.; France, S. Chem. Soc. Rev. 2014, 43, 804−818. (e)Yu, M.;
Pagenkopf, B. L. Tetrahedron 2005, 61, 321−347. (f) Mel’nikov, M. Y.;
Budynina, E. M.; Ivanova, O. A.; Trushkov, I. V. Mendeleev Commun.
2011, 21, 293−301. (g) Schneider, T. F.; Kaschel, J.; Werz, D. B. Angew.
Chem., Int. Ed. 2014, 53, 5504−5523. (h) Novikov, R. A.; Tomilov, Y. V.
Mendeleev Commun. 2015, 25, 1−10. (i) Grover, H. K.; Emmett, M. R.;
Kerr, M. A. Org. Biomol. Chem. 2015, 13, 655−671.
(12) For asymmetric cyclopropanation of alkenes with silyl diazo
compounds, see: (a) Muller, P.; Lacrampe, F. Helv. Chim. Acta 2004, 87,
̈
2848−2859. (b) France, M. B.; Milojevich, A. K.; Stitt, T. A.; Kim, A. J.
Tetrahedron Lett. 2003, 44, 9287−9290.
(13) For catalytic cyclopropanation of vinyltrimethylsilane with
diazoacetate, see: (a) Hoang, V. D. M.; Reddy, P. A. N.; Kim, T.-J.
Tetrahedron Lett. 2007, 48, 8014−8017. (b) Rios, R.; Liang, J.; Lo, M. M.-
C.;Fu, G. C. Chem. Commun. 2000, 377−378. (c)Lo, M. M.-C.;Fu, G. C.
J. Am. Chem. Soc. 1998, 120, 10270−10271.
(3) For cis-selective cyclopropanation with Rh catalysts, see: (a) Lloret,
́
J.; Estevan, F.; Bieger, K.; Villanueva, C.; Ubeda, M. A. Organometallics
́
2007, 26, 4145−4151. (b) Estevan, F.; Lloret, J.; Sanau, M.; Ubeda, M. A.
́
Organometallics 2006, 25, 4977−4984. (c) Ishitani, H.; Achiwa, K. Synlett
1997, 1997, 781−782. (d) Doyle, M. P.; Zhou, Q.-L.; Simonsen, S. H.;
Lynch, V. Synlett 1996, 1996, 697−698. With chiral Cu catalysts, see:
(e) Ito, K.; Katsuki, T. Synlett 1993, 1993, 638−640. (f) Aratani, T.;
Yoneyoshi, Y.; Nagase, T. Tetrahedron Lett. 1982, 23, 685−688. With Ru
catalysts, see: (g) Bonaccorsi, C.; Santoro, F.; Gischig, S.; Mezzetti, A.
Organometallics 2006, 25, 2002−2010. (h) Bonaccorsi, C.; Mezzetti, A.
Organometallics 2005, 24, 4953−4960. (i) Bonaccorsi, C.; Bachmann, S.;
Mezzetti, A. Tetrahedron: Asymmetry 2003, 14, 845−854. (j) Bachmann,
S.; Furler, M.; Mezzetti, A. Organometallics 2001, 20, 2102−2108.
(k) Uchida, T.; Irie, R.; Katsuki, T. Tetrahedron 2000, 56, 3501−3509.
(l) Uchida, T.; Irie, R.; Katsuki, T. Synlett 1999, 1999, 1793−1795.
(m) Uchida, T.; Irie, R.; Katsuki, T. Synlett 1999, 1999, 1163−1165.
With Co catalysts, see: (n) Niimi, T.; Uchida, T.; Irie, R.; Katsuki, T. Adv.
Synth. Catal. 2001, 343, 79−88. (o) Niimi, T.; Uchida, T.; Irie, R.;
Katsuki, T. Tetrahedron Lett. 2000, 41, 3647−3651.
(14) For preparation of functional cyclopropane carboxylates in our
group, see: (a)Su, Y.; Bai, M.;Qiao, J.-B.; Li, X.-J.;Li, R.;Tu, Y.-Q.; Gu, P.
Tetrahedron Lett. 2015, 56, 1805−1807. (b) Gu, P.; Su, Y.; Wu, X.-P.;
Sun, J.; Liu, W.-Y.; Xue, P.; Li, R. Org. Lett. 2012, 14, 2246−2249.
(15) For reaction of functional cyclopropane carboxylates in our group,
see: (a) Su, Y.; Tu, Y.-Q.; Gu, P. Org. Lett. 2014, 16, 4204−4207. (b) Gu,
P.; Wu, X.-P.; Su, Y.; Xue, P.; Li, X.-Q.; Gong, B.-L.; Li, R. Tetrahedron
Lett. 2013, 54, 4957−4959.
(16) Denton, J. R.; Davies, H. M. L. Org. Lett. 2009, 11, 787−790.
(17) The crystal structure of 3da has been deposited at the Cambridge
Crystallographic Data Centre (CCDC 1407695).
(18) (a) Nagashima, T.; Davies, H. M. L. J. Am. Chem. Soc. 2001, 123,
2695−2696. (b)Davies, H.M.L.;Nagashima, T.;Klino, J.L., IIIOrg.Lett.
2000, 2, 823−826.
(19) For a discussion about π stacking, see: Grimme, S. Angew. Chem.,
Int. Ed. 2008, 47, 3430−3434.
(20) (a) DeAngelis, A.; Dmitrenko, O.; Yap, G. P. A.; Fox, J. M. J. Am.
Chem. Soc. 2009, 131, 7230−7231. (b) Lindsay, V. N. G.; Lin, W.;
Charette,A.B.J.Am.Chem.Soc.2009,131,16383−16385.(c)DeAngelis,
A.; Boruta, D. T.; Lubin, J.-B.; Plampin, J. N., III; Yap, G. P. A.; Fox, J. M.
Chem. Commun. 2010,46,4541−4543. (d)Lindsay,V. N. G.;Nicolas,C.;
Charette, A. B. J. Am. Chem. Soc. 2011, 133, 8972−898. (e)DeAngelis, A.;
Panish, R.; Fox, J. M. Acc. Chem. Res. 2016, 49, 115−127 and references
cited therein.
(4)Suematsu, H.;Kanchiku, S.;Uchida, T.;Katsuki, T. J. Am. Chem. Soc.
2008, 130, 10327−10337.
(5) (a) Nowlan, D. T., III; Gregg, T. M.; Davies, H. M. L.; Singleton, D.
A. J. Am. Chem. Soc. 2003, 125, 15902−15911. (b) Davies, H. M. L.;
Bruzinski, P. R.; Lake, D. H.; Kong, N.; Fall, M. J. J. Am. Chem. Soc. 1996,
118, 6897−6907.
(6) (a) Tarwade, V.; Liu, X.; Yan, N.; Fox, J. M. J. Am. Chem. Soc. 2009,
131, 5382. (b) Tarwade, V.; Selvaraj, R.; Fox, J. M. J. Org. Chem. 2012, 77,
9900−9904.
(7) Paquette, L. A. Chem. Rev. 1986, 86, 733−750.
(21) Baschky, M. C.; Peterson, K. C.; Kass, S. R. J. Am. Chem. Soc. 1994,
(8) For racemic silyl-substituted cyclopropanes, see: (a) Shintani, R.;
Fujie, R.; Takeda, M.; Nozaki, K. Angew. Chem., Int. Ed. 2014, 53, 6546−
6549. (b) Li, S.-G.; Zard, S. Z. Org. Lett. 2014, 16, 6180−6183.
(c) Beaulieu, L.-P. B.; Delvos, L. B.; Charette, A. B. Org. Lett. 2010, 12,
1348−1351. (d)Berthon-Gelloz, G.; Marchant, M.; Straub, B. F.; Marko,
I. E. Chem. - Eur. J. 2009, 15, 2923−2931. (e) Glass, A. C.; Morris, B. B.;
Zakharov, L. N.; Liu, S. Y. Org. Lett. 2008, 10, 4855−4857. (f) Trofimov,
A.; Rubina, M.; Rubin, M.; Gevorgyan, V. J. Org. Chem. 2007, 72, 8910−
8920. (g) Langer, P.; Freifeld, I. Org. Lett. 2001, 3, 3903−3905.
(h)Goumri-Magnet, S.; Kato, T.; Gornitzka, H.; Baceiredo, A.; Bertrand,
116, 7218−7224.
́ ́
(22)Yus, M.;Macia,B.;Gomez, C.;Soler, T.;Falvello, L. R.;Fanwick, P.
E. Tetrahedron 2005, 61, 3865−3871 and ref 12 cited therein.
D
DOI: 10.1021/acs.orglett.6b02117
Org. Lett. XXXX, XXX, XXX−XXX