The Sanderson Group Webpages
Department of Chemistry
Durham University, Durham, UK
Organic Chemistry 2 Part B - C-C Bond Formation, Oxidation/Reduction, Protecting Groups
Dr J M Sanderson, Ext 42107, Room 112.
See http://duo.dur.ac.uk for further information.
Aims
These lectures are given to provide knowledge of methods and strategies for making C-C and C=C bonds for constructing reasonably complex organic molecules; the concept of selectivity in organic synthesis will be introduced, with particular reference to protecting groups, oxidations and reduction reactions.
Learning Outcomes
By the end of these lectures, students should be able to:
- Write curly arrow mechanisms for the formation, under acidic or basic conditions, of the enol form of a ketone or aldehyde.
- Predict the enolate(s) that will form under kinetic and thermodynamic conditions.
- Write curly arrow mechanisms for the reactions of enolates with electrophiles, including the aldol reaction and the Claisen condensation. You should be able to accurately predict the regioselectivity of these reactions.
- Describe, using curly arrow mechanisms, the use of β-dicarbonyl compounds as starting materials in synthesis, including decarboxylation and ring formation reactions.
- Write curly arrow mechanisms for the Mannich and Michael reactions.
- Define the terms retrosynthetic analysis, synthon and synthetic equivalent.
- Propose retrosynthetic analyses for 1,3-, 1,4- and 1,5-dioxygenated compounds.
- Write mechanisms for the Wittig reaction of stabilised and unstabilised ylids with carbonyl compounds and accurately predict the stereochemistry of the products.
- Write a mechanism, using curly arrows, for the reaction of lithium aluminium hydride with a carbonyl compound.
- State the relative reactivity of lithium aluminium hydride, sodium borohydride and borane and DIBAL.
- Write mechanisms for the Wolf-Kishner reaction and dissolving metal reductions of aromatic systems.
- State three of the key features of a good protecting group.
- Write mechanisms for the protection and deprotection of aldehydes and ketones as acetals and ketals respectively.
- State at least 6 reagents that can be used for the oxidation of an alcohol and the corresponding product for each.
- Write mechanisms for the reaction of peracids, osmium tetroxide and ozone with alkenes.
Lectures
Lecture 1: Introduction. Revision of key chemistry from level 1. Generation and reactions of enolates.
Lecture 2: β-Dicarbonyl compounds. Kinetic and thermodynamic enolates. Aldol reaction.
Lecture 3: Aldol cross condensations. Claisen condensation.
Lecture 4: Michael and Mannich reactions. Disconnections.
Lecture 5: Wittig reaction. Reduction of carbonyl compounds.
Lecture 6: Hydrogenation. Wolf-Kishner reaction. Dissolving metal reductions.
Lecture 7: Protecting groups. Oxidations.
Workshops
There will be two workshops towards the end of the Michaelmas term. You will be required to attend one of these. Please refer to the course noticeboard nearer this time for further information.
Reading List
General Texts:
- J. Clayden, N. Greeves, S. Warren and P. Wothers, “Organic Chemistry”, Oxford University Press, 2000.
- F. A. Carey and R. J. Sundberg, “Advanced Organic Chemistry Parts A & B”, Springer, 5th ed., 2007.
- S. G. Warren and P. Wyatt, “Organic Synthesis: the Disconnection Approach”, 2nd ed., Wiley, 2008.
Other Sources (Checked 19/09/2011):
- http://www.colby.edu/chemistry/OChem/demoindex.html#table - the bits on carbonyls, enolates and α,β-unstaurated carbonyls are relevant.
- http://www.chemtube3d.com - ChemTube3D; interactive animations of chemical reactions and bonding.
- http://www.abdn.ac.uk/curly-arrows/ - tutorial on writing curly arrow mechanisms.
On DUO in the Core Chemistry 2 area you will find:
- The lecture notes and handout under Organic Chemistry 2 in the Lectures folder (from Week 8)
- A copy of the voluntary problems and answers under Assignments (after the 3rd lecture)
- A copy of this handout under Organic Chemistry 2 in the Lectures folder
- Links to the above web sites under Organic Chemistry 2 in the Lectures folder
In addition, the problems for the workshops in Weeks 7/8, the revision workshops in the Easter term and the corresponding sets of answers, will be posted on DUO (under the "Assignments" tab) in due course.