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IV (Advance Organic Synthesis and Supramolecular Chemistry and Carbocyclic Rings) Module No Know More Weblinks http://www.slideshare.net/dragnerkar/retrosynthesis-agn-compatibility-mode https://archive.uea.ac.uk/~c286/notes/retrosynthesis.htm https://en.wikipedia.org/wiki/Retrosynthetic_analysis http://science-blogs.ucoz.com/resources/notes/msc/theory/Retrosynth.pdf Suggested Readings Overview CHEMISTRY Paper No. 14: Organic Chemistry –IV (Advance Organic Synthesis and Supramolecular Chemistry and carbocyclic rings) Module No. 7: C-C Disconnections of carbonyl compounds – II Title Organic Synthesis: The Disconnection Approach Authors Stuart Warren, Paul Wyatt Edition 2 Publisher John Wiley & Sons, 2011 ISBN 1119965535, 9781119965534 Title March's Advanced Organic Chemistry: Reactions, Mechanisms, and Structure March's Advanced Organic Chemistry Author Michael B. Smith Edition 7, illustrated Publisher Wiley, 2013 ISBN 0470462590, 9780470462591 CHEMISTRY Paper No. 14: Organic Chemistry –IV (Advance Organic Synthesis and Supramolecular Chemistry and carbocyclic rings) Module No. 7: C-C Disconnections of carbonyl compounds – II Title The logic of chemical synthesis Author E.J. Corey Publisher Рипол Классик ISBN 5885010811, 9785885010818 Glossary B Brønsted-Lowry definition of acids and bases- the formation of conjugate acids and bases is central to the Brønsted-Lowry definition of acids and bases. D Dithiane chemistry- is a classic example of polarity inversion P Peroxy acid- (often spelled as one word, peroxyacid, and sometimes called peracid) is an acid which contains an acidic –OOH group. CHEMISTRY Paper No. 14: Organic Chemistry –IV (Advance Organic Synthesis and Supramolecular Chemistry and carbocyclic rings) Module No. 7: C-C Disconnections of carbonyl compounds – II R Retrosynthetic analysis- is a technique for solving problems in the planning of organic syntheses. This is achieved by transforming a target molecule into simpler precursor structures without assumptions regarding starting materials. Each precursor material is examined using the same method. S Synthons - a constituent part of a molecule to be synthesized which is regarded as the basis of a synthetic procedure. Time-Lines Timelines Image Description 1990A.D. Elias James Corey He won the Nobel Prize in Chemistry "for his development of the theory and methodology of organic synthesis specifically retrosynthetic analysis. The concept of umpolung was also introduced by E.J. Corey and D. Seeback. CHEMISTRY Paper No. 14: Organic Chemistry –IV (Advance Organic Synthesis and Supramolecular Chemistry and carbocyclic rings) Module No. 7: C-C Disconnections of carbonyl compounds – II History of umpolung Description Umpolung or polarity inversion in organic chemistry is the chemical modification of a functional group with the aim of the reversal of polarity of that group. This modification allows secondary reactions of this functional group that would otherwise not be possible. The concept was introduced by D. Seebach (hence the German word umpolung for reversed polarity) and E.J. Corey. Polarity analysis during retrosynthetic analysis tells a chemist when umpolung tactics are required to synthesize a target molecule. UMPOLUNG IN CARBONYL COMPOUNDS Dithiane chemistry is a classic example of polarity inversion. Ordinarily the oxygen atom in the carbonyl group is more electronegative than the carbon atom and therefore the carbonyl group reacts as an electrophile at carbon. This polarity can be reversed when the carbonyl group is converted into a dithiane or a thioacetal. In synthon terminology the ordinary carbonyl group is an acyl cation and the dithiane is a masked acyl anion. When the dithiane is derived from an aldehyde such as acetaldehyde the acyl proton can be abstracted by n-butyllithium in THF at low temperatures. The thus generated 2-lithio-1,3- dithiane reacts as a nucleophile in nucleophilic displacement with alkyl halides such as benzyl bromide, with other carbonyl compounds such as cyclohexanone or oxiranes such as phenyl-epoxyethane, shown below. After hydrolysis of the dithiane group the final reaction products are α-alkyl-ketones or α-hydroxy-ketones. A common reagent for dithiane hydrolysis is (bis(trifluoroacetoxy)iodo)benzene. CHEMISTRY Paper No. 14: Organic Chemistry –IV (Advance Organic Synthesis and Supramolecular Chemistry and carbocyclic rings) Module No. 7: C-C Disconnections of carbonyl compounds – II SOURCE- https://en.wikipedia.org/wiki/Umpolung#Carbonyl_umpolung_.2F_Anion_Relay_Chem istry CHEMISTRY Paper No. 14: Organic Chemistry –IV (Advance Organic Synthesis and Supramolecular Chemistry and carbocyclic rings) Module No. 7: C-C Disconnections of carbonyl compounds – II Research journals DESCRIPTION Enantioselective synthesis of epoxides and aziridines by asymmetric methylidene transfer from a sulfimide to carbonyl compounds and imines Charlotte P. Baird and Paul C. Taylor DOI: 10.1039/A805405C (Paper) Reference Section for: J. Chem. Soc., Perkin Trans. 1, 1998, 3399-3404 Source- http://pubs.rsc.org/en/content/articlehtml/1998/p1/a805405c CHEMISTRY Paper No. 14: Organic Chemistry –IV (Advance Organic Synthesis and Supramolecular Chemistry and carbocyclic rings) Module No. 7: C-C Disconnections of carbonyl compounds – II .
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