The aim of the module is to extend second year knowledge of synthetic and physical organic chemistry.

(LO1) Students should have a good understanding of some modern synthetic reactions.

(LO2) Students should be able to deduce mechanisms on the basis of kinetic and other evidence

(S1) The ability to recognise the types of reaction taught and apply mechanistic knowledge to predict the outcome of unseen examples

Lectures: 32 x 1 hr, with one or more revision lectures.

Coursework: 6 x 1 hr small group tutorials, the last of which is for revision.

Lectures: 33 hr
Tutorials 6 hr

Rearrangements and Fragmentations (4 lectures)
• Essential 1,2-migration reactions: Baeyer-Villiger, Beckmann, Curtius, Hoffmann, Wagner-Meerwein, and (semi)pinacol reactions. Regioselectivity and stereoselectivity of those reactions
• Ionic fragmentation reactions: Grob and Favorskii reactions

Pericyclic reactions (6 lectures)
• Essential features of orbital overlap (Woodward-Hoffmann and Fukui analyses of orbital overlap)
• Sigmatropic rearrangements: 1,n-hydride and alkyl shift, [3.3] sigmatropic rearrangement
• Cycloaddition reactions: Diels-Alder [4+2] cycloaddition, 1,3-dipolar cycloadditions, [2+2] cycloadditions.
• Electrocyclic reactions for ring opening and ring closing.

Radical reactions (4 lectures)
Radical reactions follow different rules to those of ionic reactions. Bond strength is very important. Radicals can be formed with Br, Cl, Sn, and Hg. Ef&#x FB01;cient radical reactions are chain reactions. There are electrophilic and nucleophilic radicals. Radicals favour conjugate addition. Cyclization is easy with radical reactions. Dissolving metal reductions with metal-ammonia systems applied to aromatic systems (Birch reduction) and enones and their synthetic applications. Dissolving metal reductions applied to carbonyl groups - Pinacol coupling and acyloin condensation.

Organophosporous, organsulfur, and organoselenium chemistry (7 lectures)
Phosphorus: Wittig, Wittig-Horner and Wadsworth-Emmons reactions and their use in synthesis. Aza-Wittig reaction. Mitsunobu reaction, mechanism and applications.
Sulfur: Introduction to organosulfur compounds (oxidation states, names etc.). Synthesis and chemistry of sulfoxides, allylic sulfoxide-sulfenic ester rearrangement. Pummerer reaction, syn elimination of sulfoxides. Sulfones - Julia reaction, Ramberg Backlund reaction and extrusion of SO2 from sulfolenes. Chemistry of s ulfur ylids, Corey/Trost reagents.
Selenium: Comparison of sulfur and selenium compounds. Reactions of selenoxides, syn elimination and [2,3] sigmatropic rearrangements. Oxidation reactions of selenium dioxide. Selenium mediated cyclisation reactions (PhSeCl etc.).

Physical organic chemistry (11 lectures)
Equilibria, transition states and rates: Free energy diagrams, transition states, connection between equilibrium and rate constants, K = k1/k-1, Hammond’s postulate, thermodynamic vs kinetic control, Curtin-Hammett.
Kinetics: Revision of elementary kinetics, steady state for multistep reactions, primary deuterium kinetic isotope effect.
SN2, SN1: Mostly revision of year 2 material
Elimination reactions: Revision of E1, E2, E1cb, kinetics, mechanistic continuum
Addition reactions: Revision of HX, X2 additions with kinetics, some synthetic applications
Nucleophilic substitution at carbonyls: Tetrahedral interm ediates and mechanisms for ester hydrolysis.
The Hammett equation: Substituent constants, reaction constants, correlation of rates and equilibria, multistep reactions, physical basis of LFER.