Asymmetric Frontiers in Lanthanide Catalysis Andrew Lohse Hsung Group University of Wisconsin –...
42
Asymmetric Frontiers in Lanthanide Catalysis Andrew Lohse Hsung Group University of Wisconsin – Madison December 11, 2008 O F 7 C 3 O Eu O O Yb(O Tf) 3 H H NR 3 NR 3 N N O O N R' R' Ln 3 O O La Li O O O Li Li O (O Tf) 3
Transcript of Asymmetric Frontiers in Lanthanide Catalysis Andrew Lohse Hsung Group University of Wisconsin –...
Asymmetric Frontiers in Lanthanide Catalysis
Andrew LohseHsung Group
University of Wisconsin – MadisonDecember 11, 2008
O
F7C3
O
Eu
O
O
Yb(OTf)3
H
H
NR3
NR3
N
N
OO
N
R' R'
Ln
3
OO
La
Li
O
OO
Li
LiO
(OTf)3
Overview
• Background/Fundamentals• Asymmetric Cycloadditions• Multifunctional Asymmetric Catalysts
• C-C Bond Formation• C-P Bond Formation• C-O Bond Formation
• Conclusions/Future Directions
2
Location
3
The Lanthanide Contraction
4Mikami, K.; Terada, M.; Matsuzawa, H. Angew. Chem., Int. Ed. 2002, 41, 3554.
Contracted Nature of the f-Orbitals• Shielded by 5s and 5p
– Unavailable for bonding
• Lack of orbital restrictions– No ligand field effects– Sterically saturated
• Ionic character– “Hard” Lewis acids – Oxophilic
5http://int.ch.liv.ac.uk/Lanthanide/Lanthanides.htmlLanthanides: Chemistry and Use in Organic Synthesis; Kobayashi, S., Ed; Springer-Verlag: Berlin, 1999.
“triple-positively charged closed shell inert gas electron cloud”
Well-Known Examples in Synthesis
6Luche, J. L. J. Am. Chem. Soc. 1978, 100, 2226. Evans, D. A.; Hoveyda, A. H. J. Am. Chem. Soc. 1990, 112, 6447. Green, T. W.; Wuts, P. G. M. Protective Groups in Organic Synthesis; John Wiley & Sons: New York, 1999.
Luche Reduction
Evans-Tischenko Reduction
Oxidative PMB Deprotection
O OH
CeCl3, NaBH4
MeOH
OH O
nHex
MeCHO
15 % SmI2
O
nHex
O
Me OHH
OMe2HC
O
nHex
O
SmI2
Me
96% >99:1 anti:syn
R O(NH4)2Ce(NO3)6
"CAN"R OH
>99%
OMe
Why Use Lanthanides as Catalysts?
• Variation of Size/Lewis Acidity Tunability• Nature of f orbitals
– ionic character–high coordination #s
• NMR Analysis–Diamagnetic: La3+, Ce4+, Yb2+, Lu3+
–Paramagnetic: Pr3+, Sm2+/3+, Eu3+
• Water/Air stable• Recyclable
7Crabtree, R. H. The Organometallic Chemistry of the Transition Metals, 4th ed; Wiley Interscience: New York, 2005.Lanthanides: Chemistry and Use in Organic Synthesis; Kobayashi, S., Ed; Springer-Verlag: Berlin, 1999.
Aqueous Aldol
8Mukaiyama, T.; Banno, K.; Narasaka, K. J. Am. Chem. Soc. 1974, 96, 7503.Kobayashi, S. Chem. Lett. 1991, 2187.
-78 oC"anhydrous"
OTMS
Ph (HCHO)3
O
Ph
OH64%
H2OTiCl4 (3 eq.)
CH2Cl2
Ph
OTMS
HCHO (aq.) H2O-THF
rt
Ph
O
OH
1st use: 2nd use:3rd use:
94%91%93%
Yb(OTf)3(20 mol%)
• Use of ambient temperature
• Less rigorous conditions
• Recyclable
Yb(OTf)3
Catalyst mol % % Yield
1 90
Yb(OTf)3 20 94
Nd(OTf)3 20 89
Sm(OTf)3 20 91
Eu(OTf)3 20 93
Historical Perspective
9Parker, D. Chem. Rev. 1991, 91, 1441.Aspinall, H. C. Chemistry of the f-Block Elements; Gordon and Breach: Amsterdam , 2001.
Arrhenius1787
Rare-earths discoveredin Ytterby
1907
All naturallyoccurring rare-earths
isolated
O
tBu
O
Eu
3[(+)-Eu(pvc)3]
Whitesides1970
O
F7C3
O
Eu
3[(+)-Eu(hfc)3]
Danishefsky1983
"First Frontier"
Asymmetric Hetero-Diels-Alder
10Bednarski, M.; Maring, C.; Danishefsky, S. Tetrahedron Lett. 1983, 24, 3451.Mikami, K.; Terada, M.; Matsuzawa, H. Angew. Chem., Int. Ed. 2002, 41, 3554.
O
F7C3
O
Eu
3
Me3SiO
R
OtBu
H
O
Ph
[Eu(hfc)3](1 mol%)
-10 oC
O
O
R
Ph
O
TMSO
R
Ph
OtBu
TFA
[(+)-Eu(hfc)3]
R = H R = Me
58% ee 55% ee
Me3SiO
OR'
H
O
R
MXn
LnX3
(cat.)
R'O
O
R
O
MXn-1
MXn = TiCl4
TMSO
OR'
O
R
LnX3O
TMSO
OR'
R
O
O R
workup
Aza-Diels-Alder
11Kobayashi, S.; Ishitani, H., Araki, M.; Hachiya, I. Tetrahedron Lett. 1994, 35, 6325.Lanthanides: Chemistry and Use in Organic Synthesis; Kobayashi, S., Ed; Springer-Verlag: Berlin, 1999.
Ar H
N
HO
R
R'MS4Å, CH2Cl2, -15 oC
(R)-Yb cat. (10-20 mol%)DTBP (1 eq)
OH
NH
Ar
R'
R
OH
NH
OEt
N tButBuOH
NH
H
H
74% yield, 91% ee>99:1 cis:trans
OH
NH
OH
H
92% yield, 71% ee>99:1 cis:trans
67% yield, 86% ee93:7 cis:trans
DTBP:
Pre-formed (R)-Yb cat.
O
O
Yb(OTf)3
H
H
N
N
N
N
Proposed Transition State
12Kobayashi, S.; Ishitani, H., Araki, M.; Hachiya, I. Tetrahedron Lett. 1994, 35, 6325.Lanthanides: Chemistry and Use in Organic Synthesis; Kobayashi, S., Ed; Springer-Verlag: Berlin, 1999.
O
O Yb
H
H
N
N
Ar
OHN
N NtBu
tBu
NR
R'
• First catalytic asymmetric aza-Diels-Alder
• Lewis acid activation of diene
• Catalyst not poisoned by nitrogen functionality
1,3-Dipolar Cycloaddition
13Sanchez-Blanco, A. I.; Gothelf, K. V.; Jørgensen, K. A. Tetrahedron Lett. 1997, 38, 7923.Kobayashi, S.; Kawamura, M. J. Am. Chem. Soc. 1999, 120, 5840.
N
O
O
O toluene, 5 days
Yb(OTf)3 (20 mol%)iPr-pybox (20 mol%)
ArH
NOR
NOPh
tolylN
O
O
O
Jørgensen
NOBn
PhN
O
O
O
92% yield, 96% ee99:1 endo:exo
Kobayashi
54% yield, 73% ee96:4 endo:exo
MS4Å, CH2Cl2, 20 hr
(S)-Yb cat. (20 mol%)(R)-MNEA (40 mol%)
N
(R)-MNEA
N
N
OO
N
(S,S)-iPr-pybox
1. MeOMgI2. Pd/C, H2
Ph
NH2
CO2Me
OH
65%1. TBSCl, Imid
2. LDANHO
HH
Ph
TBSO
78%
ß-Lactam
Overview
• Historical Perspective• Asymmetric Cycloadditions• Multifunctional Asymmetric Catalysts
• C-C Bond Formation• C-P Bond Formation• C-O Bond Formation
• Conclusions/Future Directions
14
Concept of Multifunctional Catalysis
15Shibasaki, M.; Yoshikawa, N. Chem. Rev. 2002, 102, 2187.Shibasaki, M.; Kanai, M.; Matsunaga, S. Aldrichim. Acta 2006, 39, 31.
A
B
AB
Enzyme
A B
AB
Enzyme
"synergistic cooperation"
Preparation of Catalysts
16Shibasaki, M.; Yoshikawa, N. Chem. Rev. 2002, 102, 2187.Shibasaki, M.; Kanai, M.; Matsunaga, S. Aldrichim. Acta 2006, 39, 31.
LnCl3·7H2O
Ln{N(SiMe3)2}3
Ln(O-iPr)3
Ln(OTf)3
3 BINOL + 3 - 6 BuLi, NaO-tBu, or KHMDS
3 BINOL + 3 - 6 BuLi, NaO-tBu, or KHMDS
OO
La
Li
O
OO
Li
LiO
"LnMB"
(S)-LLB (S)-LSB (S)-LPB
Asymmetric Nitro-Aldol
17Shibasaki, M.; Yoshikawa, N. Chem. Rev. 2002, 102, 2187.Sasai, H.; Suzuki, T.; Itoh, N.; Arai, S.; Arai, T.; Shibasaki, M. J. Am. Chem. Soc. 1992, 114, 4418.
O
OMe
OH
NO2
90% yield, 94% ee3.3 mol% cat.
10% Pt(OH)2, H2
MeOH, rt, 2 hr
then acetone50 oC, 16 hr
O
OMe
OH
NH
90% yield
(S)-metoprolol
ß-Blocker
R H
O
H3C NO2
(R)-LLB (10 mol%)
THF, -40 oC, 18 hr R
OH
NO2
OH
NO2OH
NO2
OH
NO2Ph
91% yield, 90% ee 80% yield, 85% ee 79% yield, 73% ee
Postulated Catalytic Cycle
18Shibasaki, M.; Yoshikawa, N. Chem. Rev. 2002, 102, 2187.Sasai, H.; Suzuki, T.; Itoh, N.; Arai, S.; Arai, T.; Shibasaki, M. J. Am. Chem. Soc. 1992, 114, 4418.
OO
La
Li
O
OO
Li
Li
O
H2C NO2
O
O
La
Li
O
OOLi
O
HO
LiN CH2
O
O
O
La
Li
O
O OLi
O
H
O
LiN CH2
O
OR
H
RCHO
R
O
NO2H
H
= (R)-BINOLO
O
OH
NO291% yield90% ee
Tunability of Ln3+ Ionic Radius
19Shibasaki, M.; Yoshikawa, N. Chem. Rev. 2002, 102, 2187.Sasai, H.; Suzuki, T.; Itoh, N.; Arai, S.; Shibasaki, M. Tetrahedron Lett. 1993, 34, 2657.
OH
NO2Ph
79% yield73% ee
Ph
OH
NO291% yield72% ee
• 1st systematic study of its kind • Small changes (0.1 Å) cause drastic differences
Concept of Direct Aldol Reaction
20Shibasaki, M.; Yoshikawa, N. Chem. Rev. 2002, 102, 2187.Yoshikawa, N.; Yamada, Y. M. A.; Das, J.; Sasai, H.; Shibasaki, M. J. Am. Chem. Soc. 1999, 121, 4168.
Direct Reaction
R'
O
R
OH
R'
Ochiral catalyst
RCHO
"Atom Economical"
R'
O A: SiR3 or CH3
R
OA
wastes
R'
O
R'
OA
chiral cat.
RCHO
H+ or F-
wastes
R
OH
R'
O
Conventional Reaction
Direct Aldol Reaction
21Shibasaki, M.; Yoshikawa, N. Chem. Rev. 2002, 102, 2187.Yoshikawa, N.; Yamada, Y. M. A.; Das, J.; Sasai, H.; Shibasaki, M. J. Am. Chem. Soc. 1999, 121, 4168.
R'
O(R)-LLB
(20 mol%)
THF, -20 oCR
OH
R'
O
RCHO
OH
Ph
O OH O OH
Et
O
76% yield88% ee
55% yield76% ee
71% yield94% ee
Ph
88 hr 253 hr 185 hr
• Long reaction times
• Excess amounts of ketone
(5 eq) (8 eq) (50 eq)
43% yield87% ee135 hr
(1.5 eq) pKa (H2O) nitroalkanes ~ 10pKa (H2O) ketones ~ 17
R NO2
• High catalyst loading
Base Time (h) % Yield
18 trace
KHMDS 18 83
KHMDS 5 74
% ee
85
84
*KHMDS 33 71 85
* 3 mol% (R)-LLB
A Heteropolymetallic Catalyst
22Shibasaki, M.; Yoshikawa, N. Chem. Rev. 2002, 102, 2187.Yoshikawa, N.; Yamada, Y. M. A.; Das, J.; Sasai, H.; Shibasaki, M. J. Am. Chem. Soc. 1999, 121, 4168.
OH
Et
O
PhPhEt
O(R)-LLB (8 mol%)base (7.2 mol%)
H2O (16 mol%)THF, -20 oC
H
O
(5 eq)
• KOH formed in situ
• Use of (R)-LPB ineffective
Mechanistic Insights
23Shibasaki, M.; Yoshikawa, N. Chem. Rev. 2002, 102, 2187.Yoshikawa, N.; Yamada, Y. M. A.; Das, J.; Sasai, H.; Shibasaki, M. J. Am. Chem. Soc. 1999, 121, 4168.
OO
La
Li
O
OO
Li
Li
O
O R'
K
O
H
H
OO
La
Li
O
OO
Li
Li
O
KOH
HR'
O
rate-determining step
R
O
R'
O RCHOH
• kH/kD ~ 5 with d3-acetophenone
• Rate independent of aldehyde
• Coordination of aldehyde to La3+
confirmed by NMR studies
OH
Ph
O
BnOBnO Ph
O (R)-LLB (8 mol%)KHMDS (7.2 mol%)
H2O (16 mol%)THF, -20 oC
H
O
(5 eq)70% yield, 93% ee
O O
OH
O
OH
H
H
O
H
S
N
1. mCPBA2. LiAlH4
OH OH
BnO
1. (CH3O)2C(CH3)2
2. Li, NH33. (COCl)2, DMSO, Et3N
O
H O Oepothilone A
*
*
68% yield, 93% ee
Application in Total Synthesis
24Yoshikawa, N.; Yamada, Y. M. A.; Das, J.; Sasai, H.; Shibasaki, M. J. Am. Chem. Soc. 1999, 121, 4168.
Michael Addition of Malonates
25Shibasaki, M.; Yoshikawa, N. Chem. Rev. 2002, 102, 2187.Sasai, H.; Arai, T.; Satow, Y.; Houk, K. N.; Shibasaki, M. J. Am. Chem. Soc. 1995, 117, 6194.
O
CO2Bn
Me CO2Bn
Ph
CO2Me
CO2Me
Ph
O
89% yield, 72% ee-40 oC
93% yield, 77% ee-50 oC
O
n
RO
O
R'
O
OR(R)-LSB (10 mol%)
O
nCOOR
R' COOR
THF, rt, 12 hr
O
CO2Bn
CO2Bn
O
CO2Me
CO2Me
98% yield, 83% ee98% yield, 85% ee
O
CO2Bn
CO2Bn
96% yield, 90% ee
Me
Postulated Catalytic Cycle
26Sasai, H.; Arai, T.; Satow, Y.; Houk, K. N.; Shibasaki, M. J. Am. Chem. Soc. 1995, 117, 6194.Lanthanides: Chemistry and Use in Organic Synthesis; Kobayashi, S., Ed; Springer-Verlag: Berlin, 1999.
OO
La NaOO
O
Na
Na
O
OO
La
Na
OO
O
Na
Na
O
OO OMe
OMe
OO
O
La
Na
OHO
O
Na
Na
O
O
CO2MeMeO2C
O
CO2Me
CO2Me
O
CO2Me
CO2Me
H
H
H
Enantiofacial Control
27Sasai, H.; Arai, T.; Satow, Y.; Houk, K. N.; Shibasaki, M. J. Am. Chem. Soc. 1995, 117, 6194.Rappé, A. K.; Casewit, C. J.; Colwell, K. S.; Goddard III, W. A.; Skiff, W. M. J. Am. Chem. Soc. 1995, 114, 10024.
pro-(R)
pro-(S)
Favored
Disfavored+ 4.9 kcal/mol
(UFF)
OHLa
O
O
OO
O
Na
O
OHLa
O
O
OO
O
Na
O
NMR Studies
28Sasai, H.; Arai, T.; Satow, Y.; Houk, K. N.; Shibasaki, M. J. Am. Chem. Soc. 1995, 117, 6194.Shibasaki, M.; Yoshikawa, N. Chem. Rev. 2002, 102, 2187.
1
• No coordination with LLB
• LSB activates enone and controls its direction
ppm
• Size of coordination sphere
• Difference in dihedral angles of BINOL ligands
Catalyst M-O (Å)
~1.8
LSB ~2.2
La-M (Å)
6
5.1LLB
Why LSB vs. LLB?
Tunability of Alkali Metal
29Sasai, H.; Arai, T.; Satow, Y.; Houk, K. N.; Shibasaki, M. J. Am. Chem. Soc. 1995, 117, 6194.Shibasaki, M.; Sasai, H.; Arai, T.; Iida, T. Pure & Appl. Chem. 1998, 70, 1027.
BnO
O O
OBn
(R)-La cat. (10 mol%)
O O
CO2Bn
CO2Bn
0 oC
O
OMe
OH
NO2O
OMe
CHO(R)-La cat.(3.3 mol%)
-40 oC
MeNO2
Michael Addition Nitro-Aldol
(R)-La cat. % Yield
78
LSB 91
LPB 99
% ee
92
48
2LLB
(R)-La cat. % Yield
90
LSB 92
LPB
% ee
2
94LLB
NE NE
Improved Catalyst
30Kim, Y. S.; Matsunaga, S.; Das, J.; Sekine, A.; Ohshima, T.; Shibasaki, M. J. Am. Chem. Soc. 2000, 122, 6506.
0
% ee >99 >99
93% Yield 94
storage time (week) 1 2 3 4
94 94 95
>99 >99 >99
Air Stable/Storable
(R,R)-La-linked-BINOL (10 mol%)
O
CO2Bn
CO2Bn
DME, rt
O
CO2Bn
CO2Bn
La
O
O
OO
O
H
(R,R)-La-linked-BINOL% ee >99
82% Yield
cycle 1 2 3 4
94 68 50
>99 99 98
Recyclable
>99
94
0
Overview
31
• Historical Perspective• Asymmetric Cycloadditions• Multifunctional Asymmetric Catalysts
• C-C Bond Formation• C-P Bond Formation• C-O Bond Formation
• Conclusions/Future Directions
Hydrophosphonylation of Imines
32Sasai, H.; Arai, S.; Tahara, Y.; Shibasaki, M. J. Org. Chem. 1995, 60, 6656.Shibasaki, M.; Yoshikawa, N. Chem. Rev. 2002, 102, 2187.
(R)-La cat. % Yield
46
LSB 38
LPB 70
% ee
49
96
38LLB
DAM =
MeO OMe
H
NDAM
P(OMe)2
O
H
(R)-La cat. (10-20 mol%)
toluene-THFrt, 21 hr
P(OMe)2
HNDAM
O
P(OH)2
NH2
O
-amino phosphonic acid
Hydrophosphonylation of Imines
33Gröger, H.; Saida, Y.; Sasai, H.; Yamaguchi, K.; Martens, J.; Shibasaki, M. J. Am. Chem. Soc. 1998, 120, 3089.Shibasaki, M.; Yoshikawa, N. Chem. Rev. 2002, 102, 2187.
P(OMe)2
O
H
(R)-YbPB (10 mol%)
toluene-THF50 oC, 48 hr
S
NR'
R'
R
R S
NHR'
R'
R
R
(MeO)2PO
S
NHCH3
CH3
(MeO)2PO
S
NHH3C
H3C
(MeO)2PO
85% yield, 87% ee 81% yield, 93% ee
S
NHCH3
CH3
H3C
H3C
(MeO)2PO
88% yield, 95% ee
P(OMe)2
O
H
Ti(O-iPr)2(TADDOL)(20 mol%)
THF65 oC, 5 days
S
NCH3
CH3
H3C
H3C S
NHCH3
CH3
H3C
H3C
(MeO)2PO
57% yield, 46% ee
Effectiveness of Cyclic Phosphites
34Maffei, M.; Buono, G. Tetrahedron 2003, 59, 8821.Schlemminger, I.; Saida, Y.; Gröger, H.; Maison, W.; Durot, N.; Sasai, H.; Shibasaki, M.; Martens, J. J. Org. Chem. 2000, 65, 4818.
POHRO
RO
Phosphonatetautomer
Phosphitetautomer
PO
H
RO
RO
PO
H
O
OS
NCH3
CH3
H3C
H3C S
NHCH3
CH3
H3C
H3C
PO
99% yield, 99% ee
(R)-YbPB (2.5 mol%)
toluene-THF50 oC, 48 hr
O
O
O
POH3C
CH3
O
H
O P
O
CH3
H3C
O
H
no - *P=O
Stabilized 1.70 kcal/mol(HF/6-31G**)
O P
O
CH3
H3C
OH
no - *P-O
Proposed Catalytic Cycle
35Gröger, H.; Saida, Y.; Sasai, H.; Yamaguchi, K.; Martens, J.; Shibasaki, M. J. Am. Chem. Soc. 1998, 120, 3089.Schlemminger, I.; Saida, Y.; Gröger, H.; Maison, W.; Durot, N.; Sasai, H.; Shibasaki, M.; Martens, J. J. Org. Chem. 2000, 65, 4818.
O O
Yb
K
O
O
O
K
K
O
(RO)2PO
H
O O
Yb
K
O
O
O
K
K
O
O
P(OR)2H
O O
Yb
K
O
O
O
K
K
O
O
P(OR)2
H
O O
Yb
K
O
O
O
H
K
O
O
P(OR)2
K
RDS
O O
Yb
K
OO
O
K
O
O
P(OR)2
H
S
N
S
NK
O
P(OR)2S
NH
Overview
36
• Historical Perspective• Asymmetric Cycloadditions• Multifunctional Asymmetric Catalysts
• C-C Bond Formation• C-P Bond Formation• C-O Bond Formation
• Conclusions/Future Directions
Epoxidation of Enones
37
R
O
R'
La-(R)-BINOL-Ph3As=O (5 mol%)TBHP (1.2 eq)
MS 4Å, THF1-6 hr, rt
R
O
R'
O
Ph
O
Ph
O
O
Ph
O
95% yield, 97% ee3 min
H3C
OO
Ph
Ph
OO
94% yield, 98% ee 98% yield, 92% ee
95% yield, 96% ee
LaO
OO-iPr
O
AsPh3
La-(R)-BINOL-Ph3As=O
Nemoto, T.; Ohshima, T.; Yamaguchi, K.; Shibasaki, M. J. Am. Chem. Soc. 2001, 123, 2725.
Postulated Catalytic Cycle
38Nemoto, T.; Ohshima, T.; Yamaguchi, K.; Shibasaki, M. J. Am. Chem. Soc. 2001, 123, 2725.
LaO
OO-iPr
OAsPh3
TBHP
LaO
OO-O-tBu
OAsPh3
TBHP
tBuOH
LaO
OO-O-tBu
OAsPh3
R
O
R'
LaO
OO
AsPh3
R
O
R'
OO-tBu
LaO
OO-tBu
OAsPh3
R
O
R'
R
O
R'
O
Diversity in Catalysis
39Shibasaki, M.; Sasai, H.; Arai, T.; Iida, T. Pure & Appl. Chem. 1998, 70, 1027.Shibasaki, M.; Yoshikawa, N. Chem. Rev. 2002, 102, 2187.
BnO
O O
OBn
(R)-La cat. (10 mol%)
O O
CO2Bn
CO2Bn
0 oC
O
OMe
OH
NO2O
OMe
CHO
(R)-La cat.(3.3 mol%)
-40 oC
MeNO2
O O
La
Li
O
O
O
Li
Li
O
O O
La
Na
O
O
O
Na
Na
O
O O
La
K
O
O
O
K
K
O
H
NDAM (R)-La cat.
(10 mol%)
rt P(OMe)2
HNDAM
O
90% yield
94% ee
92% yield
2% ee
Not
Examined
78% yield
2% ee
46% yield
38% ee
91% yield
92% ee
38% yield
49% ee
99% yield
48% ee
70% yield
96% eeP(OMe)2
O
H
Conclusions
40
• Advantages of lanthanide catalysis‒ Tunability ‒ Diversity of possible reactions‒ Water/air stable‒ Recyclable
• Limitations‒ Long reaction times‒ High catalyst loading‒ Aggregation of complexes
Future Directions
41Aspinall, H. C. Chemistry of the f-Block Elements; Gordon and Breach: Amsterdam , 2001.
• Increase efficiency of catalysts• Application in industry• Broaden the scope of substrates
“These elements perplex us in our researches, baffle us in our speculations, and haunt us in our very dreams. They stretch like an unknown sea before us; mocking, mystifying and murmuring strange revelations and possibilities.”
- Sir William Crookes (1887)Address to the Royal Society
Acknowledgements
42
• Professor Richard Hsung
• Hsung group members
• Practice talk attendees- John Feltenberger
- Kyle DeKorver
- Brittland DeKorver
- Lauren Carlson
- Jenny Werness
- Aaron Almeida
- Kevin Williamson
- Dr. Yu Zhang
- Dr. Ryuji Hayashi
- Dr. Yu Tang
- Ting Lu
- Gang Li
- Grant Buchanan
- Yonggang Wei
- Hongyan Li
• Kat Myhre
• Colleen Lohse
