short literature - cpb-us-e1.wpmucdn.com · 11/11/2011 · 60 °c 20 °c 280 nm 280 nm 380 nm 380...
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Short Literature11/15/10
Dustin Raup
Prof. Ben Feringa
- PhD in 1978 with Prof. Hans Wynberg (Univ. of Groningen)- Research Scientist with Royal Dutch Shell (1978-1984)- Lecturer in Organic Chemistry, Univ. of Groningen (1984-1988)- Prof. of Organic Chemistry (1988-present)- Department Chair (1991-1995)- Director Stratingh Institute for Chemistry (2003-present)- J. H. vanʼt Hoff Distinguished Prof. (2003-present)- Academy Professor, Royal Netherlands Acad. of Sciences- Editor of Organic & Biomolecular Chemistry
Research Focus:
Asymmetric CatalysisChirality
Biomimetic and Catalytic OxidationOrganogels and Smart MaterialsMolecular Switches and Motors
Molecular Motors
Inspiration from Nature
Bacterial flagellum translate molecular motion to do locomotive work!
Molecular Motor Applications
Controlling the properties of liquid crystal films
S
S
S
S
hvMe
Me
Me
Me
Molecular “brakes” or Switches
Fast Propellers for microfluidics
Unidirectional Light-Driven Molecular Motors
Me Me
Me Me
Me
Me
Me
Me
20 °C60 °C
280 nm
280 nm
380 nm
380 nm
Nature, 1999, 401, 152-155
First Report of Continuous Unimolecular Motion by Feringa
Synthesis of the New System
SH 1. NEt3, toluene, 50 °C
OO O
2. AlCl3, 0 - 22 °C
67% over 2 steps
S
O
OH
O 1. EDC, HOBT, NHNMe2, DIPEACH2Cl2, rt, 83%
2. NHNH2, EtOH55%
S
N
NMe2
O
NH2
I OAcOAc
S
N
NMe2
O
N
S
S
DMF -50 to 22 °C55%
SNMe2
O
S
S
SNMe2
O
S
PPh3, 80 °C
92%
Barton-Kellogg Diazo-thioketone coupling
Schematic of How the Bidirectional System Works
How The New System Works
S
S
O
NMe
Me S
S
O
NMe
MeS
S
O
NMe
Me S
S
O
NMe
Me
S
S
O
NMe
Me S
S
O
NMe
MeS
S
O
NMe
Me S
S
O
NMe
Me
hv hv
hvhv
base
base
heatheatheatheat
The Pauson-Khand Reaction
- Cobalt alkyne complex first reported in 1971, by Pauson and Khand, reaction run but uncharacterized.- Complex first intercepted and characterized by Nicholas in the Nicholas Reaction- Formal [2+2+1] cycloaddition of alkyne, alkene and CO reported by Pauson and Khand in 1973.
R1 R2
R3
COCo2(CO)6 R1
R1
R1
O
R1OH
Co2(CO)6
then oxidantR1
Nuc
R2
R2NucH
Pauson-Khand
Nicholas
Mechanism
(CO)3Co Co(CO)3
R1 R2
(CO)3Co Co(CO)3R1 R2 Co(CO)3
Co(CO)3
R1
R2
-COCo(CO)3Co(CO)2
R1
R2
R3Co(CO)3Co(CO)2
R1
R2
R3
Co(CO)3Co(CO)3
R1
R2
+CO
+CO
R3
Co(CO)3Co(CO)3
R1
R2
OR3OR3
R2
R1Co(CO)3Co(CO)3
OR3
R2
R1
Visible Light Activated Pauson-Khand
HH R
H
O
R
XS
1 atm COCo2(CO)6
22 °C
halogen lampor sunlight
HH
O
ferrocene
HH
O
TMS
78% 78%
Using Light for Activation?
Prior Art
HH R
H
O
R
XS
1 atm COCo2(CO)6
22 °C
halogen lampor sunlight
HH R
H
O
R
XS
1 atm COCo2(CO)6
22 °C
halogen lampor sunlight
- Alkyne-Co complex undergoes homolytic bond cleavage in light and radicals
- Suggests that light facilitates loss of CO ligand (RDS as as suggested by Magnus and coworkers)
TEMPO22 °C
300 nm hvheat
37-99% yield
Org. Lett., 2005, 7 (14), pp 3033–3036
up to 95% yield