Solid phase organic reactions, part 2 - uni-regensburg.de
Transcript of Solid phase organic reactions, part 2 - uni-regensburg.de
T. Weiß31. Mai 2005Seite1
Solid phase organic reactions, part 2
(reduction, oxidation, formation of carbonyl compounds and derivatives thereof)
NMe3 ClCrO3
NMe3 BH4
NMe3 RuO4
NMe3 BH3CN
IOAc
OAc
SnBu
HBu
NN OsO4
Cl
O
NBH
O
PhPh
O
O
SO
O O5
O
PPH2
N Zn(BH4)2
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Polymer-supported reagents (PSR)
Advantages
Simplification of reaction work-up and product isolation
Reaction can be driven to completion
Potential of recycling
Higher stability, reduced toxicity
Two incompatible reagents can be used at the same time
Simplified automation
Disadvantages
Reduced activity due to unfavorable electronic and steric interaction
Slower reaction - long reaction times
Poor yields
Low loading of polymer
Large scale reactions not practicable
Leaching of metal
reagent A B reagent Bfiltrationreaction
condition
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X Y solid phasechemistry
reactive moiety X Y reactive moietycovalent bond
polymerizationreactive moiety reactive moiety
covalent bond
NMe3 ion exchangechemistry
NMe3
ionic interaction
X-reagent
reagent
Entrapment, reagent enclosed in a polystyrene network
Methods for preparing PSR
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Types of reactionA few reagents for oxidation
Oxidation of alcoholsPolymer-supported perruthenatePolymer-bound sulfoxide for swern reactionPolymer-supported chrom-basedand manganese-based oxidantsTEMPO-resin
Ozonolysisworking-up with polymerbound phosphanesor sulfides
HydroformylationPolymer-supported rhuthenium-complexes
N-oxidation, S-oxidationPolymer-bound oxirane
Formation of chinonesPolymer-supported hypervalent iodine
R1 R2
OH
R1 R2
O
R1
R2
R1
CHOR2
R2 R3
R1R1
O
R2 R3
Oi) O3
ii)
N NO
O
O
OH
OH
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EpoxidationPolymer-supported Mn-salene-complexes
Asymmetric Dihydroxylation (AD)Polymer-bound Sharpless-reagent
NtBu
O
NMn
OCl
N
R
R R
R
R R
O
N
N
NN
RO
ODHQD
ODHQD
R2 R3
R1HO
R3R2
OHR1 H
co-oxidant
R1
R2O
R1
R2
NMO, mCPBA
Types of reactionA few reagents for oxidation
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Types of reactionExamples for reduction
R1 R2
O
R1 R2
OH
R1
O
R2 R3
HN
R4R1 R2
NR3 R4
R1 NO2 R1 NH2
CuCl
R1 X R1 H
X= Br, Cl, OC(S)OPh
Reduction of carbonylsPolymer-supported borohydridePolymer-supported cyanoborohydridePolymer-bound tributylphosphane in combinationwith sodium borohydrideEnantioselective polymer-bound catalystin Corey-Itsuno procedure
Reductive aminationPolymer-supported borohydride
Reduction of nitro-groupsPolymer-supported borohydride
Dehalogenation and DesoxygenationPolymer-bound tin-hydrides
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NH CrO3X
OH
PPH2
3
RhCl
H
O
H2, xylene, 100 °C, 12h, 80%
O
OHOH
HH
HH
HON
N
NH2
O
NMe3BH4
NMe3 IO4
O
OHOH
HH
HH
HON
N
NH2
O
H2O, 79%
ApplicationsCombinations of different PSR
One-pot cleavage reaction of 1,2-diols to primary alcohols
A two step process involving alcohol oxidation and concurrent alkene reduction:
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Natural products via supported reagentsSynthesis of epimaritidine
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PSR in library generation
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polymer-supported nitrite reagent
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Steven V. Ley, J.Chem.Soc.; Perkin Trans. 1, 2000, 3815-4195Steven V. Ley, J. Chem.Soc.; Perkin Trans. 1, 1999, 1251-1252
Bannwarth W. and Felder E. (eds.): Combinatorial chemistry, A Practical Approach, Wiley-VCH, Weinheim, 2000
Literature