MCPBA-mediated metal-free intramolecular aminohydroxylation and dioxygenation of unfunctionalized olefins

Article abstract of DOI:10.1039/c5ra09024e

mCPBA-mediated metal-free intramolecular aminohydroxylation and dioxygenation reactions of unfunctionalized olefins are reported. In the presence of 1.2 equiv. of m-chlorobenzoic peracid, different N-sulfonyl 4-penten-1-amine substrates could be cyclized

Full text of DOI:10.1039/c5ra09024e

RSC Advances
View Article Online
View Journal | View Issue
PAPER
mCPBA-mediated metal-free intramolecular
aminohydroxylation and dioxygenation of
Cite this: RSC Adv., 2015, 5, 61137
unfunctionalized olefins†
a
a
a
ab
*
Gong-Qing Liu, Lin Li, Lili Duan and Yue-Ming Li
mCPBA-mediated metal-free intramolecular aminohydroxylation and dioxygenation reactions of
unfunctionalized olefins are reported. In the presence of 1.2 equiv. of m-chlorobenzoic peracid, different
N-sulfonyl 4-penten-1-amine substrates could be cyclized via epoxide intermediates, producing the
corresponding 2-hydroxymethylpyrrolidine products in up to 92% yields. The reaction could be carried
out at gram-scale, and the hydroxyl group could be further converted to a variety of different functional
groups via conventional functional group transformation reactions. When N-sulfonyl carboxylimides
were subjected to the same reaction, O-cyclization products oxolanimines were obtained. The skeletons
of these compounds were confirmed using X-ray diffraction experiments.
Received 14th May 2015
Accepted 26th June 2015
DOI: 10.1039/c5ra09024e
www.rsc.org/advances
In addition to these important achievements, metal free
catalytic aminohydroxylation of unfunctionalized olens has
Introduction
also been reported as one of the most efficient methods for the
production of 1,2-amino alcohols. For example, hypervalent
iodine reagents were able to promote aminohydroxylation of
unfunctionalized olens,16 and good to excellent enantiose-
lectivities were realized when an appropriate chiral hypervalent
iodine reagent was utilized.17 In another example, Moriyama
et al. described oxone-promoted intramolecular oxidative
cyclizations for the synthesis of substituted prolinol deriva-
tives.18 Finally, Jørgensen and co-workers reported a formal
asymmetric organocatalytic aminohydroxylation of enones via
an aziridination-double SN2 sequence.19 In this paper, we wish
to report an mCPBA-mediated metal-free intramolecular ami-
nohydroxylation approach to 1,2-amino alcohols as a continu-
ation of our program on the functionalization of unactivated
olens.20
1,2-Amino alcohols (b-amino alcohols) are widely present in
natural products or biologically important compounds (Fig. 1),1
and the Taxol side chain is one of the most famous examples of
1,2-amino alcohols. In addition, these compounds have also
found widespread application in asymmetric synthesis as chiral
auxiliaries and chiral ligands (Fig. 1).2 To this end, continuous
efforts have been devoted to the formation of 1,2-amino alco-
hols,3 and a variety of methods such as nucleophilic addition to
carbonyl and imine compounds,4 ring-opening of epoxides/
aziridines with suitable nucleophiles,5 C–H bond functionali-
zations6 or hydrogenation of a-amino ketones have been
reported.7
Among the variety of methods developed, amino-
hydroxylation of C]C double bonds is one of the most attrac-
tive strategies for the synthesis of 1,2-amino alcohols.8 Since the
pioneering and elegant work reported by Sharpless,9 huge
efforts have been made towards the transition metal-catalyzed
aminohydroxylation of C]C double bonds, and a variety of
efficient catalysts such as copper,10 palladium,11 gold,12 iron,13
rhodium,14 or platinum catalysts15 have been developed as a
result.
aState Key Laboratory of Medicinal Chemical Biology, College of Pharmacy and Tianjin
Key Laboratory of Molecular Drug Research, Nankai University, Tianjin 300071,
People’s Republic of China. E-mail: ymli@nankai.edu.cn
bCAS Key Laboratory of Synthetic Chemistry of Natural Substances, Shanghai Institute
of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai
200032, People’s Republic of China
† Electronic supplementary information (ESI) available: General information of
the reaction, characterization of products, and X-ray diffraction results for 2s
and 9a. CCDC 1400823 and 1400825. For ESI and crystallographic data in CIF
or other electronic format see DOI: 10.1039/c5ra09024e
Fig. 1 Examples of vicinal aminoalcohol-containing natural products,
biologically active compounds, chiral auxiliaries and chiral ligands.
This journal is © The Royal Society of Chemistry 2015
RSC Adv., 2015, 5, 61137–61143 | 61137

View Article Online
RSC Advances
Paper
in the absence of mCPBA (entries 1 and 2, respectively).
Replacing mCPBA with other oxidants led to a drop of isolated
yield (entries 3 to 6). The effect of the solvents on the course of
the reaction was also noteworthy, and CH2Cl2 was the most
suitable solvent for the reaction. Reactions carried out in MeOH,
THF or CH3CN gave remarkably lower yields (entries 7 to 9).
With the optimized conditions in hand, different substrates
were tested to study the scope of the reaction, and the results
are summarized in Table 2.
Scheme 1 mCPBA-mediatedintramolecularaminohydroxylationof1a.
As shown in Table 2, the intramolecular aminohydroxylation
of N-alkenylsulfonamides proceeded readily, giving the corre-
sponding prolinol derivatives in good isolated yields. N-
Substituents had some impacts on the reaction outcomes
(entries 1–6). Long reaction times and high temperatures were
essential to achieve satisfactory yields for substrates bearing
electron decient N-substituents (entries 2 and 5). This was
possibly due to the low nucleophilicity of the sulfonamide
caused by the strong electron withdrawing nitro group at the
para-position of the benzene ring (entry 2 and entry 5). N-Tosyl-
o-allyl aniline substrates could also be cyclized, giving the cor-
responding indoline derivatives in moderate isolated yields
(entries 7–12). The drop in isolated yields may be due to the
decreased reactivity of the sulfonamide aniline nitrogen atoms.
Methoxy, methyl, halogen and cyano groups on the benzene
ring could all be tolerated during the reactions. Again, the
electronic effect of the aromatic rings inuenced the course of
the reaction. The Thorpe–Ingold effect showed less impact on
the reaction, and the substrates without gem-disubstituents also
gave acceptable isolated yields (entries 13–15). Different
substituents on the main chain of the substrates did not
signicantly inuence the reaction outcomes (entries 16–18).
Substituents on C]C double bonds showed less impact on the
reaction. Di- and trisubstituted terminal alkenes were efficiently
converted into secondary and tertiary alcohols in good yield,
respectively (entries 19–20). When the E-substrate 1s was sub-
jected to the reaction, an erythro-product was obtained and the
structure was conrmed using X-ray diffraction experiments
(Fig. 2). The chiral substrate 1u gave a good isolated yield, but
low diastereoselectivity (entry 21). Furthermore, the current
protocol was also applicable to the synthesis of 2,7-diazaspir-
obicyclic compound 2v (entry 22).
Results and discussion
Very recently, we revealed that (diacetoxyiodo)benzene (PIDA)
can be used to promote halocyclization of unfunctionalized
olens.21 In the presence of 1.1 equiv. of PIDA and suitable
halogen sources, intramolecular haloamidation (iodo-, bromo-,
chloro-, and uoroamidation), haloetherication and hal-
olactonization reactions could all be realized, giving the corre-
sponding halocyclization products in good to excellent isolated
yields. Aer establishing
a general procedure for PIDA-
promoted intramolecular halocyclization of unfunctionalized
olens, a catalytic version was also tested to reduce the amount
of generally expensive (diacetoxyiodo)benzene (PIDA). Reac-
tions in the presence of 10 mol% of PIDA and different oxidants
were carried out to establish a catalytic protocol. To our
surprise, when mCPBA was used as an oxidant, an amino-
hydroxylation product (2a) was obtained instead of an iodoa-
mination product (3a) (Scheme 1).
We reasoned that 2a should be generated through a tandem
epoxidation and epoxide ring-opening sequence. Encouraged by
this preliminary result, the reaction parameters such as oxidants
or solvents were examined to get the optimal reaction condi-
tions, and the results are summarized in Table 1. The reaction
could be carried out at room temperature in the presence of 1.2
equiv. of mCPBA, and the substrate 1a could be converted to the
prolinol product 2a in 86% isolated yield. mCPBA was essential
for the successful transformation and no product was obtained
Table 1 Optimization of the reaction conditionsa
5-Hexen-1-amine substrate 1w failed to give the desired
product possibly due to the unfavorable entropy feature of the
cyclization reaction.22 In this case, the epoxide 2w0 was obtained
in 89% yield (Scheme 2, eqn (1)), and 90% of the epoxide could
be recovered aer being heated in DCE at 90 ꢀC for 36 h
(Scheme 2, eqn (2)). However, when the epoxide 2w0 was allowed
to react in the presence of base (2 equiv. of NaOH), the desired
piperidinylmethanol 2w could also be obtained in good isolated
yield (Scheme 2, eqn (3)).
To evaluate the scalability of the current protocol, the reac-
tion of 1a on gram scale was carried out and the product 2a
could be isolated in 84% yield (Scheme 3). Subsequently, the
hydroxyl group in 2a could be converted to a variety of func-
tional groups using known procedures such as azidation,23
bromination,24 acetylation,16b carboxylation 18 and Swern
Entry
Reaction conditions
Isolated yield (%)
1
2
3
4
5
6
7
8
9
Standard conditions
No mCPBA
86
NR
NR
8
NR
11
NR
15
32
Oxone instead of mCPBA
H2O2 instead of mCPBA
TBHP instead of mCPBA
AcOOH instead of mCPBA
MeOH instead of CH2Cl2
THF instead of CH2Cl2
CH3CN instead of CH2Cl2
a
All the reactions were run at 0.5 mmol scale in 20 mL of solvent.
Reaction temperature: room temperature (25 ꢀC). NR ¼ no reaction.
61138 | RSC Adv., 2015, 5, 61137–61143
This journal is © The Royal Society of Chemistry 2015

View Article Online
Paper
RSC Advances
Table 2 Substrate scope of mCPBA-mediated aminohydroxylationa
Entry
Substrate
Product
Time (h)
Isolated yield (%)
1
2
3
R ¼ Tol (1a)
2a
2b
2c
18 h
86
63
92
R ¼ 2-NO2Ph (1b)
R ¼ Me (1c)
48 h, 40 ꢀ
15 h
C
C
4
5
6
R ¼ Tol (1d)
2d
2e
2f
15 h
88
67
80
R ¼ 4-NO2Ph (1e)
R ¼ Ph (1f)
48 h, 40 ꢀ
20 h
7
8
9
10
11
12
R ¼ H (1g)
R ¼ OMe (1h)
R ¼ Me (1i)
R ¼ Cl (1j)
R ¼ F (1k)
2g
2h
2i
2j
2k
2l
36 h
24 h
24 h
83
88
78
67
70
62
48 h, 40 ꢀ
24 h, 50 ꢀ
C
C
R ¼ CN (1l)
40 h, 50 ꢀC
13
14
15
R ¼ 4-Tol (1m)
R ¼ Ph (1n)
2m
2n
2o
20 h
15 h
18 h
75
80
79
R ¼ 2-Tol (1o)
16
22 h
65
17
18
n ¼ 1 (1q)
n ¼ 2 (1r)
n ¼ 1 2q
n ¼ 2 2r
15 h
15 h
83
86
19
28 h
75 (dr > 20 : 1)
20
21
36 h
24 h
73
86 (dr ¼ 60 : 40)
This journal is © The Royal Society of Chemistry 2015
RSC Adv., 2015, 5, 61137–61143 | 61139

View Article Online
RSC Advances
Paper
Table 2 (Contd.)
Entry
Substrate
Product
Time (h)
30 h
Isolated yield (%)
22
80 (dr ¼ 2 : 1 : 1)
a
Reaction conditions: the reactions were carried out with 0.5 mmol of substrate, 0.6 mmol of mCPBA in 20 mL of DCM.
Scheme 2 Reaction of the 5-hexen-1-amine substrate.
Fig. 2 ORTEP drawing of 2s‡ with the thermal ellipsoids at 30%
probability. Hydrogen atoms were omitted for clarity.
oxidation.25 The current method therefore opened up a new
route to a variety of biologically interesting structures.26
Aer the successful aminohydroxylation of sulfonamide
substrates, the application scope of mCPBA-mediated amino-
hydroxylation was extended. When N-tosyl amide 8a was sub-
jectedtoreactionunderthestandardconditions, anO-cyclization
product oxolanimine 9a was obtained as the major product
(Scheme 4), and the structure of oxolanimine 9a was unambig-
uously conrmed using NMR spectroscopy and X-ray diffraction
studies (Fig. 3). A trace amount of the N-cyclization product,
lactam 9a0 was also detected.
Scheme 3 Gram-scale aminohydroxylation and transformation of the
hydroxyl group to different functional groups. Conditions: (a) 1a (10
mmol), mCPBA (12 mmol), DCM, r.t., 24 h. (b) 2a, DPPA, DBU, toluene/
DMF (9 : 1), 50 ꢀC, 48 h. (c) 2a, PBr3, Et2O, r.t., overnight. (d) 2a, Ac2O,
4-DMAP, Et3N, 0 ꢀC, 30 min. (e) 2a, DIAB, TEMPO, CH3CN/H2O (1 : 1),
r.t., 12 h. (f) 2a, (COCl)2, DMSO, Et3N, DCM, ꢁ78 ꢀC, 30 min.
Encouraged by this result, a variety of substrates were then
tested to study the scope of the reaction, and the results are
summarized in Scheme 5. In general, the cyclization products
were obtained with excellent regioselectivity and in good yields.
Different substituents on the main chain did not signicantly
inuence the reaction outcomes.
˚
‡ Crystal data for 2s: C25H27NO3S, M ¼ 421.54, monoclinic, a ¼ 14.198(3) A, b ¼
ꢀ
ꢀ
ꢀ
˚
˚
6.0639(12) A, c ¼ 25.178(5) A, a ¼ 90.00 , b ¼ 100.14(3) , g ¼ 90.00 , V ¼
3
ꢁ1
˚
2133.9(7) A , T ¼ 113(2) K, space group P2(1)/c, Z ¼ 4, m(MoKa) ¼ 0.179 mm
,
15 871 reections measured, 5063 independent reections (Rint ¼ 0.0444). The
nal R1 values were 0.0443 (I > 2s(I)). The nal wR(F2) values were 0.1187 (I >
2s(I)). The nal R1 values were 0.0551 (all data). The nal wR(F2) values were
0.1284 (all data). The goodness of t on F2 was 1.011. The CIF for 2s has been
deposited in the CCDC with deposition number CCDC 1400823.
Conclusions
In summary, mCPBA was effective for the functionalization
of unactivated C]C double bonds. Intramolecular
61140 | RSC Adv., 2015, 5, 61137–61143
This journal is © The Royal Society of Chemistry 2015

View Article Online
Paper
RSC Advances
Scheme 4 Oxyhydroxylation of 8a.
Scheme 5 mCPBA-mediated dioxygenation of the N-tosyl amide
substrate.
point apparatus without correction of the thermometer. Nuclear
magnetic resonance spectra were recorded at ambient temper-
ature (unless otherwise stated) at 400 MHz (100 MHz for 13C) in
CDCl3. Chemical shis are reported in ppm (d) using TMS as
internal standard, and spin–spin coupling constants (J) are
given in Hz. High resolution mass spectrometry (HRMS) anal-
yses were carried out on an IonSpec 7.0T FTICR HR-ESI-MS.
Fig. 3 ORTEP drawing of 9a§ with the thermal ellipsoids at 30%
probability. Hydrogen atoms were omitted for clarity.
aminohydroxylation and dioxygenation reactions could all be
realized in the presence of 1.2 equiv. of mCPBA. This metal-free
method will complement the existing aminohydroxylation
methods, especially osmium-based approaches. The reaction
could be carried out at gram-scale, and the hydroxyl group could
be easily converted to other functional groups via conventional
methods. We envisage that the present protocol will attract the
attention of synthetic chemists in the elds of medicinal and
agrochemical research due to the good isolated yields, mild
conditions and easy-to-operate features of the reactions.
General procedure for intramolecular aminohydroxylation
and dioxygenation
In a 100 mL round-bottomed ask alkenylamine (0.5 mmol) and
mCPBA (0.6 mmol) in dry CH2Cl2 (20 mL) were added. The
mixture was stirred at room temperature for a given time.
CH2Cl2 (10 mL) was then added and the mixture was washed
with aqueous Na2S2O3 and aqueous NaHCO3, dried over MgSO4,
and concentrated to give a crude residue which was puried
using ash column chromatography to give the corresponding
products.
Experimental section
General methods
Acknowledgements
We acknowledge the nancial support from the National
Natural Science Foundation of China (NSFC 20972072, NSFC
21272121). G.-Q. Liu acknowledges the support from The Ph. D.
Student Innovative Research Program of Nankai University
(68140001).
Reagents were used as received without further purication
unless otherwise specied. Solvents were dried and distilled
prior to use. Reactions were monitored with thin layer chro-
matography using silica gel GF254 plates. Organic solutions were
concentrated in vacuo using a rotary evaporator. Flash column
chromatography was performed using silica gel (200–300
meshes). The petroleum ether used had a boiling point range of
60–90 ꢀC. Melting points were measured on digital melting
Notes and references
1 (a) D. O’Hagan, Nat. Prod. Rep., 2000, 17, 435–446; (b)
J. R. Lewis, Nat. Prod. Rep., 2001, 18, 95–128.
˚
§ Crystal data for 9a: C13H17NO4S, M ¼ 283.34, orthorhombic, a ¼ 8.6906(17) A,
ꢀ
ꢀ
ꢀ
2 (a) A. I. Meyers, D. R. Williams and M. Druelinger, J. Am.
Chem. Soc., 1976, 98, 3032–3033; (b) A. Hirao, S. Itsuno,
S. Nakahama and N. Yamazaki, J. Chem. Soc., Chem.
Commun., 1981, 315–317; (c) E. J. Corey, R. K. Bakshi and
S. Shibata, J. Am. Chem. Soc., 1987, 109, 5551–5553; (d)
D. J. Ager, I. Prakash and D. R. Schaad, Chem. Rev., 1996,
96, 835–876; (e) I. Schiffers, T. Rantanen, F. Schmidt,
˚
˚
b ¼ 11.953(2) A, c ¼ 13.546(3) A, a ¼ 90.00 , b ¼ 90.00 , g ¼ 90.00 , V ¼
3
˚
1407.1(5) A , T ¼ 113(2) K, space group P2(1)2(1)2(1), Z ¼ 4, m(MoKa) ¼ 0.239
mmꢁ1
,
16 639 reections measured, 3374 independent reections (Rint
¼
0.0564). The nal R1 values were 0.0592 (I > 2s(I)). The nal wR(F2) values were
0.1544 (I > 2s(I)). The nal R1 values were 0.0641 (all data). The nal wR(F2)
values were 0.1598 (all data). The goodness of t on F2 was 1.038. Flack
parameter ¼ ꢁ0.01(12). The CIF for 9a has been deposited in the CCDC with
deposition number CCDC 1400825.
This journal is © The Royal Society of Chemistry 2015
RSC Adv., 2015, 5, 61137–61143 | 61141

View Article Online
RSC Advances
Paper
W. Bergmans, L. Zani and C. Bolm, J. Org. Chem., 2006, 71,
2320–2331.
1711–1726; (m) M. C. Paderes, J. B. Keister and
S. R. Chemler, J. Org. Chem., 2012, 78, 506–515.
3 (a) S. C. Bergmeier, Tetrahedron, 2000, 56, 2561–2576; (b) 11 (a) E. J. Alexanian, C. Lee and E. J. Sorensen, J. Am. Chem.
O. K. Karjalainen and A. M. P. Koskinen, Org. Biomol.
Chem., 2012, 10, 4311–4326.
4 (a) F. A. Luzzio, Tetrahedron, 2001, 57, 915–945; (b)
S. Kobayashi, Y. Mori, J. S. Fossey and M. M. Salter, Chem.
Rev., 2011, 111, 2626–2704.
5 (a) D. M. Hodgson, A. R. Gibbs and G. P. Lee, Tetrahedron,
1996, 52, 14361–14384; (b) J. B. Sweeney, Chem. Soc. Rev.,
2002, 31, 247–258; (c) X. E. Hu, Tetrahedron, 2004, 60,
2701–2743.
Soc., 2005, 127, 7690–7691; (b) P. Szolcsanyi and T. Gracza,
Chem. Commun., 2005, 3948–3950; (c) G. Liu and
S. S. Stahl, J. Am. Chem. Soc., 2006, 128, 7179–7181; (d)
L. V. Desai and M. S. Sanford, Angew. Chem., Int. Ed., 2007,
46, 5737–5740; (e) D. V. Liskin, P. A. Sibbald,
C. F. Rosewall and F. E. Michael, J. Org. Chem., 2010, 75,
6294–6296; (f) H. Zhu, P. Chen and G. Liu, J. Am. Chem.
Soc., 2014, 136, 1766–1769.
12 T. de Haro and C. Nevado, Angew. Chem., Int. Ed., 2011, 50,
906–910.
6 (a) C. G. Espino and J. Du Bois, Angew. Chem., Int. Ed., 2001,
40, 598–600; (b) J.-L. Liang, S.-X. Yuan, J.-S. Huang, W.-Y. Yu 13 (a) K. S. Williamson and T. P. Yoon, J. Am. Chem. Soc., 2010,
and C.-M. Che, Angew. Chem., Int. Ed., 2002, 41, 3465–3468;
(c) H. Lebel, K. Huard and S. Lectard, J. Am. Chem. Soc.,
2005, 127, 14198–14199; (d) K. J. Fraunhoffer and
M. C. White, J. Am. Chem. Soc., 2007, 129, 7274–7276; (e)
T. Kang, H. Kim, J. G. Kim and S. Chang, Chem. Commun.,
2014, 50, 12073–12075.
7 (a) H. Takahashi, S. Sakuraba, H. Takeda and K. Achiwa, J.
Am. Chem. Soc., 1990, 112, 5876–5878; (b) T. Ohkuma,
D. Ishii, H. Takeno and R. Noyori, J. Am. Chem. Soc., 2000,
122, 6510–6511; (c) A. Lei, S. Wu, M. He and X. Zhang, J.
Am. Chem. Soc., 2004, 126, 1626–1627; (d) S. Liu, J.-H. Xie,
L.-X. Wang and Q.-L. Zhou, Angew. Chem., Int. Ed., 2007,
46, 7506–7508; (e) P. He, H. Zheng, X. Liu, X. Lian, L. Lin
and X. Feng, Chem.–Eur. J., 2014, 20, 13482–13486.
132, 4570–4571; (b) K. S. Williamson and T. P. Yoon, J. Am.
Chem. Soc., 2012, 134, 12370–12373; (c) G.-S. Liu,
Y.-Q. Zhang, Y.-A. Yuan and H. Xu, J. Am. Chem. Soc., 2013,
135, 3343–3346; (d) D.-F. Lu, C.-L. Zhu, Z.-X. Jia and H. Xu,
J. Am. Chem. Soc., 2014, 136, 13186–13189.
14 (a) E. Levites-Agababa, E. Menhaji, L. N. Perlson and
C. M. Rojas, Org. Lett., 2002, 4, 863–865; (b) A. Padwa and
T. Stengel, Org. Lett., 2002, 4, 2137–2139; (c) S. Beaumont,
V. Pons, P. Retailleau, R. H. Dodd and P. Dauban, Angew.
Chem., Int. Ed., 2010, 49, 1634–1637; (d) W. P. Unsworth,
N. Clark, T. O. Ronson, K. Stevens, A. L. Thompson,
S. G. Lamont and J. Robertson, Chem. Commun., 2014, 50,
11393–11396.
15 K. Muniz, A. Iglesias and Y. Fang, Chem. Commun., 2009,
5591–5593.
8 (a) D. Nilov and O. Reiser, Adv. Synth. Catal., 2002, 344, 1169–
´
1173; (b) J. A. Bodkin and M. D. McLeod, J. Chem. Soc., Perkin 16 (a) S. Serna, I. Tellitu, E. Domınguez, I. Moreno and
Trans. 1, 2002, 2733–2746; (c) K. Muniz, Chem. Soc. Rev.,
2004, 33, 166–174; (d) T. J. Donohoe, C. K. A. Callens,
A. Flores, A. R. Lacy and A. H. Rathi, Chem.–Eur. J., 2011,
17, 58–76.
9 (a) K. B. Sharpless, A. O. Chong and K. Oshima, J. Org. Chem.,
1976, 41, 177–179; (b) G. Li, H.-T. Chang and K. B. Sharpless,
Angew. Chem., Int. Ed., 1996, 35, 451–454.
R. SanMartin, Tetrahedron, 2004, 60, 6533–6539; (b)
´
A. Correa, I. Tellitu, E. Domınguez and R. SanMartin, J.
Org. Chem., 2006, 71, 8316–8319; (c) B. M. Cochran and
F. E. Michael, Org. Lett., 2008, 10, 5039–5042; (d)
D. J. Wardrop, E. G. Bowen, R. E. Forslund, A. D. Sussman
and S. L. Weerasekera, J. Am. Chem. Soc., 2009, 132, 1188–
1189; (e) H. Li and R. A. Widenhoefer, Tetrahedron, 2010,
66, 4827–4831; (f) H. J. Kim, S. H. Cho and S. Chang, Org.
Lett., 2012, 14, 1424–1427.
10 (a) M. Noack and R. Gottlich, Chem. Commun., 2002, 536–
537; (b) D. J. Michaelis, C. J. Shaffer and T. P. Yoon, J. Am.
¨
´
Chem. Soc., 2007, 129, 1866–1867; (c) D. J. Michaelis, 17 (a) C. Roben, J. A. Souto, Y. Gonzalez, A. Lishchynskyi and
˜
M. A. Ischay and T. P. Yoon, J. Am. Chem. Soc., 2008, 130,
6610–6615; (d) P. H. Fuller, J.-W. Kim and S. R. Chemler, J.
Am. Chem. Soc., 2008, 130, 17638–17639; (e) T. Benkovics,
K. Muniz, Angew. Chem., Int. Ed., 2011, 50, 9478–9482; (b)
U. Farid and T. Wirth, Angew. Chem., Int. Ed., 2012, 51,
3462–3465.
J. Du, I. A. Guzei and T. P. Yoon, J. Org. Chem., 2009, 74, 18 K. Moriyama, Y. Izumisawa and H. Togo, J. Org. Chem., 2012,
5545–5552; (f) M. C. Paderes and S. R. Chemler, Org. Lett., 77, 9846–9851.
2009, 11, 1915–1918; (g) D. J. Michaelis, K. S. Williamson 19 D. C. Cruz, P. A. Sanchez-Murcia and K. A. Jorgensen, Chem.
and T. P. Yoon, Tetrahedron, 2009, 65, 5118–5124; (h) Commun., 2012, 48, 6112–6114.
T. Benkovics, I. A. Guzei and T. P. Yoon, Angew. Chem., Int. 20 (a) G.-Q. Liu, W. Li, Y.-M. Wang, Z.-Y. Ding and Y.-M. Li,
Ed., 2010, 49, 9153–9157; (i) S. M. DePorter, A. C. Jacobsen,
K. M. Partridge, K. S. Williamson and T. P. Yoon,
Tetrahedron Lett., 2010, 51, 5223–5225; (j) D. E. Mancheno,
A. R. Thornton, A. H. Stoll, A. Kong and S. B. Blakey, Org.
Lett., 2010, 12, 4110–4113; (k) F. C. Sequeira and
Tetrahedron Lett., 2012, 53, 4393–4396; (b) G.-Q. Liu,
Z.-Y. Ding, L. Zhang, T.-T. Li, L. Li, L. Duan and Y.-M. Li,
Adv. Synth. Catal., 2013, 356, 2303–2310; (c) R.-L. Li,
G.-Q. Liu, W. Li, Y.-M. Wang, L. Li, L. Duan and Y.-M. Li,
Tetrahedron, 2013, 69, 5867–5873.
S. R. Chemler, Org. Lett., 2012, 14, 4482–4485; (l) 21 G.-Q. Liu and Y.-M. Li, J. Org. Chem., 2014, 79, 10094–10109.
M. C. Paderes, L. Belding, B. Fanovic, T. Dudding, 22 (a) G. Illuminati and L. Mandolini, Acc. Chem. Res., 1981, 14,
J. B. Keister and S. R. Chemler, Chem.–Eur. J., 2012, 18,
95–102; (b) A. J. Kirby, in Advances in Physical Organic
Chemistry, ed. V. Gold and D. Bethell, Academic Press,
61142 | RSC Adv., 2015, 5, 61137–61143
This journal is © The Royal Society of Chemistry 2015

View Article Online
Paper
RSC Advances
1981, pp. 183–278; (c) T. G. Denisova and E. T. Denisov, Russ. 26 (a) P. J. Lovell, S. M. Bromidge, S. Dabbs, D. M. Duckworth,
Chem. Bull., 2002, 51, 949–960.
I. T. Forbes, A. J. Jennings, F. D. King, D. N. Middlemiss,
S. K. Rahman, D. V. Saunders, L. L. Collin, J. J. Hagan,
G. J. Riley and D. R. Thomas, J. Med. Chem., 2000, 43, 342–
23 A. S. Thompson, G. R. Humphrey, A. M. DeMarco,
D. J. Mathre and E. J. J. Grabowski, J. Org. Chem., 1993, 58,
5886–5888.
`
345; (b) J. Andries, L. Lemoine, A. Mouchel-Blaisot,
24 G. C. Harrison and H. Diehl, Org. Synth., 1943, 23, 32.
25 K. Omura and D. Swern, Tetrahedron, 1978, 34, 1651–1660.
S. Tang, M. Verdurand, D. Le Bars, L. Zimmer and
T. Billard, Bioorg. Med. Chem. Lett., 2010, 20, 3730–3733.
This journal is © The Royal Society of Chemistry 2015
RSC Adv., 2015, 5, 61137–61143 | 61143