Year 3 CH3E4 notes: Asymmetric Catalysis, Prof Martin Wills 2012-2013 You are

Year 3 CH3E4 notes: Asymmetric Catalysis, Prof Martin Wills 2012-2013 You are www.phwiki.com

Year 3 CH3E4 notes: Asymmetric Catalysis, Prof Martin Wills 2012-2013 You are

Gordon, John, Morning Host has reference to this Academic Journal, PHwiki organized this Journal Year 3 CH3E4 notes: Asymmetric Catalysis, Prof Martin Wills 2012-2013 You are aware of the importance of chirality. This course will focus on asymmetric catalysis, i.e. the use of a catalyst to create new enantiomerically pure molecules. This can be achieved in several ways: M Wills CH3E4 notes Introductory, no need to revise, but underst in addition to concepts. 2) A covalent intermediate may be as long as med – a catalytic unit binds in a temporary process to the substrate: 1) A metal atom may ‘template’ the reaction in some way e.g. Sharpless epoxidation of alkenes: M Wills CH3E4 notes 3) The reaction may take place within an asymmetric environment controlled by an external source: The key features of these approaches will be described in addition to examples from the literature will be described. Some examples of enantiomerically pure drugs: underst in addition to concepts. M Wills CH3E4 notes 9 out of the top ten US prescribed drugs in 2010 are in single enantiomer as long as m http://cbc.arizona.edu/njardarson/group/sites/default/files/Top 200 Br in addition to -name Drugs by Total US Prescriptions in 2010sm-0.pdf For in as long as mation only. No need to memorise.

Institue of Historical Research, University of London GB www.phwiki.com

This Particular University is Related to this Particular Journal

M Wills CH3E4 notes Oxidation reactions of alkenes. The Sharpless dihydroxylation reaction employs lig in addition to -acceleration to turn the known dihydroxyation reaction into an asymmetric version. Underst in addition to how each enantiomer of lig in addition to gives a different product enantiomer. M Wills CH3E4 notes Underst in addition to how each enantiomer of lig in addition to gives a different product enantiomer. Be aware in addition to learn which enantiomer is as long as med relative to the substituents using each as long as m of ‘ADmix’. M Wills CH3E4 notes Oxidation reactions of alkenes. Evidence favours the [3+2] addition mechanism: K. B. Sharpless et al, J. Am. Chem. Soc. 1997, 119, 9907. Learn the two possible mechanisms as long as the oxidation, The means by which chirality transfer is achieved is not fully understood.

M Wills CH3E4 notes Oxidation reactions of alkenes. No need to memorise the examples, but underst in addition to what the dihydroxylation achieves, in addition to how versatile it can be. M Wills CH3E4 notes Underst in addition to the concepts, no need to memorise examples. Zaragozic acid synthesis – key asymmetric dihydroxylations. K. C. Nicolaou. E. W. Yue, Y. Naniwa, F. DeRiccardis, A. Nadin, J. E. Leresche. S. LaGreca. Z. Yang, Angew. Chem. Int. Ed. 1994, 33, 2184 Underst in addition to the concepts, no need to memorise examples on this slide.

M Wills CH3E4 notes Reduction reactions of Double bonds (C=C, C=N, C=O). M Wills CH3E4 notes Reduction reactions of Double bonds (C=C, C=N, C=O). Addition of hydrogen to an acylamino acrylate results in as long as mation of an amino acid precursor. The combination of an enantiomerically-pure (homochiral) lig in addition to with rhodium(I) results in as long as mation of a catalyst as long as asymmetric reactions. Underst in addition to how a chiral environment is created around Rh(I) in addition to how the enamine substrate co-ordinates. M Wills CH3E4 notes Rh-diphosphine complexes control asymmetric induction by controlling the face of the alkene which attaches to the Rh. Hydrogen is transferred, in a stepwise manner, from the metal to the alkene. The intermediate complexes are diastereoisomers of different energy. Using Rh(DIPAMP) complexes, asymmetric reductions may be achieved in very high enantioselectivity. Underst in addition to how a chiral environment is created around Rh(I) in addition to how the enamine substrate co-ordinates.

M Wills CH3E4 notes Other chiral diphosphines are not chiral at P, but contain a chiral backbone which ‘relays’ chirality to con as long as mation of the arene rings. Underst in addition to how a chiral environment is created around Rh(I). M Wills CH3E4 notes Reduction reactions of C=C Double bonds using Rh(I) complexes– representative examples. No need to memorise examples but underst in addition to that the sense of reduction in each case is relative to the directing group X. M Wills CH3E4 notes Reduction reactions of C=C Double bonds using Rh(I) complexes– representative examples. No need to memorise examples – underst in addition to that the sense of reduction in each case is relative to the directing group X – different lig in addition to s give different product enantiomers.

M Wills CH3E4 notes Reduction reactions of Double bonds using catalysts derived from Ru(II) (C=C). Learn that Ru(II) complexes of diphosphine lig in addition to s can also direct hydrogenations. No need to memorise examples. M Wills CH3E4 notes Reduction reactions of Double bonds using catalysts derived from Ru(II) (C=C). Learn that Ru(II) complexes of diphosphine lig in addition to s can also direct hydrogenations of allylic alcohols. No need to memorise examples. M Wills CH3E4 notes Reduction reactions of isolated C=C double bonds can be achieved with variants of Crabtree’s catalyst. No need to memorise examples.

M Wills CH3E4 notes Reduction reactions of isolated C=C double bonds can be achieved with variants of Crabtree’s catalyst. Underst in addition to that Ir(I) complexes with P in addition to N donors can reduce double bonds without a directing group in the substrate, i.e. sterically-driven. No need to memorise examples. M Wills CH3E4 notes Reduction reactions of C=O Double bonds using organometallic complexes. Underst in addition to that a C=O group can be reduced by a chiral Ru or Rh complex as well. No need to memorise examples. M Wills CH3E4 notes Reduction reactions of C=O Double bonds using organometallic complexes. Underst in addition to that a C=O group can be reduced by a Ru or Rh complex as well. No need to memorise examples.

M Wills CH3E4 notes Reduction reactions of C=O Double bonds using organometallic complexes. Dynamic kinetic resolution can result in as long as mation of two chiral centres: Learn that a beta-keto ester can epimerise rapidly in addition to that one enantiomer is more quickly reduced. Be able to draw the mechanism of this. No need to memorise examples. M Wills CH3E4 notes Reduction reactions of C=O Double bonds using organometallic complexes. Dynamic kinetic resolution can result in as long as mation of two chiral centres: No need to memorise examples – these illustrate the diversity of the process. Ketone reduction by pressure hydrogenation (i.e. hydrogen gas) can be achieved using a modified catalyst containing a diamine, which changes the mechanism. M Wills CH3E4 notes Underst in addition to that the mechanism changes when a diamine is added to a Ru(II)/diphosphine complex, in addition to this allows C=O bonds to be reduced without a nearby directing group present. Be able to draw the mechanism of this.

Gordon, John Morning Call - WLDX-AM Morning Host www.phwiki.com

Ketone reduction by pressure hydrogenation (i.e. hydrogen gas) can be achieved using a modified catalyst containing a diamine, which changes the mechanism. M Wills CH3E4 notes No need to memorise the examples. M Wills CH3E4 notes The use of hydride type reagents. Transfer hydrogenation – Ru catalysts. Underst in addition to that hydride reagents can also be used in reductions. Be able to draw the mechanism of the hydride transfer step. M Wills CH3E4 notes Examples of reductions using transfer hydrogenation with metal complexes: add C=O in addition to C=N reductions. These are examples to provide an appreciation of the scope, No need to memorise examples.

M Wills CH3E4 notes These are examples to provide an appreciation of the scope, No need to memorise examples. M Wills CH3E4 notes Asymmetric transfer hydrogenation by organocatalysis. Underst in addition to that Hantzsch esters are used as reagents as long as reduction of C=N bond in organocatalysis reactions. Be able to draw the mechanism of the hydride transfer step in addition to the imine as long as mation. No need to memorise examples. M Wills CH3E4 notes Asymmetric transfer hydrogenation by organocatalysis. No need to memorise examples, but underst in addition to the concepts.

M Wills CH3E4 notes Other asymmetric reactions – as long as interest. Concluding material, non examinable. M Wills CH3E4 notes There are many other reactions which have been converted into asymmetric processes. Other reactions: Hydrosilylation Hydroacylation Hydrocyanation Epoxidation using iminium salts Asymmetric allylation Hetero Diels-Alders 1,3-dipolar cycloadditions. [2+2] cycloadditions Cyclopropanation Cross coupling reactions Conjugate addition reactions Etc. etc. Concluding material, non examinable.

Gordon, John Morning Host

Gordon, John is from United States and they belong to Morning Call – WLDX-AM and they are from  Fayette, United States got related to this Particular Journal. and Gordon, John deal with the subjects like Local News; National News

Journal Ratings by Institue of Historical Research, University of London

This Particular Journal got reviewed and rated by Institue of Historical Research, University of London and short form of this particular Institution is GB and gave this Journal an Excellent Rating.