Organic mechanisms and synthesis (CH2208)
This module aims to encompass the synthetic organic chemistry previously learnt by the student and apply it to the synthesis of more complex organic structures. It will explain some of the key features in designing organic syntheses and introduce the broad picture of how functional group reactivity and mechanistic understanding are pivotal to this area of science.
This module introduces ideas of retro-synthetic analysis and the disconnection approach to develop a better understanding of synthetic methods in organic synthesis. New transformations for the preparation of alkenes, alkynes, alcohols and carbonyl compounds will be discussed and these new techniques will be applied to understand the synthesis and properties of heterocyclic molecules. The module will consider specific reaction mechanisms involving carbonyls, the Wittig reaction, C-C and C=C bond formation and aldol condensation as well as basic heteroaromatic chemistry.
Revision of synthetic procedures previously met.
Methods in synthesis and retrosynthetic analysis :
Introduction to retrosynthetic analysis, including synthons and synthetic equivalents and the principles of the disconnection approach to complex organic target molecules. Umpolung. Common types of polar reactions used for carbon-carbon bond formation utilising carbonyl chemistry. This includes the aldol reaction, Claisen ester condensation, Dieckmann cyclisation, Michael reaction, Robinson annelation, Wittig reaction as well as cycloaddition, principally the Diels-Alder reaction. Carbon-carbon bond formation using organometallics (addition of Grignard reagents to carbonyls and epoxides), and using acetylene chemistry. Functional group interconversion.
Introduction to heteroaromatic chemistry :
Similarities in the chemistry of enol ethers, enamines, amides, thioamides and amidines, synthetic strategies for elaboration of 5-membered heteroaromatics. Extensions to the synthesis of simple azoles and 6-membered heteroaromatic systems. Methods for homologation of the parent heteroaromatics, by directed electrophilic substitution and metallation.
Practical work :
Preparation, characterisation, analysis of organic compounds, including :
Use of an inert gas atmosphere.
Distillation, (re)crystallisation, chromatography.
Safe handling of hazardous and toxic chemicals.