microcapsule enabled multicatalyst system sarah l. poe, muris kobasˇlija, and d. tyler mcquade*
DESCRIPTION
Microcapsule Enabled Multicatalyst System Sarah L. Poe, Muris Kobasˇlija, and D. Tyler McQuade* J. Am. Chem. Soc . 2006 , 128 , 15586-15587. One-Pot Multistep Reactions. advantage. Be effective at reducing the waste and cost of a synthetic route - PowerPoint PPT PresentationTRANSCRIPT
Microcapsule Enabled Multicatalyst System
Sarah L. Poe, Muris Kobasˇlija, and D. Tyler McQuade*
J. Am. Chem. Soc. 2006, 128, 15586-15587.
One-Pot Multistep Reactions
a relatively small number of systems where the catalysts are compatible with each other.
Be effective at reducing the waste and cost of a synthetic route decrease the number of work-ups and purifications decrease the the volume of solvent
These reactions are especially useful when multiple catalysts are used so that one traps an unstable intermediate formed by the other.
advantage
imitation
Patchornik, A. et al. J. Am. Chem. Soc. 1981, 103, 7620-7629.
P = polystyrene
Site–isolated catalysts
Helms, B. et al. Angew. Chem. Int. Ed. 2005, 44,6384 – 6387.
Gelman, F. et al. J. Am. Chem. Soc. 2000, 122, 11999-12000.
Synthesis of microencapsulated poly(ethyleneimine) catalyst
Span 85 / cyclohexane (2% v/v) (0.15 g/mL PEI in 6.0 mL MeOH and 1.5 mL CHCl32 min
1.0 mL 2,4-tolylene diisocyanate (TDI)/ 9.0 mL cyclohexane polymerization1 min
cyclohexane
(stopped)
washed with hexanes
Span 85 (Sorbitan trioleate) C60H108O8
PEI =
TDI =
Evans, D. A. et al. J. Am. Chem. Soc. 2005, 127, 9958-9959.
HNNH BnBn
+ NiBr2
4.3 mmol 2 mmol
CH3CN / reflux 5 h
Ni(II)–bis[(R,R)-N,N’-Dibenzylcyclohexane-1,2-diamine]Br2
82 %
dimethylmalonate
Sartori, G. et al. J. Catal. 2004, 222, 410-418.
APS : aminopropylsilica heterogeneous catalysts
TEOS (Tetraethyl Orthosilicate): (C2H5O)4Si
ATS (3-aminopropyl)triethoxysilane : NH2(CH2)3Si(OC2H5)3
O
HCH3NO2
OH
CH2NO2
H - H2ONO2
CH3NO2
NO2
CH2NO2
H
Michael Addition reactions
Ni
O
O
O
O
O
O
O
O
H
NiO.A.
NO2
Ni
O
O
O
OH
Ni
O
O
O
OH
NO2
NO2
insertionNi
O
O
O
O
NO2R. E.
O
O
O
ONO2