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 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. He won the Nobel Prize in Chemistry "for his development of the theory and methodology of organic synthesis specifically . 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 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 is more electronegative than the carbon atom and therefore the carbonyl group reacts as an at carbon. This polarity can be reversed when the carbonyl group is converted into a dithiane or a . In terminology the ordinary carbonyl group is an acyl cation and the dithiane is a masked acyl anion.

When the dithiane is derived from an such as 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 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 of the dithiane group the final reaction products are α-alkyl- 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 and by asymmetric methylidene transfer from a sulfimide to carbonyl compounds and

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