Iridium-catalyzed enantioselective allylic vinylation with potassium alkenyltrifluoroborates

Full text of DOI:10.15227/orgsyn.092.0001

Iridium-Catalyzed Enantioselective Allylic Vinylation with
Potassium Alkenyltrifluoroborates
James Y. Hamilton, David Sarlah, and Erick M. Carreira*
Eidgenössische Technische Hochschule Zürich, HCI H335, 8093 Zürich,
Switzerland
Checked by Wen-bo (Boger) Liu, Seo-Jung Han, and Brian M. Stoltz
A.
B.
OH
THF
CHO
MgCl
−78 °C to 0 °C
1
O
O
cat. DMF, neat, 50 °C
OH
OH
PCl3
P
N
Li
N
then
(1.1 equiv)
(R)-L
THF, −78 °C to rt
Ph
C.
OH
[Ir(cod)Cl2] (4 mol%)
(R)-L (16 mol%)
H
KF3B
Ph
KHF2 (1.5 equiv)
TFA (2.5 equiv)
n-Bu4NBr (0.1 equiv)
1
2
Procedure
A. 1-(Naphthalen-2-yl)prop-2-en-1-ol (1). An oven-dried 250 mL round-
bottomed flask, fitted with a rubber septum, is charged with a 2.5 cm
Teflon-coated magnetic oval stir bar and 2-naphthaldehyde (4.69 g,
Org. Synth. 2015, 92, 1-12
DOI: 10.15227/orgsyn.092.0001
Published on the Web 1/21/2015
1
© 2015 Organic Syntheses, Inc.

30.0 mmol, 1.0 equiv) (Note 1). The flask is flushed with nitrogen via a
nitrogen line inlet and charged with anhydrous THF (60 mL) via a 60 mL
syringe (Note 2). The stirred homogeneous solution (Note 3) is cooled in a
dry ice-acetone bath (−78 °C bath temp), and vinylmagnesium chloride
solution (20.6 mL, 33.0 mmol, 1.1 equiv) is added dropwise over 20 min via
a syringe. The resulting clear yellow solution is stirred at −78 °C for 1 h and
then at 0 °C in an ice bath for 30 min (Note 4). The reaction mixture is
quenched with saturated aqueous NH4Cl solution (30 mL) and diluted with
H2O (30 mL). After being warmed up to ambient temperature, the mixture
is transferred to a 250 mL separatory funnel. Additional diethyl ether
(20 mL) is used to assist transfer. The aqueous layer is separated and further
extracted with diethyl ether (2 x 50 mL). The combined organic layers are
washed with saturated aqueous NaCl solution (50 mL), dried over sodium
sulfate (20 g), filtered through a 150 mL coarse porosity sintered glass
funnel, and concentrated using a rotary evaporator (25 °C, 25 mmHg) to
afford a yellow oil (Note 5). This crude product is purified by flash
chromatography on silica gel to afford 1 (5.23–5.35 g, 95–97%) as a colorless
oil (Note 6).
B. (R)-(−)-(3,5-Dioxa-4-phospha-cyclohepta[2,1-a;3,4-a']dinaphthalen-4-yl)-
dibenzo[b,f]-azepine ((R)-L). An oven-dried 100 mL Schlenk flask, fitted with a
rubber septum, is charged with a 2.5 cm Teflon-coated magnetic oval stir
bar and (R)-(+)-1,1 -bi(2-naphthol) (2.29 g, 8.0 mmol, 1.0 equiv) (Note 7).
The side arm of the flask, fitted with a glass stopcock, is connected to a
vacuum/N2 line. The flask is evacuated and refilled with nitrogen 3 times.
Phosphorus trichloride (10.5 mL, 16.5 g, 15 equiv) and anhydrous N,N-
dimethylformamide (19 µL, 18 mg, 0.24 mmol, 0.03 equiv) are added by
syringes through the septum. The reaction mixture is stirred (Note 8) at
50 °C in an oil bath for 30 min, during which time it becomes a colorless
homogeneous solution. Excess phosphorus trichloride is removed via
vacuum distillation (Notes 9 and 10) and azeotropic removal with toluene
(2 x 3 mL) under high vacuum (see photograph) (Notes 11 and 12) to afford
the phosphochloridite as an oily foam. A separate oven-dried 250 mL
round-bottomed flask is charged with a 2.5 cm Teflon-coated magnetic oval
stir bar and 5H-dibenz[b,f]azepine (1.70 g, 8.80 mmol, 1.1 equiv). The flask is
fitted with a rubber septum with a nitrogen line inlet and flushed with
nitrogen. Anhydrous THF (47 mL) is added by syringe, and the stirred
orange solution is cooled in a dry ice-acetone bath (−78 °C bath temp) (Note
13). n-Butyllithium (5.50 mL, 8.80 mmol, 1.1 equiv) is then added dropwise
Org. Synth. 2015, 92, 1-12
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2

over 10 min with a syringe, and the resulting dark blue solution is stirred at
−78 °C for 1 h. The phosphochloridite prepared as above is dissolved in
anhydrous THF (37 mL) and added to the deprotonated 5H-
dibenz[b,f]azepine solution at −78 °C dropwise via a cannula over 20 min.
Additional anhydrous THF (10 mL) is used to assist transfer. The dark blue
solution is stirred for 12 h while being gradually warmed to ambient
temperature (Note 14). Silica gel (20 g) is added to the orange reaction
mixture, and the resulting slurry is carefully concentrated by rotary
evaporation (35 °C, 25 mmHg). Flash chromatography on silica gel yields
(R)-L (2.96–3.07 g, 73–75%) as a white solid (Note 15).
C. (S,E)-2-(1-Phenylpenta-1,4-dien-3-yl)naphthalene (2).
A screw cap
100 mL cylindrical polyethylene bottle (diameter: 4.5 cm, height: 9.5 cm)
with a 4 cm Teflon-coated magnetic cylindrical stir bar is charged with
bis(1,5-cyclooctadiene)diiridium dichloride (0.725 g, 1.08 mmol, 0.04 equiv),
(R)-L (2.19 g, 4.32 mmol, 0.16 equiv) and 1,4-dioxane (34 mL) (Note 16). The
resulting dark brown solution (see photograph) is stirred for 15 min (Note
17). 1-(Naphthalen-2-yl)prop-2-en-1-ol (1) (4.97 g, 27.0 mmol, 1.0 equiv),
potassium trans-styryltrifluoroborate (8.51 g, 40.5 mmol, 1.5 equiv),
tetrabutylammonium bromide (0.87 g, 2.7 mmol, 0.1 equiv) and potassium
hydrogen difluoride (3.16 g, 40.5 mmol, 1.5 equiv) are sequentially added,
Org. Synth. 2015, 92, 1-12
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3

and additional 1,4-dioxane (2.0 mL) is added to rinse the reaction vessel
wall. To the resulting stirred dark-yellow heterogeneous mixture is added
trifluoroacetic acid (5.17 mL, 7.70 g, 67.5 mmol, 2.5 equiv) dropwise. The red
heterogeneous mixture is vigorously stirred for 6 h, during which time it
gradually turns light yellow (Note 18). Upon completion of the reaction,
excess trifluoroacetic acid is quenched by addition of triethylamine (5 mL),
and the heterogeneous mixture is filtered through a short silica pad
(Note 19). The filtrate is concentrated by rotary evaporation (35 °C,
25 mmHg). The concentrate is purified by flash chromatography on silica
gel to afford 2 (5.74 g, 79%) as a white solid (Notes 20 and 21).
Notes
1. The following reagents in this section were purchased from commercial
sources and used without further purification: 2-naphthaldehyde (98%,
Aldrich) and vinylmagnesium chloride solution (1.6 M in THF,
Aldrich).
2. Anhydrous THF in all sections was obtained by passage over activated
alumina under an atmosphere of argon (H2O content <30 ppm, Karl
Fischer titration).
3. The mixture is stirred at 900 rpm throughout the reaction.
Org. Synth. 2015, 92, 1-12
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4

4. The reaction is monitored by TLC on Merck silica gel 60 F254 TLC glass
plates and visualized with UV light and KMnO4 staining solution. Rf
(product): 0.23 (9:1 hexanes:EtOAc)
5. Additional diethyl ether (2 x 10 mL) is used during filtration to assist
transfer.
6. The crude product is loaded onto a column (diameter: 5 cm, height:
16 cm) packed with silica gel (150 g) slurry in 9:1 hexanes:EtOAc. After
500 mL of initial elution, 100 mL fractions are collected. The desired
product is obtained in fractions 3–12, which are concentrated by rotary
evaporation (25 °C, 25 mmHg). The product has been characterized as
1
follows: H NMR (400 MHz, CDCl3) δ: 2.04 (br s, 1 H), 5.25 (dt, J = 10.3,
1.4 Hz, 1 H), 5.35 (d, J = 6.0 Hz, 1 H), 5.41 (dt, J = 17.1, 1.5 Hz, 1 H),
6.13 (ddd, J = 17.1, 10.3, 6.0 Hz, 1 H), 7.47 – 7.52 (m, 3 H), 7.83 – 7.87 (m,
4 H); 13C NMR (100 MHz, CDCl3) δ: 75.5, 115.5, 124.6, 125.0, 126.1, 126.3,
127.8, 128.1, 128.4, 133.1, 133.4, 140.0, 140.2; IR (neat): 3358 (br), 3055,
1633, 1601, 1508, 1408, 1361, 1269, 1124, 1018, 988, 926, 819, 745 cm-1;
HRMS (EI): m/z calcd for C13H12O [M]+ 184.0888, found 184.0860; Anal.
calcd. for C13H12O: C, 84.75; H, 6.56; found: C, 84.31, H, 6.57.
7. The following reagents in this section were purchased from commercial
sources and used without further purification: (R)-(+)-1,1’-bi(2-
naphthol) (98%, Combi-Blocks), phosphorus trichloride (99%, Sigma-
Aldrich), anhydrous N,N-dimethylformamide (99.8%, Sigma-Aldrich),
5H-dibenz[b,f]azepine (97%, Aldrich) and n-butyllithium (1.6 M in
hexane, Aldrich).
8. The mixture is stirred at 300 rpm throughout the reaction.
9. The reaction mixture is maintained at 50 °C throughout distillation and
subsequent azeotropic removal of residual phosphorus trichloride with
toluene.
10. The Schlenk flask is uncapped and quickly connected to a distillation
apparatus (oven-dried and N2 flushed). The receiving flask is cooled to
−78 °C in a dry ice-acetone bath, and the vacuum line from the
distillation head is connected to a liquid nitrogen cold trap. Upon
reaching 375 mmHg (membrane pump), the pressure of the distillation
apparatus is lowered carefully (50 mmHg per minute). Vigorous
stirring (800 rpm) is maintained to keep the solution from rapid
foaming. Upon reaching 150 mmHg, the distillation is maintained for
30 min.
11. After distillation, the system is refilled with N2, and the distillation
apparatus is quickly exchanged with a three-way stopcock and
Org. Synth. 2015, 92, 1-12
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5

connected to high vacuum line (0.9 mmHg) with liquid nitrogen cold
trap. Toluene (3 mL) (≥99.7%, Fluka, ACS reagent) is added into the
flask with a syringe through the three-way stopcock, followed by
swirling of the mixture to completely dissolve the oily foam. Using the
three-way stopcock and vigorous stirring (800 rpm), vacuum is applied
carefully to avoid rapid foaming. After complete removal of toluene,
another 3 mL of toluene is used to repeat the process. After the second
azeotropic distillation, the vacuum is further maintained for 30 min.
12. Care should be taken for thorough removal of excess phosphorus
trichloride and to avoid exposure of the air sensitive phosphochloridite
to ambient atmosphere.
13. The mixture is stirred at 800 rpm throughout the reaction.
14. The reaction flask is kept in a dry ice-acetone bath that is gradually
warmed to ambient temperature overnight.
15. Silica gel adsorbed with the crude product is dry-loaded onto a column
(diameter: 5.5 cm, height: 22.5 cm) packed with silica gel (200 g) slurry
in 2:1 hexanes:toluene (Rf(product): 0.31; visualized with UV light and
KMnO4 staining solution). After 500 mL of initial elution, 100 mL
fractions are collected. The desired product is obtained in fractions 2–11,
which are concentrated by rotary evaporation (35 °C, 25 mmHg). The
purified product is stored under an inert atmosphere in the dark for
long-term storage. The product has been characterized as follows:
1H NMR (400 MHz, CDCl3 (filtered through basic alumina)) δ: 6.58 (td, J
= 7.5, 1.4 Hz, 1 H), 6.91 (d, J = 8.7 Hz, 1 H), 6.94 – 7.05 (m, 3 H),
7.12 – 7.20 (m, 1 H), 7.21 – 7.36 (m, 9 H), 7.38 – 7.46 (m, 2 H), 7.48 (d,
J = 8.8 Hz, 1 H), 7.67 (d, J = 8.7 Hz, 1 H), 7.80 (dd, J = 8.2, 1.2 Hz, 1 H),
7.95 (d, J = 8.0 Hz, 1 H), 8.03 (d, J = 8.8 Hz, 1 H); 13C NMR (100 MHz,
CDCl3) δ: 121.2 (d, J = 2.8 Hz), 121.6, 122.3 (d, J = 2.0 Hz), 124.4 (d,
J = 5.3 Hz), 124.4, 124.9, 125.8, 126.2, 126.3, 126.8 (d, J = 1.4 Hz), 126.9,
127.2, 128.0, 128.4, 128.5, 128.7, 129.0, 129.10, 129.12, 129.2 (d, J = 2.0 Hz),
129.3, 130.3, 130.5, 131.5, 131.6, 131.7, 132.3 (d, J = 1.5 Hz), 133.0 (d,
J = 1.6 Hz), 135.3, 136.6 (d, J = 3.6 Hz), 142.6, 143.0 (d, J = 24.0 Hz), 148.8
(d, J = 1.2 Hz), 150.0 (d, J = 8.0 Hz); 31P NMR (162 MHz, CDCl3) δ: 137.85;
IR (neat): 3054, 3020, 1619, 1591, 1485, 1463, 1327, 1283, 1234, 1207, 1155,
1107, 1070, 982, 949, 866, 820, 802, 750 cm-1; HRMS (ESI+): m/z calcd for
C34H23NO2P [M+H]+ 508.1461, found 508.1464; [α]20 = –325.4 (c = 1.04,
D
CHCl3); mp 249–250 °C. HPLC: >99% purity, tR = 5.78 min (column:
Eclipse Plus C8 2.1 x 50 mm, 1.8 micron; method: linear gradient of A
(H2O with 0.025% AcOH) and B (MeCN), flow rate of 1.0 mL/min,
Org. Synth. 2015, 92, 1-12
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6

254 nm detection, 25 °C column temperature, linear gradient: 40–95% B
in 7 min).
16. The following reagents in this section were purchased from commercial
sources
and
used
without
further
purification:
bis(1,5-
cyclooctadiene)diiridium dichloride (97%, Combi-Blocks), potassium
trans-styryltrifluoroborate (Sigma-Aldrich, or synthesized by the known
procedure: Molander, G. A. et al, J. Org. Chem. 2002, 67, 8424.),
tetrabutylammonium bromide (≥99%, Sigma-Aldrich), potassium
hydrogen difluoride (≥99%, Sigma-Aldrich) and trifluoroacetic acid
(≥99%, Sigma-Aldrich). 1,4-Dioxane (≥99.5%, Acros) was used as
received.
17. The mixture is stirred at 400 rpm throughout the reaction. The reaction
vessel is capped, and the reaction is performed under ambient
atmosphere.
18. The reaction is monitored by TLC and visualized with UV light and
KMnO4 staining solution. Rf(SM): 0.42 (4:1 hexanes:EtOAc); Rf(product):
0.32 (19:1 hexane:CH2Cl2)
19. The reaction mixture is loaded onto a short silica pad column (diameter:
6.5 cm, height: 4.5 cm) packed with silica gel (70 g) slurry in hexanes. A
mixture of 9:1 hexanes:EtOAc (2 L) is used as eluent. The filtrate is
concentrated by rotary evaporation (25 °C, 25 mmHg) to yield a dark
red oil.
20. The crude product is loaded onto a column (diameter: 5.5 cm, height:
22 cm) packed with silica gel (200 g) slurry in 19:1 hexanes:CH2Cl2.
After 500 mL of initial elution, 50 mL fractions are collected. The desired
product is obtained in fractions 6–41, which are concentrated by rotary
evaporation (25 °C, 25 mmHg). The regioisomeric ratio is >50:1,
determined by 1H NMR. The product has been characterized as
1
follows: H NMR (400 MHz, CDCl3) δ: 4.40 – 4.44 (m, 1 H), 5.21 (dt,
J = 17.2, 1.5 Hz, 1 H), 5.26 (dt, J = 10.2, 1.4 Hz, 1 H), 6.22 (ddd, J = 17.0,
10.2, 6.7 Hz, 1 H), 6.44 – 6.57 (m, 2 H), 7.20 – 7.27 (m, 1 H), 7.28 – 7.35
(m, 2 H), 7.37 – 7.51 (m, 5 H), 7.72 (d, J = 1.7 Hz, 1 H), 7.78 – 7.87 (m,
3 H); 13C NMR (100 MHz, CDCl3) δ: 52.5, 116.1, 125.7, 126.2, 126.42,
126.44, 127.0, 127.4, 127.8, 127.9, 128.3, 128.7, 131.1, 131.8, 132.5, 133.8,
137.5, 140.1, 140.2; IR (neat): 3055, 3023, 1631, 1598, 1494, 1446, 1270, 995,
968, 914, 856, 817, 743 cm-1; HRMS (EI): m/z calcd. for C21H18 [M]+
270.1408, found 270.1417; [α]24 = –1.6 (c = 1.1, CHCl3); mp 74–75 °C;
D
SFC: Daicel Chiralcel OJ-H, 10% MeOH, 2.5 mL/min, 40 °C, 254 nm;
>99% ee (tR (minor) = 23.5 min, tR (major) = 25.1 min). HPLC: >99%
Org. Synth. 2015, 92, 1-12
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7

purity, tR = 7.41 min (column: Eclipse Plus C8 2.1 x 50 mm, 1.8 micron;
method: linear gradient of A (H2O with 0.025% AcOH) and B (MeCN),
flow rate of 1.0 mL/min, 254 nm detection, 25 °C column temperature,
linear gradient: 20–95% B in 10 min).
21. The reaction was also checked with half scale (13.5 mmol), and 2.44 g
(67% yield) of (S,E)-2-(1-phenylpenta-1,4-dien-3-yl)naphthalene) was
obtained with >99% ee.
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Org. Synth. 2015, 92, 1-12
DOI: 10.15227/orgsyn.092.0001
8

Discussion
Transition metal-catalyzed asymmetric allylic substitution is one of the
most powerful methods for enantioselective formation of carbon–
heteroatom and carbon–carbon bonds.2 Despite significant advances in this
field, there are only a limited number of methods that offer high
stereoselectivity and allow direct substitution of allylic alcohols without
prior activation.3
Iridium-catalyzed allylic vinylation described above affords highly
enantioenriched 1,4-dienes directly from allylic alcohols and potassium
alkenyltrifluoroborates.4 The reaction displays high regioselectivity under
conditions that circumvent hazardous handling of hydrofluoric acid.5
Furthermore, this catalytic enantioselective transformation can be
conveniently performed without exclusion of air or moisture, using
technical grade solvents. Alternatively, similar structural motifs can be
accessed by Cu-catalyzed processes for allylic substitution of allylic
phosphates with vinylaluminum and vinylboronic acid ester reagents,
reported by Hoveyda and Hayashi, respectively.6
The described method is applicable to a range of aryl and heteroaryl
allylic alcohols. Potassium alkenyltrifluoroborates as well as potassium
alkynyltrifluoroborates of various substitution patterns can be successfully
used under the described reaction conditions.4,5
References
1. Laboratorium für Organische Chemie, Eidgenössische Technische
Hochschule Zürich, HCI H335, Wolfgang-Pauli-Strasse 10, CH-8093,
Zürich (Switzerland). E-mail: carreira@org.chem.ethz.ch. We are
grateful to the ETH Zürich and the Swiss National Science Foundation
for financial support.
2. “Transition Metal Catalyzed Enantioselective Allylic Substitution in
Organic Synthesis”: Topics in Organometallic Chemistry, Vol. 38 (Ed.: U.
Kazmaier), Springer, Heidelberg, 2012.
3. Sundararaju, B.; Achard, M.; Bruneau, C. Chem. Soc. Rev. 2012, 41, 4467–
4483 and references therein.
4. Hamilton, J. Y.; Sarlah, D.; Carreira, E. M. J. Am. Chem. Soc. 2013, 135,
994–997.
Org. Synth. 2015, 92, 1-12
DOI: 10.15227/orgsyn.092.0001
9

5. Hamilton, J. Y.; Sarlah, D.; Carreira, E. M. Angew. Chem. Int. Ed. 2013, 52,
7532–7535.
6. (a) Akiyama, K.; Gao, F.; Hoveyda, A. H. Angew. Chem., Int. Ed. 2010, 49,
419–423. (b) Gao, F.; McGrath, K. P.; Lee, Y.; Hoveyda, A. H. J. Am.
Chem. Soc. 2010, 132, 14315–14320. (c) Gao, F.; Carr, J. L.; Hoveyda, A. H.
Angew. Chem., Int. Ed. 2012, 51, 6613–6617. (d) Shintani, R.; Takatsu, K.;
Takeda, M.; Hayashi, T. Angew. Chem., Int. Ed. 2011, 50, 8656–8659.
Appendix
Chemical Abstracts Nomenclature (Registry Number)
1-(Naphthalen-2-yl)prop-2-en-1-ol: 2-Naphthalenemethanol, α-ethenyl-;
(76635-88-6)
(R)-(−)-(3,5-Dioxa-4-phospha-cyclohepta[2,1-a;3,4-a']dinaphthalen-4-yl)-
dibenzo[b,f]-azepine ((R)-L): 5H-Dibenz[b,f]azepine, 5-(11bR)-
dinaphtho[2,1-d:1',2'-f][1,3,2]dioxaphosphepin-4-yl-; (1265884-98-7 )
(S,E)-2-(1-Phenylpenta-1,4-dien-3-yl)naphthalene: Naphthalene, 2-[(1S,2E)-
1-ethenyl-3-phenyl-2-propen-1-yl]-;
2-Naphthaldehyde: 2-Naphthalenecarboxaldehyde; (66-99-9)
Vinylmagnesium chloride: Magnesium, chloroethenyl-; (3536-96-7)
(R)-(+)-1,1'-Bi(2-naphthol): [1,1'-Binaphthalene]-2,2'-diol, (1R)-; (18531-94-7)
Phosphorous trichloride; (7719-12-2)
5H-Dibenz[b,f]azepine; (256-96-2)
n-Butyllithium: Lithium, butyl-; (109-72-8)
Bis(1,5-cyclooctadiene)diiridium dichloride: Iridium, di-µ-chlorobis[(1,2,5,6-
η)-1,5-cyclooctadiene]di-; (12112-67-3)
Potassium trans-styryltrifluoroborate: Borate(1-), trifluoro[(1E)-2-
phenylethenyl]-, potassium (1:1), (T-4)-; (201852-49-5)
Tetrabutylammonium bromide: 1-Butanaminium, N,N,N-tributyl-, bromide
(1:1); (1643-19-2)
Potassium hydrogen difluoride: Potassium fluoride (K(HF2)); (7789-29-9)
Trifluoroacetic acid: Acetic acid, 2,2,2-trifluoro-; (76-05-1)
Org. Synth. 2015, 92, 1-12
DOI: 10.15227/orgsyn.092.0001
10

Prof. Erick M. Carreira obtained a B.S. degree
from the University of Illinois at Urbana-
Champaign (1984) and a Ph.D. degree from
Harvard University (1990). After carrying out
postdoctoral work at the California Institute of
Technology through late 1992, he joined the
faculty at the same institution as an assistant
professor of chemistry and was subsequently
promoted to the rank of full professor. Since
September 1998, he has been professor of
chemistry at ETH Zürich. His research program
focuses on asymmetric synthesis of complex
natural products, the development of catalytic
along
with
stoichiometric
reactions
for
asymmetric stereocontrol, chemical biology, and
medicinal chemistry.
James Y. Hamilton was born in South Korea. He
received his Bachelor’s degree in chemistry and
biology from the University of Wyoming (2006)
and Master’s degree from the University of
California, Berkeley (2008) under the supervision
of Prof. Dirk Trauner. Since May 2011, he has
been a doctoral student in the group of Prof. Erick
M. Carreira, working on design and development
of
transition
metal-catalyzed
asymmetric
reactions.
David Sarlah was born and raised in Slovenia,
where he obtained his Bachelor’s Degree in
Chemistry (University of Ljubljana). He obtained
his Ph.D. in chemistry in 2011 for research
conducted under Professor K. C. Nicolaou
involving the total synthesis of complex natural
products. In the fall of 2011, he joined Professor
Erick M. Carreira’s group as a postdoctoral
researcher where he is currently developing new
stereoselective
methods
involving
allylic
substitution. His research interests encompass
chemical synthesis, reaction design and their
application to complex natural product synthesis
and chemical biology.
Org. Synth. 2015, 92, 1-12
DOI: 10.15227/orgsyn.092.0001
11

Wen-Bo Liu was born in China and he received
his Bachelor’s Degree in Chemistry from the
Nankai University in 2006. He obtained his Ph.D.
in organic chemistry (2011) from the Shanghai
Institute of Organic Chemistry (SIOC) under the
supervision of Professor Li-Xin Dai and
Professor Shu-Li You. Then He joined the
Professor Brian M. Stoltz laboratory at Caltech as
a postdoctoral scholar, working on asymmetric
catalysis and sustainable chemistry.
Seo-Jung Han graduated with a B.S. in chemistry
from Sogang University in 2008. She received
her M.S. degree in 2010 from Sogang University
under the direction of Professor Duck-Hyung
Lee. She then moved to the California Institute
of Technology and began her doctoral studies
under the guidance of Professor Brian M. Stoltz.
Her graduate research focuses on total synthesis
of complex polycyclic natural products.
Org. Synth. 2015, 92, 1-12
DOI: 10.15227/orgsyn.092.0001
12