One-Pot l-Proline-Mediated Stereoselective α-C(sp2)–H Fluorination of α,β-Unsaturated Aldehydes through Methoxyfluorination–Elimination

Article abstract of DOI:10.1002/ejoc.201700622

A one-pot, two-step l-proline-mediated stereoselective α-C(sp²)–H fluorination of α,β-unsaturated aldehydes towards their corresponding (Z)-α-fluoro-α,β-unsaturated aldehydes has been developed. The first step utilises Selectfluor as a fluorinating agent in CH₃NO₂/MeOH forming (Z)-α-fluoro-α,β-unsaturated aldehydes and their corresponding dimethyl acetals through methoxyfluorination-elimination. In the second step, water is added to promote the hydrolytic cleavage of the dimethyl acetals. The obtained (Z)-α-fluoro-α,β-unsaturated aldehydes were smoothly reduced to the corresponding alcohols by using NaBH₄.

Full text of DOI:10.1002/ejoc.201700622

A Journal of
Accepted Article
Title: One-Pot L-Proline-Mediated Stereoselective α-
C(sp2)−H Fluorination of α,β-Unsaturated Aldehydes via
Methoxyfluorination-Elimination
Authors: Jiadi Zhou, Xinpeng Jiang, Can Jin, Zhicheng Guo, and
Weike Su
This manuscript has been accepted after peer review and appears as an
Accepted Article online prior to editing, proofing, and formal publication
of the final Version of Record (VoR). This work is currently citable by
using the Digital Object Identifier (DOI) given below. The VoR will be
published online in Early View as soon as possible and may be different
to this Accepted Article as a result of editing. Readers should obtain
the VoR from the journal website shown below when it is published
to ensure accuracy of information. The authors are responsible for the
content of this Accepted Article.
To be cited as: Eur. J. Org. Chem. 10.1002/ejoc.201700622
Link to VoR: http://dx.doi.org/10.1002/ejoc.201700622
Supported by

10.1002/ejoc.201700622
European Journal of Organic Chemistry
COMMUNICATION
One-Pot L-Proline-Mediated Stereoselective α-C(sp2)−H
Fluorination of α,β-Unsaturated Aldehydes via
Methoxyfluorination-Elimination
Jiadi Zhoua, Xinpeng Jiangb, Can Jinb*, Zhicheng Guoa, Bin Suna, and Weike Sua*
Abstract: A one-pot, two-step L-proline-mediated stereoselective α-
C(sp2)−H fluorination of α,β-unsaturated aldehydes to their
corresponding (Z)-α-fluoro-α,β-unsaturated aldehydes has been
developed. The first step utilises Selectfluor as a fluorinating agent in
CH3NO2/MeOH forming (Z)-α-fluoro-α,β-unsaturated aldehydes and
their corresponding dimethyl acetals via methoxyfluorination-
elimination. In the second step, water is added to promote the
hydrolytic cleavage of the dimethyl acetals. The obtained (Z)-α-
fluoro-α,β-unsaturated aldehydes were smoothly reduced to the
corresponding alcohols by NaBH4.
most of these procedures generally suffer from several major
drawbacks including the requirement of metal catalysts, harsh
reaction conditions, and the use of expensive or complex
starting materials.
“N-F”
reagents,
commercially
available
electrophilic
fluorinating reagents, are widely employed for fluoro
functionalization of organic compounds. Jørgensen12and
Barbas13 reported the formation of stereogenic carbon–fluorine
bonds through a direct, catalytic α-fluorination of aldehydes.
MacMillan14 reported the enantioselective organo-cascade
hydrofluorination of α,β-unsaturated aldehydes (Scheme 1b).
Brenner-Moyer15 reported an organocatalytic asymmetric olefin
aminofluorination reaction to synthesize chiral α-fluoro-β-amino
aldehydes (Scheme 1c). Arimitsu16 reported the first highly regio-
and stereoselective organocatalytic synthesis of α, α-difluoro-
γ,γ-disubstituted butenals (Scheme 1d). However, the direct α-
C(sp2)−H fluorination of α,β-unsaturated aldehydes was not
Introduction
In the past few years, there has been an increased interest in
the monofluoroalkene compounds, which are important in drug
development as it serves as a peptide bond isostere and are
found in a number of biologically active compounds with various
reported.
Herein,
we
report
an
L-proline-mediated
stereoselective α-C(sp2)−H fluorination of α,β-unsaturated
aldehydes to their corresponding (Z)-α-fluoro-α,β-unsaturated
aldehydes (Scheme 1e).
pharmacological
activities.1
Among
this
class
of
monofluoroalkene compounds, 2-fluoropropenal and 2-
fluoropropenol derivatives are key intermediates for the
synthesis of biologically active compounds and more complex
structures such as (Z)-β-fluoroconiferin, retinoid X receptor
agonists, RXR-selective modulators, Factor Xa inhibitors, chiral
2-fluoro-3-phenylpropionic acids and chiral fluorinated allyl
amines.2, 3
In most syntheses, 2-fluoropropenol is obtained by the
reduction of the corresponding ester synthesized by Wittig,4 thia-
Wittig,5 Horner–Wadsworth–Emmons,6 Peterson,7 Julia8 or
deacylative olefination9 reactions with a strong reducing reagent
such as DIBAL-H. The corresponding 2-fluoropropenal is
obtained by mild oxidation of the corresponding alcohol. The
direct approaches for the preparation of 2-fluoropropenals are
based on the reaction of β-fluorovinamidinium salt with Grignard
reagents,10a hydrolysis of aryl-substituted α,β-difluoroallyl
alcohols10b or treatment of Weinreb amides with DIBAL-H.10c In
2011, Rolando reported a strategy for the synthesis of α-fluoro
conjugated aldehydes based on the palladium-catalyzed
formylation by carbon monoxide of α-bromo-α-fluoroolefins
obtained by a Wittig-Burton reaction (Scheme 1a).11 However,
[a]
Collaborative Innovation Center of Yangtze River Delta Region
Green Pharmaceuticals, Zhejiang University of Technology,
Hangzhou 310014, China
*E-mail: pharmlab@zjut.edu.cn;
Tel: +86 57188320899
Scheme 1. Synthesis of α-Fluoro Aldehydes
[b] College of Pharmaceutical Sciences, Zhejiang University of
Technology, Hangzhou 310014, China
* E-mail: jincan@zjut.edu.cn
Results and Discussion
Tel: +86 57188871087
Supporting information for this article is given via a link at the end of
the document.
Our initial studies were carried out with readily available 4-
chlorocinnamaldehyde 1a as the test substrate (Table 1). A
This article is protected by copyright. All rights reserved.

10.1002/ejoc.201700622
European Journal of Organic Chemistry
COMMUNICATION
mixture of 4-chlorocinnamaldehyde 1a (0.3 mmol, 1.0 equiv), L-
proline 2a (1.0 equiv) and Selectfluor (2.0 equiv) was stirred in
acetonitrile at 60 °C for 15 h, then water (1.0 mL) was added
and the mixture was hydrolysed at room temperature for 5 h.
The volatile and unstable aldehydes formed were converted to
corresponding alcohol by NaBH4 in situ, only trace yield of 4a
was detected (Table 1, entry 1). As might be expected, we
identified that the use of a nucleophile was essential for the
reaction. A series of nucleophiles such as MeOH, EtOH, PhOH,
PhCH2OH, CH3CO2H, CF3CO2H, DABCO and PPh3 were
screened, MeOH gave the highest yield (Table 1, entries 2−5).
The nucleophilicity of MeOH was stronger than other
nucleophiles in this reaction, the steric hindrance of phenyl and
nucleophiles might have a great influence. When decreasing L-
proline to 0.2 equiv or 0.5 equiv, even if the fluorination time
extended to 30 h, the yield of 4a dropped accordingly down to
21% and 43%, respectively (Table 1, entries 6 and 7). Further
screening of organic additives revealed that other amine
additives gave worse yields than L-proline (Table 1, entries
We next screened temperature, solvents, fluorinating reagents,
basic additives and hydrolysis reagents (Table 2). Screening the
reaction temperature in the range of 35 to 75 °C , and the best
yield of 4a was obtained when the reaction was conducted at
65 °C (Table 2, entries 1−4). Among different solvents being
tested, CH3CN and CH3NO2 resulted in good yields, whereas
other solvents gave a sluggish reaction or a complex reaction
mixture (Table 2, entries 5−10). Switching the N-F reagent from
Selectfluor to NFSI or F-TEDA-PF6 gave 4a in 0% and 58% yield,
respectively (Table 2, entries 11 and 12). A series of basic
additives, such as K2CO3, NaOCH3, NaOH, CH3CO2Na,
CH3CO2K and CH3CO2NH4 were screened, CH3CO2Na was
proved to be the best basic additive (Table 2, entries 13−18).
When L-proline was not used, only trace product was detected
(Table 2, entry 19). When 10% H2SO4 or 10% HCl was used as
hydrolysis reagents, the yields were not further improved (Table
2, entries 20 and 21).
Table 2. Optimization of the Reaction Conditionsa
8−11).
Table 1. Amine Additive and Nucleophile Screeninga
entry
basic additive (equiv)
solvent
temp
(oC)
35
55
65
75
65
65
65
65
65
65
65
65
65
65
65
65
65
65
65
65
65
yield of
4a b(%)
25
40
55
40
trace
60
10
mixture
15
0
0
58
mixture
mixture
mixture
68
64
61
trace
67
65
1
2
3
4
5
6
7
8
9
10
11c
12d
13
14
15
16
17
18
19e
20f
21g
MeCN
MeCN
MeCN
MeCN
MeOH
CH3NO2
DCE
DMF
THF
entry
amine additive
nucleophile
yield of
4a b(%)
trace
toluene
CH3NO2
CH3NO2
CH3NO2
CH3NO2
CH3NO2
CH3NO2
CH3NO2
CH3NO2
CH3NO2
CH3NO2
CH3NO2
1
2
2a
2a
EtOH or PhOH or
PhCH2OH
CH3CO2H or
CF3CO2H
DABCO or PPh3
MeOH
trace
K2CO3 (1.0)
NaOCH3 (1.0)
NaOH (1.0)
CH3COONa (1.0)
CH3COOK (1.0)
CH3COONH4 (1.0)
CH3COONa (1.0)
CH3COONa (1.0)
CH3COONa (1.0)
3
2a
trace
4c
5
2a
2a
2a
2a
trace
50
21
43
trace
6d
7e
8
MeOH
MeOH
MeOH
2b or 2c or 2e or
aReaction conditions: (1) 4-chlorocinnamaldehyde 1a (0.3 mmol,
1.0 equiv), L-proline (1.0 equiv), Selectfluor (2.0 equiv), MeOH
(2.0 mL), solvent (2.0 mL), N2, 15 h. (2) water (1.0 mL) at room
temperature for 5 h. (3) NaBH4 (5.0 equiv) at 0 °C for 1 h, unless
otherwise noted.
2f or 2i or 2j or 2k
9
10
11
2d
2g
2h
MeOH
MeOH
MeOH
20
25
10
a Reaction conditions: (1) 4-chlorocinnamaldehyde 1a (0.3 mmol,
1.0 equiv), amine additive (1.0 equiv), Selectfluor (2.0 equiv),
nucleophile (2.0 mL), MeCN (2.0 mL), N2, at 60 °C for 15 h. (2)
water (1.0 mL) at room temperature for 5 h. (3) NaBH4 (5.0
equiv) at 0 °C for 1 h, unless otherwise noted.
b1H NMR yield.
b1H NMR yield.
cNFSI (2.0 equiv) was used as fluorinating reagent.
dF-TEDA-PF6 (2.0 equiv) was used as fluorinating reagent.
e L-proline was not used.
f10% H2SO4 (1.0 mL) was used as hydrolysis reagents.
g10% HCl (1.0 mL) was used as hydrolysis reagents.
cDABCO or PPh3 (1 equiv).
dL-proline (0.2 equiv), 30 h.
eL-proline (0.5 equiv), 30 h.
With the optimized conditions in hand, we subsequently
explored the reaction scope (Table 3). In general, a variety of
α,β-unsaturated aldehydes with different substituents on the
This article is protected by copyright. All rights reserved.

10.1002/ejoc.201700622
European Journal of Organic Chemistry
COMMUNICATION
aromatic ring could be converted to the desired products in
moderate yield with exclusive Z-selectivity, along with trace
alcohols reduced from the corresponding starting aldehydes and
some unidentified acids. Substrates with electron-withdrawing
and electron-donating substituents at the para, meta or ortho
positions of the aryl ring resulted in the desired products (Table
2, entries 1−10). In addition, when the volatile and unstable
trans-2-hexenal was used, the fluorination was conducted at
room temperature and gave the desired product in 28% 1H NMR
yield (Table 2, entry 11). Unfortunately, a complicated mixture
was obtained when 3-(2-furyl) propenal and 3-(2-thienyl)
propenal was used (Table 2, entries 12−13).
Scheme 2. Mechanistic Investigations
Iminium-catalyzed conjugate additions of MeOH to α,β-
unsaturated aldehydes have been reported,17 as have enamine-
catalyzed fluorinations of saturated aldehydes.12,13 MacMillan,14
Brenner-Moyer,15 Córdova19 and Jørgensen20 have proposed
the mechanism of iminium-enamine activation. Barbas III21a and
Table 3. Scope of Substratesa
Córdova21b
reported
the
aza-Morita–Baylis–Hillman-type
reaction of α,β-unsaturated aldehydes catalyzed by proline and
nucleophilic amines to form C(sp2)-C(sp3) bond. Recently,
Chen22 developed the sulfenylation of α,β-unsaturated
aldehydes via Michael addition-electrophilic addition-elimination
to synthesize α-thioenals with excellent Z-configuration.
A plausible organo-cascade catalytic cycle of the asymmetric
methoxyfluorination-elimination has been proposed (Scheme 3).
As such, the exposure of α,β-unsaturated aldehydes to L-proline
would generate activated iminium species A. Iminium species
can undergo an oxa-Michael addition of MeOH, liberating chiral
enamine B. Reaction of enamine B with Selectfluor would
produce the α-fluoro-β-methoxy iminium C. At last, the
elimination of MeOH to obtain (Z)-α-fluoro-α,β-unsaturated
aldehydes 3 and the corresponding dimethyl acetals D. When
the fluorination was finished, water was added to promote the
hydrolytic cleavage of the dimethyl acetals D.
entry
1
2
3
4
5
6
7
8
R
yield of 4b (%)
4a, 60
4b, 50
4c, 48
4d, 65
4e, 70
4f, 44
4-Cl-C6H4
Ph
4-F-C6H4
3-Cl-C6H4
2-Cl-C6H4
4-Br-C6H4
4-NO2-C6H4
4-MeO-C6H4
3-Me-C6H4
2-Naphthyl
n-Pr
4g, 55
4h, 45
4i, 48
4j, 47
4k,28
9
10
11c
12
13
Furyl
Thienyl
mixture
mixture
aReaction conditions: (1) α,β-unsaturated aldehydes (1.0 mmol),
L-proline (1.0 mmol), CH3CO2Na (1.0 mmol), Selectfluor (2.0
mmol), MeOH (5.0 mL), CH3NO2 (5.0 mL), N2, at 65 °C for 15 h.
(2) water (3.0 mL) at room temperature for 5 h. (3) NaBH4 (5.0
mmol) at 0 °C for 1 h, unless otherwise noted.
bIsolated yield, the stereochemistry was determined by chemical
shift (CH, CH2 and CF) and J value (3JHF of CF/CH and JHF of
3
CF/CH2) of 19F and H NMR spectroscopy comparing with the
1
references.11,18
cThe fluorination was conducted at room temperature, 1H NMR
yield.
Preliminary mechanistic investigations have also been carried
out. Notably, the difluorination byproduct 5a was detected by
GC-MS analysis, while the corresponding monofluorinated
intermediate was not observed. We tried to obtain the α-fluoro-β-
methoxy aldehyde with α-methyl-trans-4-chlorocinnamaldehyde
as the substrate, but the reaction was failed due to the α-methyl
group inhibited the activated iminium species generated
(Scheme 2). Based on the amine additive screening
experiments, the presence of acidic functional groups in
secondary amines can play a critical role in this reaction, we
inferred that the intramolecular hydrogen bonding was important
to stabilize the iminium intermediate.
Scheme 3.Proposed One-Pot Organo-Cascade Reaction
Conclusions
In summary, we have successfully developed a one-pot, two-
step L-proline-mediated stereoselective fluorination of α,β-
This article is protected by copyright. All rights reserved.

10.1002/ejoc.201700622
European Journal of Organic Chemistry
COMMUNICATION
2.
For recent synthesis involving 2-fluoropropenals intermediates, see: (a)
P. Y. Michellys, M. F. Boehm, J. H. Chen, T. A. Grese, D. S.
Karanewsky, M. D. Leibowitz, S. Liu, D. A. Mais, C. M. Mapes, A. Reifel-
Miller, K. M. Ogilvie, D. Rungta, A. W. Thompson, J. S. Tyhonas, N.
Yumibe, R. J. Ardecky, Bioorg. Med. Chem. Lett. 2003, 13, 4071. (b) N.
Fishkin, R. Yefidoff, D. R. Gollipalli, R. R. Rando, Bioorg. Med. Chem.
Lett. 2005, 13, 5189. (c) H. Tsuchikawa, N. Matsushita, N. Matsumori, M.
Murata, T. Oishi, Tetrahedron Lett. 2006, 47, 6187. (d) C. Lamy, J.
Hofmann, H. Parrot-Lopez, P. Goekjian, Tetrahedron Lett. 2007, 48,
6177.
unsaturated aldehydes to their corresponding (Z)-α-fluoro-α,β-
unsaturated aldehydes 3. The obtained (Z)-α-fluoro-α,β-
unsaturated aldehydes 3 can be smoothly reduced to the
corresponding alcohols by NaBH4. This method provides a
practical, simple, and mild synthetic approach to 2-
fluoropropenal and 2-fluoropropenol, which are important units in
biologically active molecules. Further studies to refine the
mechanism and to expand the application scope of this reaction
are currently underway in our laboratory.
3.
Representative biologically active 2-fluoropropenols: (a) C. D. Poulter, C.
H. R. King, J. Am. Chem. Soc. 1982, 104, 1422. (b) H. X. Wei, M.
Schlosser, Eur. J. Org. Chem. 1998, 11, 2603. (c) D. Michel, M.
Schlosser, Tetrahedron 2000, 56, 4253. (d) J. P. Burkhart, P. M.
Weintraub, C. A. Gates, R. J. Resvick, R. J. Vaz, D. Friedrich, M. R.
Angelastro, P. Bey, N. P. Peet, Bioorg. Med. Chem. 2002, 10, 929.
G. Lemonnier, L. Zoute, G. Dupas, J. C. Quirion, P. Jubault, J. Org.
Chem. 2009, 74, 4124.
Experimental Section
General procedure: Stereoselective α-C(sp2)−H Fluorination of α,β-
4.
5.
Unsaturated Aldehydes.
T. Satoh, N. Itoh, K. I. Onda, Y. Kitoh, K. Yamakawa, Bull. Chem. Soc.
Jpn. 1992, 65, 2800.
6.
7.
8.
S. Sano, K. Saito, Y. Nagao, Tetrahedron Lett. 2003, 44, 3987.
J. T. Welsh, J. Org. Chem. 1990, 55, 4782.
A flame-dried flask was charged with α,β-unsaturated aldehydes (1.0
mmol, 1.0 equiv), L-proline 2a (1.0 equiv), CH3CO2Na (1.0 equiv),
Selectfluor (2.0 equiv) and MeOH (5 mL) and placed under an nitrogen
atmosphere. CH3NO2 (5.0 mL) was then added and the resulting mixture
became a light yellow solution after being stirred for 30 min. The reaction
was allowed to stir at 65 °C for 15 h. After cooling, water (3.0 mL) was
added and the mixture was hydrolysed at room temperature for 5 h. Then
the aldehydes formed were converted to corresponding alcohol by
NaBH4 in situ. The mixture was extracted with dichloromethane (3 x 10
mL). The organic solvent was removed under vacuum. The crude
product was purified by column chromatography on silica gel (petroleum
ether/ ethyl acetate 4/1) to afford the corresponding product.
D. A. Alonso, M. Fuensanta, E. Gómez-Bengoa, C. Nájera, Adv. Synth.
Catal. 2008, 350, 1823.
9.
J. L. Qian, W. B. Yi, M. F. Lv, C. Cai, Synlett 2015, 26, 127.
10. (a) H. Yamanaka, Y. Odani, T. Ishihara, J. T. Gupton, Tetrahedron Lett.
1998, 39, 6943. (b) K. Funabiki, E. Murata, Y. Fukushima, M. Matsui, K.
Shibata, Tetrahedron Lett. 1999, 55, 4637. (c) M. Kanai, J. M. Percy,
Tetrahedron Letters 2000, 41, 2453.
11. R. Zemmouri, M. Kajjout, Y. Castanet, S. Eddarir, C. Rolando, J. Org.
Chem. 2011, 76, 7691.
12 M. Marigo, D. Fielenbach, A. Braunton, A. Kjærsgaard, K. A. Jørgensen,
Angew. Chem. Int. Ed. 2005, 44, 3703.
13 D. D. Steiner, N. Mase, C. F. Barbas, Angew. Chem. Int. Ed. 2005, 44,
3706.
14 Y. Huang, A. M. Walji, C. H. Larsen, D. W. C. MacMillan, J. Am. Chem.
Soc. 2005, 127, 15051.
15 C. Appayee, S. E. Brenner-Moyer, Org. Lett. 2010, 12, 3356.
16 S. Arimitsu, M. Nakasone, J. Org. Chem. 2016, 81, 6707.
17 (a) T. Kano, Y. Tanaka, K. Maruoka, Tetrahedron Letters 2006, 47, 3039.
(b) T. Kano, Y. Tanaka, K. Maruoka, Tetrahedron 2007, 63, 8658.
18 (a) M. Engman, J. S. Diesen, A. Paptchikhine, P. G. Andersson, J. Am.
Chem. Soc 2007, 129, 4536. (b) F. Luo, P. Wang, Y. F. Gong,
Tetrahedron Letters 2010, 51, 1693.
Acknowledgements
We are grateful to the Natural Science Foundation of China
(No.21506191 and No. 21406200) for financial help.
Keywords: one-pot • stereoselective C(sp2)−H fluorination •
19 G. L. Zhao, R. Rios, J. Vesely, L. Eriksson, A. Córdova, Angew. Chem.
Int. Ed. 2008, 47, 8468.
organo-cascade
reaction
•
2-fluoropropenol
•
methoxyfluorination-elimination
20 M. Marigo, T. Schulte, J. Franzen, K. A. Jørgensen, J. Am. Chem. Soc
2005, 127, 15710.
1.
Compounds with a fluorovinyl group show useful bioactive properties;
see: (a) L. Xue, L. Lu, S. D. Pedersen, Q. B. Liu, R. M. Narske, D. J.
Burton, J. Org. Chem. 1997, 62, 1064. (b) H. Zhang, C. B. Zhou, Q. Y.
Chen, J. C. Xiao, R. Hong, Org. Lett. 2011, 13, 560. (c) T. Furuya, T.
Ritter, Org. Lett. 2009, 11, 2860. (d) N. A. Meanwell, J. Med. Chem.
2011, 54, 2529. (e) T. Liang, C. N. Neumann, T. Ritter, Angew. Chem.,
Int. Ed. 2013, 52, 8214.
21 (a) N. Utsumi, H. Zhang, F. Tanaka, C. F. Barbas, III Angew. Chem. Int.
Ed. 2007, 46, 1878. (b) J. Vesely, P. Dziedzic, A. Córdova, Tetrahedron
Letters 2007, 48, 6900.
22 Y. T. Dong, Q. Jin, L. Zhou, J. Chen, Org. Lett. 2016, 18, 5708.
This article is protected by copyright. All rights reserved.

10.1002/ejoc.201700622
European Journal of Organic Chemistry
COMMUNICATION
Entry for the Table of Contents (Please choose one layout)
Layout 2:
COMMUNICATION
Key Topic* stereoselective C(sp2)−H
fluorination
Author(s), Corresponding Author(s)*
Jiadi Zhoua, Xinpeng Jiangb, Can Jinb*,
Zhicheng Guoa, Bin Suna, and Weike
Sua*
[a] Collaborative Innovation Center of
Yangtze River Delta Region Green
Pharmaceuticals, Zhejiang University of
Technology,
Text for Table of Contents: A one-pot, two-step L-proline-mediated stereoselective
α-C(sp2)−H fluorination of α,β-unsaturated aldehydes to their corresponding (Z)-α-
fluoro-α,β-unsaturated aldehydes has been developed. The obtained (Z)-α-fluoro-
α,β-unsaturated aldehydes 3 can be smoothly reduced to the corresponding
alcohols by NaBH4.
Hangzhou 310014, China
*E-mail: pharmlab@zjut.edu.cn;
Tel: +86 57188320899
[b] College of Pharmaceutical Sciences,
Zhejiang University of Technology,
Hangzhou 310014, China
* E-mail: jincan@zjut.edu.cn
Tel: +86 57188871087
*one or two words that highlight the emphasis of the paper or the field of the study
stereoselective C(sp2)−H fluorination, organo-cascade reaction
This article is protected by copyright. All rights reserved.